Last summer I was merrily heading into Toronto’s inner harbour through the Eastern Gap*. I was busy lounging behind the wheel and talking with friends when one casually said “we are headed straight for a big green thing”. That big green thing being the big steel buoy making the inner entrance to the Eastern Gap. I turned the boat to port and the wake pushed the buoy away from the a boat, only to have the buoy swing back back with a vengeance and smack the hull just below the rub rail on starboard. Ouch.
The impact shattered the gel-coat and the underlying layers of fibreglass. It didn’t look too bad and I left it for the season as it is well above the waterline close to the forward sling marks.
What king of sailor sails straight into a big green buoy that he knows is there… ugh.
Peeling back the layers of crushed gel-coat and fiberglass mat, I discovered the damage was much more extensive than it appeared. There was considerable de-lamination between the many layers however the lowest layers were just bruised, not cracked. The damage also extended in a much larger radius then the gel-coat damage itself, presumably from the fibreglass flexing in.
I couldn’t access the damage from the interior unless I did a massive cabin disassembly, so rather than cut a hole , I decided to grind down and re-glass from the outside, leaving the bottom most layer intact.
After applying a few layers of mat and resin I levelled the patch with a sander and enlarged the grind. You can see the wound get bigger in the photos. Complicating the repair job was an unusually cold spring. I used a heat gun to warm the hull first and then gently warm the repair at several intervals to ensure the resin kicked.
Due to the incompetent teen-age dock hand in Ganaonque, I also has a scratch on the same side from a screw protruding from the municipal dock. I thought it gouged the hull but the damage was just a void that was revealed by the pressure of the screw. The void is a heart shape – kinda cool.
The port side the suffered an end of season indignity. I was towing a friend’s Alberg 22 alongside to haul-out. The water got a little rough and the fenders, while in place, didn’t protect the hull when the smaller boat rolled and rose at the same time.
A pin from the chain-plate/shroud dug into the hull about a eight of an inch deep, quarter inch wide and three inches long. arrh. Below is a during and after. I left some gel on the red stripe so I could find it!
Mixing gel-coat to colour match is really really tricky. I used a single yellow that was like a dijon mustard as the pure white gel coat is just too bright. When mixing, the colour seemed to go from too cold/blue looking to yellow/green instantly. In the future I would mix the gel coat and fill small voids. I did clean and de-wax a patch of hull but the shape and wetness of the mixed gel-coat made it very hard to tell which I was looking at. Also full sun vs shade made it difficult to tell what I was looking at, even when using a hole cut out from the radio installation.
The final coats of gel coat were rolled on, the peaks and valleys were so high that I practically removed the whole layer just flattening it – I think I might try spraying using the small jar/cylinder that was sold at the boat shop. I did try different rollers and also thinned down the gel but much the same results. I think that getting a smoother final coat would make fewer cycles of apply/sand down needed. Perhaps I wasn’t putting it on thick enough.
I would spend a bit more time making sure the final layer of cloth and resin was flat. I had some hight points that created a thin spot in the gel, causing a dark shadow. Also I mixed a couple of batches of colour matched gel and the unevenness created tree ring like colour halos – I finally covered them with the top gel coat but it would have been easier to mix a bigger batch of gel and get it right.
Over all it was a very satisfying project.
Mixing Colloidal Silica with Polyester Resin
Most literature (Don Casey) recommends using microbaloons above the waterline, but I have a can of colloidal silica which is recommended for fairing below the waterline. I wanted to know if the silica was OK to use with polyester resin, not just epoxy. Given it’s a West product most literature is for epoxy.
I found a few references to this:
“For simple cosmetic scratches and dings I find the easiest thing is to make a paste out of some white get coat. To do this you need to add colloidal silica to thickin it. Colloidal silica comes in a variety of different types and some do not change the color of the gel coat. I think the one you want is colloidal silica 406 from West marine. It’s a white fluffy powder. You mix it in, add wax and hardener. Apply it with a small scrapper or tongue depresser.” Catsailor.com
“406 Colloidal Silica is a thickening agent for epoxies, polyesters, and urethanes. This Fumed Colloidal Silica can be used to thicken resins to the user desire by adding varying amounts. Colloidal Silica is ideal for making adhesives and putties for gluing wood, fiberglass, stone, concrete, etc. Cures OFF WHITE but can make cured resins much more difficult to sand.” fibreglassshop.co.nz
*Eastern Gap – a 120 metre (390 ft) channel between the mainland and Ward’s Island. It was originally a thin sandy spit connecting the islands to the city until a storm flooded sand pits on the peninsula in 1852. The channel was widened and made permanent by a violent storm in 1858. The gap was widened and deepened to accommodate freighter traffic coming down the St.Laurence Seaway in the 1950s.