Minifish Holds Pressure - but water gets in hull!

craigimass

New Member
Hey all - owner of new Rocket (sunfish type) and also ancient Minifish.

The MF definitely gets some water into the hull. A one hour sail without any dunking (capsizing), etc. will see maybe 1 or 2 cups in there - yes, I installed one of the 6" clean out to the left of the dagger trunk so I can dry it out and get in there.

I had it dried out to about 85 lbs total....must be a little moisture in the foam.

But here is the question/comment. The hull holds air pressure nicely! When I got the boat I sealed the mast hole and the dagger slow just to be sure...with clear epoxy. At first I just blew into the air hole and noticed that it held that pressure. I could put my finger over the hole and 30 seconds later it would still have air when I let go. I tried the soap trick and no go anywhere.

And so, I hooked up a real air pump to the hole and put in about 5-7 pounds of pressure. At 7 lbs you could start to hear a few creaks in the boat hull so I cut it down closer to 4 lbs, which should have been plenty. I soaped everything - NO GO AGAIN. I removed the air pump and LOTS of air was being stored within the boat hull.
(only slight leak I found ever was a screw hole in the brass hook in front wall of cockpit)

This is an ancient MF - doesn't even have a bailer (which I like not having!).

Has anyone had leaks they were unable to find with high pressure and soap?

Let's assume I cannot find. Is there a relatively reasonable paint or other compound I can cover:
1. Rolled Edge - so I'd cover that seam underneath in case it leaks under load.
2. Cockpit - same, I'd paint or cover the area where I sit, etc. in case same - under load.
3. Last item might be to put another coat of something on the bottom - assuming good paints stop "less than pinhole" leaks.

Do any of the 303 type coatings seal microscopic holes?

It's probably going too far to try to soap test it under real load. I completely epoxied the inside of the mast hole right when I got it - that has to be good.

I'm stumped and I am not usually unable to solve mechanical things! It if comes to it I'll just have to rig up a fast dry system and put up with it - since I am never in the water for over 2 hours (boat is not wet - stored inside on trailer) - that might work with heated air.
 
Slight update - which may help some.
Boat still holds air nicely - BUT, when hosing it off after soaping it, this did a better job of allowing soapy water to hang on the rolled seam - and I did find some very small leaks (bubbles) along the hull/deck joint. I suspect that's not all the tiny leaks, but it's a way to get started.

So file this under - don't just use soap and brush....after you finish that, bail the soapy water out of the cockpit and let it run down all edges of the boat and over the edge. Look closely.....

Now to sand and seal that part. Then onto doing some double duty on some parts that aren't leaking...then take it out a few times.
It's hard to imagine why they built any Sunfish without draining capability - since the smallest holes and condensation WILL make them leak. But that's why we make them better.
 
I see you taped over the centerboard trunk. You should tape one side of the centerboard trunk and draw the soap film over the other side. To have water coming in like that it has be part of the boat that is in the water a lot like the centerboard trunk. I would also draw a bubble over the mast hole and not just tape over. The taping can be hiding the leaks as they can't vent.
 
wait, I want more details about the new Rocket! maybe start a new thread to give your feedback on it, some pictures, etc!
 
I can get to most of the CB trunk from inside also - it looks perfect but I will put a coat of something or another in from the inside and, do more sealing and checking on the outside of it. It really does look perfect - almost like flat copper lined (color) and smooth, except where it meets the hull and deck.

There are not a lot of threads here about resealing rolled edge deck-hull joints. Mine looks very good - nothing evident where it is separating, but there are pinholes in it. I will post some pics soon. I am going to sand, clean and then carve a small channel in the center of the bottom of it (razor or similar) and drill small holes every inch or so (1/4" deep upwards) to hold the caulk better. Then I will put two thin coats of 4200 on the bottom of that joint, making sure to feather it up both rolled edges. I might rub some sort of wax or clear coating over that (or clear thinned poly or something!).

All in all, I think this MF is in great shape - just making it a little better. I picked up a (now discontinued) Harbor Freight Jon Boat trailer - hardly even used. I modified it for the MF and put a second story on it for the dolly and/or for throwing another boat on (I have an 8" Walker Bay Rowing Dinghy). Will post pics....
 
Pics.....
of the pinholes in the bottom of deck/hull rolled edge
of the trailer - including second story (no, the zip ties aren't all that is holding the wood- metal brackets). U bolts hold mast.
Of the entire trailer - still working on it, but you get the idea.
It's hard to find small trailers at decent used prices- I was going to modify a PWC trailer but got luck and found this.

I have a brand new sail (PRYDE) - but figure I will use this old one until I get everything ship-shape.

Was going to use "used car racks" or alum. tube for cross, but wood (PT) is very strong.
FB Marketplace and Craigslist and even Amazon (new-off brand $80) - have car roof rack beams that could work for folks wanting a 2nd story on their trailers.
 

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I'd look real close along the chine for a crack, even a small one can let water in.

You are the man!

I went sailing in very rough conditions (Newport 20 MPH gusts) yesterday and after 90 minutes there was about a full pint or more of water in the hull. Too much - considering how much I traced down leaks and sealed the boat.

I had checked the boat over and over - BUT, some things I let go - like hairline cracks. Turns out, as you mention, there is an area near the cockpit on the chine which is probably the main culprit (or one of them!). I have a feeling that sealing that main crack will get me in much better shape.

My guess- other than boats thin out and get brittle with age, is that some areas like this are where it's likely a boat is dropped - or maybe even the stress of the Dollies which put some pressure on the hull right near this spot (I can change all that now that I know...change the way the boat sits in the Seitech).

Anyway, here's some pics. I tend to use what I have sitting around, so I sanded it out, put some wet (epoxy) cloth in random areas inside the hull near it (just to stiffen the general vicinity) and now will built up with cloth and paste epoxy - I have PC-11 sitting around which should do the job for the first coats (structural). Not sure what I will finish it with - looks do not matter, so likely whatever is inexpensive and strong. Not even sure I need gelcoat if I use some good epoxy in the finish coats and then sand and wax it (boat is never in water for more than 2 hours).

I'm tempted to add thickness to the exterior (already did to interior) just because....but I tend to overdo things. That is I could use some thin cloth and a couple coats of white epoxy on top of the existing hull for the area and then feather it out. If the dolly and dropping in that area are truly causes this would help.

The hull is quite thin there Maybe a result of it being cracked and letting water in and out. The old FG didn't come out in pieces - there was one or two horizontal cracks (you might see in the soap pic)

I wonder if there is an interior coating of some sort that can help protect the Fiberglass longer term - like pouring something in there and then roaring the boat so it coats all the interior surfaces. Has anyone done similar? I could use 303?
 

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Yes it was dropped there, you can see stress cracks radiating out and away from the point impact. So the fiberglass sheared along a fracture line but the gelcoat flexed a bit.

We put the extra support inside, we use woven roving as the internal backer patch, it is the same as what was used to build the hull. So that is your strength. Then we build the hole up with 4 oz fiberglass cloth, leaving it a bit shy of level with the original gelcoat, so we can fair and coat. That gives you original hull thickness x 2, no need to over do it. The resin and cloth do need a protective coating from UV, a bit of gelcoat could be brushed, sanded and buffed, other folks are pros at that. We'd mask the area off and spray a couple of coats of Rust-Oleum on it.


I can tell you that the starboard bow of this boat was shredded during Hurricane Sally, and when we recovered pieces from the yard the patched area had stayed intact while the surrounding original chine we bashed to bits. So we can testify that the repair method is Hurricane Tested.
 
Thanks! Since I had the regular cloth sitting around I used that (covered on both sides with epoxy) as the backing patch. Then I built up with two layers of epoxy and cloth, one of which layers is solid afix to the old hull at the edges.

I cut a little cardboard to make sure I stayed with the proper hull shape.

I am about even with the hull right now although not smooth - I intend to sand/file it a bit so I can add a coat of smooth epoxy or gelcoat. In my case, looks don't count, although I will do the best I can.
I suppose the repair is 2 to 3 times the original thickness at that point.
 

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[QUOTE="craigimass, post: 212421, member.
Was going to use "used car racks" or alum. tube for cross, but wood (PT) is very strong.
FB Marketplace and Craigslist and even Amazon (new-off brand $80) - have car roof rack beams that could work for folks wanting a 2nd story on their trailers.
[/QUOTE]
I've been looking for damaged masts and booms to replace the 5/4ths beams atop my pickup truck bed. (Sawed to length).

Not so much for strength, but for cachet. ;)
 
Ok, I'm done with that repair - going sailing before I do too much more.
For those who haven't used it yet, this JB Marine Epoxy is top notch for thin coatings! I think, in my case, it may even take the place of gelcoat or other UV product, especially since I may paint the sides of the boat at some point. Boat is in New England and stored inside so UV not a big problem.

I'm no expert - but I'm happy with how smooth the repair is. I used some boat clean wax and 303 on and around it just because I want to go sailing soon. I'll let it weather a bit and then decide on painting the hull.

Oh, that Epoxy is $10. - of course, it's a tiny amount but it's thin and spreads well. I can imagine it may be a good "keel protector" if I rub a thin coat down the bottom of the boat.
 

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