Marine windshield

[BellBoyBob]

Hi All:

I am looking around to find some sort of channel aluminum extrusion for 1/4" Plexiglas (with a rubber gasket). I called Taylor-Made as they have their factory here in upstate NY. They were not too helpful saying that they don't sell the aluminum but will build the project themselves (at an exorbitant price, I am sure!!) My original BB bottom windshield frame is what I would like to replace. I want to mount the windshield in a cleaner way (as I have to remove it to put the boat in my garage) This necessitates a new bottom frame.
Any ideas where I might look?

Thanks,
Bob

Have your tried googling "extruded metal"? Take a gander at McMaster Carr too.

[Tim McCrain]

Bob,
I'm assuming that the existing frame bolts or screws in place and that is what you want to avoid dealing with every time you park the boat. Perhaps you could install a latch system that would use the existing frame? I have experience in designing / engineering knock-down fixtures and assorted weird things, maybe we could figure something out that would work for you?

Tim

[BellBoyBob]

Tim -

Thanks. I will post some detailed shots of what I have now once the boat is out of storage.
Best,
Bob

[Tim McCrain]

Great, there's got to be something we can do without jettisoning the original frame. Does the orginal fasten into place with screws from underneath into the aluminum? If so, a good close-up of the bottom of the frame would help.

[BellBoyBob]

Tim -

Actually, the windshield is hanging on the rafters in my garage. I could show you what I did to attach the plexiglass to the frame so that it (the entire bridge windshield) could be taken on and off the boat. I will post tonight.

Bob

[BellBoyBob]

Ok, Tim here is what we have. I typed captions on each picture to point out exactly what is going on. What I am dissatisfied with is the sloppy way in which the windshield "fits" against the cabin top with the cut off bolts blocking the bottom frame from securely snugging up to the top of the cabin. I though I might use a Dremel cut off wheel and cut half of the nuts away to make it fit better. If you have a better way of securing the bottom of the glass to THIS frame, I am open to any ideas. I also thought it might look neater to have the bolts protruding out from the inside and to secure the frame with cap nuts?

What do you think?

Bob

[Tim McCrain]

Bob,
A few questions:

Are the bolts through the windshield and lower frame necessary to hold the shape of either? In other words, if you removed the bolts would the windshield and frame both retain their shape? If not, how out of shape would they be? I'm trying to understand how much tension the assembly is under.

How many bolts do you feel are necessary to hold the windshield in place on the boat? How many are you using now?

Am I correct in assuming that to install the windshield now you hold it in place and insert bolts from the outside through the lower frame with nuts on the inside?

[BellBoyBob]

When I restored the bridge windshield, I used a product called polycarbonate. This plastic glass can be bent "cold" - that is without the need for an oven and dehumidifying processes that is required for the stiffer Plexiglas products. I do not believe that the polycarbonate would spring out at this point if I removed the bolts that hold the bottom frame to the glass. The top frame also holds the curvature.
I used six 2" bolts to attach the windshield to the cabin. The bolts are inserted from the outside of the bottom frame, pass through the glass and then are screwed into "T" nuts which are in wood blocks epoxied onto the inside of the cabin ceiling under the headliner. I think I can get by with six bolts to securely attach the windshield to the boat.

So -

1). Can I restore the bottom frame by buffing and polishing the aluminum to get all the scratches and gouges out?

2). Can I fill the bolt holes with some sort of metal filler, polish and re-drill for another type of attachment technique?

3) Can you think of another way to attach MY bottom frame to the glass that would allow a better (smoother) seam against the cabin roof than with all those bolts?

Thanks,

Bob

Bob
You really have some nice scratches in the aluminum. You can actually start by sanding out the worst scratches. I like to use a good wet/dry automotive quality sandpaper for this. You will have to decide how course to go but usually 400 grit is course enough then going to 600, 800 and 1000 grit. At this point I use a little polishing wheel on a die grinder with polishing compound in a couple different grits to bring it back to the "chrome" finish.
As for the holes the only success I've had to fill them is to have them tig welded and then use the above process to blend them in as good as possible.
I'm also interested in what you find out here as I would like to do something similar with a small windshield on top of my Sedan. Barry

[Tim McCrain]

When I restored the bridge windshield, I used a product called polycarbonate. This plastic glass can be bent "cold" - that is without the need for an oven and dehumidifying processes that is required for the stiffer Plexiglas products. I do not believe that the polycarbonate would spring out at this point if I removed the bolts that hold the bottom frame to the glass. The top frame also holds the curvature.
I used six 2" bolts to attach the windshield to the cabin. The bolts are inserted from the outside of the bottom frame, pass through the glass and then are screwed into "T" nuts which are in wood blocks epoxied onto the inside of the cabin ceiling under the headliner. I think I can get by with six bolts to securely attach the windshield to the boat.

So -

1). Can I restore the bottom frame by buffing and polishing the aluminum to get all the scratches and gouges out?

2). Can I fill the bolt holes with some sort of metal filler, polish and re-drill for another type of attachment technique?

3) Can you think of another way to attach MY bottom frame to the glass that would allow a better (smoother) seam against the cabin roof than with all those bolts?

Thanks,

Bob

Bob,
Sparrowhawk has the right approach for dealing with the scratches. As far as the fastening, here's my suggestion. This method assumes that the windshield will hold its shape without a great deal of tension when the bolts are removed.

First, remove the lower frame and sand / polish until you're happy with the finish. Then run a good bead of clear silicone along all surfaces where it contacts the windshield and bolt it back together. Make sure everything is really really clean before applying the silicone. After the silicone sets really really well, take out the bolts. In the locations where you feel you need the fastening, do what you've been doing to fasten the windshield to the cabin. In the other locations, which served only to fasten the frame to the windshield, cut off bolts to a length that will not protrude past the back of the windshield / frame assembly and glue them in place with silicone. These "dummy" bolts are for appearance only. The idea is that the silicone will hold the frame to the windshield when the assembly is not bolted to the boat. When the windshield is installed, it fits tightly against the cabin. To minimize movement, a very thin rubber gasket could be applied to the frame where it contacts the cabin, this greatly reduces the transmission of vibration and reduces the effective holding power required from your fastenings.

When doing this sort of thing with knock-down fixtures, we would normally install some alignment pegs that would protrude from the main assembly (in this case the boat) and socket into holes drilled into the sub-assembly. (the windshield/frame) This would allow one person to quickly place the sub-assembly and then install the bolts. We would use nylon pegs or threaded studs so they didn't scratch. If you didn't want to do this, you could get some nylon threaded studs that you would thread into a couple of bolt holes a little ways, slide the windshield on to them, install the other bolts, then remove the studs and install the last two bolts.

Does this make sense? This is the simplest thing I could think of that uses your existing stuff without permanently altering anything.

Tim

[BellBoyBob]

Very interesting, Tim. Do you think marine silicon adhesive would be strong enough to hold the aluminum frame to the plastic glass? Then, precisely what would you use to attach the windshield to the boat?

Tim / Bob

Just a suggestion here. I have an older Airstream travel trailer that I have had trouble with sealing roof vents on. I recently learned through the Airstream club that silicon does not react well with aluminum and this is probably why my vents are not staying sealed for long. I am changing to a different sealer and suggest this might be a good idea for the boats as well. Barry

[Tim McCrain]

Oops.

Bob,
In re-reading your posts, I can see that I goofed in what I thought we were working with. I missed the fact that the frame and glass are held together by t-nuts in the frame, my approach was based on the incorrect assumption that ALL the bolts were thru-bolts from the outside. So, my thoughts on the "dummy" bolts should be ignored. Sorry for what must have been confusing reading ...

However, I still think that your present method of bolting the windshield on is as simple and reliable as you're going to get, so the problem to solve is the protruding nuts / bolts. If the bolts originally went all the way through the frame, glass and cabin, and if they are all in the same locations, perhaps the simplest thing to do is to drill the holes in the cabin large enough to clear the nuts and the glass will fit snug against the cabin. If that isn't an option, (I know I hate to drill any more holes than I already have) then adhering the glass to the frame seems like a good idea still. With Barry's advice about the silicone / aluminum issue, it seems that another adhesive would be a better idea. In any case, the adhesive would only serve to hold the frame to the glass when removed from the boat, you would still fasten it the way you are now. And studs screwed into the cabin with acorn nuts on the outside would look nice, and probably make installing the thing easier as you could slide it over the studs to support it while you put on the nuts.

Tim

Tim
Haven't entirely thought this through but suppose there were "studs" that were fixed on the cabin roof but were made so they pointed forward and angled up slightly. That way the windshield would be set down just in front of them and slid back to engage. Then possibly only three over center latches used from behind the windshield to pull it back firmly onto the studs? I also think I'd be looking into some kind of rubber/plastic edging or seal to go along the bottom of the windshield frame to better seal and conform to the cabin roof?