solar boat/s ?

[skip53]

hey guys
i've been searching the net for boats (for my family and me) and found among others this site: ***Spam deleted . OP banned ***** can you tell me what do you think about that?
i'm new to boating and i find it a nice touch sailing the sea without a "traditional" engine. does a boat like this work out for daytrips with my family?

 

[gestalt]

a boat like this would seem to be ideal for day trips as it uses a battery in conjunction with the solar panels. to be honest, due to the lack of much tech info on the site I would imagine that to get any real traveling speed with this craft you would be running mostly off the battery. which if I am to read the site properly you supply yourself or they have varying degrees of for a selection. but to have a boat that can sit in port, or on a trailer charging for the next time you use it is just great. crap, i would name it "day tripper" and put some hippie flowers on it so when I'm rollin' down the river in my flip flops, captains hat and john lennon glasses people know where the party is at.

 

[Jeremy Harris]

Its a reasonably practical boat, but way too inefficient for solar operation. The real problem is that big, wide, immersed transom. This will cause a great deal of drag at low speed and suck power out of the propulsion system.

The key to using the limited power of solar cells is to start with a hull shape that doesn't need much power to propel. Very early power boats are usually a good example, as old engines didn't give much power and the designers had to use it efficiently. The shape of the stern is more important than the shape of the bow when it comes to efficiency, the secret is to get the boat to produce as little wake as possible, as the wake consumes a lot of power.

Boats with a canoe shaped stern, or a stern like mine where the underwater shape curves up gently to the surface, tend to be far easier to propel and so more readily lend themselves to solar power. As a guide, you can expect to get around 40 to 50 watts per square metre of usable power from a horizontal solar panel. Even a fairly big boat will struggle to get more than four or five square metres of panels on board, so you need to be able to work on only getting maybe 1/3hp of solar power.

If you can accept a fairly low duty cycle (time spent cruising vs time spent tied up) and have a big battery bank (maybe 8 to 10 hours worth of batteries) then you can just about get away with pure solar power with a good hull design and efficient propulsion system. I'm afraid this particular boat design just isn't going to fit the bill as a solar powered boat.

Jeremy

 

[sharkmobil]

50w per meter square is a bit understatement. Unless you are crossing the Bering Strait in November, you should be expecting two-to-three times more power from your solar panel(s).

I got these puppies on my boat, they seem to deliver all the 180w per panel for their 1.6m2 size.

http://www.wholesalesolar.com/products.folder/module-folder/sharp/sharp180.html

 

[Tiberius]

50w per meter square is a bit understatement. Unless you are crossing the Bering Strait in November, you should be expecting two-to-three times more power from your solar panel(s).

I got these puppies on my boat, they seem to deliver all the 180w per panel for their 1.6m2 size.

http://www.wholesalesolar.com/products.folder/module-folder/sharp/sharp180.html

180 W from 1.6 m2 sounds like the output when they are directly facing bright sunshine. We don't know where the OP is, but Jeremy is at 51 N and he did say he was mounting the panels horizontally.

I recently had to do some calculations for a solar powered system in Scotland. By the time you figure in cloudy days, low angle of sun and short winter days, its more than an order of magnitude different to you California dudes. In this particular case it just meant that the size of panel and the size of float battery were not what the customer had been quoted by the supplier.

Nick

PS. That Scotland example was actually pretty similar to crossing the Bering Straits in December.

 

[Jeremy Harris]

50w per meter square is a bit understatement. Unless you are crossing the Bering Strait in November, you should be expecting two-to-three times more power from your solar panel(s).

I got these puppies on my boat, they seem to deliver all the 180w per panel for their 1.6m2 size.

http://www.wholesalesolar.com/products.folder/module-folder/sharp/sharp180.html

My panels are rated at 50W apiece, around 0.44m² each, with an efficiency that's typical for monocrystalline panels of around 14% - 15%. I have four of them mounted horizontally on a canopy. Max insolation at the equator at midday is maybe 1000W/m², which equates to around 150W per m² for a typical monocrystalline panel. I have 1.76m² of panels, so theory says that I should get around 1.76 x 1000 x 15% = 264W under those conditions, or around 150W/m² maximum. The very best solar panels available at the moment might get around 180W per m² under lab conditions with a full 1000W/m² of insolation.

However, the real world intervenes to make things much worse. If you're anywhere but at the equator and at midday the panels will be at an angle to the incident solar radiation, so reducing output, in proportion to the angle of the sun relative to the panel. Also, at any time except midday horizontal panels won't give their rated power even at the equator. Add in cloud cover, the odd rainy day etc and the average output really starts to drop - if anything, my estimate above was very, very optimistic for all year round power.

There's a pretty good webpage here that explains why you never get the maximum power rating published for any given solar panel: http://lightbucket.wordpress.com/2008/02/24/insolation-and-a-solar-panels-true-power-output/

For example, where I live the best I can hope for is about one tenth of the rated power during daylight hours, simply because of the combination of my latitude (around 51deg N) and weather.

For a solar powered boat you need to derate the panels to allow for the typical average daily power output through life. If you're relying on solar power to provide propulsion, then you have to size the panels to be able to generate enough power for the worst conditions - you can't work on the basis that you will get anything like the rated power, all day, every day, even if you only intend to operate at, or near, the equator.

Jeremy.

 

[John in CR]

It looks to me like that boat may be far more efficient than it's above the waterline look indicates. Notice how the squared part of the transom doesn't touch the water? What really indicates efficiency to me is the lack of wake in the pics of the boat moving. My complain would be in the styling. Why so darn square? I'd want to be efficient through the air as well as through the water with such a low power boat. With the ocean waves I'll have to deal with I want to go with a sailing catamaran hull and go out to at least 10m of length for a decent boat speed due to the 15-20 mile run out to the prime fishing grounds. It will have as much battery and solar panel as I can afford, a pair of large windsurfer rigs for wind assist when it's right, and a diesel genny in each hull as the primary power source on the higher than boat speed run out and back. All day trolling will be batteries, solar, and wind only. I call it a quadbrid.

 

[amberwolf]

Funny. One spammer's thread has been spammed by another.
OP's spam can be found here, too:
http://forums.iboats.com/showthread.php?p=2751555
http://www.ybw.com/forums/showthread.php?t=241467
http://www.boatforum.ca/threads/628-solar-boat-s
and probably lots of other places.