f_inscreenname

Just reading a thread and the idea of removing the circulation pump would add extra HP to your numbers. Then an idea popped up I came up with years ago but never got an answer if it would work so here I am.
Why don't race boats and such use a separate a motor for accessories? Nothing big but something like a lawn mower (small) motor for cooling, oil pressure, charging batteries, etc etc. Think about it. How much does (on a twin set up) 2 water pumps, 2 Alts, oil pumps, etc, etc, suck from your HP total? A little motor to do that stuff while leaving the real motors just to drive the boat. You would think someone would have done that already. I mean Brownie put 2 motors into 1 V drive just so he wouldn't have to drag along a 2nd prop, running gear and rudder. Made the boat faster but a bit more complicated. If you got rid of the things that drag on the drive motors the boat would be faster wouldn't it?

Uncle Dave

Because at some point the complexity weight, additional plumbing and failure points are a diminishing if non existent return against any saved power one might expend running accessories.

(After the easy stuff like a freshwater boat dumping an unneeded recirculation pump)

Especially if the conditions preclude using all the power you have available anyway - like a 28 FT boat ocean racing can rarely if ever run wide open for any real length of time anyway.

The simpler the better.

UD

tmmii

A lot of weight, space and headache to save what 15 horsepower combined?

always looked at a crossover as a way to remove a moving part that could fail over a power gain.

f_inscreenname

1st let me say I'm not an expert by a long shot but I have read an insane amount of posts of people doing everything to squeak out a HP or 2. In the racing world its even more insane. I mean you can run a thinner oil and pick up 10hp. Not that its recommended for long term use but.... That's why nascar started your qualifying motor is your race motor because they were running mineral oil in their qualifying motors which tended to explode after a lap and a half to 2 laps.
So think of this. Two motors in a offshore boat,
2 mech oil pumps (use a dry well electric system) = 8hp (at least)
2 circulation water pumps (change to electric) = Some say up to 20hp each, lets say 15ea....30hp
2 Alts = depending on load could be up to 10 hp each but lets say 5......10hp
raw water pumps, either in drives or on the motors themselves = 10hp each at a min .... 20hp
Some sort of power assist steering = ....????hp
Fuel pumps ....
It all adds up. If you ran everything electric all you would need is a (small) external generator so to speak to keep the batteries hot. Back in the day I could see Brownie using a period 5hp lawnmower motor with a pulley welded to the blade shaft and a alternator screwed to the deck. I'm not saying this for a pleasure boat. No one is going to start their generator just so they can start their boat but people have done some crazy stuff in the racing world. I am also sure in 2017 we have moved well past these crazy tricks but it shocks me no one ever did this before.......It's some time in the past and everyone has the best motors on the market all making about the same hp but one team decides to get rid of all the parasitic horsepower drains on their motors. Who is going to be faster? It just seems so simple.

SB

iTrader: (1)

68hp = 50,708 watts

50,708 watts = Amps x 12 volts
Amps = 4226


You think a 5hp motor will feed this ?

f_inscreenname

I hear ya but ........IMHO my 10,000 watt portable generator that admittedly weights around a 100lbs but only burns about a gallon an hour could keep 2 batteries hot under that load. Hell when I back feed my house it runs my 220 heater, 220 well pump and 220 hot water heater along with half the lights in my house with no issue. And to be honest I don't think you would need anything nearly that big. Just thinking out of the box.

Uncle Dave

What 10K generator weighs 100 pounds? A honda 2K weighs 46.

It wont burn 1 gallon an hour making 10K.

an onan 7000 running full tilt burns 1.2 GPH so no way a 10K gasser burns less.

UD

f_inscreenname

I think the gas issue would be irrelevant being my raceboat held 300+ gallons of gas.

Uncle Dave

Im simply pointing your numbers aren't adding up in any column.
A cheapie generac I wouldn't trust to run my house in a outage weighs 325LB add in the wiring and plumbing - that weight and complexity offsets a bunch of HP.

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UD

ICDEDPPL

iTrader: (1)

I think it`s time to get that thinking back in the box.