glass panel in bottom of punt

[dylan winter]

I am going to built duck punt out of 6mm ply

I would love to have a glass panel in the bottom

for filiming the fish

I want -t to be at least 8 inches wide

and 12 inches long

some-one said I could use windscreen glass - windsheild

can I cut it

would side window glass do just as well

Dylan

[Ian McColgin]

I used lexan on one boat but that can scratch. On the other hand, you know you can stand on it. Great in the dink and I'm thinking of putting something such in a kayak.

Auto glass is laminated and hard for a non-pro to cut so you might have to get it from an auto glass shop.

Have some sort of rim that you can arrange a hood on since glare can be a problem at times.

[P.I. Stazzer-Newt]

Glass is NOT a good idea - laminated windscreen material doubly so.

Makrolon or Lexan -and if you you can source the scratch resistant varieties use in industrial guards then you're set.

[dylan winter]

Brilliant

how thick do I need it and how big can I make it

Dylan

[P.I. Stazzer-Newt]

Its considerably stronger than plywood - though not as stiff - and available in eight by four sheets at half inch thick - which would be very expensive. The eight inch by twelve inch size mentioned in the initial post should be easy enough - spec it to cope with the full weight of a large clumsy man wearing boots.


http://www.theplasticshop.co.uk/lexa...2mm-thick.html

ten foot by six and a half foot and half inch thick - £2471.18

[dylan winter]

Its considerably stronger than plywood - though not as stiff - and available in eight by four sheets at half inch thick - which would be very expensive. The eight inch by twelve inch size mentioned in the initial post should be easy enough - spec it to cope with the full weight of a large clumsy man wearing boots.


http://www.theplasticshop.co.uk/lexa...2mm-thick.html

ten foot by six and a half foot and half inch thick - £2471.18

righto

see through boat then

price a mere £5,000 for materials

Dylan

[P.I. Stazzer-Newt]

You want to see the fish, or you want the fish to see you?

[P.I. Stazzer-Newt]

Alternatively.....


http://www.gentrycustomboats.com/gallery.html

[keyhavenpotterer]

Lots of eBay suppliers can supply small rectangles of lexan. http://www.ebay.co.uk/sch/i.html?_nk...=p3286.c0.m359

[JimConlin]

Acrylic (Plexiglass, Perspex) is not as tough as polycarbonate (Lexan), but does not scratch as easily. For a 9" x 12" window, I'd try 1/4" polycarbonate or 3/8" acrylic.

A 12" x 12" piece of either should cost $15-20. Try McMaster and other fine stores.

[kenjamin]

I got my 1/2" thick Lexan for Xena's waterproof motorwell port from a glass shop. It was a left over piece from a clear dance floor installation. I got it for 1/2 price but even then it was a pretty pricy project. The finished product is pretty awesome though. It is jump up and down on it tough and it's really cool to see the bottom going by in thin water. Since it is set down in the bottom of the motorwell, many times there is much less glare on that 10 inch port of Lexan than the water surface outside the boat. I use four stainless wing nuts to hold it in place and there is a large o-ring around the perimeter to make it waterproof. In place it is clear and completely flush with the bottom of the boat but it was very well designed to be that way by an instrument maker at a major university. The brown is layers of marine ply and the light blue is the layers of Lexan. The dark dots are the o-ring seal. The layers of Lexan were bolted together with big flat headed screws and threads in the holes of the Lexan were done with a kit I bought at a home center. I used silicon to seal the layers of Lexan and epoxy for the layers of ply.

[Thad]

You can't bed lexan or other plexies with urethanes, butyls, etc, without risking crazing from interaction with solvents. Silicone is recommended.

[dylan winter]

beginning to think laminated glass is the way to go

Dylan

[Thad]

I think it simpler and better viewing. I rode in a number of glass bottom boats in my youth giving great views of reef life. I'm sure they were glass and probably heavy "plate", not laminated. BUT, googling for designs the only one I found uses car window glass, laminated. I know that is easy to get from glass people, but I don't know what it gets you in the way of security -- I'd think not much, but it's probably easier to get a couple of 1/8" pieces laminated than 1/4" plate much less 3/8" or greater.

[Todd Bradshaw]

Mt Starboat had a 1/4" Lexan window on the bottom so that you could see if there were weeds on the keel and it was extremely tough. I can't imagine needing anything thicker than that for your use. Scratches on the bottom (outside surface) don't seem to matter an awful lot as they pretty much disappear when the boat's in the water and that surface is wet. It is a good idea though, to be careful about scratching the inside (though with a little water wiped over the surface they also diminish greatly). A black cloth glare hood of some sort would be a really good idea if you intend to shoot photos through it or want a really good view. It beats trying to shield it with your hands, which is what we had to do.

How tough? When I re-did the bottom and decided I didn't need the window, it was calked-in with some sort of adhesive, plus countersunk screws, and they were buried in some sort of resin. So naturally my first thought was just to knock it out or break it up with a hammer. No freaking way! I pounded on that thing just about as hard as I could and it neither budged or broke. I finally ended up cutting out the fills with a Dremel and small chisel, cutting out the calk and finally could pry it out in one piece. I don't think there is any way that a small 1/4" Lexan window would fail on a boat that gets anything close to reasonable care.

[JimConlin]

One other issue with the plastics, whether polycarbonate or acrylic is that they're thermally active, meaning that they expand and contract in response to temperature changes more than glass.
A foot-long piece of acrylic or polycarbonate will grow/shrink about .05" in length in response to a 100 degree F temperature change, so if you fasten it with screws, drill the holes sloppy. Better yet, design a joint that uses flanges and compliant sealant rather than through fastenings.

[dylan winter]

bum

Todd just talked me into Lexan

and then Jim talked me out of it again

back to laminate glass

sinking is not a terminal thing with the boat as it is shallow sailing all the time

annoying leaks will be really ----- annoying as I will be sitting in the bottom of the boat

laminate is cheap too
D

[Ron Williamson]

Build it into a well that's higher than the waterline,then you can eliminate glare and any worries about leaking or breakage.
R

[The Bigfella]

A number of people have said don't use laminated glass, and I'll say the same. Laminated glass is a couple of pieces of thin glass with plastic in the middle. Its advantage is that when it breaks, it breaks into small pieces, rather than shards. That adds nothing to this purpose.

When I replaced the old glass windows on Grantala... all but one were solid glass. One was laminated. The only one that broke as I removed them was the laminated one. I replaced them all with tempered glass, mostly in 8mm and 10mm thickness. I think I may have used 12mm for the main screens.

[The Bigfella]

What I meant to say was.... the laminated glass breaks a lot easier than thick tempered glass.

[MiddleAgesMan]

Mr. Winter--I have a good supply of Lexan off-cuts and would be happy to send you what you need. My stuff is 3/16ths or 5mm thick. Even at that thickness you will not be able to break it IMO.

Lexan expands and contracts with temperature changes so your screw holes should be larger than the screws. At the size you mentioned this problem will be minimal, though.

[dylan winter]

wow

great offer

although I am in the Uk

so postage costs might make a nonsense of getting it to the UK

still confused about what to use - although I am probably a month away from decison day

D

[P-man]

i would vote for the lexan. as long as your holes are slightly oversized and your sealant is flexible, the size you are considering shouldn't give much trouble from expansion/contraction. make sure to leave a slight gap around the edge also (ie, it shouldn't fit tightly in a wooden frame. leave room for a bead of sealant.)

good luck.
perry

[MiddleAgesMan]

wow

great offer

although I am in the Uk

so postage costs might make a nonsense of getting it to the UK

still confused about what to use - although I am probably a month away from decison day

D

Just let me know if you can use it. I can cut it to your 8 by 12 size to keep the package/shipping costs at a minimum. I have both clear and smoked but I assume you'll want clear.

This windscreen was fabbed up out of three pieces of the smoked stuff:


I've carted this stuff around for years and wasn't sure if age and exposure to the elements had hurt it so I did a little test before I made the windscreen. I tried to drive a nail through a small piece. The nail just bounced off; I could not get it to shatter or even distort.

[CWSmith]

Buffing scratches out of plexi isn't hard, but it takes time. I would recommend a shallow, but stiff, door over the plexi so you don't scratch it from the inside. Still could scratch from the outside, though.

[tpelle]

I just keep having visions of hauling up the anchor and dropping it in the bottom of the boat.............and I think you get the picture.

But back to the subject at hand, I think I'd use something cheap and easy to work and just plan on replacing it as needed. If dragging the boat up on the the beach was in the plans I think I'd have to add some skegs to guard it.

[dylan winter]

I just keep having visions of hauling up the anchor and dropping it in the bottom of the boat.............and I think you get the picture.

But back to the subject at hand, I think I'd use something cheap and easy to work and just plan on replacing it as needed. If dragging the boat up on the the beach was in the plans I think I'd have to add some skegs to guard it.

no anchor

boat is only 15 foot x 4

I am planning on some protective skegs

might go cheap and cheerful

the aim is to film through the panel - so scratches will be bad

Dylan

[Gib Etheridge]

You can fold 1/4 " polycarbonate in half (if you're strong enough, probably not) and it won't break. Whatever you use remember that if it breaks or dislodges you'll have a big hole in the bottom of your boat. If you put it at the bottom of a well that extends up as high as the sheer you will not have lost any freeboard should that happen, and it will be shaded as well. Also, you won't be able to step on it if it's in a well. Put a cover on the well and you have a seat. Drop a piece of foam on top of the polycarbonate to protect it and you have a good little protective storage locker for the camera. Caulk it into a slightly oversized rabbet and hold it there with stops or bolts with washers in oversized holes and you'll be good. You can get cut-offs at your local plastics supply, look in the yellow pages.

[dylan winter]

the well idea would work

but this is the boat

where is it going to go

http://www.keepturningleft.co.uk/blogs/duck-punt/

dylan

[flyinwall]

just a little idea check this out

http://www.glen-l.com/designs/special/glassbottom.html