Help with solar powered boat

This is my first post. I teach a high school class called Alternative Fuel Vehicles. We recently participated with 17 other boats in the Northern California Solar Regatta, a race using boats that are 16' maximum length and powered by 4 solar panels producing approximately 12 amps at 12 volts. We used an old canoe and an electric trolling motor in this, our first year of participation. We would like to design and build a boat and motor for next year's competition. I have a little boat building experience, having built an El Torro sailboat a few years ago. We have a machine shop with lathe, CNC mill and other equipment, as well as woodworking tools in our shop. We also have students who are pretty proficient in CAD and a 3D printer and laser etcher. What I don't have is any experience in hull and motor design. I was wondering if there is someone out there who would be willing to work with us as a mentor for this project. I am in the San Francisco Bay area but the mentoring could be done long distance.

 

My personal take on this competition is that the event is poorly designed as far as a technology learning exercise. Never the less, if you concentrated on selecting appropriate junkyard devices that could be hacked by the students to create an assortment of propulsion options and let them spend a year testing them to figure out what works best and why, that would be a very good use of their time. Clean-sheet design really needs graduate degree level team members in several disciplines. Think rehab treadmills (nice controllers on some), washing machines, waterpumps, Elipti-cycles/Air-Striders (for shafts and gearing), electric scooters and mobility devices, cordless tools and vacuums. I doubt you can do better than an old outboard leg for the final drive (or troller, if you go that way.) Check with RV, boat, golfcart, off-road conversion shops, solar suppliers; and there are half a dozen electric bike conversion kits on the market worth looking at. I saw a battery powered chainsaw a while back - that might be interesting. Small garden tillers are a good source of little transmissions with deep ratios.

And get a supply of those little batteries they use in the comp (from several sources) and teach everybody the care and feeding of those things. Make it like a pet - everybody has to keep one with them at all times and keep it charged. See whose still works after two months. Take some apart to see whats inside. Find out how fast you can discharge the things and how much power they make at different discharge rates. Try them at different temperatures. Battery charging may seem boring, but it is half of the actual challenge in the competition.

I guess an MMPT controller is a basic necessity under the rules. They are getting cheaper, but not peanuts, and you definitely need to test and verify their performance. There are allegations of non-MPPT controllers being sold as cheap MPPTs. Get a sponsor to cook you up a purpose-built, true 4 input, MPPT for the race and you will have a good chance against anybody in the solar portion. I don't recall seeing anything in the rules baring solar concentrators, so a few mirrors might be put to use as well.

 

DO NOT take batteries apart unless you know what type they are and have the proper safety gear. Lead/acid batteries have sulfuric acid and Li ion, depending on the type, have electrolyte that if touched will destroy the nerves in the area. I work on this and we have Calgonate and eye wash/safety showers next to the work areas.

 

Thanks Gonzo, IIRC, the batteries in the contest are the little standby batteries commonly used in emergency lights and the cheap sort of UPS's. Yes, need to be careful. I wasn't suggesting sawing one in half fully charged, but they can be uncanned without much difficulty. Something for the team leader to do, not the kids.

 

Sure would love to help you. May I suggest you sign up on electric-boat-forum.com and start a thread on your project, and I can answer any questions.

 

We at the University of British Columbia Naval Architecture program would be happy to help.

Personally, I own a solar-electric 36 foot sailboat, and have spent many a happy day on SF Bay on that boat.

I suggest you contact me outside this forum:

mckesson -at- mech.ubc.ca

Chris McKesson, PE, Ph.D.
Instructor

www.mckesson.US