Installing ports without fasteners - any results?

[Beersmith]

I am about ready to install some largish portlights/windows on my boat and am looking for other people's experience with this particular type of installation.

I plan on following these instructions: Hints For Replacing & Sealing Acrylic Boat Windows | THE PLASTIC SPORK BLOG

it is sort of a modified version of the "Sexy Windows" method that has been discussed here: How to install boat windows and port lights

instead of using the tape, it relies on the Sikaflex for the whole bond. The Sexy Windows article even mentioned in the updates that he might go this route of not using the tape.

My biggest concern was that the bond is only as good as the paint on the cabinside, so I plan on grinding off all of the paint under the windows so it will be bonded directly onto the gelcoat.

Of course the alternative would be to thru-bolt the ports, still using the Sikaflex with spacers. However, the methods in the links above are designed so that no fasteners are needed, which is where leaks seem to show up.

Has anyone had experience good or bad with bonding ports without fasteners?

thanks

[44'cruisingcat]

I can see difficulties in not using at least some double sided tape. You want the sealant bed to be fairly thick, so it can handle sheer loads from expansion better.

Tape can be used as a "dam" to stop sealant going where you don't want it on the inside of the boat, and will work as a spacer while the sealant sets. Holding the windows in place until the sealant sets without using any fasteners or tape could be tricky, and end up a mess.

Also, acrylic can be difficult to bond to. Not many sealants will stick well to it. There are double sided tapes that bond well though.

[skipperaris]

Originally Posted by Beersmith

Has anyone had experience good or bad with bonding ports without fasteners?

thanks

My boat has Goiot ports which hinge open or shut by a handle which is screwed through the plexiglas which in turn is glued to the aluminum frame round it.

I have had lots of experience with these. Mostly bad
But also some good expeience.

The bad experience is from the smaller ports ( about 35x20 cm ) which have a friction hinge to keep the port in whatever position it is left. The hinge is really the problem. If it is not used a lot it seizes and when pushed hard enough the hinge does not budge and the plastic comes off, usually with all the sealant attached to it.
So you start all over again. It does not matter what sealant is used. Silicone is good and sikaflex is also good up to a point.

My main hatch ( 60x60 cm ) which has a different hinge with a spring to help it on opening has stood the test of time This is the good experience.

What I'm really saying is that the strength of the bond has limits. If you press hard enough it will fail.

So you need to think of what forces can be applied to your ports in use.

Hope this helps a little and wish you luck.