High pitch trolling motor prop for solar boat

Unless you can tilt the whole panel to be at 90 degrees to the sun at all times, the best performance is going to be about 40% average for maybe 6hours. Use any of the online calculators, they are free. Also at 10 W/sq.ft, an electric motor will require about 25 square feet for ideal conditions. If there is any wind, the boat will go backwards because the panels will act as a sail. For a solar panel boat to work, it needs a large flat deck with the crew and equipment below.

 

Our idea was to mount three panels on each hull, so that they could be rotated towards the sun without casting a shadow on each other. In front of the row of solar panels would an aerodynamic windshield on each side to reduce drag.

Its beginning to look like a lot of our design needs to change though... we are having another meeting soon to discuss.

On a side note are there any good canoe or outrigger canoe plans for a 20-24 footer? I can't seem to find many.

 

here's an Everglades challenge craft I was looking at (Also Florida challenge).

Sail plus paddle. Weight runs from 425 to about 850 depending on water ballast used for sailing. The hull is optimized for sailing at a slight heel and probably has more form stability than you require. It also is designed for a wider range of speeds than you would need. But the shape would work pretty well for solar electric + HPV with a standard sliding seat rowing arrangement.

 

I was just looking at ocean row boats that had a similar hull. Our plan to sleep one at a time would work nicely if we built a small sleeping cabin in the front. Looks great, now we have to see if we can build something like that ourselves.

Could something like this be built in 300-400 man hours?

 

What's the length of that boat phil? Are those keels retractable?

 

http://youtu.be/pYr1_2F4Ez0

So this is sorta what we wanted to do. Just with a much lighter deck.

 

... And yes, there are several designs for longer canoes, mostly up your way in Michigan, Wisconsin, and Minn. They supply canoes to summer camps. If you wanted to build your own, you could hack a smaller canoe by cutting it longways and fitting a 6" wide strip in the middle. That is actually more work than it sounds if you want to get the displacement curve exactly where you want it, but the material cost could be very low, and if 90% of the surface area is from a commercial canoe such as a XL Tripper, the numbers are going to be pretty good. Make sure you can bond the materials, the Trippers are a very low energy plastic and can be a challenge to bond to. A fiberglass, or even an aluminum one might be easier to cobble.

Take a look at the batteries by Odyssey and see if they would be useful to you after the race. They are significantly lighter than wet lead, and aren't prohibitively demanding from a charging stand point. Like I said before, the trick to these systems is to gain control of the charging system. It will probably be the most expensive part of a decent solar electric system for this sort of race.

If you run amps through the battery, you can figure about 100W of panel output for every 70W of motor controller input. The efficiency of the batteries depends a lot on the type of battery and on the rate of charge/discharge and on the state of charge. For cheap wet lead charged at a slowish rate, the round trip efficiency will be around 80% up to a charge state of 80%. Then the efficiency begins to drop off. At 95% state of charge, the round trip efficiency is only about 50-60%. So you would design the batts to cycle between about 40% and 85% state of charge - less than 50% of the nameplate AH. With better sorts of batteries, this can be improved upon a lot. The Odysseys have a better round trip efficiency at higher charge rates and on up to higher charge levels, so maybe 40% to 95% by design for them. There are other brands with similar tech and efficiencies.

 

So what about using something like this and adding length to the middle? I cant seem to find the brand but it looks to be the shape we need.

http://louisville.craigslist.org/boa/4723882685.html

 

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Canoe plans are relatively easy to get. For example, the "Canoes and skin boat of North America" for ideas. There is no need for outriggers, they only create more resistance. We built 30' canoes in the UK for 13 passengers and a trolling motor with a 27 series battery run about 1 hour at 3 kt with five people onboard. That was in protected waters with no wind.

 

So we have settled on extending a canoe. Building a new boat from scratch goes beyond our ability and time limit. 24 foot seems to be the maximum we could go. 21 would be much easier.

Would a 24 footer be much more efficient than a 21 footer?

Gonzo I like the sound of that, I'm sold on a long canoe.. now we just have to make it happen.

We are also thinking about building a small sleeping area in the front 7 feet and fiberglassing it in like this.

http://www.oceanrowing.com/sale/Roberto_Coin_sm.jpg

 

The design of those rowing boats is based on the conditions of the race. It is all downwind, so any drag helps. It is the exact opposite of what you are looking for. Keeping the boat light and simple is the goal. A small tarp and sleeping on the bottom will save weight and decrease windage; cheaper too. Modifying an existing canoe will probably take you as much time or more as building a new one, with worse overall performance. This can only work if you keep it "bare bones".

 

Ok that makes perfect sense. Would it be efficient to build one out of plywood and resin with a flat plywood bottom?

Or would our hull need to be more v-shaped for efficiency?

 

http://makeacanoe.com/opencanoesover17.htm

What about something like the 24' canoe here?

 

Hacking a canoe and adding a middle to it can be done. I have added 5' to a 16'er (and didn't do a very good job of it). It is more work than you might suspect, though, if you want decent results. You basically have all the prep work of a full build, you just don't have near as much fairing to do because 60% of the hull is already faired. It works when you can get free or nearly free canoes. And don't worry to much about their condition, you are going to be spending about 100 hours getting the hull matched up anyway, plenty of time to patch worn out keels and whatnot. Make a splash of the middle 5' of the hull outsides. Then cut the hull and set up regular molds on a strongback and screw battens to the molds every three inches or so. Attach the splash and use it as a plug mold. Attach the bow and stern half to the molds. Then fill the middle section with the core of your choice and glass and fair the whole boat. Turn over and glass the inside. The sheer will be wonky. Just add a sheer plank and trim it to suit. You will want a bit more freeboard on the longer boat, and you will need some more longitudinal strength as well. It is fussy work to get the volume distributed well and have the sides match up. You may need to saw some kerfs fore and aft to get the old hull to fair to the new molds.

Here is the curve of displacement from my design at 800 pounds. The transom has a bit of bury, but my boat is on the heavy side at 800#. It is a bit cleaner at 600#