Monday, March 4, 2013

Making the fiberglass hawser tube for the bulwark.

The new solid bronze hawsers that I want to install have a smaller O.D. flange than the spun bronze ones on the boat now. This creates a problem as the opening in the boat is too large for the new hawsers. The new ones will cover the opening, but the screws have nothing to grab onto. I have to fiberglass the existing holes smaller so the new hawsers will fit
 My friend Marty at the marina came up with the great idea of fiberglassing a tube from one side of the bulwark to the other for the hawser to mount in. I like the idea as it will make the area completely waterproof and not depend on sealant to keep the water out. You can read about it here.  (FYI for my boat nomenclature challenged friends the bulwark is the "wall" at the very edge of the deck. Most small boats don't have these. It keeps you in and the water out..some of the time. For a better description look here at #4.)
Original spun bronze
New solid bronze 

The old spun bronze hawser versus the new cast one. No wonder the spun ones would crack! All of mine are cracked.

First I have to make a tube. I used polyester resin as it is cheaper than epoxy and didn't need to be structural. I needed the tube to be 3 5/8" O.D. (outside diameter) and the I.D. (Inside diameter) to be just large enough for the bulwark hawser to slide into.
I made a wooden caliper that was the O.D. of what the tube needed to be.

I needed a form that was the correct size for the hawser to slide into.
I found that the paper core of a wide format printer was the correct size. It was just a tad bigger than the hawser...perfect.  So I cut it to 18" long, wrapped it with saran wrap and packing tape and screwed it to a piece of wood to hold it in the vice. (The resin will not stick to saran wrap or packing tape.)

You can see I covered my bench with saran wrap to catch the drips.
I used some cloth my neighbor gave me to build up the thickness as I needed about a 1/4" all around.
I kept using the wooden caliper to check my progress as I added layers. Finally I had the thickness I needed.

I waited for the resin to harden then I removed the "form" tube from the fiberglass tube. I wish I could say it just slipped right out but I really had to just tear it out. It wasn't stuck to the fiberglass, it was just really tight!

(Looking back at the way I made the tube I would have made someway to be able to rotate the tube so I could see all of it easily. Or just put the jig in the vice with the tube hanging over the floor sticking out so I cut see it all the way around and have better access to the back. With it being over the bench I did not have great access to the back of the tube.)

I cut off the ragged ends of the tube and squared them up with 36 grit sand paper and 80 grit.

Time for a test fit.
Looks good. So I cut a 3 1/4" long piece and squared up the other end. The bulwark is 3" wide, at least the ONE that I measured. (There are four.) I left the tube a little long so I can "fit" it at the boat.

Next I took to cutting down the hawser itself. The over all length of the two halves together are over 3" long so they have to be cut down.

I figured out how much I needed to cut off and marked it on the longer half of the hawser.
Then took tape to mark the cut area. This would be a better guide that just the black line.

And I started to cut away with the hacksaw. I thought about using the abrasive chop saw I have but I don't think I would be able to get an accurate cut with out making a jig. So the hacksaw it was.
I was able to get a fairly square cut. I did lay a sheet of 80 grit flat on my bench and sanded off the high spots of my cut.

Now I put the hawser inside the tube to see what it would look like.

Not too bad if I say so myself. Lets wait and see how all this really works this weekend when I go to install it!

So the weekend came and went. I was able to get one of the tubes installed. I had to grind down the tube exterior to get it to fir in the existing opening. I used a 4" grinder. This made short work of it. The fit was really tight and I had to hammer the tube into the opening. It took several attempts to get the tube to fit. I wanted it to be a tight fit so I took my time.  I had cut the tube a 1/4" long so that I could grind it flush to the bulwark. I hammered the tube in from the deck side flush with the outside so any grinding would be done from the deck.

Here is the tube after I ground it down and had a force fit. Mind you I did check to make sure the bronze hawser did fit because if I got the fit to tight the fiberglass tube could distort and the bronze hawser may not fit.
The final deck side fit with the fiberglass tube ground down and a slight bevel ground into the bulwark to give some "bedding" room for the epoxy. 

The outer side with the tube in place. This side already had a bevel on the bulwark so I just had to had epoxy.
Below are the openings with epoxy installed. I did sand and clean everything before I put the epoxy on. I used a syringe to fill the existing screw holes.

These last few shots are the final test fitting of the bronze hawsers into the installed tube. I did have to sand a bit of the epoxy off. I did put it on a bit thick so I could make sure I covered everything and made the final fit as snug as possible.

I did put some sealant around the outer flange and the new screw holes. Plus I put a bead where the two halves of the hawsers meet in the tube itself. 

One down three to go. I did get the other three tubes installed and epoxied in. I just have to cut down the three remaining bronze hawsers and install them.