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[zstine]

750W is 1hp... The OP linked a pic. and assumeing those are standard 60cell panels, about 250W each, that is 14Hp worth of panels. You will make that power for 5 hours during mid day. The problem with taking a power cat and trying to go all solar is that the power cat is heavy and designed for what, 20-30Hp in each hull. So your not going to charge Tesla batteries with solar panels unless you plan to use it for a day on the weekend and allow it to charge all week. If this is your plan... then go for it. Yes, you could supplement the solar with a diesel gen set. But there's more inefficiency in this than just running an engine connected prop. So the feasibility really comes down to how you use the boat. Let's assume a 40 some foot power cat needs 28hp to cruise at ~6.5knots. With the solar alone, you could power it for 2 to 3 hours and go ~15 miles a day. Or, with battery storage, you could go ~75 miles after 5 days of sitting at anchor charging. I don't think that's very practical for most users and that is why you don't see much of it around.... custom built, light weight boats will fair much better then converting a power cat, but still very limited.

[sagablu]

Originally Posted by valhalla360

By that definition, just about any power source with the possible exception of geothermal is solar powered.

Dino-juice is just stored solar energy from millions of years ago.

Apologies, the job of over-analyzing my comments that are meant to be slightly humorous has already been filled by my girlfriend. Unless of course you are a really attractive brunette with an ivy league education, then we can talk.

[Capn Jimbo]

"I'm seriously interested in building a retrofitted solar boat out of a power catamaran, but why do I seem to be the only one?"

Well, from what I've seen here, it wouldn't be for lack of trying. Seems the notion of electric finds either limited use at either end of the voyage, or otherwise requires a backup generator. The main propulsion remains the sails.

What's your budget? What have you done so far? What calculations and costs? Preliminary design? Any model testing? Or just having fun?

[Paul54]

This guy is doing it on a small DIY scale. J Mantzel. Look for his uTube videos.
Interesting character.

[oleman]

I have always found amusing how the uneducated mind is able to come up with ways to ignore the realities of physics.

[timber1]

G'day to all.
Just a few pieces of information to add.
A friend has a 38ft steel monohull weighing around 13 tonnes. He fitted this with a diesel/electric hybrid drive - 40hp diesel, 7.5kw electric generator/motor. Figures that came out in testing - Top diesel speed 6.5 knots, top electric speed 5 knots. 1.5 knots on the power produced from the two solar panels. Lots more data available but tedious to read through.
Not all solar panels are created equal. A typical house size panel of 1.65m x 1.0m can produce 250w from one manufacturer to 320w from another.
A diesel horsepower does not do the same work as an electric horsepower (real world).
Thanks for the interesting discussions and stay positive.

[valhalla360]

Originally Posted by timber1

A diesel horsepower does not do the same work as an electric horsepower (real world).
.

I'll bite.

Please share the physics on how electric HP is magic in the real world?

[valhalla360]

Originally Posted by sagablu

Apologies, the job of over-analyzing my comments that are meant to be slightly humorous has already been filled by my girlfriend. Unless of course you are a really attractive brunette with an ivy league education, then we can talk.

Sorry but sometimes it's hard to tell the jokes from people who really believe this stuff.

[jag2501]

Originally Posted by Capn Jimbo

Well, from what I've seen here, it wouldn't be for lack of trying. Seems the notion of electric finds either limited use at either end of the voyage, or otherwise requires a backup generator. The main propulsion remains the sails.

What's your budget? What have you done so far? What calculations and costs? Preliminary design? Any model testing? Or just having fun?

First off, you are all possibly the the most educated and cordial forum I've ever belonged to. Thank you for your thoughtful responses.

TÛRANOR PlanetSolar, averaged it's circumnavigation speed at 5.5 knots and that's a solar boat designed for pure speed. So I am trying to be realistic and cub my enthusiasm but not about to throw in the towel on a dream.

I'd be comfortable spending 150-200k and though I've never built a boat before my past projects usually come in under budget (insert boat joke here about "under budget")

I've looked at a coastal cruiser that could generate 5.7hp electric a day but never make it to blue water.

My current project would be a 40' aluminum power catamaran that with foldable/directional 4' solar wings provide 5.3hp electric a day.

I already have 10kwh Li-ion batteries which spurred my interest. I have thought about a small sail, wing sail, wind turbines, and thrown out all but the small conventional sail which defeats the purpose. I've even considered a solar or even wood stirling engine.

The appeal is a floating home that I could take anywhere and live in comfort, have little maintenance and not be limited or dependent on others.

[timber1]

Ah yes, wording didn't come out right did it.
I'm not a physicist but rumour has it that one horsepower is something to do with torque x rpm.
In the real world I reckon it's more to do with things like efficiencies at different rpm, gearbox efficiencies, where companies measure their hp readings etc etc.
If a catamaran used two 10hp outboards you wouldn't use two 7.5kw electric motors.

[jag2501]

I understand timber, I was just calculating it for simplicity sake. Nobody wants to hear about kilowatts and amps.

[Andrew Grace]

And the first decent seaway , those side panels will be gone..,

[Rorzech]

Originally Posted by jag2501

I know wind sailing is a blast, power boats are not for me, but there are Solar boats out there that get very little attention.

From an electronic point of view with maintenance included it seems a real bargain. Used Tesla batteries from Ebay, Solar panels in California are quite cheap. Of course a generator would be on board.

From an excitement point of view it seems a bore. The commercial solar yachts are capable of a 24 hour cruising speed of 6.1 knots with burst speeds of 10 knots and at 6 knots average a day that's 144 nautical miles a day.
Solarwave 62 - Zero Emission - Tesla on the sea

I'm seriously interested in building a retrofitted solar boat out of a power catamaran, but why do I seem to be the only one?

I think the solar panel roof wood have to withstand a wave breaking on it with tons of water landing on it. Otherwise its doable, lots of shade, lots of room,, and lots of money.
I was planning to just use solar assist via big trolling motor in doldrum conditions. Maybe get two knots which is still better than no knots.
Nothing ventured nothing gained.

[RaymondR]

Personally I think that either steam or Stirling cycle engines burning fire wood which one collects with only an axe would be much more environmentally friendly and even far more practical than the solar boat. Or, how about Brayton cycle with deck collectors and a small turbine? (We'd need insulated sole deck shoes but not a problem)

[GordMay]

Originally Posted by Mike OReilly

A few years ago I met a 40+ foot cata trimaran fellow through CF that had converted his engines to electric. Still had the sail, but had covered his coachhouse and some deck area with solar panels. Seemed like an interesting idea.

Unfortunately this cat was a home-built ferro-cement FRG boat. He was a cement guy so everything inside was constructed of cement. It seemed way too heavy to move, let alone sail.

GordMay, remember this guy?

Yes indeed.
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