T-Pain Is On A Boat: [Electric Boats] Re: Boats over 30'

Thursday, June 4, 2009

[Electric Boats] Re: Boats over 30'

Merrick White,

Thank you so much for the real-world data. You have indeed optimized your sailboat for motoring. You do have a tremendous advantage with your well designed hull and unstayed topsides. Your boat (Freedom 32, with about 26' LWL) is much easier to push through the water, especially if there is any headwind. Still, almost 4 knots with less than 20amps @ 48volts, that is the ballpark that I suspect everybody would like to play in, the sailboat ideal (or other displacement hull), the reason so many of us are spending all this time, money, and effort chasing our green marine repower dreams.

My bad for not clarifying my HondaEU2000i assumption: instead of powering an onboard charger (Zivan NG1 @ $500 to NG5 @ $1400), I was thinking of the Honda's own built-in teeny 12v charger.

Regarding two separate 48v banks: there is wisdom (redundancy) in that. At your low amperage draws, Peukert's Law is insignificant.

Thanks again,
Mark Stafford

--- In electricboats@yahoogroups.com, "merrick white" <r__merrick_white@...> wrote:
>
> Mark,
>
> As a cruiser I would like to relate a real-life experience. In my Freedom 32 with my Electric Yacht 48v motor and 2 seperate banks of 4 - 100 amp batteries (yes, I know they should all be together - that's another discussion) I have powered for 17 hours straight, at 18 amps (3 knots) using my Honda 2000i generator connected to my Zivan 48v charger and arrived with 90% power in bank one and never used bank two at all. Now that I have a new prop that same 18 amps will yield 3.8 knots.
>
> I am not sure what you mean by saying the the 2000i will only slow charge one 12v battery at a time?
>
>
> Merrick White
>
>
> --- In electricboats@yahoogroups.com, "Mark Stafford" <mstafford@> wrote:
> >
> > SailingPM (other names?... I care!),
> >
> > Mark Stafford here echoing Keith (aweekadaysailor). He has lot's of water credit. Sure start small, get some performance numbers, but plan to at least add another motor (dual motors driving your one prop shaft). Two 19 peak hp motors will give you adequate thrust (90% - 99% hull speed) for short term "situations". 48volts of 8 Trojan T105 should give you a safe 10 minutes of high dual motor thrust, provided you auxiliary cool the motors. Hardly enough to battle adverse wind and current for transport, but plenty for short safety maneuvers.
> >
> > The HondaEU2000i is great, but inadequate since it can only slow charge one battery at a time. 8 Honda 2000's would be cumbersome, but make you a happy motor/sailor. Alternatively, a more expensive DC genset would make you an ecstatic motor/sailor. I am still looking into those for myself (55' x 10' Herreshoff in Berkeley).
> >
> > Mark Stafford