Wood framing to Fibreglass berth ceiling: Adhesive or screws?

[John Franklin]

I’ve removed the headliner and framing in my v-berth and will be installing new framing with insulation between frames and new headliner.

I am looking on some advice as to which option is best for securing the framing to the fibreglass; an adhesive or screws?

The original work had nails, which leaked. I’ve patched the holes and am weary of screwing or nailing the new framing into the Fibreglass for obvious reasons.

Will adhesive bond the dissimilar materials enough to not fail at some point? If so, which type of adhesive would I need?

Can screws be used with a sealant to prevent leaks?

I feel screws would be more practical for securing due to the curvature of the fibreglass vs the elasticity of the wood framing wanting to return to a straight plank.

Any insight would be greatly appreciated

[rbk]

Kerf the wood you are applying to help match the curvature, bed in place with thickened epoxy and wedge in place until cured. An adjustable shower rod or two works well. Anything not meant to be glued i.e clamps, spreaders etc should be wrapped in cellophane so they do not become part of the project.

[Terra Nova]

If the glass is cored, bond with epoxy using screws through the inner skin to hold the wooden strips in place while the epoxy cures. If the glass is a single skin you can use spots of hot glue to hold the strips while epoxy cures; just press in place til the hot glue hardens.

[Don C L]

I'm no shipwright, just a DIY guy, but I prefer to avoid making any holes between the wet and dry parts of the boat. Do you have any photos? My inclination is to say to laminate the wood arches from thin strips to the curve you need and then glue them in with some kind of a jig to hold it tight... if I am understanding the situation correctly. Hopefully those shipwrights will chime in here for you!

[Cheechako]

I would use screws and either a fiberglass slurry, tough sealant like 5200, or even marine Bondo. It's just easier using screws going through the lower layer of glass to hold everything. What will the "framing" be? Often it is plywood, with partial cuts across the narrow width to make it flex to fit the curve. This gives the glass, bondo, glue more to hold to also. Some people will fiberglass strips across the framing with thin boat cloth, but really not necessary.

[rbk]

Originally Posted by Cheechako

I would use screws and either a fiberglass slurry, tough sealant like 5200, or even marine Bondo. It's just easier using screws going through the lower layer of glass to hold everything. What will the "framing" be? Often it is plywood, with partial cuts across the narrow width to make it flex to fit the curve. This gives the glass, bondo, glue more to hold to also. Some people will fiberglass strips across the framing with thin boat cloth, but really not necessary.

This is called a kerf cutting. Do not use bondo as it is not very strong or flexible and will crack, even kitty hair; it is meant for making things look good, not making structural components. Use an epoxy with colloidal silica as a minimum or other high density additive or as mentioned 5200.

[Sailorman Ed]

Kerf the wood you are applying to help match the curvature, bed in place with thickened epoxy and wedge in place until cured. An adjustable shower rod or two works well. Anything not meant to be glued i.e clamps, spreaders etc should be wrapped in cellophane so they do not become part of the project.

this is the best way, no holes in the deck but 2 suggestions. Clean off any paint so the epoxy sticks better and LIGHTLY bush a coat of unfilled epoxy first to promote adhesion, then use epoxy thickened like peanut butter. Spread a sheet of PE under your work area, much easier to clean up later.
Ed

[Cheechako]

Originally Posted by rbk

This is called a kerf cutting. Do not use bondo as it is not very strong or flexible and will crack, even kitty hair; it is meant for making things look good, not making structural components. Use an epoxy with colloidal silica as a minimum or other high density additive or as mentioned 5200.

Yeah I know about Kerf. But I figured the OP didn't. I have tried all three in the past, bondo, 5200 or kitty hair. They all work fine. Hull defects are filled with the bondo and it stays in place. Hulls flex. I agree though, not my preference, but easy peasy. I think 5200 is my preference as it does have a bit of flex to it and is tenacious! But the downside is it takes a long time to cure. Kitty Hair can be lumpy causing bulges in the strips if you are not careful.
The first boat I built in '80 I used bondo for the cleat strips that hold the "ceiling strips" on the "side walls" of the V berth. (solid hull, no screws) I put lam resin on the kerf side of the strips first. I saw that boat last year. Mahogany ceiling strips still there 37 years later and those hull sides flex a lot when beating to weather!
These overhead Port Orford Cedar strips were attached the same way. And these strips behind the book case also. (pics from last year)

[rbk]

Originally Posted by Sailorman Ed

this is the best way, no holes in the deck but 2 suggestions. Clean off any paint so the epoxy sticks better and LIGHTLY bush a coat of unfilled epoxy first to promote adhesion, then use epoxy thickened like peanut butter. Spread a sheet of PE under your work area, much easier to clean up later.
Ed

Excellent addition, grind and wipe with cleaner (methyl hydrate is my go to as it leaves zero residue.)

Yeah I know about Kerf. But I figured the OP didn't. I have tried all three in the past, bondo, 5200 or kitty hair. They all work fine. Hull defects are filled with the bondo and it stays in place. Hulls flex. I agree though, not my preference, but easy peasy. I think 5200 is my preference as it does have a bit of flex to it and is tenacious! But the downside is it takes a long time to cure. Kitty Hair can be lumpy causing bulges in the strips if you are not careful.
The first boat I built in '80 I used bondo for the cleat strips that hold the "ceiling strips" on the "side walls" of the V berth. (solid hull, no screws) I put lam resin on the kerf side of the strips first. I saw that boat last year. Mahogany ceiling strips still there 37 years later and those hull sides flex a lot when beating to weather!
These overhead Port Orford Cedar strips were attached the same way. And these strips behind the book case also. (pics from last year)

Ya i don't trust bondo, seen it pop out and or crack far to often. Agreed on set time for 5200. The fast cure 5200/4200 apparently have the same strength properties as its regular siblings but sets up in 4-6 hours? (Can't remember).

[John Franklin]

Thank you so much for all the input! I appreciate it very much.
The deck is cored btw.
She’s a 1980 Hans Christian 38T being returned to her former glory
Beautiful work btw Cheechako!

[Singularity]

Food for thought:

I know these things as "click bonds" but apparently that's the name of the company. Essentially a bolt where the head has been replaced with a flush disk. Made to inbed into or applied onto a composite structure. Leaves you with a threaded post wherever you want/need it (if having a proud fastener stud is acceptable/works). Installing these will not violate current structures (i.e. does not add new holes).

Cut a little square (or two) of glass cloth (e.g. 5cmx5cm each), poke this thing through the middle of the glass square, temporary tape on the threads, saturate the cloth, figure out a way to hold to the structure until glue sets, remove tape, instant stud anywhere.

My apologies I don't know how to resize this.



https://www.clickbond.com/product-de...site-base-stud

[coopec43]

I'd just use contact cement adhesive - Bostik, Selleys etc. It is not a structural part and you might want to "undo" it all some time down the track.

I used contact cement to attach wood paneling to the bulkhead and it has caused no problems.


Clive

[Wotname]

Originally Posted by Terra Nova

If the glass is cored, bond with epoxy using screws through the inner skin to hold the wooden strips in place while the epoxy cures. If the glass is a single skin you can use spots of hot glue to hold the strips while epoxy cures; just press in place til the hot glue hardens.

An alternative to using spots of hot glue is to use spots of fast setting epoxy glue along with the normal epoxy adhesive.

Get or make a 2 or 3 minute epoxy glue mix and use in lieu of the hot glue.

[dkenny64]

food for thought..
I was told be a former sailboat building engineer.
per destructive testing..
bonding a bulk head with 5200 was stronger than tabbing with fiberglass cloth..


just an fyi..


If it makes a difference..
I adding a plywood panel, non structural, using 5200 and fiberglass tabbing..just because..


so I'd suggest using 5200.. but make sure the surface to clean and rough so the glue has something to grab.


-dkenny64

[coopec43]

3M Marine Adhesive Sealant 5200 - CH Smith Marine

"5200 Fast Cure Marine Sealant. ... 3M Marine Adhesive Sealant 5200 is used for bonding and sealing wood to fibreglass, portholes, Deck fittings or moldings requires a product having structural strength. ... Ideal for Through-Hull fastening, Deck fittings, railing & transducers, above & ..."