T-Pain Is On A Boat: Re: [Electric Boats] Using original transmission.

Tuesday, October 12, 2010

Re: [Electric Boats] Using original transmission.

From what I can tell what efficiency difference may exist between gear reduction and belt reduction is negligible. Check out this chart:

http://www.roymech.co.uk/Useful_Tables/Drive/Gear_Efficiency.html

The 1% or so in efficiency that is given up going with gears is a trade off for having a big reliable gear box instead of belts (which are also reliable, just less so), and having the problem of thrust taken care of. There are lots of reasons to go one way or the other but loss of power isn't one of them.

Think about motorcycles, shaft and chain drives are both very common. The big plus for shaft drives is they are reliable, breakdowns are uncommon; the big plus for chain drives is they are easy to fix, inexpensive, and are more efficient. I've never seen the efficiency difference adequately quantified so I suspect its pretty small and with motorcycle shaft drives we're talking about have a 90 degree turn like a differential and that type of gearing is less efficient than the parallel shafts with helical gears in a gear box. Again though, we're only talking about a few percent of efficiency either way. I don't think its really a factor.

David

On Tue, Oct 12, 2010 at 12:58 PM, Steamboat Willie <stmbtwle@yahoo.com> wrote:

" I'm sure if Diesel engines could reverse with the flip of a switch they would not have coupled them to a cumbersome gearbox."

That's exactly what is done with the really big ones. Stop the engine and start it up again the other way. No transmission, no reduction, nothing; just straight direct drive.

I think there's a lot of drag in a conventional marine transmission, and I'd avoid it if I could.

Willie

--- On Tue, 10/12/10, Peter <peter@sintacha.com> wrote:

From: Peter <peter@sintacha.com>
Subject: [Electric Boats] Using original transmission.
To: electricboats@yahoogroups.com
Date: Tuesday, October 12, 2010, 12:08 PM

This is a great forum, and I've learnt a lot from lurking and reading through past posts, but the recent discussion on leaving in the original transmission has flushed me out into the open.

Converting to electric, one is looking for the greatest simplicity and efficiency possible. Running electric power through an ICE transmission, with it's cone clutch, gears, and oil bath, seems to me a poor idea. I'm sure if Diesel engines could reverse with the flip of a switch they would not have coupled them to a cumbersome gearbox.

Just my thoughts on the matter....
Peter.