Seal tiny leak portlight caulk

[skunther]

I’ve noticed a small leak on the inside of a portlight (pictured), and can’t identify the exact source. It seems the PO put some silicone on the seam of the bedding compound on the exterior (pictured), which is failing likely due to torsion on the hull while under sail. It’s a very small leak, but I’d like to seal it. Can I rectify this by removing the failing silicone and sealing the seam of the bedding compound with something more appropriate?
I’m sure rebedding the entire portlight would probably be the most thorough method, but due to the fact that this is a boat, and the simplest projects have a tendency to complicate exponentially, I’d prefer to keep this as simple and tidy as possible

 

[Don S/V ILLusion]

What a mess! The appearance would bother me more than a small leak.

First, it’s very difficult to remove silicone completely. If you don’t, nothing else will adhere to the frame. While your intent to simplify the work is everyone’s goal, it isn’t that difficult to do this correctly by removing, throughly cleaning both the ‘glass’ and frame and re-bedding with a proper sealant.

 

[rgranger]

Ahhhh..... that is going to baloon.... You will never be okay with the results if you don't just remove the port... clean out all of the old adhesive and rebed it. I'd suggest butyl tape or one of the 3M products like 590. If you remove the screws and then work an ice pick or other sharp stabber through the bedding... then work a piece of fishing line (or even dental floss) through the hole... and with someone on the inside and someone outside... use the string to saw the bedding comound and get the port off of the boat.

 

[skunther]

Got it. Those mounting screws are only on the port side (identical port light on starboard side has no mounting screws). It seems the window is held by the bedding compound/caulk, and not the screws, so I don’t know that butyl tape would be appropriate.
Any recommendations for mounting compound/caulk given this scenario?
How long should I anticipate this job will take, and any recommendations/guidance/resources on how to do it well/right?

 

[Foswick]

Yeah, I hate to say it, but I am firmly in the completely-rebed camp. In my experience there is no way to patch a small deadlight leak. First, you don't actually know where the water is coming in - you only know where it is coming out.

The first thing I would do is create a little effigy doll of the previous owner, stick pins in, and seal them in place with silicone.

But then, yes, it is remove, clean, and rebed. I would use butyl tape, as suggested ... I think ... depending on exactly how those are bedded. It looks like they might be bedded in such a way that relies on adhesive, in which case, you'll need an adhesive.

If you really just need a temporary fix that you know might not work and probably won't last, you could clean it up as well as possible from the outside then lay down a generous bead of polyurethane sealant. This might work - possibly even permanently - but it might not.

One little parting thought. On a previous boat, we had a leak from the inside corner of a deadlight - really similar position. I removed the outer frame and resealed ... twice. It still leaked with no apparent improvement. I finally removed the entire window to completely rebed, which is how I discovered the ingress was actually from a poorly-sealed mounting screw for the grab rail ... a good 20 inches from the detected leak. Water had been seeping through the core and finding its way out at the window frame.

I am not suggesting that unlikely scenario is where your boat is leaking - just a cautionary tale against quick fixes.

 

[skunther]

Yeah, I hate to say it, but I am firmly in the completely-rebed camp. In my experience there is no way to patch a small deadlight leak. First, you don't actually know where the water is coming in - you only know where it is coming out.

The first thing I would do is create a little effigy doll of the previous owner, stick pins in, and seal them in place with silicone.

But then, yes, it is remove, clean, and rebed. I would use butyl tape, as suggested ... I think ... depending on exactly how those are bedded. It looks like they might be bedded in such a way that relies on adhesive, in which case, you'll need an adhesive.

If you really just need a temporary fix that you know might not work and probably won't last, you could clean it up as well as possible from the outside then lay down a generous bead of polyurethane sealant. This might work - possibly even permanently - but it might not.

One little parting thought. On a previous boat, we had a leak from the inside corner of a deadlight - really similar position. I removed the outer frame and resealed ... twice. It still leaked with no apparent improvement. I finally removed the entire window to completely rebed, which is how I discovered the ingress was actually from a poorly-sealed mounting screw for the grab rail ... a good 20 inches from the detected leak. Water had been seeping through the core and finding its way out at the window frame.

I am not suggesting that unlikely scenario is where your boat is leaking - just a cautionary tale against quick fixes.

How would I best clean up the existing silicone without damaging the existing bedding compound? Any recommendations on good PU sealant? It seems going this route would clearly establish if the issue lies with the window or elsewhere (I am 99.9% certain it is the existing window sealant).
If it were fixed the simpler way, I would be quite content, and if I have to rebed later, it doesn’t seem much labor would be lost on trying the simpler path first.

 

[Tally Ho]

Trying to speak this ‘over the top’ of the old bedding is a bandage at best, and probably won’t seal the leak.

As others have said, you really need to bite the bullet and remove the window, and rebed it correctly.

I put my O’Day 322 away for the winter this week, in a big rain storm. Water leaked in from my main hatch as the yard blocked my boat “nose up” to allow water to run into the s uppers. But that allowed water puddle around the recessed hatch. I thought about smearing some caulk around it, but I knew the best thing was to remove the hatch, remove the old caulk. And rebed it correctly…which I did. I will sleep better over the winter knowing the hatch is sealed properly.

Greg

 

[Don S/V ILLusion]

How would I best clean up the existing silicone without damaging the existing bedding compound? Any recommendations on good PU sealant? It seems going this route would clearly establish if the issue lies with the window or elsewhere (I am 99.9% certain it is the existing window sealant).
If it were fixed the simpler way, I would be quite content, and if I have to rebed later, it doesn’t seem much labor would be lost on trying the simpler path first.

How many times do you want to do this?

 

[marcham]

Another vote for there is only one way to do this: remove all sealant, pull the acrylic, clean it all up and reinstall.

Once silicone is applied, nothing will stick to it. The only fix is removing everything, sand, reinstall properly. Need a temporary fix? Use tape to seal the joints. Note that if water is getting through, the structural strength of the bond holding the window in place is compromised.

It's about a 4-5 hr job, per window, but you'll get another 25 years if done well. DO NOT use butyl tape. The sealant (DOW 795) is also an adhesive. The screw holes are there just to hold the acrylic in place while the DOW cures. Then the screws are removed and the holes filled with Dow 795. Another method is secure the acrylic with VHB, then seal around the edges with 795. I have attached the original repair instructions from Hunter and the VHB method as well.

Where is the water going? What damage is it causing? How much work will that be to fix compared to just re-sealing the windows? I'd reseal all the others as well, if they have not leaked, they are about to! .... welcome to boating There's the list of what we want to do, then there's the list of what the boat makes us do....

 

[skunther]

Another vote there is only one way to do this: remove all sealant, pull the acrylic, clean it all up and reinstall.

Once silicone is applied, nothing will stick to it. The only fix is removing everything, sand, reinstall properly. Need a temporary fix? Use tape to seal the joints. Note that if water is getting through, the structural strength of the bond holding the window in place is compromised.

It's about a 4-5 hr job, per window, but you'll get another 25 years if done well. DO NOT use butyl tape. The sealant (DOW 795) is also an adhesive. The screw holes are there just to hold the acrylic in place while the DOW cures. Then the screws are removed and the holes filled with Dow 795. Another method is secure the acrylic with VHB, then seal around the edges with 795. I have attached the original repair instructions from Hunter and the VHB method as well.

Where is the water going? What damage is it causing? How much work will that be to fix compared to just re-sealing the windows? I'd reseal all the others as well, if they have not leaked, they are about to! .... welcome to boating There's the list of what we want to do, then there's the list of what the boat makes us do....

Thanks for those. Yes, I need guidelines for how to do this.

 

[Project_Mayhem]

BoatWorks Today has some excellent videos on how to do this properly. Hopefully this is the correct one. As others have stated, your screws are there just to hold the window in place (lightly hand tighten) while the DOW 795 cures. If memory serves me correctly, it takes about a week to cure but this is the stuff that holds windows in high rises. This is the only application on a boat that I would advise to use silicone. To remove silicone, I generally use a plastic chisel, rub my finger over it, sandpaper or if it's really stubborn or I'm impatient, a Scotchbrite wheel on a 120v drill. The scotchbrite wheel works great but it will scratch up the gelcoat underneath.

 

[rgranger]

Water had been seeping through the core and finding its way out at the window frame.

I had a similar experience on my H26. Water looked like it was coming in through an opening port in the head... but it was actually coming in through a stopper in the slide of the companionway hatch. Then the water migrated through the headliner and oozed out at the port.

 

[fred1diver]

How wide is the frame around the window?
You might be able to use 3m vhb tape to hold the window in place and caulk the surrounding, that is what I did on my old Grampian 26 and from the new owner it is still holding strong

 

[JBP-PA]

Just a couple more thoughts.

The bedding compound under the window is probably not silicone. Someone added the silicone to the outside to avoid rebedding the window.

I've found a good temporary fix is clear Gorrila tape. It lasts a couple months, enough to get to the end of the season and rebedding becomes a winter project.

Since one side is screwed on and the other not, it would suggest the screws were added as yet another fix for failed bedding.

For screwed on windows, butyl is OK. Bed-It brand seems to work best of the three I've tried.
For glued on windows, thick 3M VHB followed with a bead of DOW 795. The VHB holds the window in place. You want the 795 thick so it can flex with the window and boat movement.

 

[Project_Mayhem]

Just a couple more thoughts.

The bedding compound under the window is probably not silicone. Someone added the silicone to the outside to avoid rebedding the window.

I've found a good temporary fix is clear Gorrila tape. It lasts a couple months, enough to get to the end of the season and rebedding becomes a winter project.

Since one side is screwed on and the other not, it would suggest the screws were added as yet another fix for failed bedding.

For screwed on windows, butyl is OK. Bed-It brand seems to work best of the three I've tried.
For glued on windows, thick 3M VHB followed with a bead of DOW 795. The VHB holds the window in place. You want the 795 thick so it can flex with the window and boat movement.

Clear Gorilla tape leave very little residue compared to other tapes. I had some cables taped to a wood floor for two years. When I pulled them up, there was little to no residue and no discoloration of the wood. Gorilla tape on the other hand will pull lacquer off of a floor but it will keep cables taped to an unswept NYC street!

I wouldn't use butyl for this application. It's too difficult to compress on this large of a scale. If you try to use screws to compress it, you'll likely get cracks in the window down the line. I tried this on a smaller window with a frame. I was never able to fully compress it and there was exposed butyl collecting dirt and occasionally smeared on to other things

 

[Foswick]

Clear Gorilla tape leave very little residue compared to other tapes.

OK, but aren't clear gorillas exceptionally rare?