What is the goal of the project?
Hey Chris, we meet again.
I think your idea has a lot of merit, and not just because I like proas and EVs.
My 20' proa LOL has a 55lb Haswing trolling motor. Last year I used an 80AH lead acid battery, a Chinese PWM controller and 110W flexible panel. The motor would push LOL at 3 to 3.5 knots. Running time was about 1.5 hours at top speed. The battery would recharge in about 2 sunny (Vancouver) days.
How much will your batteries weigh? My group 24 battery weighed about 50lbs - a lot in a little proa. I'm working on an LFP battery system to replace it - about 60% of the weight, and twice the capacity. And waterproof.
You've designed your proa with a lee pod for buoyancy in case of knockdown while sailing - a very good thing. But the motor on the lee side will get completely submerged if that happened. My motor's speed control didn't like being submerged at all during a capsize. But my solar panel still works fine - it is sealed well, including the wiring connections. Something to think about.
The midship motor placement may reduce wiring distances, but won't be as effective at spinning the boat as motors near the vaka ends would be. If both motors are on the windward side of the vaka, then there's little risk of damage while docking.
Will your panels be on the vaka decks, or between the akas or both? The wiring length may work out the same whether the motors are at midships, or at the vaka ends.
I've read older posts where trolling motor efficiency has been significantly improved through prop substitution and fairing of the motor shafts (add a foil). Also, PWM motor controllers increase efficiency, but can be added later. My motor uses separate windings that are switched in and out.
Keep us updated.
Curtis
---In electricboats@yahoogroups.com, <yahoomail@...> wrote :
Hello to the group. My name is Chris Curtis. I'm building an obscure type of sailing muiltihull called a proa as a technology demonstration project. Due to my Proas hull design there is a massive amount of available real estate to mount PV's. Further the Proa has protuberances that will allow for drop down trolling motors on sleds. This allows for electric power, steering and "spin" type of operations.
My current entry level plan is primarily dictated by my budget (2K). I'll have each motor system have its own PV's (400w each), MPPT controller, and two T105's (220AH). The motors will be standard saltwater 35lb thrust type. Based on my painfully (likely wrong) rough calculations, in full sun I should get over 90 percent of current into the batteries (30A) that the motor is pulling (about 35A). What I'm looking for is the ability to run in full sun with very little battery assist. On a sunny day I'd like to be able to take off in the ICW (or Abaco Sea) and go until the evening all on electrics without worrying about completely depleting the batteries. If the project is successful, I'd like to add just a bit more and be able to run at full speed and still have enough power to charge the batteries. For some perspective, the Proa is 30 feet long, has a 18 inch draft, all told is 20 feet wide and weigh's 3500LBS fully loaded in cruising mode. The main hull is 32 inches wide at the waterline, 8 feet at the deck. The small hull or outrigger is like a very large kayak. His (Proas are He's!) planned areas of use are the PNW and the Florida/Bahamas areas of the SE. He is trailer-able at just over 2000lbs.
I created a folder called VolksProa Dual Electric Proa (or something like that). If interested please take a look as its a hard boat to understand without a picture. Please feel free to comment on my idea and plan. I'm not expecting the world and I do have some experience living under PV (on a boat). I'd prefer to go with a single system, higher voltage, better motors, etc but it does not fit with the design brief. It must be a fairly low dollar affair. Thanks for any time you give this.
Chris Curtis
Posted by: Kev <captainyoung@gmail.com>
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