Al,
Capt. Mike is absolutely correct - by the time the diesel engine delivers the energy to the shaft it has already used quite a bit of it. My husband is an electrical engineer and he explains it that you can roughly figure kw x3 to see what size electric motor will replace a diesel on your boat. So, a 9000 (or 9kw engine) x 3 replaces roughly up to a 27 hp ICE. As Mike said, the electric only has to run your propulsion so all of that energy is going right to the prop. My husband, David, has read David Kerr's book several times over and has it pretty well digested now. :-)
Go electric - you'll be happy with it!!!!
Sally
On Sat, Apr 9, 2011 at 8:15 PM, Rob Johnson <dopeydriver@yahoo.com.au> wrote:
This is the engine http://www.westerbeke.com/productBrochures/w20.pdf .It is made by Bukh , and is one very tough little diesel , a gem.Designed to be used in lifeboats .The stuff I have put up gives a good rundown on the diesel , now see if you can find some performance figures for electric motors to compare it to.If you decide to go electric , you will have no difficulty finding a buyer for the Bukh.Regards Rob J.
Sent: Sun, 10 April, 2011 7:06:13 AM
Subject: [Electric Boats] a dilemma
Hi,
I just bought a Buchan '37 whose hull is perfect and whose inside is bare, and whose engine has run for a total of 15 minutes. Its a Westerbeke Pilot 20, reputed to be able to put out 20 HP to the propellor. My calculations from displacement and waterline length using Dave Gerr's book, Propellor Handbook lead me to believe that the engine is undersized and that I need 24 HP or 18 KW.
I looked in on the Nonsuch conversion using the Thoosa 9000 at 9 KW and the 35 foot C&C using an electricyacht 180i at I think 8KW and see that their owners are pleased. So, my dilemma is why are they happy when they have only half the power required in their conversion. Is this a trick?
I'd rather go green, but its a big step to scrap a perfectly fine installation of a diesel for a flyer on something that's more expensive.
Cheers,
Al Maxwell
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