Thanks, Denny.
I've never had to wire anything where I didn't have instructions.
I was thinking about putting 100 amp resettables near each battery (+) terminal, the battery hot wires then leading to a 4 position (off, 1, 2, all) battery switch. A pair of hot wires (each protected by a 50 amp resettable) would lead from the battery switch, one to each of the controllers. I'll take a look inside the controllers to see if there is a light duty wire I can interrupt with a $10 kill switch.
I think I'll try making my fairing from plastic decking boards cut on a bandsaw.
I bought 4 APC props (10x6, 10x7, cw and cc) to test on a 30 pound thrust motor pushing the cat hulls but had not got around to it.
At the weight I was testing (about 650 pounds) each 50 pounds of weight took about .1mph off top speed. My recollection is that you had achieved 5.0 mph with a 300 pound canoe, and I was already achieving 4.3 mph with some setups, which is about what I would predict from your numbers. I was concerned that the big props have to be run deeper to avoid cavitation, and this may cause me problems running up on the beach or operating in shallow water.
My motors draw progressively less watts the longer (say, 15 minutes) that I run them, so it is difficult to say what is a faster setup unless I use a freshly charged hot battery, or normalize for watt draw. I don't know whether this is caused by motor, battery or leads. Everything I was using (ultimately) was new. If you figure it out, let me know.
John Casperson
--- In electricboats@
>
> John,
>
> That sounds like a pretty good way to get a very efficient electric boat. I imagine google will find you some safety switches - they probably go in the control wiring, not the power cables.
>
> A fuse or circuit breaker should be right at the + terminal of the end of the battery string.
>
> Fairing the motor tubes will give a great improvement in efficiency. The round shaft has a Cd of .49, an NACA 0025 foil Cd is .09.
>
> Try an APC 10x6 pusher prop made for an RC model airplane ($3 at a hobby shop). You will have to bore it out to 3/8" and cut a slot for the MK shear pin but the prop is also a good bit more efficient than the weedless model that comes from MK. It won't be as durable as the MK either, but at $3 who cares?
>
> Keep us posted on your results.
>
> Denny
>
>
> ----- Original Message -----
> From: john_casperson
> To: electricboats@
> Sent: Sunday, January 24, 2010 6:01 PM
> Subject: [Electric Boats] kill switch
>
>
>
> Hi all--
>
> Last year I picked up a pair of 16' Prindle cat hulls for free, and a few days ago I found a pair of 45# thrust 12V saltwater Motorguide trolling motors (with continuously variable controllers) which I picked up for $225. This spring, I'll build a deck connecting the hulls to mount the motors, a pair of type 27 Walmart batteries, and a 200 watt solar panel on a T-top for charging the batteries. The controllers will be disconnected from the motors and moved to an amidships helm location, with the batteries stowed underneath.
>
> I plan to test it in the surf this summer, and it occurred to me that even at low thottle, without me on it, it will run much faster and further than I can swim.
>
> Does anyone know of a suitable kill-switch for this setup?
> What about fairing for the motor shafts?
> Also, how should it be fused?
>
> John Casperson
>
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