Nordhavn delivers an unusually complete fuel manifold with
far more flexibility than most production boats. In fact, the manifold is
sufficiently complex that some new owners can find it difficult. More than once,
I've heard of an owner accidentally closing the return path for the main engine
or generator, leading to fuel leaks or, worse, engine fuel pump failure.
Even with the unusual flexibility offered by the Nordhavn
fuel manifold, we found it didn't do some of the things we wanted it to be able
to do so we made fairly substantial fuel manifold modifications on Dirona. Some
of these modification were driven by us extending some of the applications of
the manifold and some were driven by us operating the fuel systems a bit
differently from some. Let's start first with how the standard manifold works,
look at the most common operating modes, and then at the manifold changes we
made and why.
Most Nordhavns come delivered with a separate day tank to
feed just the get-home (also called wing) engine. One of the most common causes
of diesel engine fault is dirty fuel, so having a separate fuel tank where no
fuel is even placed there unless first proven to be good via use for days in
the main engine adds considerable security. The wing engine has a separate,
known clean fuel in addition to its own mechanical control system,
transmission, prop shaft, and prop. It shares almost nothing with the main
engine, reducing the likelihood of a correlated main and wing failure.
In addition to the day tank feeding the wing engine, there
is a supply tank which feeds all other engines on the boat. The supply tank is
always the fuel source for the engine(s) and generator(s). There are also
multiple bulk storage tanks. On Dirona, we have two side tanks of 835 gallons
each, a supply tank of 65 gallons, and a day tank of 15 gallons. The day tank
feeds only the wing engine, and the supply tank feeds all others engines and
generators. The bulk tank contents are moved into the wing or supply tanks
prior to using the fuel.
The picture above shows the fuel transfer manifold on Dirona
when it was delivered in early 2010. It's similar in functionality and design
to the manifold delivered on most Nordhavns, although many have more tanks,
engines, and generators. The lower manifold is the transfer manifold and the
upper is the return manifold. All engines, except the wing, draw fuel from the
supply tank and return it to the return manifold. The fuel transfer pump sources
from the transfer manifold (the lower one). This transfer manifold selects
which tank the transfer pumps draws from. The return manifold gets the output
of the transfer pump and the return from all engines except the wing. It's this
manifold that sets which tank the return goes into. Understanding how the
systems are laid out, let's look at how they are typically used and why some of
our usage models are different and the design extensions we implemented to
support these other operating modes.
The most common operating mode for Nordhavns is to choose
one of the bulk fuel tanks to draw fuel from and to open the valve at the
bottom of that tank to gravity feed into the supply tank. The return manifold
is set to send return fuel back to the supply tank. Since the supply tank
bottom is below the bulk tank bottoms, the supply tank won't run out in this
mode. As the fuel draws down, the selected bulk tank gets lighter and the boat
will eventually start to list away from it. At that point, the gravity feed
from the first selected bulk tank is closed and another is opened on the other
side. This keeps the supply tank full and keeps the boat relatively well
To further improve the trim, some owners chose to have all
the bulk tank gravity lines open. This has the advantage of pulling them all
down equally but there are two downsides: 1) you might want to more more fuel
on one side to correct a list (perhaps the dinghy is down) and 2) having tanks
on both sides of the boat connected allows fuel to move side-to-side which
isn't ideal from a stability perspective. Consequently, I don't recommend
running with more than one of the gravity feed lines open at a time.
Another variant of the single-gravity-feed-at-a-time model
is to return fuel to the bulk tank that is currently gravity feeding into the
supply tank. The tanks will all run at the same levels in this mode of
operation, and it can allow cooler operation. Here's why. The bulk of the fuel
the engine draws from the supply tank is not consumed, but is used to cool the
injectors and other fuel parts and the warmer fuel is returned. If just the
supply tank fuel load is in circulation, that fuel will heat up. Whereas, if
the entire bulk tank and supply tank fuel load is in circulation, there is much
more fuel and much more fuel tank surface area to cool and the fuel will run
cooler. Modern engines measure fuel temperature and take into account changes
in temperature when computing the amount to inject, and cooler fuel does allow
just slightly more power. This mostly is irrelevant but just barely useful
enough that, if you do chose to gravity feed as most do, I recommend
transferring back to the bulk tank that is currently gravity feeding rather
than directly back to the supply.
We chose to not gravity feed to the supply tank even though,
as described above, this is an easy to manage and reliable way to operate the
fuel system, and it would keep the fuel cooler. Instead we chose to explicitly
pump fuel from the appropriate bulk tank to the supply tank every four hours rather
than gravity feed. This is a slightly more manual operating mode but has some
advantages that we really like. The first advantage is if there is a leak on
the engine, at the filters, or in any of the fuel lines, you can't possible
loose more than the volume of the supply tank. If you are gravity feeding, you
could lose the entire bulk fuel load and could end up out of fuel and risking
environmental damage via a large fuel spill. Avoiding this is important any
time but even more important when doing long ocean crossings sometimes more
than 1,000nm from the closest shore. Having no fuel when days from shore could
really be a disappointment.
The second advantage of the explicit fuel transfer system
is all fuel has to pass through the transfer filter before it gets to the
supply tank. Given the uncertainty of fuel quality world-wide, we really like a
layer of filtering prior to the fuel even getting to the supply tank. The
combination of keeping the bulk fuel locked up and safe from leaks and the
additional layer of filtering makes this operating mode important to us. It is
a bit more manual work but it feels worth it. This is the source of the first
fuel system modification we made. The standard fuel pump, a Walbro 6802, is
incredibly slow at 43 gallons per hour. In fact, so slow that this way of
operating the boat can be frustrating. So we replaced it with a Jabsco
VR050-1122 pump capable of 822 gallons per hour.
Like many modifications, when you make one change, it can
drive others. To accommodate the transfer rate of this pump, we needed to go
with a much larger transfer filter. We went with Racor FBO 10, pictured below, which is commonly
used in bulk transfer commercial fuel management applications. This filter has
the advantage of supporting large transfer rates but it also has large
filtration area so few filter changes are needed.
One of our goals is to be able draw fuel from the supply
tank and return it to the supply tank while polishing one of the bulk tanks.
The standard manifold design doesn't support this. The engine return goes to
whatever tank the transfer pump is returning into. Unless you are
gravity-feeding, polishing one of the bulk tanks while underway has the
downside of the supply tank being completely pumped out every 30 to 60 minutes
and runs the risk of running the main engine out of fuel. So we made manifold
changes to support what we wanted.
Dirona's manifold pictured at the top of this post supports many extension
from standard. The first to address the issue we just brought up. If you look
closely you'll see that we can polish fuel from a bulk tank back to the same
bulk tank but still direct the main engine fuel return to the supply tank.
There is a bypass that runs between the engine return and the supply tank fill
that allow the main engine to return fuel to the supply tank while still being
able to polish fuel in any other tank. This bypass hose can be seen running
through a valve on the right side of the manifold.
Another addition we made to the manifold is provision to
drain pump out of the supply tank. We have added a hose from the bottom of the
supply tank into the transfer manifold allow the supply tank to be polished if
a fuel problem is encountered. It also allows the supply tank to be pumped out
if there is a need to service it or some of the fuel lines in that area.
Because we can pump out the supply tank, and the supply tank is below the wing
tank, we can actually pump out the wing tank as well by first pumping the
supply tank level to below the bottom of the wing tank and then opening the
wing and supply return manifold valves and allowing the wing tank to drain down
into the supply tank. We think it is super important to be able to pump out,
service, or re-filter the fuel in any tank and especially the wing and supply
tanks. These changes allow the supply tank to be directly polished underway and
supports draining the wing and supply tanks if needed.
The next extension is to allow Dirona to carry more fuel in
those rare times when greater range or higher speed over long distances are
needed. Dirona as delivered is capable of around a 2,400nm range and this is
more than enough for 99% of all she will ever do. However, there are times when
very long crossings are planned or when we want to run faster on a passage that
is within range. The nicest solution is to put more tankage on Dirona but it's
impractical to install more and it's probably not worth the space compromise
that has to be paid every day for the entire life of the boat just to get more
range or speed on a long crossing. You may only need this greater range every
few years and yet more tankage take up more space all the time. Our solution is
to run on-deck fuel tanks
when we do want to run more or ran faster. This is more of a hassle but, since
the extra fuel is rarely needed, it feels like a better answer on a small boat
than giving up more space inside the boat. Our longest run has been 2,600nm ,
and having more fuel made this much more practical. But, in five years, we have
only needed this additional capacity once and only used it twice. On-deck fuel
bladders are a good compromise when you don't want to give up more space and
very rarely need more fuel.
To make the bladders easier to manage, we have a bulkhead
fuel fitting in the cockpit plumbed into the fuel manifold at bottom left (and pictured above). When
we install the bladders, we install a short length of fuel hose between the
bladders and the bulkhead fitting using cam lock snap fittings. This allows us
to drain the bladders without going on deck and without having the fuel intakes
open to potential water ingress. When we are ready to draw them down, we just
turn on the fuel transfer pump, select the tank we want to pump into, and the transfer
pump quickly does the work. This has the added advantage of putting all bladder
fuel through a filtration phase before bringing it into the fuel tanks.
We've mostly gotten good fuel, but there have been a couple of
times over the last fifteen years when we've bought some expensive water, or
picked up some fuel with lots of foreign matter. We buy fuel all over the world
and the good news is that bad few is fairly rare. But it does happen. Our
defense against it is mass filtration with lots of spare filters. The way we
use the boat, fuel will be filtered at least four times before reaching the
engine injection pump: 1) through the transfer filter to the supply tanks, 2)
through the primary filters to the main engine, 3) through the first on-engine
filter, and 4) through the final on-engine filter. We have a lot of filter
spares on board, with more than 40 of our primary filters stored away. If we
get bad fuel, we probably have the filtration to be able to manage the problem.
The final issue is complexity and human error. Nordhavns
have very flexible fuel transfer systems but with flexibility comes some
complexity. On Dirona, we have extended the design but, with those extensions
comes some additional complexity. It's hard to avoid. And where there is
complexity and potential tired boat operators, mistakes can happen. The most
common mistake is to close an engine return valve or close the return manifold
tank connection. This causes the running engines to not be able to return,
which will very quickly lead to leak or pump failures. You can disable an
engine quickly this way. Another mistake is to accidentally pump fuel
We battle complexity and potential error every way we can
think of, including posting the fuel transfer diagram at the manifold and
having all valves brightly and clearly labeled. We have also calibrated the
sight gauges in our all our tanks and installed redundant digital tank level
monitors. We have installed a digital fuel transfer timer and both calibrated
it and labeled it for the number of gallons transferred per minute. So, if you
are moving 17 gallons, you can see exactly how many minutes of transfer time is
needed, substantially driving down the risk of mistake. But it is still possible.
To catch mistakes in either direction, we also have digital level indicators on
all tanks, a high-level alarm on the supply tank, and low level alarms on the
wing and supply tanks.
Finally we label all fuel transfer valves as normally off or
normally on to make it clear where they should be in normal operating mode.
But, even this isn't enough. In a storm with only two people on the boat, there
is a risk of getting tired. And, if there is a fault at the same time, mistakes
get harder to avoid. So, we tie-tag all valves open that need to be open to
avoid the blocked return problem described above. The only way to close a valve
that could hurt an engine is to go and get wire cutters and cut the tie tag
All these design changes give Dirona a flexible system that
can polish fuel while operating at sea, can't lose all the fuel in a fault,
supports easy service, and helps manage human error while still offering a
fairly flexible system.
One of our
eight Lifeline AGM GPL-8DL batteries recently went into
thermal runaway, and we've had
a few questions on the nature of the problem and why we chose to replace the
full house battery bank.
The lazarette smoke/CO alarm had gone off at 3am, and upon investigating we found a rotten egg smell
(hydrogen gas) and a lot of heat in the lazarette, with water dripping from the ceiling. We dug around a bit more and found two batteries
were at 170F on the outside of the case, and probably well over 300F inside. A normal battery temperature on our boat is around 80F. Two of the
batteries were boiling their electrolytes out--one of our eight batteries had gone into thermal runaway and taken its pair with it.
A nice Nordhavn design feature is to have battery isolation switches for every pair of batteries. We can turn a switch
to isolate the failed pair, and the boat continues to operate fine, just with less
house battery capacity. That night, we turned off battery pair #3,
the batteries were cooling, and went back to bed. The following morning they were still
at 131F. One question sent to us was what if that had happened at sea? We would
probably have seen it sooner with more frequent engine room and lazarette
checks, but otherwise there would be no difference: we'd just turn off the
battery pair isolation switch.
All our chargers are multi-step smart chargers. They go
through three phases: 1) bulk charge where current is as high as can be
delivered and the voltage rises as charge goes up until it hits a max of 28.6V,
2) absorption where the voltage is held constant at 28.6V and current drops as
the battery gets more full, and 3) float where the voltage is maintained at
26.6V. These voltages are assuming 77F batteries.
The battery problem occurred while on float charge.
Thermal runaway can occur in most battery types including flooded lead acid, valve regulated lead acid, and even non-lead/acid designs such as Lithium-Ion. The general condition is when increased temperature cause more energy to be released which yields yet more temperature and a feedback loop develops. In flooded lead acid batteries, this can be caused by plate warping or plate material sulfating, and sloughing off to the bottom of the battery. The warpage or sloughed off plate material can cause a plate-to-plate connection, which generates heat, which leads to more warpage, more current, and more heat. Absorbed Glass Matt
(AGM) batteries like our Lifelines are not prone to plate shorting from sloughed off plate material, and plate warpage causing shorts is not a common fault, but they still can suffer from thermal runaway. Fortunately, it’s not a very common failure mode. Usually batteries just get old, lose capacity, and quietly fade away. But, thermal runaway does happen and, when it does, the energy released is somewhere between amazing and scary.
Dirona's Lifeline AGM batteries are rated for 1,100 cycles down to no
less than 50% charge. They have seen far more than that, so we were getting
close to replacement time anyway. We could just change the two damaged batteries
since the rest continue to operate fine. But, with the use they have had, the
bank was due for replacement some time back. We expected that we'd need to
change them in Hawaii, but they tested fine at that time
Midtronics MIDMDX-640 Digital Battery Analyzer).
We now need eight Lifeline GPL-8DL batteries that list for a booming $8,264.
And they are 156 lbs each, which each means we'll be changing a half ton of
With one string of two batteries disabled, we are down to 75% capacity but otherwise there is no change.
So fortunately we don't need to be in a rush to replace them.
Most autopilots have NAV mode, which essentially asks the pilot to steer to a plotted route rather than just in a specific direction.
It's particularly useful in cross-currents and strong winds, or when travelling longer distances.
NAV mode has not worked on our system since day one, and now that we're doing longer trips it would be quite useful.
We've been wrestling with this for about a month, where the pilot is getting all the data it needs to properly execute NAV mode (pictured above),
but reports an error.
On advice from Furuno, we redundantly sent navigation data from the Furuno NavNet 3D Black Box to the autopilot.
In the picture below, you can see the jumper cables while we were testing this temporarily.
Presumably the pilot is looking for some proprietary Furuno data that wasn't being sent through the normal path.
It works great now, so we wired it in permanently. An added advantage of what we've done is the autopilot now gets all
the rest of the navigation data redundantly, so a system fault is less likely to affect the autopilot.
Steering is a great area to be picky about in overall mechanical system health. About three months back, we noticed a tiny amount of play at the spherical bearing that forms part of the rod end where the steering cylinder connects to the rudder. The play was minor, but spherical bearings should exhibit close to no detectable free play.
Replacing the rod end is actually a fairly easy task, and we have the spare. So, we put it on the list to be changed before the offshore run to New Zealand. That 1,100 nm stretch of water isn't that long, but many boats have been lost there over the years, so it's worth being careful. Over the last few hundred hours, we noticed the bearing has loosened up considerably more and the play was quite noticeable. Since we had a spare hour, we figured we would just get it changed.
The job is super-easy: the cotter pin holding the rod end to the rudder yoke is first removed, then the large stainless nut and bolt can be removed. Then the large lock nut on the ram can be backed off the rod end unscrewed. It's about thirty minutes worth of work.
Once the rod end was disconnected, we noticed that the bushing in the other end of the steering cylinder was seized so we took off the other end to investigate. We found the bushing was actually heavily worn. Arguably this wear is a bit early at 3,400 hours, but we've seen a fair amount of rough water in the Alaska area. A day and a half in 40 kts of wind, 150 nm offshore in the Gulf of Alaska comes to mind as the most memorable.
Because the inner bearing is integral with the steering cylinder, replacing it requires replacing the entire cylinder. This is unfortunate for two reasons: 1) cylinders are notorious fluid leaders and we are lucky to have one that has never leaked a drop -- we hate to replace a cylinder in such good shape, and 2) during new boat commissioning, the cylinder was replaced due to, you guessed it, leaking and it took three tries and more than a day of labor with two technicians to get it properly bled. We hated changing a non-leaking cylinder since the new one may leak. And we really hated the prospect of bleeding the system, especially at anchor, since we can't move until we get it right.
Changing the cylinder itself was easy. Except for bleeding, the entire job was fully done and everything cleaned up in under an hour. Then we went after bleeding it. Our first attempt was to pour steering fluid into a plastic container and insert plastic extension hoses on each bleed screw (see pictures below). Then we cranked the wheel back and forth, pumping out the air and pulling in new fluid. This was working pretty well, but wasn't all that fast.
As we bled the system using this technique, the fluid reservoir was getting low so we took off the fill port seal and topped it off. While doing that, we noticed the fluid level was going down fairly fast when the fill port plug was removed. It turns out that if you leave the bleeders open down below and remove the fill port plug, the weight of the hydraulic fluid slowly pushes fluid out of the two cylinder bleeder ports. This is actually a fairly useful discovery. We let that process continue and then took the fluid that had come out below and used it to top off the reservoir, and repeated the process. This bled the system in minutes. We then closed everything off and tested it. The steering had exactly the right number of turns lock-to-lock and was rock solid when it hit the travel limiters, confirming that it was fully bled. And the autopilot pumps are all working correctly.
The only issue we found with this five-minute bleeding process is that it doesn't bleed the upper helm pump, since the pump is above the reservoir. This is an unfortunate design, but unavoidable, in that here is no higher point in the house or flybridge area for the reservoir. We managed to find a quick solution for this one as well. We opened the fill port in the upper helm pump, pushed in a funnel, and filled the funnel to near the top. Then we spun the upper helm wheel, keeping the funnel filled, which keeps it from sucking air but still allows excess air to escape. We also opened the bleed port in the steering manifold. This valve is normally closed but can be opened to bleed the upper helm pump. Again, the wheel was spun in both directions and then everything was closed off. We retested everything and it was all good.
The final test is if the upper helm pump collects more air during operation--the cause of all the repeat bleeding attempts during new boat commissioning. We'll keep an eye on it, but it's been quite a few hours and all is rock solid, so we're pretty sure this one is done. It's nice to have a brand new steering ram on Dirona for the crossing to New Zealand and also the one later this week to Vanuatu. And, it's good to have systems for bleeding the steering in minutes instead of hours to days.
A recent question on Bayliner 4087 fuel consumption:
We are currently in negotiations to purchase a Bayliner 4087, 2001 model with 330 Cummins Engines. Can you set my expectations for fuel burn?
Second question, we have just sold our Grand Banks 32 for a faster boat. However, much of the time I do anticipate cruising in the 8- to 10-knot range. Will the Bayliner do that efficiently? I expect that it will run fine at those speeds, but with some hulls that are semi planning such as the 4087's, it may not be that comfortable.
Our 4087 is heavier than most at 29,000 pounds, so our fuel efficiency and speed numbers will be slightly lower than some. Wide open, the Cummins 270s will burn 29 GPH. The engines will not live long at that throttle position though. We run our boat very conservatively to get good engine longevity. We chose to use two basic speeds: 7.75 knots and around 13 or 14 knots. At 13 to 14 knots we burn 15 to 17 GPH. It takes roughly 320 HP to maintain that speed in our boat. You may chose to run faster than we do – most do – and, if you do, your burn rate will be higher.
At displacement speeds, you basically just pay for moving the displacement of the boat. The hull shape matters a bit but it's mostly just weight. At 7.5 to 7.75 knots, you'll burn under 3 GPH (right around 2.5GPH). We've lasted as much as 73 hours on a single fuel load (220 gallons) at those speeds and still had more than a quarter tank remaining. Because the Bayliner is lighter than your Grand Banks at displacement speeds, it'll consume less fuel down there.
For comfort at low speed, the boat does wander a bit and doesn't really like an aft quartering sea, but I just put it on autopilot and let the autopilot deal with it. It doesn't bother me a bit.
Some time back I came across a query on whether synthetic oil could be safely used in marine diesels. My response:
Most manufacturers permit the use of synthetics, but don't allow longer oil change intervals when employing them. The question I've always had is whether the gain is worth the cost. Some of the advantages of synthetics that spring to mind are 1) better performance at temperature extremes, and 2) slightly lower engine internal friction. In the past, when racing cars, we used synthetic engine oil at times on the premise that synthetics would provide adequate lubrication for very high load applications using lower viscosity oil. We were after the slight increase in usable horsepower provided by the small decrease in internal engine resistance obtained using a thinner oil. I believe this is likely measurable, but I don’t know if it’s really significant. I somewhat suspect that it’s close to an irrelevant gain but, when racing, we would take every trick we could get even if the gains were slight. I feel less inclined with recreational marine diesels and there is no way I would recommend using a lower viscosity oil than specified by the manufacturer, whether synthetic or not.
On the temperature extreme front, we felt that synthetics would allow us to operate the race engine longer before catastrophic failure when an engine was failing with low oil pressure or overheating. We might be able to get a lap or two more before it completely stopped operating. Overheating a diesel is close to the worse thing you can do, so the ability to operate somewhat longer under these conditions is not something I’m willing to pay all that much for. However, if you live in the arctic, the ability to start easily and get better lubrication faster on extreme low temp start-up could easily be worth the additional investment of synthetic engine oils.
When I was working as an auto mechanic in the early days of synthetics, I saw many instances of moving to a synthetic in an automotive engine causing much more oil leaking. Nothing catastrophic, but noticeably more leaks were common. It seemed that those that didn’t leak before changing didn’t leak after. But, those that did leak, would leak more after the change.
Like all things in engineering, it’s a cost/benefit trade-off. For me, the additional cost isn’t justified in my usage, but I know it works well for many. We’re still using dino oil in Dirona. I changed the oil this weekend, warmed it up, and checked levels as usual. The oil hardly showed any color (see below) -- just what we like to see. Whatever oil you chose, change frequently.
Some time back I got a question from an owner of a larger Bayliner concerned that he wasn’t running his engines hard enough and that, as a consequence, they may not last as long. The advice he’d been given was that diesel engines need to run wide open for at least one hour in 10. In this case the comment was attributed to a professional service technician, but it’s not the first time I’ve heard it. I just shake my head when I hear these things. That's dangerous advice to be giving customers. It's 100% true that diesels hate running cold. If the engine isn't up to full operating temperature on each run, it is hard on them. No debating that point. But, wide open for 1 hour in 10 is a great way to get short life with the high-output, recreationally-rated diesel engines typically found in planing powerboats such as the Bayliner in question. Running low horsepower density, continuous duty rated engines at wide open is, of course, fine. But you’ll not find these engines in planing power boats.
Remember the height of the muscle care era of the 60’s and 70’s. The highest HP Corvette of 1970 put out roughly 1 HP/CID (cubic inch displacement). The B-series Cummins at 480HP is way beyond that 1 HP/CID mark – these are very high performance engines. These are not the huge, low stress, continuous-duty diesels that developed the deserved reputation for running “forever”. Modern recreationally rated (non-continuous duty) diesels are high performance engines and need to be treated with considerable care. Specifically, running at WOT for anything other than short duration is asking a lot and, if maintenance and propping is not perfect, short life result.
Our engines haven’t ever run at 100% throttle for more than 30 to 60 seconds at a time. I do this once every 6 months to check to see that they are operating correctly and can reach rated RPM +50 or more at full throttle in a fully loaded boat. If you can’t do this, your engines are over-loaded (see: Diesel Engine Overload) or suffering from a mechanical problem that needs attention. I’ve seen $50k destroyed in a few hundred hours via the combination of overload and running hard. See the pictures below sent to me from someone who had just read the Diesel Engine Overload article saying “I only wish I knew earlier.”
It’s one the leading destroyers of recreational marine engines. People buy a new boat and over time more and more “stuff” ends up on board and the bottom paint picks up minor growth. More often than not, a year later the boat becomes over-propped from these factors and, as a consequence, the engines are overloaded. Most owners think they can run at “200 RPM off the top”. They do so without worry, but wonder why they are smoking badly and sooting the transom heavily. If they are lucky, someone helps them. If not, another pair of engines won’t likely reach 1,000 hours without major service.
It’s worth mentioning that just about every larger Bayliner (and Meridian) is propped near the limit for a lightly loaded boat. If you have a Bayliner and haven’t taken 1” of pitch out from the factory configuration, you are probably over-propped. Some, including ours, needed 2” of pitch removed to get rated RPM+50 at WOT with a fully laden boat.
Back to the advice of running one hour in ten at wide open throttle. You’ll hear folks warning you that you need to run 75% load or better, or that you need to run 1 hour in 10 at max. The former is absolutely fine for a healthy engine, although unnecessary, and the later is a recipe for short engine life. You absolutely do need to ensure that the engines reaches full operating temp on every run and that is the intent of the 75% rule. By full operating temp, I don’t just mean that the coolant got to full temperature. You need the oil hot as well and you won’t get this idling at the dock. You can only get the oil hot when under load but, trust me, any of the larger Bayliners are under plenty of load well before 75% of WOT.
We chose to cruise Dirona’s engines at 150HP which is only 55% of rated output (Cummins 270Bs) and we often operate them for weeks at a time never over 30 HP (7.5 kts) when exploring new areas. This means that for weeks at a time, they never go beyond 10% of rated load but, at this load both oil and water are get hot, which is the important factor. You will hear terrible horror stories about how dangerous light load is to diesels but, as long as the engine is at full operating temperature and sees varying load conditions, this simply isn’t a problem. Dirona’s engines have well over 3,600 hours on them and we load forward to thousands more.
If you want to play it safe, run conservatively as we do and get the 5,000++ hours you deserve. There is no guarantee, a part failure can still get you but the odds are much better if you run conservatively. If you really feel need to run close to the HP limit, get proper instrumentation, especially pyrometers, and keep a very close eye on the engine operating conditions and maintenance. Under these high load conditions you have a much higher chance of early failure as there is no headroom at this load. For example, check out this thermostat failure: Cummins 270B Thermostat Failure. If we were running at very high loads when this happened, this small part failure could have overheated the engines perhaps before we noticed. At high load, you need to have perfect maintenance, great instrumentation and be very vigilant to any changes in engine health. No matter what you chose to do, make sure you can reach at least 50 RPM over rated (see the diesel overload article referenced above). If you are overloaded, backing off a few hundred RPM won’t protect you from catastrophic failure.
My view is that we need to prop correctly (no overload), get to full operating temp, run conservatively, and enjoy our engines for years. Running high output recreational rated diesels wide open for 1 hour in 10 is just plain bad advice.
I recently had a question on how to eliminate diesel-engine sooting at the transom. It’s an interesting topic because almost everyone is convinced they have a solution. These solutions run from expensive diesel fuel additives to passing the diesel through permanent magnets on the way to the engines.
Overall, I’m pretty resistant to paying $300 for a simple permanent magnet even if it is packaged in a nice machined aluminum case. I’m a believer in simple systems and solutions. Generally, my preference is to start with looking at why the engine is smoking in the first place. One common cause of excess sooting in marine environments is engine overload. Boat builders specify props that allow the boat to produce the best speed possible when new and lightly loaded, and the engine manufacturer will ensure that configuration doesn’t overload the engine. But, as boats get older, more equipment is brought on board and boats typically get heavier. Dirona is perhaps an extreme example, but it makes the point clearly. Bayliner advertised the 4087 at 24,000 lbs and when it was last pulled out of the water, it was over 29,000 lbs. For those whose boat manufacturer props for maximum speed, problems can develop as the boat gets older, the tanks are filled, and the bottom becomes less than perfectly clean. The boat ends up dangerously over-propped and the engines will be overloaded under many conditions. Again, using Dirona as an example, Bayliner shipped the boat with 22x21x4 props. We’ve reduced pitch twice since it was new in 2000 and are now using 22X19X4 (see Avoiding Diesel Engine Overload for more details on how to know if you are correctly pitched).
When diesel engines are overloaded, they emit large amounts of soot. Black clouds aft are a sure sign that something is wrong and needs quick attention. I took the picture on the right back in 2004 at the end of the Memorial Day weekend. We were part of the usual stampede back to the Seattle area from the San Juan Islands, and I was amazed at how much smoke many of the boats were producing. The boat pictured below is a Bayliner 4788 and its engine is seriously overloaded. The best thing the owner of that boat could do is remove 2” to 3” of propeller pitch. If they did that, they would find they spent less time cleaning soot off the back of the boat and the engines would be under considerably less stress. Our Bayliner 4087 produces no visible smoke when under power and its engines will likely last much longer than the engines powering the boat in the picture.
Check to see if you are over-propped. It’s surprisingly common and, if you are, reducing pitch is easy and cheap, will reduce or eliminate transom soot, and your engines will have a much better chance to living a long and healthy life. It’s nice not having to clean the transom at each stop and potential longer engine life is an additional benefit that is hard not to like. Dirona’s engines have just crossed over 3,600 hours and we’re hoping for many more smoke and trouble free hours in the years to come.
The only thing worse than no backups is restoring bad backups. A database guy should get these things right. But, I didn’t, and earlier today I made some major site-wide changes and, as a side effect, this blog was restored to December 4th, 2007. I’m working on recovering the content and will come up with something over the next 24 hours. However it’s very likely that comments between Dec 4th and earlier today will be lost. My apologies.
Update 2008.04.13: I was able to restore all content other than comments between 12/4/2007 and yesterday morning. All else is fine. I'm sorry about the RSS noise during the restore and for the lost comments. The backup/restore procedure problem is resolved. Please report any broken links or lingering issues. Thanks,
James Hamilton, Windows Live Platform Services
Bldg RedW-D/2072, One Microsoft Way, Redmond, Washington, 98052
W:+1(425)703-9972 | C:+1(206)910-4692 | H:+1(206)201-1859 | JamesRH@microsoft.com
H:mvdirona.com | W:research.microsoft.com/~jamesrh | blog:http://perspectives.mvdirona.com
A recent question:
I am just learning about these pumps and at 1000 hrs on 330B, my starboard raw water pump began leaking at a rate to great to ignore. So after plunking down over $1600 with California’s 8.75% sales tax for two, if one’s bad the other must be near death right? However after reading your article (Changing the Raw Water Pump), maybe not. I thought I’d read up on replacement. Would you return these and get the Seamax pumps? Do you know if anybody has any real time using the Seamax 1730X? What do think? 1000hrs isn’t horrible mostly in salt water. My big-block in the last boat needed valves at 1600hrs. I agree that Cummins makes a great engine. In case tractors the Cummins engine is good for at least 8000hrs.
I had spare Sherwood pumps kicking around when the Seamax was first released. I considered returning or selling the spare Sherwoods, but decided it wasn't worth the hassle. When I do install them, I'll replace them with Seamax. I've just heard too many good things about them.
I'm actually getting respectable pump life out of the Sherwoods these days. I still favor Seamax based upon what I’ve been hearing, but my Sherwoods have been doing fine lately.
The only reason I would return your pumps is the price. $1600 is way high. You can get them, or the Seamax pump, for much less. Personally, I would lean towards returning them.
I recently came across a posting that is a good reminder for all of us. It was a standard 30-amp shore power cord. On the outside, there was slight evidence of heat. Upon taking the plug apart, it’s completely melted. It’s not my picture so I’ll not post it here but you can see it at: http://www.baylinerownersclub.org/forum/showthread.php?t=13761. Also on that thread is a posting by a Harbormaster showing one that completely failed and burned.
When flowing through a corroded connection, even considerably less than 30 amps will produce a dangerous amount of heat. Corrosion brings resistance and resistance brings heat. One good technique to efficiently chase these problems down is to use a small infrared heat sensor. When you are running an electrical load, check for warming at the connectors and in the wiring within the boat to the main breaker panel. A good electrical load is an electric space heater. Where there is heat there is resistance, and you want to catch it before it becomes a fire risk.
I use a Fluke 561, pictured below. This one runs around $150, but I’ve seen IR temperature sensors as low as $35. And, of course, you can feel for warmth as well. I use the IR temp sensor for so many different purposes that I wouldn’t dream of doing without it at this point.
Check out the pictures referenced above and remember to check your cables and connections a couple of times a year. Replace them when there is any evidence of corrosion, browning, or heat.
James Hamilton, firstname.lastname@example.org
When we’re cruising farther from home, we typically move the boat each day. The engines are run enough to charge the house batteries fully, and power is never a problem. But when out on the weekends, we often work and don’t move the boat as much, if at all. Usually we have several computers running and, in the winter, the lights and furnace are on much of the time, so we consume considerable power. In a recent Pacific Yachting article, Portable Power, we wrote about using a portable generator to recharge at anchor. And in a recent PassageMaker article, In Pursuit of a Perfect Charging System, we described how to configure and tune the main engine charging system to get the most from it. However, there are times when we simply need more house battery capacity than is available, and fixing that was last weekend’s project.
For start batteries, our boat came with one 8D for each engine. These seem like overkill for engine start banks, but Cummins uses engine intake air heaters to improve starting and reduce exhaust smoke when cold. The air heaters draw over 110A when operating, which is more than the alternators produce, so large start batteries are a requirement in this configuration.
For a house battery bank, we use golf cart batteries and argue that they are the best value available. Golf cart batteries are sold in enormous quantity for commercial applications and consequently, they are inexpensive. At 66 lbs each, they are much easier to manage than the 8Ds, which are just over 140 lbs each. The only downside to golf cart batteries is that they need to be topped off every couple of months depending upon your usage patterns and charging rates. If you don’t mind adding water, it’s hard to find better value than the golf carts batteries.
The challenge we face with Dirona is that we have already placed house batteries in all the easy places. We have four golf cart batteries between the engines and four more on the starboard side between the engine and the hot water heater. All are easy to see, easy to service and don’t block access to other equipment. The challenge was to figure out how to add two more golf cart batteries to our house bank without resorting to hand-fabricated battery boxes or operating without boxes. Since golf cart batteries are six volts each, they are typically added in pairs connected in series to yield a 12-volt pair or quads to get 24 volts depending upon your house voltage level. As a consequence, most battery boxes house pairs of golf cart batteries and there simply is nowhere left in Dirona for another pair of golf cart batteries side-by-side where they would still available for service and excessively long cabling isn’t required.
I did find a wonderful location from a servicing perspective behind the starboard engine. The steps running from the salon to the aft stateroom are directly above this location and, in a Bayliner 4087, these steps are removable as a unit offering access to the starboard transmission and potentially for easy servicing of these batteries. However, two golf cart batteries will not fit side-by-side in this location. There is room for two batteries end-to-end, but a ½” hull stiffening member crosses through the middle. Allied Battery produces a twin golf cart battery box where the batteries fit end-to-end, http://www.alliedbattery.com/boxes.htm, which is worth keeping in mind for future projects. But we really needed individual boxes and they couldn’t be much bigger than a golf cart battery. We found the perfect unit: Single golf cart battery box. These Noco HM306 boxes fit perfectly and, as an added bonus, the price (and service) from J.C. Whitney was excellent at only $8.99. We almost overlooked this box because the exterior dimension was listed at 10 1/8”. This however is the width at the widest point, the lid. The width at the base is less than 8 inches.
The final solution is neat and tidy and adds 25% more capacity to our existing house battery bank. We now have 1,125 Ah of house battery bank capacity. It’s great waking up in the morning with more than a 60% charge instead of less than 50%.
I got a question earlier this year that essentially asked: I can’t quite reach full rated RPM under load but I’m only 50 to 100 RPM low in my Bayliner 4788. I’m considering playing it safe and repitching my props but my dealer recommends that I not bother until next season. Is it OK to wait until next year since I’m close to correct and don’t run the boat hard for long periods of time?
When giving other people advice, I'm conservative. Having spent 6 or 7 years servicing cars professionally, I know just how upset a customer can get when you say "it'll be OK” and it ends up not being. The safe answer is to remove 1" of pitch.
However, you aren't nearly in as bad shape as many 4788s. Since you clearly care and have a good strong set of engines to start with, invest up front in great instrumentation. Buy boost gauges, pyrometers, and digital tachs. Boost gauges and pyrometers provide valuable engine load information to help avoid overload (http://www.mvdirona.com/TechnicalArticles/DieselEngineOverload/Default.htm). The standard Faria tachs tell you when the engines are running but not much more—get good digital tachometers (http://www.mvdirona.com/TechnicalArticles/DigitalTachometer.htm). Also get the fuel curves for your engine from the local distributor or the Cummins marine support team (email@example.com). From the fuel curves sheet you'll see exhaust gas temp at full rated RPM. It'll be around 850F. My general rule is to not cross that line although many argue this is unnecessarily conservative. Some engines have acceptable load levels that produce exhaust temperatures above those at rated RPM. I chose to avoid this condition entirely.
The right answer is to do both: 1) get the instruments I recommend above and 2) re-pitch right away. However, if you are careful, don't run hard, and watch the instruments, you'll probably be fine running with the current pitch. The pyro's will tell you for sure.
I needed to take out a second inch of pitch in mine, but since I'm both careful and cheap, I didn't want to re-pitch the second time right away. Instead I did three things: 1) ran light at lower RPM, 2) watched the pyros and didn’t ever go over the max rated temp (I prefer it 50F under), and 3) read the fuel burn. From fuel burn you'll know the HP you’re consuming at cruise. With your engines, multiply gallons/hour/engine * 19 and you'll find how much HP you’re asking for at cruise. The constant 19 is the horsepower produced per gallon per hour and it’s very constant across all high speed diesels. Newer common rail engines are closer to 20 HP/gal/hour but these numbers are remarkably stable across all manufacturers. I was introduced to this approach by Tony Athens (http://www.sbmar.com/Articles.cfm). Ensuring the HP you are using is always less than the manufacturer performance curves at that RPM will ensure that you are not overloaded.
In your case, I lean slightly towards re-pitch now. That way you can get to know the boat with everything running correctly.
I get the odd query, and this one is perhaps of broader interest.
Gerald Albertson wrote:
Hi James and Jennifer,
I absolutely love your pics, especially Desolation Sound at Christmastime.
It is a fine goal that I obtain the proper skills and confidence to do an Around-Vancouver Island adventure one day.
One of the next additions that I plan on making is the digital tachs that you describe.
My 34 Tollycraft has 210 hp 5.9 Cummins diesels of late 1988 manufacture….turbocharged but not aftercooled.
My neighbor has a 37 Nordic Tug that has a Cummins diesel (approx 350 hp) and it came with a block heater. I think his is a simple headbolt heater as opposed to a tank heater, but I’m not sure about that.
Anyway, I thought the block heaters might be a nice addition to my boat. What do you think?
We don't chose to use block heaters on Dirona but they are a good option to increase engine longevity (cold start with cold oil is hard on them) and to warm the engines and engine rooms (decreases condensation and reduces rust). Mechanically injected engines such as ours tend to smoke a bit when cold, and a block heater can reduce cold start smoke markedly.
Cummins sells core plug block heaters. These are installed by removing an engine block core plug and inserting a block heater to take its place. They heat the coolant and it circulates by convection.
Another solution I've seen is a pump and heater in the coolant. A variant of that used in over-the-road applications uses a diesel furnace to heat coolant (and heat the cab) when the engine isn't running. This allows the cab heater to function when the engine isn't running, and warms the engines.
A common installation I've heard used successfully in Cummins marine applications is Wolverine oil pan heaters: http://www.wolverineheater.com/. They are used by Seaboard Marine extensively on Cummins with good success: http://www.sbmar.com/. They sell at reasonable prices and can offer wattage advice for your conditions.
Diesel engines have a great reputation for incredible longevity, yet most recreational marine diesels fail well before they should. The two primary killers are 1) overload (discussed at Diesel Engine Overload and Tony Athens’ Engine Life vs. Engine Loading) and 2) poor maintenance & operating conditions. Both are easy to avoid with a bit of knowledge, particularly overload.
On the second big killer, poor maintenance and operating conditions, it’s clear that a high quality scheduled maintenance program is a good investment. Beyond that I’ve adopted two simple techniques that have really paid off for me: 1) spend a bit of time with the engines, and 2) know your specific engine’s weaknesses and failure modes.
For the first one, just spend time in the engine room. If you know what it should smell like down there, what sounds are normal, and you frequently visually inspect, it’s amazing what you will find before it becomes a dangerous problem. From spending just 30 seconds in the engine room each day, I’ve found a variety of problems that could have become more serious. For example, the support bracket for the engine-coolant header tank broke once. At that point, the header tank was hanging from the hoses. If the hoses break or abrade, there is a good chance the engines will overheat, one of the quickest ways to shorten diesel engine life. Spotting this early means it’s a complete non-issue. In another engine room sniff, I smelled diesel. It never smells like diesel down there, so I looked more closely and found a fuel-tank vent-hose clamp had rusted through. If you keep the engine room clean and well lit, any leak from any component can be seen quickly. I’ve had several raw water pump failures, each of which was proceeded with a raw water leak at the pump seal (Changing the Raw Water Pump). Catching these problems early keeps the engines safe.
The second of my two simple techniques is to know your engines and their failure modes. This one also is incredibly easy. Find a forum where your engines are broadly discussed. For Cummins Marine, Boat Diesel is an excellent resource. From reading about your engines, you’ll start to learn the weak points and where a little extra attention is well worth paying. In the Cummins B-Series engines, I keep a close eye on the raw water pump and engine accessory-drive belt-idler pulley. Both fail more frequently than they should and warrant a bit more attention. I just posted a short article on checking the engine accessory drive belt and idler pulley: Belts and Idler Pulley.
Those of us with recent Cummins engines (since they started using air preheaters) will notice that the factory alternators are actually pretty respectable. My 2000 270Bs come with 105A Delco alternators. You would think this means I can charge at over 200A with the two installed in Dirona. Well, it turns out that the 105A specification is more of a marketing number than an engineering specification. Yes, they can produce 105A of output. However, they can’t do this for more than a few minutes at a time, which is close to useless. Now that we know that they can’t really produce 105A continuously, what can they do?
Sometime back I wrote up an article investigating what charging rates can be produced continuously and reliably and how to achieve that number at minimum cost and hassle. It was published in the May 2007 PassageMaker and we just put it up online at: http://www.mvdirona.com/TechnicalArticles/ChargingSystem.htm. I’ve found that you can reliably get 70 to 80A and the alternators will run trouble free for years configured that way. The article documents the investigation, discusses the limiting factors and shows how to configure your charging systems to get good results.
In the previous posting, Cumins Power Curves Confidential I talked about why having Power Curves for your specific engines is a good idea and why and argue it was a mistake for Cummins to not make this data available to customers. This data is now reported to be available. Apparently the Cummins folks I spoke with at 1-800-diesels were incorrect in saying the power curves were Cummins Internal Use Only and should have released them. They directed me to PowerMaster@cummins.com who sent this letter explaining why customers don't need the data and that they were unable to release it due to corporate policy. Apparently they were incorrect as well. Tony Athens and Etienne Grobler both followed up with Cummins and both were told the folks at PowerMaster and 1-800-diesels made a mistake.
Etienne has approved me posting the letter they sent to him explaining the error: WaveMasterAtCummins.htm which offers more detail. The good news is we can get the data we need (thanks for following up with Cummins Tony and Etienne). The bad news is there appears to e a surprisingly large number of folks in Cummins customer support willing to take a firm position with insufficient data. Nonetheless, I'm glad to see the power curves available to all.
The updated article is at: http://www.mvdirona.com/TechnicalArticles/CumminsPowerCurves.htm.
Since new, I’ve had the Cummins Performance Curves for my CPL 2205 engines but it was for a different rating. Apparently the CPL 2205 engine was sold in a 260 HP Recreational rating and a 225 Medium Continuous rating. Sometime back I asked Cummins for the exact Performance Curve for my 270B (260HP Recreational) and was amazed when they said “sorry, we can’t get them to you, they are Cummins Confidential.” This is doubly weird in that 1) customers absolutely need this data to protect their engines and 2) the current generation Performance Curves are actually posted on their web site.
Their letter refusing to supply this data at: http://www.mvdirona.com/TechnicalArticles/CumminsPowerCurves.htm. That page also gives an email address for you to send feedback to Cummins if you agree that not providing the data is bad for customer nor good for their business. Thanks,
James Hamilton, Windows Live Platform Services
Bldg RedW-D/2072, One Microsoft Way, Redmond, Washington, 98052
W:+1(425)703-9972 | C:+1(206)910-4692 | H:+1(206)201-1859 | JamesRH@microsoft.com
H:mvdirona.com | W:research.microsoft.com/~jamesrh