The Bow Repair

The bow looked a bit suspicious with a bit of a droop on the port side and some unevenness. I thought that they might have banged in to something and filled the cracs with some filler but it was a bit more involved...

The bow has been repaired by someone pinning a piece of wood using long dowels and then glassing over it with weave.  

First step was to dig the old slightly moist foam out and pour fresh 2 lb foam in its place.

After sanding the foam I taped the wood with thin duct tape 

and laid a single layer of 1-1/2 mat over it.

Since it is only one layer it was quite easy to wrap it under the lip

After the fist layer had set I added three more layers to get some rigidity to it.

I was thinking a bit on what to do next, I needed some sort of mold release. I had PVA but I had no experience with it as mold release agent. I used it to cover laminating resin to reduce tackiness when cured. What I came to think of is that resin basically sticks very poorly to about everything but well prepped resin but since my mold was a fresh piece of Resin I was a bit worried. What I di then was to basically give it two coats of regular red spray paint and after that cured I sprayed it with a few layers of PVA.

After the resin cured I pryed the mold of the tape, I painted it inside with Krylon and then a layer of PVA as mold release

After the mold was finished I pryed the old wood out of there leaving the top glass layer so I had something to build from.

After cleaning it up it is easy to see that the guy repairing it had simply cut the bow and put the wood right against the cut line.

As you can see here there is a bit of a droop towards the front. I was trying to flatten it but it was to stiff so I will need to deal with that later when I do the top of the boat.

The glass was tapered on all the edges so that the new and old glass is able to form a good joint.

Mold is held in place with a few clams and by a soft pad from the bottom.

As you can see here there is a gap between the mold and the old glass.

The old glass was sealed to the mold with fairing compound, If I did it over I would use the Hull and Deck putty I been using lately.

After the fairing compound was starting to set I laminated up 4 layers of 1-1/2oz csm  mat
and let that cure before popping off the mold.

Some very small sheets of spray paint flaked off but that has no implications since this will be sanded.

Excess glass sanded down and it looks pretty reasonable.

After sanding the raw edge and filling the corner with deck putty and glas+resin it is ready for the foam.

Before pouring the foam i looked closer at the other side before i stopped myself i tore that side and rebuild that also..,

I cut the lower flange off the old mold, flipped it over and used 3M outdoor masking tape on the bottom. I used the hull and deck putty to make a fillet in the tape-mold corner and when was that set i laminated it with csm an vinyl ester. 

Here I got both sides glassed and it is ready for foam.

Initially I used 2 lb foam but after working on the gunwale I concluded that the 2 lb stuff is to soft and is hard to work with so I got a 6lb foam kit that gives a harder, easily shaped foam that also provide better strength.

I poured the foam in three rounds waiting about 15 min between each layer. I use a disposable brush to make sure I wet all surfaces. The foam does not stick well against surfaces later in the expansion process when it starts to skin.

Three rounds of foam, 100ml first, followed by a 200ml batch and then a 100ml batch that I injected with a syringe in the voids under the lip. That is why you see balls of foam in a few locations.

To shape the foam i used the Harbor freight multi tool with a knife blade. It allows for relatively easy shaving of the foam and creates less mess than cutting with a hack saw blade.

After shaping with the multi tool I quickly sanded with the orbital sander and vacuumed it.

Overall it was pretty good but there was one area where the foam had pushed the old glass up a little that had to be sanded down and also a few voids that has to be topped up.

Initial sanding of the foam.

To fill the voids I simply mixed up about 40 ml of foam and brushed that on the depressions in the foam. The 6 lb foam gives a pretty decient work time before it takes off. I typically stir it very hard for about 10-15 seconds and then if I act quick I can even suck it up in a syringe before it take off and expands.. 

Filling of voids in the foam using a disposable brush.

Even if it feels like one just brushes on a thin layer, it never fail to surprise in how much it expands... 

All voids and low spots remaining after initial shaping and sanding filled with fresh foam brushed on.

Next step is to finalize the shape using flexible sanding blocks and then undercut the edges and apply glass.

The finished foam ready for undercutting.  I might sand down little more. One can allways fill back up bit if I am to high I will have issues.

As one can see here the edge is not perfectly fair but It looks like it is within about 1/16" so I should be able to work with that. I might use CSM to fill the voids before putting on fairing compound at the end.

Before building the structure I undercut the foam all the way around with the Multi-Tool. I only cut about 1/4" to 3/8" deep and about 1/8" thick. 

The edge undercut with the MultiTool

In the beginning I had a lot of problem wetting the glass around the edges of the old glass. The glass is to stiff and there is to much volume to fill so it is very easy to get voids that are hard to clear without overfilling with resin. Recently I been refining a method where I first glass over the foam and make sure it goes under the lip of the glass. Then I add the Hull and deck putty followed by two or more layers of CSM and glass.

The multi tool makes a cut that is about 1/8 thick and 1/4-3/8" deep gives enough to grip on for the patch.

This is the overall structure before the repair showing the build up process to that point.

The first step is to lay 2 layers of glass over the foam and make sure it goes in under the old glass.

The groove is then filled up with Merton's Hull and Deck putty so that it is easy to glass over the repair without creating voids.

After the cut is filled the whole patch is covered with two layers of CSM.

 

Finished lamination showing the hull and deck putty along the edge (gray)

I did half the bow on one shot. This used about 100 ml hull and deck putty and 200ml Resin. 

Next day i finished the other side. After sanding i think it will be pretty good.

Second side finished. 

No more crummy wood. Just foam and glass. Just like a Whaler!

 

Sanded and glassed one more layer and also the area around the bow eye is filled up.