Installing Lewmar Portlights with Bed-it?

[jigray3]

I plan to replace Lewmar Old Standard portlights with their New Standard version on my '94 Bnenteau largely because my demands in the Chesapeake are modest, the new version has been redesigned for easier maintenance to prevent leakage, but primarily because I can use the same cutouts.

The instructions for both versions state that a sealant with adhesive qualities, i.e. silicone, should be used. As a fan of Bed-it butyl tape, I'm tempted to ignore the instructions, however the Lewmars install a little differently than other portlights. Other portlights will have an inner and outer frame similar to the Lewmars, but the screws that attach the frames together go through the coachroof. On the Lewmars, the screws are inside the cutout opening and clamp the frame to the edge of the cutout. The screws do not go through the fiberglass, and there's not what you'd call lot of frame overlap.

Theoretically that means the portlight could slide vertically or horizontally, depending on how much clearance/slop there is between the installed screws and the edges of the cutout. At this point I'm in the planning stages and have not removed a portlight, so can't comment on how much slop actually exists, but I'm guessing not none. In an older HTM article, Rod stated that had bed -it existed when he installed his New Found Metals portlights, he would have used it. But in his installation the screws pass through the coachroof to lock them in place, so no chance of sliding.

Love to hear from you guys on this subject, particularly if you've replaced portlights, and especially if you have used Bed-it for the install. If not, what did you use?

 

[kappykaplan]

Dow 795 should work well for this application.

 

[danooxnard]

I used butyl tape on my Catalina 22 windows, and it was a great decision. Worked great I could reposition and was not a mess. And no leaks in three years. Dano

 

[dlochner]

As I read your description I'm inclined to agree with @kappykaplan advice to use Dow 795 or GE Silpruf. Both of these products were designed to seal and mount plate glass windows in buildings. While silicone based they are not the typical silicone that we often advise against using, they are an architectural silicone.

 

[dmax]

I replaced my 6 portlights with Lewmar Standards and bedded with Bed-it - no leaks. The frames do not slide at all as Bed-it is a decent adhesive plus the clamping pressure.

 

[jssailem]

I have found that Bed-it is an excellent material when there is a mechanical fastener involved holding the fixture in place. Yes there are strong adhesive/caulking properties.I believe, constant movement will strain the adhesive feature of the caulk.

Last season I used Bed-it on the 10 windows (ports) I removed and replaced. While it functioned to seal the ports I have found over the past 14 months some leaking around the edges of 3 of the ports. I will be removing the leakers, this spring, and reinstalling them using 795 or similar product. This process can get messy. Be sure to tape and cover the area you do not want the caulk to attach itself. Clean-up is messy at the least.

 

[Tally Ho]

As long as the fasteners provide some decent clamping force, it should be OK.

But I tried butyl tape under one of my hatches, and the screws (not thru-bolted) didn’t really have enough bite and the butyl didn’t squeeze very well. If my hatch was thru-bolted, I believe it would have worked fine. But I removed it and changed to Sika Flex for that application.

Greg

 

[jigray3]

Thanks everybody for your contributions so far. All food for thought.

 

[jigray3]

Dow 795 should work well for this application.

It would work well, but reports are it can be messy and difficult to work with

 

[jigray3]

I replaced my 6 portlights with Lewmar Standards and bedded with Bed-it - no leaks. The frames do not slide at all as Bed-it is a decent adhesive plus the clamping pressure.

On point response, dmax. How long ago did you replace the portlights? No evidence of Butyl flow from the Bed-it? To get good clamping pressure I would need to choose the right length screws that provide enough clamping force without bottoming out the screws in the outer frame. Might have to start with longer screws to start the butyl squeeze and finish with shorter screws. With stainless machine screws in aluminum they'll be coated with Loctite 8023 Marine Grade Anti-Seize to prevent galling and corosion.

 

[dlochner]

It would work well, but reports are it can be messy and difficult to work with

All caulk grows legs once it leaves the container.

Patience, lots of paper towels and a pile of nitrile gloves can help.

 

[jssailem]

With stainless machine screws in aluminum

Sensible approach. You can also use Lanocote by Forespar.
"LanoCote® is the safe and natural product that stops and prevents rust, oxidation and electrolysis."
Practical Sailor identified it as a budget buy in their article here. Tef-Gel vs. Lanocote - Practical Sailor
Many tools to use.

 

[jigray3]

Sensible approach. You can also use Lanocote by Forespar.
"LanoCote® is the safe and natural product that stops and prevents rust, oxidation and electrolysis."
Practical Sailor identified it as a budget buy in their article here. Tef-Gel vs. Lanocote - Practical Sailor
Many tools to use.

Practical Sailor has been my go to for product advice for 30 years. You may be interested to know a more recent review of multiple products including Lanocote and Tef-Gel by Practical Sailor had the Loctite 8023 as both "Best Choice and Best Buy" and called it a "must have". They still like Tef-Gel for rigging based on long experience and Lanocote remains an excellent product with a well earned reputation.

These days I never do something without considering how I may have to undo it. For that reason I view silicone and similar products as equal parts god-send and curse. In the case of my old portlights, once removed I am likely to find silicone that will require removal. Complete removal. That means sanding gel coat until it no longer beads water.

Anti-Seize Coatings for Spars - Practical Sailor

Since 1974, Practical Sailor’s independent testing has taken the guesswork out of boat and gear buying.

www.practical-sailor.com

 

[Mac Smith]

Lewmar replacement "LID", is the port from the hinge up, so NO bedding work! Size 30 for $496 April 2023.
Defender
Lewmar Ocean Series Replacement Hatch Lid
No link

 

[RitSim]

If you decide to caulk, No caulk works well if squeezed to .010" thick. Expansion and contraction/elongation is based on a percentage of the thickness. Another way to handle it is to use 3M double sided glazing tape (approx 3/32 or1/8" thick) to mount the port and then use a glazing caulk (Dow 795 or equal). Then the caulk is thicker and has normal expansion/contraction. The 795 is certainly different to work with. I masked all of the fiberglass outside of the frame area with blue tape and was very careful not to over fill the joint. The tape was removed before full cure. Cleanup is different also.

 

[Project_Mayhem]

start the butyl squeeze

It won't squeeze much. I used it on one of my window frames. Three years later the frame still isn't flush with the fiberglass

 

[east coaster]

Having just used DW 795 to bed new windows on my 2002 310, I can attest that DW 795 is unbelievably messy even using lots of tape. I have found that it is a good sealer but the slight curvature in the windows and 7 days of pressure did not ensure a proper leak proof fit. I switched to sikaflex 295 UV. Better results but still messy as heck. I even used 3m vhb tape to ensure a proper fit but the 795 had "no grab" in the corners. Ended up drilling and screwing the unstuck parts to ensure a water tight fit. Now waiting for rain as it seems to have passed the hose test. The clean up in both cases is worse than the actual job.

 

[dmax]

On point response, dmax. How long ago did you replace the portlights? No evidence of Butyl flow from the Bed-it? To get good clamping pressure I would need to choose the right length screws that provide enough clamping force without bottoming out the screws in the outer frame. Might have to start with longer screws to start the butyl squeeze and finish with shorter screws. With stainless machine screws in aluminum they'll be coated with Loctite 8023 Marine Grade Anti-Seize to prevent galling and corosion.

I replaced the ports 4 years ago, no sign of movement or leaks. I had to trim the screws (72 of them) to the right length with a Dremmel so they wouldn't bottom out as you say.