Fixing electronics backing board to fibreglass hull

[infaddict]

I'm rewiring my boat (10m sailing yacht, GRP) and this will mean having to screw lots of electronic components in place inside the boat. Things like bus bars, AIS transceiver, b2b charger, inverter etc). Most of these will go in the quarterberth or near nav table.

Therefore I need some sort of backing board that I can screw into, as I can't screw into the hull. I'm investigating the best material for such a board, but my question is about how to fix a board to the hull.

I was thinking of sanding back the inside until clean, wiping down, then using some sort of epoxy glue or other suitable adhesive. And perhaps I only need to do that for 4 smaller corner mounts, which the bigger board then attaches to.

Any advice much appreciated thanks.

 

[Tranona]

12mm ply is commonly used for this. I use CT1 to attach to GRP and screws to ply bulkheads. I tend to make the panels up in the workshop to get the layout right, then paint or varnish them before attaching. couple of examples in the photos. The first is the shorepower CU and GI. lower down is another panel for the main bus bars. The second one shows some smaller panels that put related connectors close. These are all on ply bulkheads so screwed as I try to avoid that but I have done a couple like that

 

[Dellquay13]

12mm ply is commonly used for this. I use CT1 to attach to GRP and screws to ply bulkheads. I tend to make the panels up in the workshop to get the layout right, then paint or varnish them before attaching. couple of examples in the photos. The first is the shorepower CU and GI. lower down is another panel for the main bus bars. The second one shows some smaller panels that put related connectors close. These are all on ply bulkheads so screwed as I try to avoid that but I have done a couple like that

I’ve never tried CT1 for bonding to the hull. Is it as reliable as epoxy? Does previous bilge paint stop it working?
I’d like to fasten some ply blocks to the cockpit locker lid to mount the boat hook etc, I was planning on the usual stiffened epoxy pudge, is it worth trying CT1 instead?

 

[Tranona]

Yes. Couple more photos showing the use of CT1 In first one the mini bulkheads for the bookshelves are bonded to the GRP hull and in the second the battens that the T&G lining is secured to. I usually use masking tape to hold in place while the stuff cures.

 

[Poignard]

I’ve never tried CT1 for bonding to the hull. Is it as reliable as epoxy? Does previous bilge paint stop it working?
I’d like to fasten some ply blocks to the cockpit locker lid to mount the boat hook etc, I was planning on the usual stiffened epoxy pudge, is it worth trying CT1 instead?

I have used epoxy before I discovered CT1. Both were fine.

CT1 is easier and less messy to use than epoxy.

You must remove paint from the bonding surface, otherwise you will have a very weak bond because are attaching your ply blocks to paint and not to fibreglass.

 

[Boathook]

I've used nonails waterproof for non structural items in the past. As mention bond is only as strong as the surface you are bonding onto.

Following another thread a while back, I have purchased west resins G/flex, 655 epoxy resin. Easy to use as in tubes and squeeze out what you want to use. Not cheap though.

 

[William_H]

The weight of the omponent to be fixed is what will dictate the strength of the attachment of the backing board. I would suggest material used for backing board for power meter fuses etc because it is fire proof. Of concern in some certification regimes. Will take a thread tapped in.
The larger the area of contact to hull the better the strength of mount. As said clean the grp many glue types might be suitable. ol'will

 

[merjan]

+1 for CT1. I used it for the same application and it worked very well. The inside of the hull could was in a bad shape, residues of fabric liner over old paint. After a year the backing board feels very solidly fixed, and it's good to know that it's less permanent than epoxy.

 

[PaulRainbow]

As others have said, 12mm ply fixed with CT1 or OB1 will be fine. Clean back to GRP for the best adhesion, if done correctly you'd destroy the ply if you tried to remove it at a later date. No need for fire proof board.

 

[Alex_Blackwood]

As others have said, 12mm ply fixed with CT1 or OB1 will be fine. Clean back to GRP for the best adhesion, if done correctly you'd destroy the ply if you tried to remove it at a later date. No need for fire proof board.

Whilst I Don't feel qualified to comment on fixing, I agree with above. I would just add, make sure the mounting board is big enough to take the additions you will put on in the future

 

[AngusMcDoon]

As others have said, 12mm ply fixed with CT1 or OB1 will be fine. Clean back to GRP for the best adhesion, if done correctly you'd destroy the ply if you tried to remove it at a later date. No need for fire proof board.

I recently moved my bow thruster battery to install a freezer. The original builder battery installation had a base made from 8mm plywood held down by 4 screws and a single zig-zag of adhesive. Screws came out easily, but despite a lot of trying I could not get the base off without destroying it because of the adhesive.



I made a new one. When installing it I used screws and CT1. I applied the adhesive only near the edges because if it needs to be removed again that can be reached with a blade to cut it. Adhesive in the middle is impossible to do anything about.

 

[PabloPicasso]

12mm ply is commonly used for this. I use CT1 to attach to GRP and screws to ply bulkheads. I tend to make the panels up in the workshop to get the layout right, then paint or varnish them before attaching. couple of examples in the photos. The first is the shorepower CU and GI. lower down is another panel for the main bus bars. The second one shows some smaller panels that put related connectors close. These are all on ply bulkheads so screwed as I try to avoid that but I have done a couple like that

Hey, nice job, very neat

 

[zoidberg]

Like others, I've used CT1 for multiple jobs with great success. However, holding a hefty component or section of reinforcement in place up under the deckhead, f'r instance, while the bonding agent 'went off' needed another approach.

The answer I found was from the same stable as CT1 - 'Power Grab and Bond'. I spoke with the company's helpful tech guy at their head office, and he assures me the two products have almost exactly the same substantial shear/peel strength once cured. The 'PGaB' is ideal for overhead bonding, and I've used it successfully on several tricky situations. I'll certainly use it again.

Be aware it is significantly more viscous than CT1 and benefits from warming through in a bucket of water before application, and a robust caulking gun. It is also harder to clean off tools, hands, hair and spectacles, so beware!

 

[Neeves]

I recently moved my bow thruster battery to install a freezer. The original builder battery installation had a base made from 8mm plywood held down by 4 screws and a single zig-zag of adhesive. Screws came out easily, but despite a lot of trying I could not get the base off without destroying it because of the adhesive.

View attachment 188528

I made a new one. When installing it I used screws and CT1. I applied the adhesive only near the edges because if it needs to be removed again that can be reached with a blade to cut it. Adhesive in the middle is impossible to do anything about.

View attachment 188529

It is quite possible to detach if you use the adhesive in the middle of such an assembly.

Try a filleting knife, its sharp, it bends and has a neat handle.

If you don't have a filleting knife, take a hack saw blade and sharpen one end, both sides and to a point, make a handle - masking tape. It then works like a filleting knife. You can source cheap plastic handles specifically made to accept a hack saw blade - but I don't know they are easily available. The same equipment can be used to cut sealant securing acrylic windows if you need to remove, replace, the windows.

You are limited by the length of the hack saw blade or filleting knife.

You can source other thin, flexible saw blades that might more appropriate a filleting knife and hack saw blades have always sufficed. Hack saw blades do snap - and we keep the blades for this sort of need - sharpened at one end, side.

Jonathan