Window Caulking

Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
Do they open? Or are they fixed in the hull?
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
Hi sailors, what kind of clear caulking should I put around my leaking window. Thanks
Nothing you buy in a hardware store. You will rue the day.

The most effective way to stop leaking ports is to remove them and recaulk with an appropriate caulk. Ports come in many different styles, a few photos will help us help you.
 
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Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Hunter used Dow Corning 795 for caulking during manufacture.

You may be able to fudge the job and put in a temporary caulking repair with DC 795 as I did about 5 or 6 years ago. Check where it leaks inside and repair 6" on either side of the leak on the outside. Still not a drop so that one slipped to the bottom of the TO DO list.

See this post starting with #2:

 
Apr 26, 2021
9
Hunter 306 CVDM
Hunter used Dow Corning 795 for caulking during manufacture.

You may be able to fudge the job and put in a temporary caulking repair with DC 795 as I did about 5 or 6 years ago. Check where it leaks inside and repair 6" on either side of the leak on the outside. Still not a drop so that one slipped to the bottom of the TO DO list.

See this post starting with #2:

What do you think of the 3M marine grade silicone sealant? I need a clear sealant. Thanks.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
What do you think of the 3M marine grade silicone sealant? I need a clear sealant. Thanks.
Generally, using silicone sealants on a boat is a poor idea unless absolutely necessary. The silicone embeds in the gelcoat and affects the adhesion of any good sealant, paint, or gelcoat that may be necessary later. Which, if you just smear some silicone around the edges of the port will be sooner rather than later. Once cured the silicone can not be removed with solvents. Aggressive removal of gelcoat is the only known cure.

The only way to effectively cure a leaking port is to remove it, hope no one has used a silicone sealant, and rebed it properly. If you research your options, you will see some recommending Dow 795 or GE Silpruf as a sealant, both of these are silicone based but the chemistry is much different. The original application for these products was glazing windows into sky scrapers. They do not have the foul characteristics of the acetic acid based silicones. If the silicone caulk smells a little like vinegar, it is acetic acid based and should be avoided.

Rebedding ports is not a particularly difficult job nor a technically challenging one. Do it right, do it once.

Treat your boat kindly and it will treat you well.
 
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Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
What do you think of the 3M marine grade silicone sealant?
Sorry, no experience there. May just be the same as DC 795. Only way to tell is to go with the 3M and watch for the next 22 years to see if it still looks new as does my factory installed DC795. I must say the stuff does amaze me for 22 years. No idea what the life expectancy of this stuff is.

Out of curiosity, why the need for clear caulking as opposed to the black DC795 you already have ?
 
Apr 26, 2021
9
Hunter 306 CVDM
Sorry, no experience there. May just be the same as DC 795. Only way to tell is to go with the 3M and watch for the next 22 years to see if it still looks new as does my factory installed DC795. I must say the stuff does amaze me for 22 years. No idea what the life expectancy of this stuff is.

Out of curiosity, why the need for clear caulking as opposed to the black DC795 you already have ?
There is already a clear sealant on the other windows. I was hoping I could only correct the leaking zone of my window (probably not a smart idea...).
Thanks for your help.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
There is already a clear sealant on the other windows. I was hoping I could only correct the leaking zone of my window (probably not a smart idea...).
Thanks for your help.
Because the prior owner did something silly, doesn't mean you have to follow. ;)
 
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Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
A little less snarky.

For a temporary fix sealing the outside of the window frames will work, for a while. Much better to do the job correctly.

Try using some BoatLife Life Caulk or 3m 4000. These will do a passable job for a while and will be much easier to remove when it is time to do the job correctly.
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Because the prior owner did something silly, doesn't mean you have to follow. ;)
My thoughts exactly. The PO's strike again.

Take a close look and see if you can remove the clear stuff (Bath and Kitchen Silicone sealant) and replace with black DC 795. You will have nothing but leaks with with the clear sealant.

DSC_1987.jpg


This is the way all fixed hatches and portlights were caulked from the factory. Look good and still as good as new 22 years later.
 
Apr 8, 2010
1,942
Ericson Yachts Olson 34 28400 Portland OR
If the sealant is in contact with plastic lenses or frames, do not us the BoatLife LifeCalk product.
Their other formulation, "LifeSeal" is the right one; it comes in clear also. I have used it for decades. Easy clean up and no leaks.
Sikaflex 795 LOT is also a great choice.
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
If the sealant is in contact with plastic lenses or frames, do not us the BoatLife LifeCalk product.
Their other formulation, "LifeSeal" is the right one; it comes in clear also. I have used it for decades. Easy clean up and no leaks.
Sikaflex 795 LOT is also a great choice.
My bad, polysulfide caulks are bad for plastics. :facepalm:
 
Apr 8, 2011
768
Hunter 40 Deale, MD
I'm working up the courage (and time) to pull out a leaking port and rebed properly. Great advice on here about that, and even some project photos. I did make a temporary repair which has worked really well for the last 7 months (including significant temperature changes over the winter and spring). I applied an unbroken length of butyl tape around the exterior frame of the fixed port, carefully pushing the butyl into the seam and onto the gelcoat around the seam. So the butyl covers half the frame, the seam, and gelcoat. Its not the prettiest of fixes, given its gray butyl on white gelcoat, but it has completely stopped the leak until I can get the time to do the right thing and remove/rebed. And the temporary fix will take all of 30 seconds to remove with no lingering residue to remove. Butyl is great stuff.