Minifish hull damage

B

bhm

Active Member
Last Fall I bought a 1973 Minifish, as an upgrade from my aluminum sailing canoe. So far I've sailed it only a few times (a test-sail last season, and three or four times this season). The beach I launch from on Cayuga Lake is very rocky (all rocks, from gravel up to baseball-sized, no sand at all). This was never a problem for my aluminum canoe or plastic kayak, but apparently this hull is more fragile than those, and now I've dinged it in three places. (I thought the hull was fiberglass, but it seems to be something a lot thinner and more fragile than that.) Evidently I'll have to treat it more gently in the future. But in the meantime, can I fix or fill these dings with the same "Thixo" thickened-epoxy that I used to fill some dings in my mast step, following advice on this site from last Fall?

Ding #1, on the side or corner edge:
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Ding #2, also on the corner edge. This was evidently a previous repair of some kind, maybe also this same Thixo stuff, but of a brown color. When I got the boat it was a smooth slightly raised brown area that I thought was a fiberglass patch to a fiberglass hull, but now it has cracked in the middle and is peeling off, revealing the same kind of squishy fibrous stuff underneath as in ding #1.
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Ding #3: this is a simple crack, in the flat part of the bottom of the hull.

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So, can I patch these with this same "Thixo" stuff? I have some left over from the tube I used for the mast step, though it was getting pretty hard to squeeze it out with my hand-squeeze caulking gun, and I might need a fresh tube.

Thanks for any advice on this. And by the way, what is this hull made of, if it's not fiberglass?
 
Minifish are fiberglass. As you have now found out, fiberglass is a lot more fragile than plastic or aluminum. The damage is pretty serious - well beyond a quick Thixo repair. The “soft stuff” you are seeing is damaged fiberglass - you’ll need to remove that as part of the fix. Take a look at post 53 in this thread - it covers the type of repair you will need to make. You’ll be needing Acetone, fiberglass cloth, polyester or epoxy resin and hardener, and a few misc supplies. Scorpion sailboat
 
So for dings #1 and #2, I guess that means punching or cutting through that soft material all the way into the empty space inside the the hull? Rather than just smearing something over the top, as was evidently previously done for #2?

But for the thin crack #3, wouldn't that mean doing a lot more damage?
 
So for dings #1 and #2, I guess that means punching or cutting through that soft material all the way into the empty space inside the the hull? Yes - you need to get into the hull for the patch. The soft material needs to be cut or ground out - all of it. The you’ll sand the area around the hole about 2 inches back all the way around. The fiberglass applied to the outside needs to have that area to adhere properly.

Rather than just smearing something over the top, as was evidently previously done for #2? Yes.

But for the thin crack #3, wouldn't that mean doing a lot more damage? Well, it’s really what is needed to repair the damage. That’s a crack right thru the glass! You’ll need to remove broken and damaged fiberglass and have an area for the patch to adhere too. It may be possible to fix that with an external patch, but you’ll find a lot of damaged fiberglass is hidden beneath the white gelcoat.

Hopefully Signal Charlie himself will weigh in with his thoughts.

Once you get this fixed, you should buy a dolly to roll the boat in and out of the water. As you can see, fiberglass cannot be dragged and/or dropped on rocks.
 
So if a proper fiberglass repair requires cutting away the damaged part, it seems that I would lose nothing by trying a quick-and-dirty external patch first?

I only have this boat in the water for 2-3 hours at a time, just doing slow recreational cruising at 2-4 mph. I was thinking that I might just be able to glue a sheet of rubber roofing or rubber gasket material over the top of each damaged area, like patching a bicycle inner tube. I suppose this would add some drag, but that is not an issue for me since I am not trying to go fast, just to enjoy being out on the water. Or maybe try Thixo first, and if that still leaks, then lay down a sheet of rubber over the top of that?
 
I agree with Beldar but if you want to try an easier fix, you could take a sharp chisel and remove the old yellow resin patching material, sand the damaged
areas with 100 grit sandpaper, then fill the dings with white Marine Tex two-part fibeglass mending putty. Cover the areas with plastic wrap to get a smooth repair, let cure with the plastic in place, peel off the plastic when cured and sand a little with 220 grit sand paper; go sailing.

Try Myers Point Park on Cayuga Lake near Lansing. Nice sandy beach.

Alan Glos
Cazenovia, NY
 
Thanks, I'll try that. I guess that means this stuff, that I just ordered from Amazon? How is it different from the two-component epoxy Thixo?
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Also, do you have an opinion about my fallback idea of just gluing a sheet of rubber over the top of these patches if the boat still leaks after that? In principle it seems that this should work, i.e. putting a flexible waterproof layer over a solid but not waterproof foundation, like a skin-on-frame kayak.

I saw Myers Park on the map but was deterred by the $6 admission fee for non-residents of Lansing, so I've been launching from the public beach at Salt Point Nature Preserve, just north of there, not knowing that all the rocks there would be a new problem when I switched to a fiberglass boat. But now that I am aware of this problem I think I will first try to just roll on into the water with my existing dolly wheels from Sailboats-to-go that I've been using to wheel all of my boats from car to launch site, and take them off only after the boat is floating.
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Yes, white Marine Tex. It harden rock hard, but you probably need about 75 degrees f. ambient temp for it to cure well, so don't do it outside here in Almost Canada until it warms up more. Not wild about the rubber mat fix. You will like the Marine Tex fix better.

Alan Glos
Cazenovia,NY
 
How about in an enclosed but unheated garage, under a heat lamp? It would be nice to get this repair done now, so I can go out again as soon as we get another nice day.

I remember that when you dropped off the Force Five mast sections last Fall you said that on Caz lake you usually wait until May, but I went out on Cayuga three times already this month when the temperature was mid-fifties and sunny (wind circa 10 mph), and felt quite comfortable, just with dollar-store nitrile gloves and calf-high rubber boots to keep my feet dry while launching. (Except of course for evidently tearing up the hull in the process! But I hope I can now avoid that in the future.)
 
No, but other sailboats are always rare in this part of the lake; I only saw a few all last season. I did see one windsurfer and one stand-up paddleboarder this season, in addition to several fishermen in kayaks or power boats. The windsurfer was too far away to see what he was wearing; the SUP'er was wearing knee-length shorts.

So I guess "in the forties" means water temperature as opposed to air temperature? I hadn't thought of that as a factor, since with wind under 10 mph and never cleating the sheet and having a boat with outriggers, I didn't think I had any real chance of ending up in the water. On the other hand I do still wear a PFD just because I know that's what you are supposed to do, and I want to follow good safety practice whether I actually believe that the risk in question is real or not. So if you as a more experienced sailor tell me that I should be wearing a dry suit in addition to PFD this early in the season, I'll order one right now and wear it until May.
 
Yeah, I agree that it's pretty lame, and I hope that the Marine-tex putty surface-fill patch will work without resorting to that. But since I already have sheet rubber on hand from prior repairs to my rubber roof, this seems worth a try, as something I can do quickly and easily, without having to master a whole new skill of working with fiberglass. Since I am not sailing the boat very fast or keeping it in the water for very long (2-3 hours at a time), it seems at least possible that this kind of external patch might hold, at least for a while.

There has already been some water inside the hull from these existing leaks; that's how I found out about them. I heard it sloshing around when I hit the brakes in my car, since I carry the boat in the back of my car and the stern is right next to my head. I just poured it out through the drain hole when I got home, and left the boat tilted on its side, hoping to get it all out. This boat has no inspection ports so I can't do the standard business of drying out with fans that I've seen described; all I can do is leave the drain cap off. But I presume that the internal styrofoam won't absorb very much water weight in such a short time, and the boat doesn't feel any heavier than it did before. Anyway I am still able to move it around single-handed, so whatever water remains doesn't seem to be causing any problem. Indeed, I could imagine just living with a small leak, and just dumping the water out at the end of each outing, as I already do with my old aluminum canoe that leaks along the seam. The problem is just that water does not drain very quickly through the small Minifish drain hole, so draining it out takes a bit longer than just tipping the canoe up on its side.
 
In regards to water temperature, be aware of hypothermia risks - especially if you will be out by yourself. Have a plan for if you capsize and run into trouble. Can you get help quickly? If you get wet, do you have means to warm yourself quickly on shore? Know the signs of hypothermia and how quickly they can set in. Benefit of a dry suit in very cold waters is that it keeps you dry and warmer with warm clothes underneath (wool is provides warmth even if you do get wet).
Many sailing textbooks will have this information in a safety section. I’d expect the coast guard may have some public resources on this subject as well.
Be safe! Have fun!
 
Your boat is made of fiberglass, with an outer layer of gelcoat that protects the fiberglass. The areas you showed are crushed, the fiberglass should not look cloudy like it does. Crack #3 is probably all the way through and a leaker.

The brown stuff is old polyester resin, from a previous poor repair.

Marine Tex is a 2 part epoxy product that is also thickened, so it can fill small holes.

A piece of rubber may stop the leak but id does not address the damage. A quick fix might be Flex tape.

A blind patch is the best long term fiberglass repair for all three damage areas.
 
I already proceeded with the Marine-tex quick fix as suggested above by Alan Glos. I mixed and applied it on Thursday when the air temperature was in the mid-60's, and left it to cure in a garage under a sunlamp for several hours while I was away. Apparently during this time some waves and wrinkles formed in the plastic wrap and the epoxy then set in that wrinkled shape; and also some air-bubble cavities in #2 became visible after I peeled back the plastic today (Saturday). But still I am very pleased with the result, considering the relative ease of application; and if the leaks are now stopped I may just leave it as is, rather than try to sand it down any further or re-apply any more of the epoxy to fill the cavities in #2. I deliberately built it up somewhat higher than the surrounding hull, just to be sure of having a thick enough layer of the epoxy to be mechanically strong. I don't care about drag since I don't sail very fast anyway; I just want the boat to not leak. And as long as the epoxy formed a watertight seal to the surrounding hull surface, then this quick fix looks as if it should do that job. Of course I won't know for sure until I get the boat into the water again.

Ding #1, before:
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Ding #1, after:
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Ding #2, before:
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Ding #2, after (showing cavities from air-pockets which came to the surface during the curing):
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Ding #3, before:
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Ding #3, after. There is a piece of clear plastic packing tape still covering it, which I left on since it was hard to get off. I expect that it will come off by itself once I start sailing the boat.

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