Hi, Mike, I like your "everything DC" plan, although I wonder about the 24 volt system and the hydraulic drives. I don't recall the length of your boat, but I believe that, traditionally, the break point is about 50' for 24V. I'm sure that the manufacturers have availed themselves of the cost savings on smaller boats than 50', but I don't believe that's in the best interest of the owner. Even though there's a cost and weight savings for the materials, the installation labor will cost the same. I find that 24-volt equipment is not always available, whether in the States or Caribbean. For instance, stereos, fluorescent bulbs, cabin fans, solenoids, starters, etc. Even adapters for laptops, shavers and the like are rare in 24V. That may mean the expense and inconvenience of carrying spares you'd otherwise not. You'll also pay more for 24V expendables such as bulbs, and so the initial savings may well evaporate in a few years of buying replacements and keeping a stock of spares. I have 165A Balmars on the main and get-home, and they are limited at 125A. I find that after a 10-12 hour night at anchor, the battery (5 8D AGMs) will recharge in about 4-6 hours of main engine run time. I don't know if this is typical, but assuming it is, it would seem to indicate that two 200A alternators, even if limited to, say, 150A each, might be overkill, even for short-day gunkholing. When passagemaking, with constant run time, I'd think the need for such large machines would be even less. Just playing angels' advocate, I think that today's belt-drives are pretty reliable. When I bought "Seahorse," she had the original serpentine flat belt on the Lugger, and at 3200 hours it was just beginning to look worn. I think that's pretty impressive. Although I have hydraulic steering on "Seahorse," I have never liked hydraulics, ever since I had to maintain Bosch Hydrostarter systems on some Cat main engines. These had replaced 24-volt starters, and, after several years, thousands of dollars in repairs and many gallons of hydraulic oil (all over the engine room and into the bilge from blown hoses), we replaced them with Ingersoll-Rand air starters. Hydraulics, in my view, are, by comparison to belt drives, heavy, and will generate a lot of heat. They are also expensive to install and maintain, and generate a lot of heat. They are also inefficient, from the standpoint of power transmission. Then there is the possibility of fire from a blown hose, to say nothing of the mess. Perhaps there is something that I am missing, here, and I'd be pleased to hear of any information or data you may have, as I am always looking for ways to improve the efficiency of what I have and how I use it. John (aboard "Truelove" in Soufriere, St. Lucia, West Indies) "Seahorse" P.S. Where and how will you get your "box of adapters?" Do you have a source which details those needed in different countries? Mike Schooley writes: > I plan on ~1000 AH battery bank using AGM batteries at 24 volts. To charge > underway, I'll have two 200 amp 24 volt alternators driven by hydraulic > motors. Since I'm using variable displacement hydraulic pumps on the main > and auxiliary the alternator speed will be independent of engine speed and > either engine can drive them both, which provides 400 amps for a total of > 9.6 KW. This arrangement also eliminates drive belt wear and replaces belt > maintenance with hydraulics maintenance. The auxiliary engines speed will be > controlled by a hydraulic pressure demand throttle control, which assures > that it runs just fast enough to meet the power load of the hydraulic loads, > as opposed to an AC generator which must maintain constant speed regardless > of load. This arrangement is more fuel efficient, improves engine life and > produce less noise than an AC generator. Another advantage is I can produce > full electrical from the main engine while underway without running the > generator or auxiliary. > > > > To combine the output of the two alternators and assure that they both > provide current to the battery bank, I'll use a Balmar "CenterFielder" > <http://www.balmar.net/page21-centerfielder.html> > http://www.balmar.net/page21-centerfielder.html . > > > > As a backup for total hydraulics failure, the alternators will be mounted > one on each engine with belt drives but the belts removed. By disconnecting > or bypassing the hydraulic motor and installing the belts, I'll have 50% of > normal capacity from either engine or 100% if I run both (although I'll only > get 50% when the engine is running at moderate to high speed). > > > > I was worried about drive belt side loads on the water pump, but I saw a > solution to that at the Helicopter conference last week. They mount an idler > on the opposite side of the engine from the water pump and an extra set of > belts going to the idler. A spreader bar pushes the alternator and idler > apart to provide belt tension. This arrangement assures that the belt and > idler belt tension matches and since they are in opposite directions the > side loads cancel. > > > > Regards; > > Mike Schooley > > Designing "Portager" a transportable Passagemaker > >