Leaking hatch

[RDW]

I have 27 inch square bomar hatches. One has a small leak. I see a bead of water at one corner every once in a while in a heavy rain.
Where do I start to trace it down and repair it?
rdw

[Orion Jim]

Have you replaced the gasket? Is it leaking from the interior trim? That would indicate removal, cleaning the mating surfaces of all old caulk, and reinstallation. Normally the lens will never leak but that is the only other possibility.

[UNCIVILIZED]

Aside from what's already been mentioned, have you ruled out condensation? And how long has the hatch been leaking? As sometimes, with the changing temp's of a new season, the different thermal expansion rates of various materials will cause gaskets or bedding to pull loose, & leak. Plus, the age of the various seals play a role as well.

As to tracking down the problem. Take a felt tipped pen or marker, that has water soluble ink, & draw perimeter lines around the hatch, especially in the vicinity of where you suspect leaks. And as you narrow down the location of the leak, based on where the lines get blurred by the water's ingress, you then can draw smaller 'circles' to nail down exactly where the water is coming from.

[model 10]

Originally Posted by Orion Jim

Normally the lens will never leak but that is the only other possibility.

Our boat has 14 ports. The 45 year old seal around the "lens" is dry as a bone and leaks. I'm working on them one at a time. I can do one in a day, then I quit for a while. I'm about 1/2 done.

[MarkJ]

Clean the rubbery stuff.

Whenever mine begin to leak and i think expensive thoughts i just go get the spray bottle and toilet paper and give the who,e thing a scrub.

Then no more leaks!

[RDW]

These are very helpful ideas. I realize I am lazy by asking but I find I often get good suggestions like these.
RDW

[RDW]

As far as sealing the lens, one friend suggest just digging out some of the old and reapplying a sealant with out actually pulling the lens off. Is this good advice?
rdw

[Sailmonkey]

Originally Posted by RDW

As far as sealing the lens, one friend suggest just digging out some of the old and reapplying a sealant with out actually pulling the lens off. Is this good advice?
rdw

Awful. The lens needs to be pristine clean for the sealant to bond to it. There are two types of sealant I've had good luck with for this. One is Dow 795, the other is sika 291 with the primer.


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[zeehag]

i woul d begin this repair with a tarp for over head to rule out condensation. completely cover hatch , yet allow it to open in rainstorms without allowing water intrusion.
then grab your beer and sit, during a storm, and watch as water does or does not form on hatch cover.
if it does-- fukitol. the name for this phenomenon is condensation. drink more beer. place a towel for collection of dripping water, or open the hatch slightly so it is not so inclined to form.
if it doesnt, maintain status quo, open hatch in rains, and enjoy another beer,. you are done for now.
you WILL need to remove hatch entirely, clean both surfaces and rebed. better yet, replace the gasket. many times i have sailed boats with leaky overhead hatches. so much fun. oh yeah-- once leaky , they donot reseal without good complete cleaning and rebuilding.
i am sooo glad mine are wood. i put up a tarp,repair and rebed the works and maintain the tarp to keep both sun and rain off my decks. if rain comes into my closed hatches , it means we has us another furycame.

[Sailmonkey]

Originally Posted by Sailmonkey

Awful. The lens needs to be pristine clean for the sealant to bond to it. There are two types of sealant I've had good luck with for this. One is Dow 795, the other is sika 291 with the primer.


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I had my Sika's wrong.....it's 295 with 209D primer. Not 291.

[RDW]

Zeehag, I am pretty sure it is not condensation. I only see a drop formed at corner of wood trim inside. I have never seen it actually drip.
I will do your condensation trick to check that first.
Then I plan to remove the wood trim to see closer to try to tell if it is around where the hatch is seated. I plan to also use the water based markers as suggested above.
Do you have any experience removing a whole hatch. Mine is a 27 inch square aluminum cast Bomar hatch with 4 dogs. I think the part number is C139 LAR STD-b
RDW

[Sailmonkey]

Our boat also has Bomar cast Alu hatches, however they're 16X16. I have removed both, quite easy, they're just screwed on with wood screws. I did lenses on both as well as rebed both. So far so good, no more leaks, and new acrylic!!


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