This is for my boat, so it has two gentle simple curves, no compound nonsense. The few times I've been involved in doing this the person I was helping just didn't do anything correct and they ended up getting cracking and crazing and all sorts of ugliness
Example of the windshield, the curve at the top is a sign of age or god-knows what and shouldn't be there
Not plexiglass ever. Shatters into vicious shards. I have tried big curves with lexan and it likes to warp but I have a friend who had pretty good success with a curved windshield by leaving it in the sun on a hot day on top of the old glass one. It collapsed into a pretty close approximation. But those are some major curves you are trying to replicate.
Google "drape forming lexan"
It takes a large oven. We made the form with plywood with felt pulled over it. It was easy but takes careful monitoring of the temperature.
I have made curved door window glass for a Zagato bodied abarth this way. It wasn't difficult, just careful work.
I'm hoping it's not too difficult to do one from polycarbonate since I don't have the budget for a custom piece of glass. The curves I need aren't anything like that boat though.
Polycarbonate "Lexan" can be bent pretty well cold. I have even put tight folds in it with a sheet metal brake. Acrylic "plexiglass" has much less formability. Acrylic could be made into that windshield, but if bent cold would be very close to its stress failure limit, possibly over, and like Bearmtn says, it shatters sharply when you excide that limit. Photo below is .090" Lexan bent cold and held to shape by the aluminum flange. Made to replace shattered acrylic.
In reply to Trent (Generally supportive dude) :
Did you make your own oven? It looks like 140-150 C is about the pliable point of it.
I'm wondering if I can make something out of my own heating elements.
I did the rear window on my rx7 cold. Just started in the middle and pop riveted it in place as I went around.
Trent (Generally supportive dude) said:Google "drape forming lexan"
It takes a large oven. We made the form with plywood with felt pulled over it. It was easy but takes careful monitoring of the temperature.
Trent is on track with that.
The only thing I want to add is to heat it slowly at first, it drives off moisture that can cause bubble if heated too quickly in some plastics.
Lexan isn't real bad about it but I have ruined many pieces (various plastics) getting in a rush and bubble city!
I have bent them by draping the Lexan over the glass version of what I am trying to make. Used a propane torch and heated them very slowly making sure to keep the flame far enough away to not burn the surface. Not easy, but it works. Next time I will just make a big box, stick the torch in one end, and just wait for it to happen.
I have never used heat but Lexan will take a lot of bending without breaking. Formed a curved windshield by bending and mechanical clamping in place. I have taken strips of Lexan a couple inches wide and 3/16 thick and bent it double with out breaking. Think you would definitely need to heat form the boat windshield over a form.
Let me know how it turns out. I tried and wasted big dollars on a large sheet of polycarb only to ruin it. I used a hair dryer because I didn't want to risk overheating it with a heat gun or a torch. One side I got too warm and it refracted and got too thin. The other side I didn't get hot enough and it sent a crack halfway across the sheet. That stuff isn't cheap.
I ended up going to a boat junkyard and finding a windshield I could adapt. This was for a runabout much like yours (but aluminum). Mine died when a buddy slipped and dropped a cooler on it, so I went and bought a walk-through windshield for $50 and was able to bolt it on with minimal fuss. Nice for shore landings, too. Now I can just open the center and walk on the hood instead of crawling my arthritic butt over it.
Other bonus is that it had flat, tempered glass in a rigid aluminum frame. If a buddy ever drops another cooler on it, I can just have new glass cut.
Nice boat, by the way. Is that a Lone Star? About a '68?
Lonestar Flamingo, 1959 according to the DMV.
Reading into it, I'm thinking it might be easier to just get a new one made, if I can find a local place that does them.
Mine was a 58 Sea King from Montgomery Ward. Sturdiest boat I have ever seen.
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