Small but Annoying Deck Leak – Best Fix?

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ViewColin

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Hi everyone,

I’ve got one of those tiny but persistent leaks where the deck meets the cabin trunk on my 28-footer. It’s not a gusher – just enough to drip on my bunk after heavy rain. I’ve tried tightening the bolts and replacing the sealant, but it keeps coming back.

Anyone else dealt with this? Is there a specific sealant or technique that’s worked for you? Prefer something I can do myself without hauling out.

(It’s a fiberglass boat, if that helps!)

Thanks
 
ViewColin said:
Hi everyone,

I’ve got one of those tiny but persistent leaks where the deck meets the cabin trunk on my 28-footer. It’s not a gusher – just enough to drip on my bunk after heavy rain. I’ve tried tightening the bolts and replacing the sealant, but it keeps coming back.

Anyone else dealt with this? Is there a specific sealant or technique that’s worked for you? Prefer something I can do myself without hauling out.

(It’s a fiberglass boat, if that helps!)

Thanks
Click to expand...

Yes, dealt with lots of leaks on a hull and deck.

It would be worth describing the boat make and model and the exact spot where you think the leak is coming from, plus describe any fittings you thing are involved. As you have only posted once, I am not sure if you can post pictures, you may need to have a few posts. However, worth trying to post a picture as I may be wrong.

Any further advise can only be very general without the specifics. This is one method of sealing Bedding Deck Hardware With Bed-IT Tape - Marine How To. This Youtube video is a much bigger process and different methods
 
Captain Tolley's is very effective, but as mentioned the water can travel quite a distance from where it entered before it emerges.

I had a dripping rudder gland fitting where the water was dripping in around one of the gland mounting studs. With the boat out I removed the nut from the stud and periodically dribbled in CT for several weeks at weekly intervals, until the gap around the bolts was completely filled with dried CT. When the boat went back in the leak was permanently fixed.

You can try to seal the boat interior and use a powerful fan to partially pressurise the interior and then soak the deck with a strong solution of washing up liquid and look to see where the bubbles rise, but getting an effective seal can be a challenge.
 
As per others need to find where the leak is. I've got a few on my boat on the deck hull joint and a lot I've managed to seal by removing the nut on a bolt, covering with sealant, repair washer and nut back on.
 
superheat6k said:
... You can try to seal the boat interior and use a powerful fan to partially pressurise the interior and then soak the deck with a strong solution of washing up liquid and look to see where the bubbles rise, but getting an effective seal can be a challenge.
Click to expand...

Interesting, have you ever sealed a boat and pressure tested it to find leaks? I would have thought that was very difficult to do. However, PBO mentions it in this article of leaks Tracing tricky leaks on a boat - Practical Boat Owner.
 
Leaks can track a long way but often they are found very close to the source. I have just spent the winter tracking and curing leaks on my new to me boat.

Most I fixed by just removing and resealing with either sikaflex or butyl tape.

But in what is known to be a weak point on southerlies,I raised the fitting by putting discs of fiber glass underneath them and sealing this to the deck and then sealing the fittings onto the discs, in this way even if there is water on the deck it won't creep under the fitting.
 
There are several ways to try and find the source of the leak. Then you can stop it.

Dust the area with talcum powder where you think the leak is and everywhere above this point. A leak will show a water run by the talcum powder getting washed away.

Use blue elephant paper roll and tape as above and where the paper goes dark, that is the leak point.

Use several different coloured food dyes in some water. Flood different areas and see what colour comes through.
 
RunAgroundHard said:
Yes, dealt with lots of leaks on a hull and deck.

It would be worth describing the boat make and model and the exact spot where you think the leak is coming from, plus describe any fittings you thing are involved. As you have only posted once, I am not sure if you can post pictures, you may need to have a few posts. However, worth trying to post a picture as I may be wrong.

Any further advise can only be very general without the specifics. This is one method of sealing Bedding Deck Hardware With Bed-IT Tape - Marine How To. This Youtube video is a much bigger process and different methods
Great advice this reminds me of how https://www.concretesrichmondva.com/ stresses proper surface prep for lasting seals!
Click to expand...
The boat’s a 2005 Catalina 28, and the leak seems to originate where the starboard deck joint meets the cabin trunk near the chainplate. No visible fittings in the immediate area, but there’s slight flexing in the deck when stepping near that spot.

I’ll try uploading photos once I hit the post threshold in the meantime, does that flex suggest I might need to address the core material before resealing? The Bed-IT Tape method looks promising for a permanent fix.
 
ViewColin said:
The boat’s a 2005 Catalina 28, and the leak seems to originate where the starboard deck joint meets the cabin trunk near the chainplate. No visible fittings in the immediate area, but there’s slight flexing in the deck when stepping near that spot.

I’ll try uploading photos once I hit the post threshold in the meantime, does that flex suggest I might need to address the core material before resealing? The Bed-IT Tape method looks promising for a permanent fix.
Click to expand...
You say near the "chainplate" it should be top of the list for investigating and if the deck is cored it's possibly ( probably) the cause of flex due to the core having got water logged.
 
ViewColin said:
The boat’s a 2005 Catalina 28, and the leak seems to originate where the starboard deck joint meets the cabin trunk near the chainplate. No visible fittings in the immediate area, but there’s slight flexing in the deck when stepping near that spot.

I’ll try uploading photos once I hit the post threshold in the meantime, does that flex suggest I might need to address the core material before resealing? The Bed-IT Tape method looks promising for a permanent fix.
Click to expand...
There is no constraint on uploading photos. Just use the "Attach Files" if you have them in jpeg. You may need to resize first.

Is your boat like this? catalinayachts.com/wp-content/uploads/2016/12/Brochure-C-28.pdf If so there is no joint between the deck and the cabin trunk. You mention the chain plates and bolts which seem to be attached to the cabin trunk with tie bars inside taking the loads down to the hull and keel structure. It is quite possible the sealing has failed. Resealing is likely to be a fairly big job as the chain plate will need removing which means the mast will be unsupported on that side. If you are not experienced in such things suggest you take professional advice.
 
Tranona said:
There is no constraint on uploading photos. Just use the "Attach Files" if you have them in jpeg. You may need to resize first.

Is your boat like this? catalinayachts.com/wp-content/uploads/2016/12/Brochure-C-28.pdf If so there is no joint between the deck and the cabin trunk. You mention the chain plates and bolts which seem to be attached to the cabin trunk with tie bars inside taking the loads down to the hull and keel structure. It is quite possible the sealing has failed. Resealing is likely to be a fairly big job as the chain plate will need removing which means the mast will be unsupported on that side. If you are not experienced in such things suggest you take professional advice.
Click to expand...
Looking at the photo I would be looking at the stanchion bases and jib sheet track as likely sources.
 
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