T-Pain Is On A Boat: Re: [Electric Boats] Re: does anyone have current real world performance figures please

Wednesday, March 27, 2013

Re: [Electric Boats] Re: does anyone have current real world performance figures please

Hi Eric

- As no prop man would guesstimate speed for my boat, maximum efficiency was all I could head for that they seemed able to calculate to.

- I know I'm a bit on my own when it comes down to it, just didn't want to be at the "bleeding edge" and be first-in-my-class but hey someone has to do it as they say.

- I'll publish/post all my results and hope I don't have to either new props made or the proposed ones turned down (the only cheap mod I can think of) as they are costing me £1000 each!!!

- I know I could have had off-the-shelf guesses way cheaper but I thought if I went to a "proper" prop maker I would get what was optimum for my boat............... time will tell I guess, "a fool and his money" as they say.

Cheers, Julian

On 27 March 2013 18:46, Eric <ewdysar@yahoo.com> wrote:

Hi Julian,

My point is that your suggested prop may be the most efficient, but it won't deliver the boat speed that you said that you wanted for your stated motor speed. It's all about compromises. I just wanted to warn you of what you are signing up for.

Personally, I prefer a boat that has enough power to motor at at least 1kt above my personal cruising speed. It's up to you to pick that speed for your boat. My ketch can motor electrically at full throttle at 6kts, (1/2kt faster than it could with the 12hp diesel) and my cruising speed is usually somewhere between 4.5 and 5kts.

My suggestions were based on these personal preferences and I tried to make that clear. This is largely conjecture on my part, I don't know of any other conversion like yours. That said, you get to be judge of whether you have faith in my reasoning, I have already included why I have made the suggestions that I have.

Eric

--- In electricboats@yahoogroups.com, Julian Webb <julian.proto@...> wrote:
>
> Hi Eric
>
> - I get that torque is flat....
>
> - As I was scaring prop makers away, all I asked them to do in the end was
> to design/make me a LH and a RH prop that were the *most efficient *for motors

> that I had and it's the prop maker has spec'd the 500RPM as being the best
> match for the 23 x 22 props. which he said were the most efficient given
> they are the largest I can swing under the boat leaving 15% clearance.
>
> - While you won't lose me on anything from the shore power inlet to the
> motor coupling, please give me an honest opinion on what you think would be
> the best prop, as it's the one part where you can lose all your hard work
> in the rest of the system.
>
> - At the moment I calc at 6 knots I will run at 1/2 the Diesel consumption
> she used to on her old Diesel engines but not if the props are wrong, and
> as custom made props are expensive in this part of the world I really need
> to get it as near to right as I can.
>
> Thanks again, Julian
>
>