Leak testing/sealing

hospadar

tiny boat fiend
Wondering a little about sealing up leaks - was hoping to get some clarification/tips on stuff that was not entirely obvious to me from other sources

I have a new to me boat that's in decent shape but has water problems - there was a crack through the cockpit floor (now repaired) and quite a bit of standing water in the hull, and, though I haven't weighed it yet, but I assume waterlogging problems. I'm going to install at least one port (unless the foam is miraculously not waterlogged) and begin drying it out.

The leak testing procedure makes sense to me, but I'm wondering a little more about leak repair (if needed) -
  1. When repairing leaks in the daggerboard trunk/hull joints or mast step/deck joint, what sealant is preferable? Sunfishdirect suggests (I think?) thickened epoxy but it seems like 3M 4200 would also work fine (and would be easier to deal with)? Any opinions?
  2. What about repairing deck edge leaks - Injecting (not thinned?) resin into the joint seems to be the main approach here (and thickened if it's a big gap?) - thoughts? experience?
  3. Anything else I should be particularly mindful to repairing/sealing in any special way?
 
you have limited yourself to 3 options.

The real answer really depends on what the real problem is.

While I am sure th 4200 might be a solution, if the fiberglass is damaged you want to grind out the damage and put in good glass or even epoxy.

With each repair you need to ask yourself what needs to be done to the surface to ensure adhesion of what you are using.

Lots of pictures here are your best resource. Let those who have worked on the fish tell you what is their best solution. Often there are more then one way to to make a repair that is good. I have in my 3 years of fixing sunfish at my yacht club seen TOO many bad repairs by people with no experience. I have also seen the repairs done years ago that are still working fine. So I have a good idea of what can work and what is not such a good idea.
 
you have limited yourself to 3 options.

The real answer really depends on what the real problem is.

While I am sure th 4200 might be a solution, if the fiberglass is damaged you want to grind out the damage and put in good glass or even epoxy.

With each repair you need to ask yourself what needs to be done to the surface to ensure adhesion of what you are using.

Lots of pictures here are your best resource. Let those who have worked on the fish tell you what is their best solution. Often there are more then one way to to make a repair that is good. I have in my 3 years of fixing sunfish at my yacht club seen TOO many bad repairs by people with no experience. I have also seen the repairs done years ago that are still working fine. So I have a good idea of what can work and what is not such a good idea.
It's also of matter as to what kind of aesthetic youre going for..a patch that looks not perfect but works is possible. Are you wanting a completely restored looking hull with access to inside or do you just want something to get you on the water to bang around. The season is fast approaching, and good hulls are out there. Something to consider. It seems I always find another too good of deal to pass up on. And even if it's the same exact color scheme, I seem to come across a nicer one on a regular basis. Right now, I'd go fast and nasty to get out there..then evaluate as you go.
 
We've been through about 50 boats of various make/model, and our go to is thickened epoxy from a 2 part caulk tube, THIXO Flex. There is no 4200 or 5200 in our shop now.

Thickened epoxy can be injected into any seam void, and will stay there, while thin resin may not fill gaps or could just run right back out. Flex epoxy is formulated to flex better than traditional epoxy.

Post pics.
 
We've been through about 50 boats of various make/model, and our go to is thickened epoxy from a 2 part caulk tube, THIXO Flex. There is no 4200 or 5200 in our shop now.

Thickened epoxy can be injected into any seam void, and will stay there, while thin resin may not fill gaps or could just run right back out. Flex epoxy is formulated to flex better than traditional epoxy.

Post pics.
thickened epoxy in a syringe works great. especially if you can stand the seam up. then i file or use a sanding block to cut back the high bumps when its cured.
 
THIXO FLEX or Pettit Flexpoxy in a tube. If you plan to do more than a few tubes on different projects, invest in a High Thrust 25:1 caulk gun vs the basic 7:1 gun. The unused product will store for many months, unless exposed to temperature extremes like a PODS shipping container...

CHIP THIXO keel.jpeg
 
Ahhh yeah flex epoxy! I've never used it but I've stared at it in the hardware store many times and wondered what I'd ever need it for :)

Nothing to post a picture of really (yet), there's nothing visible that needs repairing. I suspect that when it's not 35° out and I get around to leak testing that I'll find some leaks one of the deck/hull/trunk/step/cockpit joints.
 
There was a pretty decent amount, I've already drained it out but haven't had a chance to weigh the boat yet
 
THIXO FLEX or Pettit Flexpoxy in a tube. If you plan to do more than a few tubes on different projects, invest in a High Thrust 25:1 caulk gun vs the basic 7:1 gun. The unused product will store for many months, unless exposed to temperature extremes like a PODS shipping container...

View attachment 50737
i bought the 20v makita for doing teak deck sealant. omg.....its one of my most favorite tools. lol. totally excessive. but its pretty great.
 
"i bought the 20v makita for doing teak deck sealant. omg.....its one of my most favorite tools. lol. totally excessive. but its pretty great...."

You know, Mother's Day is coming up. I bought Skipper a 20V DeWALT Compact Trim router, maybe she wants a cordless caulk gun as well...
 
My caulk gun broke. I got a mid level caulk gun with stamped steel parts and simple rivets. It broke, the rivet broke and bent and tore the ratchet pawl.

Next time I am at the store I am buying the heavy duty one. I dont do enough to justify electric ones.
 
best to create at least two inspection ports, one at each end, so you can use a small fan to force the moist air out of the hull.
 
Update!
Finally got around to weighing the sunfish - 140# - so probably some weight gain but not catastrophic. Still haven't gotten around to leak testing. I'll probably put in ports for drying but doesn't seem terribly urgent at 140 (opinions?).
 
139 pounds is what Sunfish weighed until around 1988, when the weight dropped to 129. What year is your boat?
 
Personally, at 140 I wouldn’t add ports. If it’s an older boat (with old style rudder) and you decide to upgrade to the kick-up rudder you’ll obviously need to add one port in the stern, but I wouldn’t add a second one. You can put a fan in the stern port and use your open deck drain for air flow if needed.
That leak test should be the next thing on your list.
 
139 pounds is what Sunfish weighed until around 1988, when the weight dropped to 129. What year is your boat?
1976 - new style rudder bracket so nothing needed there and none of the deck fittings seem problematic at present.

Happy to hear I shouldn't bother with ports! Seems like a miracle given the big hole in the floor that it came with :)

Re leak test - I was planning on stuffing my little 12v pool toy inflater into the drain hole and just letting it run - I assume that thing can't generate a dangerous amount of pressure. Does it matter if I tape over the vent hole or not?

This is the kind of inflater I'm talking about:
1652716866019.png
 
Those 12 volt inflators aren't designed for continuous effort. Some instructions say to "rest" the inflator after five minutes of operation! :confused:

Stores that sell aquarium supplies should have a $5 air compressor that runs on house current, puts out an acceptable testing pressure, is silent in operation, will run forever, and keep your Sunfish dry in its off-time.

Chewy has one online at $5.83.
 
(Tetra "Whisper" Air Pump)
Also, very low amperage--like a night lamp!

Link was very long, so here is a tinyurl version.

Thanks L&V. Another question for you.

Do you think that 10 gallon pump would be enough to dry out my foam from slow leaks (that I think I may have finally repaired) that leaves an inch of water in my boat after 4 hour long sails?

I've currently got a PC fan that I have started to use in one of my inspection ports to suck the air in through the other port but that fan tends to get warm after running for a long time, even when it's in the shade. I worry about leaving it unattended.

Thanks! :)

- Andy
 
Andy, my computer didn't like L&VW's link above, so I don't know the fan specs there, but I've also normally just used a small computer fan.

I haven't set it up yet, but I recently picked up a 4" duct fan from Home Depot (similar to this one at Amazon) - I would think this type of fan would be heavier duty and stand up to running longer periods of time and move a lot more CFM than a computer fan. just a thought.
 
Do you think that 10 gallon pump would be enough to dry out my foam from slow leaks (that I think I may have finally repaired) that leaves an inch of water in my boat after 4 hour long sails?
No.

That $5 air pump is for economical, long-term, safe, circulating, drying--and for non-destructive leak-testing.

For severe drying cases, a large (4-inch) "muffin fan" is again, cheap, safe, quiet, economical, and will run forever.

For more on "muffin fan", see the link at: "Starbrite (or other) chemical dehumidifier"

High quality "take-outs" cost less than $10. (Double that for "new").
 
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Finally got around to leak testing the boat, results were promising:
  • One leak at the tub/deck seam at the very back of the storage compartment
  • 2 very (very) small leaks at the hull/deck seam near the bow
  • small-ish leak at one of the stern corners - there's some spider cracks in the gel coat so I assume the corner got bumped hard at some point (or points)
  • No leaks in the daggerboard trunk or mast step (yay)
Planning squeeze a little WEST 655 (west's thickened flex epoxy that I happen to already have a tube of) into tub/deck leak and skip fixing the hull/deck leaks for now (they seem very minor, I'd prefer to be sailing instead of re-installing rub rail).

I ended up using the pool toy inflater instead of the aquarium pump because I couldn't find the aquarium pump. I didn't tape the vent hole. I didn't need to run the pump for more than 30-60 sec at a time (and honestly the pool toy pump seems like it probably generates more pressure than is needed/ideal so intermittent running seemed better anyways).
 
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Can someone explain in a little more detail, how I can pump air into the hull and do the leak test?
 

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