catspaw nester....glassing the seams

[vinegar joe]

help! after stitching the pieces of the dingy together, i glassed (epoxy and 10 oz cloth) the interior seams without apparent problem. i thought the exterior seams would be easier.......however, as the epoxy set up, several areas of the tape/cloth lifted up and cured in that position (i.e., there's a gap between the tape and the hull.

question: i can cut the problem areas out i with a utility knife without difficulty. should i just retape/glass (with slight overlapping) the problems areas and then fair down the overlap areas, or attempt to take the entire tape off in the problem areas? or?

also, i'm thinking that the problem must have been caused by not wetting out the surface well enough before laying the tape/cloth down....is that right? is there something else i could have done?

thanks for any/all input.

v.joe

(btw....wire ties were a little labor intensive. but cleaned up nicely prior to glassing and the shape of the boat seemed very symmetrical from the get-go.)

[Melissa Goudeseune]

Hi Joe,

I recently did the same work on my mini-paw. What I found was that I needed to cut a "dart" (that's a sewing term) in a couple of places, to get the glass cloth to lay flat. This was done while the epoxy was still wet, so I could immediately see the improvement.

I had the same issues with cloth that cured with a bubble, but they were 1/2" diameter max, so I just filled them with epoxy filled with milled glass fibers.

For larger areas, I would be tempted to put a small patch over that area.

As for the cause of the problem -- I think it's related to the curve in the joint, and the fact that the glass tape runs over the corner, so it doesn't want to follow the curve. What I did to minimize this problem was what I'd call "poor man's vacuum bagging". Once the glass tape was wetted out, I covered that with a strip of nylon peel ply, covered that with several layers of newsprint to soak up the excess epoxy, then taped the whole thing down with clear packing tape. The tape was applied at right angles to the fiberglass, from the bottom of the boat to the side. This applied pressure on the corner, without having to "bag" the entire hull. I'll post pics on my website soon.

Michel

[Designer]

Your problem might have been having the corners too sharp. 10 oz. glass does not like to be bent around tighter than a 1/4" radius, preferably larger. It will lift on one side or the other or both. Now that you have the problem, you can cut out the bubble, sand the glass around the bubble to a nice taper and glass in a patch and it will be just fine. It is also a good idea to monitor the glass till the epoxy kicks to avoid these surprises.

Michel, there should have been no need to cut darts in the tape as the loose weave is specially designed to conform to compound curves. Before applying resin to the glass on outside curves you can rub your hands along the glass working it into shape, you will be surprised at how it will conform to compound shapes. If you are in the middle of wetting out the glass and feel that you need to cut a dart, go to the end of the tape and pull gently on the outside or middle fibers depending on which way it has to conform and you will see the problem area disappear.

If the bubbles are small like yours it is fine to cut them out and fill as you did.

[vinegar joe]

thanks much for the replies and info....this board is really great.

will be repairing my bubbles this weekend and then on to the gunwhales.

thanks again.

v.joe

[mustangermatt]

I agree 100% with Graham on the radius of corners. I rounded my outer seams to about 1/2" radius and was able to put on piece of glass around the three way bend at the transom corners. It gives the joints a nice appearance as well.