T-Pain Is On A Boat: [Electric Boats] Re: New member

Monday, October 5, 2009

[Electric Boats] Re: New member - 37' sailboat

Hi Eric,

You are correct, the A30 has the prop partially enclosed in an aperture between the keel and rudder. At low speeds I get no regeneration at all, say under 3 knots. The prop begins to generate between 4 and 6 knots. My battery bank has a capacity of 200 amp hours. Just doing some rough analysis, based on the % of charge expended then recovered on activities like entering and leaving harbour, I recover 1 amp hour every 4.5 hours underway.

So the prop regen is suitable for topping up the energy a day sailer may expend going in and out of harbour.Sail- 4 to 6 hours and recover the two or three amp hours expended.

From a depleted state(up to 50% discharge), it would take up to about 400 hours underway to completely recharge. That is 16 days underway. Clearly, prop regen adds to the solution, but cannot be counted on as the total solution.

My sailing habits are those of a day sailor- out overnight or for the weekend. If I am in light airs, motor sailing- I regularly rely on a set of smart battery chargers to top up when my bank of amp hours gets depleted hen I get back to the club. I will also be looking at a solar or a wind generator to augment.

I have not noticed a tremendous difference in performance. I may lose a 1/2 knot due to prop drag. Important to a racer, not so much for me.

regards, Brad

--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Hi Brad,
>
> You mention regeneration as a power source. Am I correct in remembering that the Alberg 30 has the prop in an aperture? Since your boat is already converted, have you been able to generate any power into your batteries under sail? If so, what kind of charging rate were you getting? It's my understanding that the reduced flow around a prop in an aperture really cuts down the already limited power that is available through regeneration.
>
> Many people have reported regen of somewhere around 100 - 150 watts with fully exposed props, and 100 watts is less than 2A of charging with a 48v system. On the electric condo cats, some people have reported that the regen really slows the boat down, as much as 2kts or more, but they do have 2 props, twice the drag.
>
> On my full keel Bermuda 30 ketch, I'm going to skip the regen aspects and focus on other efficiencies to get maximum range.
>
> Fair winds,
> Eric
> 1964 Cheoy Lee Bermuda 30 - Serenity (being converted)
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "BA" <oconnell_brad@> wrote:
> >
> >
> > Hello JB,
> >
> > I recently repowered my Alberg 30 with a system from Electric Yacht(www.electricyacht.com). They provide a great plug and play motor, controller, battery monitoring system, along with coupling to the existing shaft.
> >
> > There are multiple alternatives for regeneration, not limited to wind or solar.For example, the unit from Electric yacht will regenerate under sail, simply by allowing the prop to turn. The motor becomes a generator. This is ideal for offshore and longer passages.
> >
> > If you want I'll send you the contact information of the guy I was dealing with there.
> >
> > best regards, brad
> >
>