Mystery leak at aft cabin bulkhead

[skunther]

I have a small but not insignificant leak coming in the top seam of the aft bulkhead of the aft cabin, just aft of the binnacle on my 1993 Hunter Legend 35.5. It only happens when water gets into the cockpit, from rain or washing down. It’s enough of a leak to soak my bedding and leave an inch in the bilge after a good rain (with the canvas removed, letting full rain hit the cockpit). I have confirmed all the cockpit lockers are draining properly and no water is entering at those points. It seems the only likely place is at the helm. Everything aft of the bulkhead is bone dry. Does it seem the likely source is at the binnacle? Am I potentially missing something? The entire ceiling of the aft cabin is one molded piece so I can’t really inspect the bottom surface of the cockput, but water is only entering at the trough under the binnacle.
there are four bolts at the binnacle and mounting plate that penetrate the cockpit sole. They appear pretty well sealed. The trough under the binnacle shows no cracks or any potential points of ingress (see 3rd picture).
In the picture of the cockpit side of the trough, the green tape indicates the position of the affected bulkhead.

 

[sailcapt340]

The holes I pointed out with an arrow….they look very wide.
How long are the 2 screws that hold the deck in place, that go in those holes?
On my Hunter 340 I found that these 2 screws were 2 inches long!! They only needed to be 1 inch, but someone used too long a screw and pierced through and into the aft cabin. I bought my boat new in 2000 and I am the only owner so I know I did not do this. It was an over zealous worker with a screw gun and a box of screws the day they put the sliding deck plate on.

You say it only happens after washing down or rain. Thats where I would look next.

I fixed mine by using a 2 part filler that can be drilled and tapped after it hardens. Then used 1 inch screws to hold the deck in place.
As a quick “fix” to just check if this is the source of your leak….get some “duct seal” (in the plumbing department at Home Depot), fill the holes and run some water over the area. It stays pliable and is easy to remove, but seals great.
Try this and let us know. I hope this helps you.

 

[skunther]

Thanks for that. I was thinking of letting everything dry out and then running water along the cockpit sole to see what happens. It seems like such small holes wouldn’t allow the flow necessary to produce the results experienced (1” of water in the bilge and soaked bedding), but perhaps I underestimate the amount of flow from a solid day of rain.
I’m not eager to remove the binnacle to check those holes, so I’ll start with covering these and see what results. If still dry, I’ll try once more with them uncovered and see if there’s then any seepage.

 

[sailcapt340]

I found a leak I didn’t know I had in the same area as you. On my 340 there is an access panel in the aft stateroom, I was rerouting a cable for a VHF and reached in to grab the cable and felt water a trough in the ceiling liner. The trough held the water and it never leaked into the stateroom bedding and wall.
But those 2 small holes can really allow some water to enter.
I hope this is your issue as it is very fixable. Keep us updated.

 

[capta]

If I am looking aft? at the two shelves, it appears that the section holding the shelves has torn away from the port side and has either been secured there or is unsecured. I see three holes there that could contribute to the leak.
If I were looking to find the leak, I'd get some food coloring and create the leak. You might get lucky the first time, or need to recreate that leak several times to find the culprit.
Not related, but those shelves appear as if they haven't turned in a decade. I'd suggest you get in there, clean off all the corrosion and lube the shelves with a waterproof grease.

 

[skunther]

If I am looking aft? at the two shelves, it appears that the section holding the shelves has torn away from the port side and has either been secured there or is unsecured. I see three holes there that could contribute to the leak.
If I were looking to find the leak, I'd get some food coloring and create the leak. You might get lucky the first time, or need to recreate that leak several times to find the culprit.
Not related, but those shelves appear as if they haven't turned in a decade. I'd suggest you get in there, clean off all the corrosion and lube the shelves with a waterproof grease.

Ah! Sheaves! Not shelves. Ok. That view is forward, under the binnacle. The trough in the bottom of that picture drains aft to the stern, so there is no concern of any water from above at that location.

Yes, I see the nut is missing from that port sheave mounting bolt. Good eye, thank you - I missed that. I will lube them as well.

I’m not sure what you’re referring to as a section holding the sheaves that appears to have torn away - everything seems intact there, aside from the mounting nut. Am I missing something?

 

[jssailem]

Water ingress can come from unusual start points. Your internal "ceiling" pan can transport water that hits it.

Covering the 2 screws as suggested by @sailcapt340 is a good place to start. If that does not resolve the issue, then begin expanding your area of suspects to any hardware that punctures your cockpit deck above the pan. This would be my next area to get attention.

 

[capta]

Ah! Sheaves! Not shelves. Ok. That view is forward, under the binnacle. The trough in the bottom of that picture drains aft to the stern, so there is no concern of any water from above at that location.

Yes, I see the nut is missing from that port sheave mounting bolt. Good eye, thank you - I missed that. I will lube them as well.

I’m not sure what you’re referring to as a section holding the sheaves that appears to have torn away - everything seems intact there, aside from the mounting nut. Am I missing something?

Slightly above half way up on the left side, it looks as though the blackish area about 1 inch below the shelf, there appear to be three or four screw holes in the fiberglass. I can’t quite figure out why there would be any screws there.
As for the leak, sorry I got off topic, I’ve used food coloring in water in a syringe to find leaks, with some success. And oops, I do try to get the spelling right, but once in a while a bad one slips past the guard dogs.

 

[skunther]

Slightly above half way up on the left side, it looks as though the blackish area about 1 inch below the shelf, there appear to be three or four screw holes in the fiberglass. I can’t quite figure out why there would be any screws there.
As for the leak, sorry I got off topic, I’ve used food coloring in water in a syringe to find leaks, with some success. And oops, I do try to get the spelling right, but once in a while a bad one slips past the guard dogs.

I think that’s just some grime I failed to clean for the picture. Dye sounds like a good technique, but I wouldn’t want to leave any permanent marks. Think I’ll wait til it all dries and do some targeted/controlled spills see it/where it comes out.

 

[capta]

I think that’s just some grime I failed to clean for the picture. Dye sounds like a good technique, but I wouldn’t want to leave any permanent marks. Think I’ll wait til it all dries and do some targeted/controlled spills see it/where it comes out.

I've never had food die even die cloth permanently, let alone fiberglass. Good luck.

 

[skunther]

View attachment 237339
The holes I pointed out with an arrow….they look very wide.
How long are the 2 screws that hold the deck in place, that go in those holes?
On my Hunter 340 I found that these 2 screws were 2 inches long!! They only needed to be 1 inch, but someone used too long a screw and pierced through and into the aft cabin. I bought my boat new in 2000 and I am the only owner so I know I did not do this. It was an over zealous worker with a screw gun and a box of screws the day they put the sliding deck plate on.

You say it only happens after washing down or rain. Thats where I would look next.

I fixed mine by using a 2 part filler that can be drilled and tapped after it hardens. Then used 1 inch screws to hold the deck in place.
As a quick “fix” to just check if this is the source of your leak….get some “duct seal” (in the plumbing department at Home Depot), fill the holes and run some water over the area. It stays pliable and is easy to remove, but seals great.
Try this and let us know. I hope this helps you.

Did you drill, tap and then use bolts? Or did you use screws? I thought tapping was threading holes for bolts? Also, did you use any additional sealant on the holes in addition to the screws?

 

[sailcapt340]

Sorry for any confusion I caused. “Tapped” was the wrong word in this case. If I am going to fill a hole I just associate drilling and tapping together as the final end product. I apologize.
So to answer your question….I filled the 2 holes that had the 2 inch screws in them. Let the 2 part epoxy harden, then drilled a pilot hole in each to accept a 1 inch stainless steel “wood” screw. The same type and width (flat head) as the 2 inch screw that was used by Hunter but smaller. And to be extra cautious I did put some flexible sealant around the area just in case there might be an opening in my repair.
In my boat there is an access panel in the aft cabin ceiling. I was able to reach in and put some of the duct seal into the holes to keep the 2 part epoxy from dripping out. If you can’t do that just make the epoxy thick enough to hold a shape. It will work and hold.
I found the product I used since you posted this question. I filled the holes with Marine-Tex.
Just get creative with the thickness of the mixture to hold itself in place.
I hope this clears up the confusion I caused. In my case it worked and holds like new. There are 4 screws holding the deck in place as you mentioned, 2 vertical on the end and 2 horizontal holding it down. Neither need to be so tight or deep to hold the deck.
So was this your source of the leak?