Rebedding Lewmar Lenses

[arjand]

Ok.... I have put new lenses in four Lewmar hatches using Butil tape. However, the lenses are now all a touch below the frame which means that rainwater will likely stay on the lens. Does this mean I have to do it all over again as this would cause leaks at the handles or am I ok? Any comments greatly appreciated!

[Sailmonkey]

you used Butyl tape to bed hatch lenses?! That really seems like the wrong tool for the job. Typically hatch lenses will be bed with something like Sika 295 and the lens and frame prepped with the sika primer.

Butyl doesn't have any real adhesive qualities, im afraid your lenses will come out of the frames with the slightest provocation.

[Training Wheels]

Dunno, but I did mine with closed cell hatch tape and silicone sealant.

[arjand]

Dow 795 is next on the program to fill the gap between the lens and the frame. I believe that is also how they were constructed

[Training Wheels]

That’s what I used. Just had to find the right thickness hatch tape to get the correct height.

[Sailmonkey]

Originally Posted by Training Wheels

Dunno, but I did mine with closed cell hatch tape and silicone sealant.

Hatch tape is more like 3M vhb tape correct? an adhesive, not butyl with sealing properties only.

[hellosailor]

The Dow 795 data sheet pretty much does NOT endorse using that product on acrylics but suggests going to:
https://consumer.dow.com/documents/e...df?iframe=true

To look for better solutions.
GE also used to say that NO silicone product would ever make a permanent bond to acrylic or polycarbonate, the only question was how long it would take them to fail, as the glazing keeps expanding and contracting, fwiw.

And Dow points out that 795 takes 14-21 DAYS to reach full strength, if you are intent on using it, glue 'em up and then set the hatches aside for three weeks.

[arjand]

Thank you all very much. KEY question is whether I have to undo all the work to get the lenses to at least par with the frames or whether this is not really such a big issue. That would be hours and hours of cleaning.....

[hellosailor]

Butyl tape is not an adhesive. So, if the lenses are physically secured and the butyl is only there as a caulk to prevent leaks? You probably can leave it until the leaks bother you. At which (probably inconvenient) time you'll still have all that work to do. Looking on the bright side, at least butyl tape is WAY easier to clean off than real adhesive sealants would be.

[arjand]

yeah.... why did I not do just one and see how it all came out..... ?? thank you!

[Training Wheels]

Originally Posted by Sailmonkey

Hatch tape is more like 3M vhb tape correct? an adhesive, not butyl with sealing properties only.

No, closed cell foam tape, adhesive on one side. Like what you would use to seal an opening hatch. Chose the appropriate thickness so the lens was slightly raised above the frame.

[Sailmonkey]

Originally Posted by Training Wheels

No, closed cell foam tape, adhesive on one side. Like what you would use to seal an opening hatch. Chose the appropriate thickness so the lens was slightly raised above the frame.

Ok, only to raise the lens to the height of the frame, then use the goo of choice for the seal?


I've re-sealed my lenses but the old cast bomar hatches dont have a problem of needing to shim the lenses.

[Training Wheels]

Yes, that’s what I did, which is essentially (as near as I could tell) the way they were done originally. I put slight pressure on the lens to compress the foam tape a bit. Because I had imperial (3/8” I think) acrylic instead of metric, I shimmed the hinge a bit.