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%.

                        --jrh

James Hamilton

jrh@mvdirona.com

http://www.mvdirona.com/

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?

My response:

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 (wave.master@cummins.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.

James Hamilton

jrh@mvdirona.com

http://www.mvdirona.com/

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?

James’ response:

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.

            -jrh

James Hamilton

jrh@mvdirona.com

http://mvdirona.com

The Seattle Boat Show seminar schedule has just been posted. We’ll be presenting on the red stage at 4:15 on Saturday February 2^nd. Our presentation will include highlights from our upcoming Waggoner sister publication Cruising the Secret Coast: Unexplored Anchorages on British Columbia’s Inside Passage.

While docked in La Conner recently, we were fortunate to walk past the Pacific Mariner plant at just the right time. They were wheeling a huge, empty hull, likely of a Pacific Mariner 85, around the building. It appears that they mold the hulls on one side of their property, then transport them to the other side for completion. Another large boat looking near completion was next to the slot where this one was destined.

The tractor operator did an amazing job—the clearance at many points was barely inches.