Cracks in Hull - Storm Damage

[bilbo]

My first experiment with gelcoat was a fail. I tried painting it on several surfaces and some cured, some didn't. One area had patches of cured and uncured gelcoat. I read a few things after that. One, the droppers aren't great. Two, the gelcoat needs to be a certain thickness to cure out. I used the dropper and brushed a single coat on, so it probably was too thin. The Boatworks Today guy said to brush one direction and let the solvent flash off for a couple of minutes, then brush perpendicular to that, alternating direction each coat. I also picked up some syringes at Tractor Supply to use for the MEKP.

I tried it again tonight and used the syringe to ensure I got the amount of catalyst I was looking for. And tried the cross-brushing. I definitely mixed the gelcoat too hot. I was able to get three coats on, but it went from runny pudding to a solid lump of gel in a span of about 10 seconds while I was brushing the third coat. Pot life was about 6 minutes and not a second more. That was at 1.75%; I'll try 1.5% next time.

I've got some wax that can be mixed in with the gelcoat from the supplier to use in the final coat. I've got some plastic sheeting too. If it's calm I intend to try the plastic. If it's windy I'll probably go with the wax. I'll hopefully be able to get this done this weekend.

[GreenLake]

I remember I used a spreader to apply the gelcoat, not a brush.

What about this? You could use a notched spreader to get a consistent amount of gelcoat and then immediately follow it with a straight spreader to flatten it. Again, something I would experiment with on something that isn't your boat, so you can discard attempts that didn't work.

Maybe overthinking this.

I did manage to get the droppers to work, but I'd adjust the count if eyeballing suggested over/under delivery.

[bilbo]

The cross-brushing did work well. It allowed me to build up thickness, before the gelcoat started to cure anyway. I think if I can extend the cure time some it will be the ticket.

I expected the gelcoat to be thicker; maybe mine's too thin? It's more like syrup-coat when its' first mixed. I don't think I'd be able to put it on with a spreader as it has no body. I've read gelcoat is usually sprayed so maybe that's why mine's so thin.

I do like the syringes. I think I'm going to pick up some larger ones for the gelcoat. Trying to pour it out of the paint can it came in is messy, and since I'll be using such a small amount each time I should be able to just draw it up with a syringe and eliminate the mess.

[GreenLake]

Thanks for the details. I've always used gelcoat that was marketed for repairs, as opposed to gelcoat intended to cover a mold. Some products are actual paste, but generally, yes, the consistency isn't that different from paint.

(The paste was a specialized clear gelcoat, intended to fill minor scratches. It simply fills the scratch and as you can see the existing color through it, there's no need for color matching. It works only for scratches that don't penetrate into the laminate below. And, of course, not applicable as a UV blocker over epoxy. It's main function is to restore surface to an unbroken glossy state. I've used it "off-label" so to speak to seal laminate in the bilge where the supports for the wooden floor slats had rubbed through. That application was hidden from view, so pigmentation wasn't needed.)

I noticed that gelcoat from different sources or differently formulated don't all work the way I expect and now I make sure that I purchase the precise product from the same brand.

I can see how syringes can come in very useful.

[bilbo]

Last week I worked on getting the color right. It doesn't matter too much since it's on the bottom I suppose, but I still wanted to get it as close as I could. I saw a trick in one of the videos from boatworks today to just put uncatalyzed resin on the hull and see how it matches after drying out. Then it's easier to see how it matches and can be easily wiped off with some acetone. I had the color pretty good (or so I thought) so next step was to apply it. I didn't want to have to worry about the dew collecting on it before it cured, so I waited until Saturday to put gelcoat on the boat. I made a calculator spreadsheet that gives me the amount of MEKP I need for a given amount of resin and concentration. Sometimes when I'm working on things I lose focus and end up picking the wrong numbers from tables. Since my last test batch cured so quickly at 1.75% I decided to use 1.5% this time and punched that into my calculator.

Unfortunately I didn't hit enter so it kept the MEKP number from 1.75% and I didn't notice it until I made the second batch. Even with the extra catalyst, the gelcoat worked really well this time. I had about 5 minutes in the cup before it started to thicken a little, and about 5-8 minutes to work after that. Plenty of time to use it all up. It was earlier in the morning and much cooler than last time so I believe that played a role in why the mixture worked better this time. I also decided to patch some chipped areas on the keel too. I was going to put epoxy in these since I'm more comfortable with it and it's a harder material, but figured I'd give the gelcoat a shot since I was already doing it. Brushing on these areas was difficult, and I ended up just leaving them alone until the gelcoat had thickened some and it would stay put after I globbed it on. At any rate, I ended up putting 9 coats down in three batches of gelcoat, with the last batch being mixed with wax.



Once the gelcoat was on the hull I didn't like the color anymore. It's not quite as bad in person as the photos show it, but it's still very noticeable. My bigger concern was whether I messed something up and the gelcoat wouldn't cure, but it appears it has. It's good and hard all the way through from what I've been able to see. While researching gelcoat on epoxy, one article said that the amines in uncured resin, hardener, and/or blushed epoxy link with and terminate the chains of polyester so it stops crosslinking. So that's one big reason for issues with combining the two and why the resin/hardener ratio is very important if one intends to use gelcoat. I left it alone yesterday and overnight and today I intend to mess with it a bit to see if it bonded well. Also the brushed areas are pretty rough, so today is sanding day. Maybe a mini-roller would have been a better applicator?

[bilbo]

The boat is upright again! I started out sanding by hand this morning. A couple of years ago I injured my right shoulder and it decided it wasn't having the manual sanding. I ended up running to Harbor Freight and getting an air-powered jitterbug sander. It worked quite well, and allowed me to wet sand without worrying too much about getting on the wrong side of any electrons. A DA air sander probably would have worked better, but this way I could use the sandpaper I already have instead of buying a bunch of discs. I probably could have used another coat or two of gelcoat as there are a few spots where the brush strokes show, but all in all it faired out quite well. The color is bad of course, but as long as I don't capsize nobody but scuba divers should ever know. Next step is fixing the rudder gudgeon but I'm taking a break for the night.

[GreenLake]

When I look at that first picture you shared, I think you made pretty good progress!

[bilbo]

Thanks, it sure feels good to have it on the trailer again. I was looking at the rudder mounting last night and noticed there is no core on the inside behind the area the where the lower gudgeon is. The inside slopes a little bit, so it's just glass behind the nuts and that may be why they sunk in a bit. There is plywood in there, bonded to the outer side of the transom. My original plan was to inject some resin in there to soak the wood, but that obviously won't work. I also need to minimize what runs down as it could plug up the path for water to get out the bilge drain. I'm going to try to get some epoxy putty or something stuffed in there as a dam of sorts, then put some thickened epoxy in to build it up and provide some backing for those nuts. When I put all of it back together I'm going to either use fender washers or make a plate to spread the load across a larger area, as the force on the rudder will want to pull those through the transom. Originally it was just some small flat washers.

[bilbo]

I figured out the sticker this morning. It references two 12 meter racing boats. The guy I got the boat from had purchased it from someone else a couple of years prior, so I'm guessing that's who put the sticker on there. I've no idea what the association was, if any. Maybe they just thought the sticker was neat. They also must have been members of the association as there were some magazines that came with the boat and some stickers on the transom.

[GreenLake]

Gudgeon: a diagram or picture would make it easier to follow what you are doing. If you see a depression around the washer, you have unsupported glass. Either air, or wood that's rotted. With solid glass underneath there would be no give, even with a really small washer. Normally, the transom should have a plywood core.

One way of doing a repair like this is cutting off your transom and rebuilding it. I'm not joking, there's someone who posted here who did just that. Another option could be to take a hole saw and cut a plug out of your transom wide enough to contain the holes for the two bolts. That would let you assess the situation and give you a bit better access. If you find some material there that's beyond any attempt to handle with products like RotFix, you can clear it out (a bit beyond the edge of your hole). You can then build your "dam" below, and perhaps up the sides, before filling with thickened epoxy.

To close the surface, you would proceed like you did with your other repairs. If you were able to undercut the opening and feel there is a good bond from the outer skin to the new plug you created, you could even just glue in the circle of skin laminate and simply fix the remaining circular crack. After that it's a matter of drilling new holes and possibly upping the washer size.

(If you find wet wood that's not fully gone, look into possible strategies for stabilizing it. SystemThree has a series of products and some literature on the process, but you can get similar stuff from other sources).

Anyway, looking forward to learning how you skinned that particular cat.

Sticker: the US-33 is likely the sail number for the particular 12m they were enthusiastic about. That's how far I got when looking at the sticker the first time you posted it. It's not really my area of interest or expertise. Do you think the flag with the "26" identifies the fleet? I admit I did a search for the words, but it didn't pull up anything.

[bilbo]

Here's a photo of the holes after I opened them up. The area immediately behind it is hollow, and I can see a bare face of the plywood material of the transom core. It's somewhat crusty in there, with evidence of rot on the surface of the plywood. It doesn't look like it was ever coated with anything. As you can see, the boat had water in the deck for a few days after we moved down here which probably didn't help matters. Standing water in Florida turns gross and grows algae in like 13 seconds.



Here's a sketch of the stern, sectioned from the side. The bilge drain is actually right at the bottom of the hull, not up a little bit like in my sketch. It looks like originally there was an upside down "U" cut in the plywood to clear the area where that hole is. With the gaps there, any runny epoxy I inject will just run to the bottom and out the bilge drain. I found a piece of 3/4" copper pipe fits almost perfectly in that hole, so I think I"ll use that to keep any epoxy from running down there and causing problems.



As for the sticker, the numbers on the flags are sail numbers, and the boats are called "Defender" and "Courageous." I have no idea if they're related to one another, or how they're related to this sticker or boat. I also found nothing until I combined the names and numbers and either "yacht" or "sailing."

**Edit: I found where I could rotate the pictures from within the gallery so they are properly oriented now.**

[GreenLake]

Let me see whether I understand what I am seeing. You write:

The area immediately behind it is hollow, and I can see a bare face of the plywood material of the transom core. It's somewhat crusty in there, with evidence of rot on the surface of the plywood. It doesn't look like it was ever coated with anything.

What I see: The upper part of the picture would be the cockpit sole with a drain hole through which you can see the ground. The lower half of the picture is the inside of the transom, with the area of interest wiped clean. I understand the two small holes to be for the through bolts. I do not understand the larger hole above them. (Situated below them in the picture). I also don't know which of the two larger round holes the bung is intended for.

I'm more sure of my interpretation of this, even though I have to tilt my head to view it . You write:

Here's a sketch of the stern, sectioned from the side. The bilge drain is actually right at the bottom of the hull, not up a little bit like in my sketch. It looks like originally there was an upside down "U" cut in the plywood to clear the area where that hole is. With the gaps there, any runny epoxy I inject will just run to the bottom and out the bilge drain. I found a piece of 3/4" copper pipe fits almost perfectly in that hole, so I think I"ll use that to keep any epoxy from running down there and causing problems.

If you liberally wax the pipe before you stick it in, you should be able to remove it even after you pour epoxy.

Random thought: What about injecting a bit of foam there? After you finished your repair, you should be able to remove enough of it with a long bent piece of stiff wire to ensure passage for the water.

Random thought 2: What about using a more paste-like material. Like 3M High Strength Filler. You could even push a flat bit of metal through your holes in a shape of an L. That should be enough to keep the paste from falling as a piece to the bottom while it cures or while you push more material on to of it. Still probably a good idea to do it in two stages. First do the portion immediately below your openings, and when that's cured, add material to the top. The hard lower plug should help in pushing stuff up into the space above the hole.

The filler I'm thinking of cures faster than epoxy, so it's easier to work in stages.

Random thought 3: What about injecting some RotFix or similar in the pieces of the plywood that are accessible? And also using a sprayer to coat all of the free surface with something like BoardDefense? That cuts down further rotting.

[bilbo]

I tried to rotate the photos on my phone before I sent them, apparently it didn't work. I'll figure out what happened there. In the meantime yes, the first pic is 180 degrees so the sole is at the top. The hole is where the auto-bailer goes. The bung is what I assume is used to drain the cockpit should the auto-bailer not work. The other holes were where the bolts for the gudgeon went through the transom. I enlarged them with a holesaw so I could see what's going on behind them.

I think the paste is the ticket. Anything not viscous is going to run down and wind up at the bottom of the bilge, and I don't want to create any high spots that would prevent all the water from draining out. I don't see a way I could get tools in there to remove it either.

I used some epoxy with microballoons to fill out some areas when I did the repair, and I found it was very difficult to get it to a point where it wouldn't run at all. I kept adding more and more of the microballoons but it seemed like it thickened to a point and wouldn't go further. There was a sweet spot when it was gelling up but it went from perfect to unworkable quickly. Really, turning the boat over would have been the best way, as I could have just filled it up until it ran out the bilge drain then.

I believe I'll end up doing something similar to Random Thought 2. I have some pipe repair dough that is epoxy based. It comes in logs and the hardener is isolated from the resin in the core of the log. You knead it to mix, and it's like playdoh. I can push that in and form it into a shelf for the filler paste to sit on and support it until it cures. I'll have to try to get my hands on some of that high strength filler. I believe there was no backing here from the factory so I think anything is an improvement.

**Edit: I found where I could rotate the pictures from within the gallery so they are properly oriented now.**

[GreenLake]

Embed a string or something in your paste and let it hang out through the hole. Simply anything easy to trim later that will prevent your budding shelf from dropping in if adhesion isn't perfect.

Nice work on the pictures.

[bilbo]

I ended up taking a piece of wire and bending it back and forth inside the hollow area to give support to and catch the putty shelf if it fell. Ended up not needing it, the putty stayed put and provided support for the filler. I couldn't get 3M high strength filler locally and I was kind of impatient to get this done as it's supposed to rain this weekend and I didn't want things getting wet. I ended up making my own filler from the dust captured by my sander while sanding the hull and some glass that I chopped up myself. It's nowhere near perfect but it did work.



I probably could have even skipped the putty shelf as it stayed put wherever I put it and packed into the void quite nicely. I cut the hole large enough for my finger to easily get in, and was able to pack it in all directions. Smoothing and tooling was kind of a pain due to the long fibers. Even though I chopped them up I'm sure they're not as short or consistent as milled glass.



As I was working on smoothing it out and shoving the excess off to the side, my glove ripped and I went to my workshop in the back of the shed for another. I heard a noise coming from my storage cabinets and opened it up to check it out. My work came to an abrupt halt due to this little guy or gal:



This town has a fair amount of feral cats around and it appears one of them had kittens. I went back inside for a few minutes to see if Mom would come for it. When I went back to check I found Mama nursing three kittens in my cabinet. She was less than happy with my presence so I let them be again for a little bit, then we moved the kittens to a crate by the door. I'm not real familiar with cats, so no idea of the age, but their eyes were not open yet and they weren't really ambulatory. She came and collected them one by one. I wish there was a way to post video, we set up one of our webcams and caught her on video grabbing the last one, kinda neat. Once they were all gone I promptly shut the shed door.

I couldn't really finish my epoxy out as I have the boat parked in front of the shed door and I wanted the cat to be able to get her kittens out, but it was nearly done anyway. We will let the kittens grow up a little bit, and then we should be able to live trap them and bring them to the shelter in town.