All up weight should be about 80 lb less than the temporary deck and four car batteries. I will try to weigh her before launching. I thought about moving the motor back, but there is the rear strut that holds the hulls together, and I would have to move it behind that, which may be too far back for the weight. Also, I was worried that in with the banana shaped hulls, any wave action would cause the prop to catch air. I did get a little more angle on the motor by re locating the steering bar. It seems at slow speed the turning radius is not bad, but at speed she just wants to keep going straight. Possibly a bit of a learning curve to drive her in the marina.
Thanks for the note on the discharge, it's easy to forget to leave some reserve in the calculations
The cells are actually large format, not the little pouches or cylinders, and each on will be individually balanced with each charge. The BMS monitors each cell and warns if any one is below a pre programmed voltage for 30 seconds.
Thanks for the help,
Dave E
--- In electricboats@yahoogroups.com, "andrew.gilchrist57" <andrew@...> wrote:
>
>
> Sparky hi great project, I have a Prindle 16 and considered converting it.
>
> What is all up weight like compared to the lead acids used initially.
>
> I notivced you commented on the turning circle. The boat will be limited because the hulls are deeper in the water than with a sail boat.
>
> However, the major issue should be that the steering acts at a point very close to the fore-a balance point, which is the axis about which the boat will turn. This positioning is like use a short lever to move a load; much more input is required to achieve the desired effect.
>
> A larger skeg will increase steering moment but the drag will also increase.
>
> A more efficient way may be to move the steering moment rearward to or beyond the hull transoms. By increaszing the length the "lever" the same steering input should see responsiveness restored and turning circle reduced. Getting rid of mass will assit this.
>
> ALso I note you have made some calculations on battery use to near full discharge. The usual safe minimum charge for the entire battery at low C rates (discharge amps/AH capacity)is 85%.
>
> In this setup in which there are many small cells making up the batteries the failure of one small cell is much more likely. Observerving the 80-85% limit will keep your voltage high, give long reliable battery life and keep the batteries well away from the part of the discharge in which cell discharge caharacterisitcs diverge and the likelihood of damage is increased
>
> Finally you mention the speed whihc is good altho not at the speed you would like. Displacement and draught are key. However, you might enjoy looking at the Solar Splash site
>
> http://www.solarsplash.com/index.php
>
> these guys have low power electrics going quick using simple hydrofoils
>
> http://www.youtube.com/watch?v=xFnv7rPHhDY&feature=player_embedded
>
> hydrofoils have been used on cats to lift the hull, reducing draught and thereby drag; and to improve stability.
>
> looking forward to more pics !
> ---
>
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