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Hull

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Re: Hull

Postby Gio » Wed Jun 27, 2012 9:43 pm

I don't know XD. Tomorrow i will draw a better hull. I've done a triangle hull because we can have a big space for the solar panel. Thanks for your help and sorry for my bad explanations and my misunderstandings.
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Re: Hull

Postby Gio » Wed Jun 27, 2012 9:57 pm

Another problem: the hull will be very strong. If a shark attacks it??
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Re: Hull

Postby Scorp1us » Wed Jun 27, 2012 10:04 pm

From what I know about sharks, they may be curious, but if you're not chumming and it doesn't look like a seal, you'll be ok. Fiberglass would be the choice. But any kind of sealed plastic would work.

See, I would just say don't worry about mounting the solar panel. Deign your hull, then just bolt it to the top. If you want to get really fancy, you could control it base on time of day and GPS location, so that you're always aimed at the sun. This could be computed by the computer.

Also look into getting a lens that can focus more light on the panel. You can cheat like that. :-) If you have a lens that can concentrate light, your solar panels can be smaller.

See, with solar, you only need the force of a gentle continuous push to get there. Everything else just gets you there faster.
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Re: Hull

Postby Gio » Wed Jun 27, 2012 10:11 pm

OK. Thanks a lot for your help!
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Re: Hull

Postby hbarrass » Wed Jun 27, 2012 10:50 pm

Have you considered a bi-stable design?

If you imagine a tri-marin with relatively tall hulls. The superstructure between the centre hull and each of the outer hulls can be kept clear of the water. For the additional expense of 2 sets of solar panels, you could make a design that can flip over but continue running.

Is that an idea worth kicking around for a while? I'm concerned that even the most stable design can never guarantee to avoid a knock-down and it's hard to imagine a self-righting design which can also expose a wide, flat surface to the sun.

Best of luck,

Hugh.
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Re: Hull

Postby FishPi » Wed Jun 27, 2012 11:10 pm

hbarrass wrote:Have you considered a bi-stable design?

If you imagine a tri-marin with relatively tall hulls. The superstructure between the centre hull and each of the outer hulls can be kept clear of the water. For the additional expense of 2 sets of solar panels, you could make a design that can flip over but continue running.

Is that an idea worth kicking around for a while? I'm concerned that even the most stable design can never guarantee to avoid a knock-down and it's hard to imagine a self-righting design which can also expose a wide, flat surface to the sun.

Best of luck,

Hugh.


Hello Hugh,

Someone, somewhere did mention the idea, its just the cost that was putting me off.

A monohull, catamarano, or a trimaran are all possibilities, the solar panels I am looking at using can be adapted to either design.
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Re: Hull

Postby Scorp1us » Wed Jun 27, 2012 11:32 pm

Ok, so here is my current favorite. It's a B-wing fighter configuration.
rect4227.png


The top pod has almost everything, there is a centerboard and a ballast (batteries?). This will never capsize. It has a low profile, so wind should not effect it much.
At the very top is your solar panel deck.
Below that is your main pod full of flotation, batteries, logic boards and motors.
Fascinating fact, batteries can require cooling. Putting them in the ballast pod makes sense. Also, if your ballast pod is the same size as your floatation pod, and top & bottom are symmetrical, then that's very easy on the manufacturing. Also on the bottom pod, you can put an intake tube if you decide you need additional cooling up above.

I toyed with the idea of putting a prop on the bottom pod, but I like it at the top.

The pink boxes are various areas - batteries, CPU, etc.
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Re: Hull

Postby FishPi » Wed Jun 27, 2012 11:37 pm

I like the design, simple an effective.

what about rotation between the upper and lower pods caused by the forward motion of the prop at the top, and the dragging caused by the lower pod. It might cause the prop to lift out the water. maybe a thrid small pod in the middle could house the drive system? that will help with the motors cooling.
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Re: Hull

Postby cgorton » Thu Jun 28, 2012 2:13 am

I think if you can avoid any thru-hull penetrations you should be able to keep the inside dry. A bilge pump would likely be more susceptible than it would help. You always get a little back-wash and one-way valves just leak.

There are marine fittings for passing wires through water-tight bulkheads and if you a wire to penetrate the deck you might be able to use something like this.

I think having the prop shaft penetrate is trouble. You'll never get a truly dripless shaft seal. You are wise to investigate the external drive idea.

I definitely agree with those advocating a monohull. A cat would be a nightmare if one prop out performed the other and this vessel will definitely turn over. It's not the huge waves you need to worry about. Even a near gale will have small 8' waves that have breaking crests. It's that crest that will roll the hull. But, at such a small scale, it's a simple matter of getting the center of gravity kind of low, and it will roll right back up.

Have you settled on hull material? If you made something like an Optimist sailboat (boxy) out of aluminum you wouldn't have a heat problem- the whole thing would be a sink. But, not easy to weld.

If you go with fiberglass or even marine grade ply coated with West system epoxy, I bet you could mount a plate outside the hull and maybe transfer heat passively. But, I think you should see whether you have heat issues on the POCV first.
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Re: Hull

Postby Scorp1us » Thu Jun 28, 2012 2:23 am

Well, it depends on the swell and overall length. With the ballast it should not rock much. It'll just bob. And the torque for the motor should not be that much.

If you want a dual prop design, then put one on the bottom as well.

A stuff box should be fine for an inboard motor. Don't forget that we're dealing with low voltage, and we're going to fill this with foam. I'd even contemplate a wet design.
Last edited by Scorp1us on Thu Jun 28, 2012 2:30 am, edited 1 time in total.
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Re: Hull

Postby knightwolf » Thu Jun 28, 2012 2:26 am

is there another way to propel it, my thoughts are around a fish tail as that would reduce the possibility of getting something caught.

propellers are renowned to get fouled and small ones on a boat even more so.

also just an idea well a question and an idea. does the solar panels work just under the surface, if so then you would get a lot less turbulence if it was just submerged.
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Re: Hull

Postby Scorp1us » Thu Jun 28, 2012 2:31 am

I forget the actual number, but I saw it recently, and water does degrade it quickly. And don't forget that water clarity is variable. In the surf it's pretty brown.
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Re: Hull

Postby Scorp1us » Thu Jun 28, 2012 3:09 am

What does everyone think about just getting a Subn fish hull and using that?
Here's a boat and trailer!
http://cgi.ebay.com/ebaymotors/sunfish- ... 2c66558069

Or this: http://cgi.ebay.com/ebaymotors/porpoise ... 41677e3ef1
Getting a prefab hull is a steal. Then we'll just have to seal it.
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Re: Hull

Postby Scorp1us » Thu Jun 28, 2012 3:23 am

knightwolf wrote:is there another way to propel it, my thoughts are around a fish tail as that would reduce the possibility of getting something caught.

propellers are renowned to get fouled and small ones on a boat even more so.

also just an idea well a question and an idea. does the solar panels work just under the surface, if so then you would get a lot less turbulence if it was just submerged.


There is a reason why boats don't use fish tails for propulsion. They are mechanically more complicated. Have you ever tried to scull a boat? It's not much fun or efficient. Fish incorporate the whole body into movement.
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Re: Hull

Postby knightwolf » Thu Jun 28, 2012 5:16 am

that is true,

with the shape above, depending on how big the end concept was you could always make it out of aluminium shaped and welded. would be very strong and corrosion resistant. Heavier than fiberglass but stronger. and perhaps some sort of shielding or cover for the propellers so it not totally exposed.
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