Urgent Window Advice Needed -Leaking... Falling off!

I used 3M VHB clear tape to affix my polycarbonate windows, then sealed edges with LifeCaulk. (the fixed windows)

Turned the hose on them (as well as 3 huge sliding windows I designed) and no drips.

The windows were fine for weeks in the building. Now that im outside, the sun is heating them more and thermal expansion or crappy VHB tape that can't handle heat is causing major problems!

Windows are falling off! VHB is doing nothing!

A little Life Caulk is all thats holding them.

Where do I go from here??

I'm in horrible, torrential, daily tropical rain. Water is leaking in and im afraid im going to lose more windows completely off the boat before i can solve this!

I want the wrap around glass look, which I habe, but VHB tape is garbage. falls off.

What can I do to bond polycarbonate to Imron with some gap filling properties??

 

3m 4000

 

One of the few places silicone works best. Toss a tarp over the areas now, until you're ready to pull the ports and make the cleaning, change out.

 

I'm ready to change them out tomorrow.

Thanks for the advice.

Silicone will hold these in place as an adhesive? Polycarbonate to Imron bond?

How long will that last? How thick a bead?

Clamping isn't possible due to geometry. Is this an issue?

 

If this was simply bonding polycarbonate to itself, I'd recommend SCIGRIP Weld-On 16 Cement. This is a TAP product. TAP Poly-Weld Adhesive is an epoxy formulation that would also work. SCIGRIP Weld-On 16 Cement has a solvent that could screw with the paint. The Poly-Weld would likely fair better on the paint. Both of these products are available though Amazon and other suppliers.

3M 08061 Plastic adhesive might do, Loctite has a few products, one is a bond promoter for epoxy, each works.

In the end, I've found straight 100% silicone the most commonly available material to do a reliable job, remain a waterproof seal and tolerate UV for some time. The polyurethanes seem to let go with age, the single part polysulfides about the same, though the two part polysulfides are much better, likely because of the solvents attacking the plastic a bit.

Some pressure will be necessary during the cure, if only to insure good contact, between the two elements. The bead needs to be big enough to bridge any gaps, but no more.

 

GE Silpruf works well

 

3M make a black urethane adhesive for car windshields / windscreens which is applied with a caulk gun and sticks so well you better get it right first time. not personally used it in marine applications, but on the roads with icy winters (de-icing salt) and hot summers it last the life of the car.

 

This is Lexan over paint he's using this adhesive on . . .

 

Hi Snowbird
Forgot to mention ,lightly sand both surfaces to be bonded both Acrylic and painted surface to remove glaze, then clean using IPA then double sided tape and GE Silpruf
Worked for me so far 5 years no problem in Oz sun

Al

 

GE Silpruf is a silicone . . .

http://www.siliconeforbuilding.com/pdf/weatherseal/Data_Sheet_SCS2000_SilPruf_P.pdf

I guess GE has had the same results as I have with polycarbonate.

 

Thank you for all the replies.

As a used boat owner of 20+ consecutive years, I've developed a certain joy in rebedding things. There is some satisfaction to rebedding and doing it right.

I'll grab some silicone today and get to it. I'll look for the one with good adhesion qualities, as that's all that holds the lexan on the imron. And the lexan is pretty heavy!

It's a bonus that i can use something available at my local hardware store because I'm in an isolated, rural area and my vehicle sold instantly. (was a very popular one) All I haveb is a bicycle at this point.
(and Amazon)

 

Damn it, Silicone looks terrible. It's actually off white rather than clear and generally looks sloppy. it's of course, uneven under the poly carbonate, looking like someone did a half *** job.

There is also literally no way to apply outside pressure to the majority of windows. I tried it on the only one I could apply pressure to. Naturally, that's the one *I* have to look at being on the backside of the deckhouse.

looks ridiculously amateur to have blobs of junk under the lexan forming random shapes of goo.

What's next? Frames?

 

Paint the edge.

 

I've made applicators from plastic putty knifes (cut a notch) to lay down a uniform bead. I've also used tape to create a uniform channel, which is laid the goo in, so I could level the bead with a putty knife. All of this to make a uniform height and width beam, that looks good under glass. Painting the glass is an easy way to hide this too.

 

They make black silicone. You should have used that. Too late?
Regarding holding the windows in, it doesn't look like much pressure will be needed. Build a sturdy frame against which to push using sticks. Some provision for maintaining pressure while adding more sticks will be necessary. If you made maybe six "spring sticks", the right size springs would attach to the end of each stick by whittling the stick end down to form a shoulder. The window end could be coated with silicone and left to cure. It will not slide out when pressured against the boat.
You could do one window at a time.