PB vs CSM For Gluing Wood To Fiberglass

[Ryan87LX]

In most of the posts here regarding transom replacement, the consensus seems to be to use PB and spread it with a notched trowel to adhere the wood to the existing glass skin.

Is there any reason this is more effective than say, simply wetting out a layer of 1.5oz CSM and sandwiching it between the two?

I'm sure there is, but I'd like to know the answer. The CSM seems to be much easier to do.

 

[mxcobra]

Re: PB vs CSM For Gluing Wood To Fiberglass

I used PL premiam for all glueing and fillet needs

 

[ondarvr]

Re: PB vs CSM For Gluing Wood To Fiberglass

It depends on how flat the surface is, putty will fill and provide better contact if the existing laminate surface is uneven with high and low spots. A layer or two of mat will be a little stronger, but neither typically fails.

 

[93bayliner1800]

Re: PB vs CSM For Gluing Wood To Fiberglass

I say if it if wood to wood...you cannot beat PL, but if any of it is glass...resin the wood then mix up PB and you cannot go wrong.

 

[Woodonglass]

Re: PB vs CSM For Gluing Wood To Fiberglass

For wood to wood Laminations, Titebond III wood glue is about as good as it gets if the surfaces are flat. If the surfaces are uneven then PL Or PB is recommended. With PL you have a LONG cure time before you can glass it in. PL has outgassing during the curing process and it will affect the glass adhesion if you attempt to glass over it prior to the PL being cured. For Glass to Wood adhesion such as attaching the wood transom to the outerskin of the hull then either the PB or the CSM and Resin will work, but as ondarvr said it all about the flatness of the surfaces being bonded. If you do a good job of grinding the outer skin flat then CSM and Resin will do the job. If Not then PB will take care of the imprefections. PL will too but you have a long wait for the cure, usually 72 hours.

 

[Ryan87LX]

Re: PB vs CSM For Gluing Wood To Fiberglass

Wait, are you saying that I could use PL Premium to actually adhere the wood to the existing fiberglass skin?

That could prove to be very interesting, and potentially save me a lot of trouble, as I need to ship in most of my supplies. Anything that can save me resin interests me.

I am restoring a Powercat. Rather than stringers, the boat has a thin layer of plywood attached to the bottom of each of three sponsons, and then glassed in. So, I could clean and prep the surface, cut new plywood, PL the pieces down! Let it cure for 72 hours, and then simply glass over top? And the same for the transom? Prep the glass, glue the transom with PL, and then glass over top?

The extra working time seems like it would also be a big advantage to the first timer such as me. Is this something a lot of people do?

 

[Woodonglass]

Re: PB vs CSM For Gluing Wood To Fiberglass

Wait, are you saying that I could use PL Premium to actually adhere the wood to the existing fiberglass skin?

That could prove to be very interesting, and potentially save me a lot of trouble, as I need to ship in most of my supplies. Anything that can save me resin interests me.

I am restoring a Powercat. Rather than stringers, the boat has a thin layer of plywood attached to the bottom of each of three sponsons, and then glassed in. So, I could clean and prep the surface, cut new plywood, PL the pieces down! Let it cure for 72 hours, and then simply glass over top? And the same for the transom? Prep the glass, glue the transom with PL, and then glass over top?

The extra working time seems like it would also be a big advantage to the first timer such as me. Is this something a lot of people do?

Not saying it has not been done, just saying it is not the norm. The description I gave in post #5 is the most common method of glassing stringers and transoms. The first link in my signature below has drawings and descriptions of the most commonly accepted methods. A lot of guys use PL to Bed their Stringers and do their Filleting. Not very many use it to actually glue the Wood transom to the outer skin of the boat. Not saying it hasn't been done, just saying it is not the norm. Again, if you do, there is a minimum of 72 hour cure time and the adhesion could be less than the other methods. However most of the strength in the transom will come from the tabbing and inner layers of CSM and 1708 to the hull.

 

[mxcobra]

Re: PB vs CSM For Gluing Wood To Fiberglass

Thats exactly what I did- for the same exact reson as your describing.
Check my boat rebuild thread in my sig.

I took a notched trowel and spread the pl out on transom boards then clamped and screwed to transom.
also glued all stingers in with the stuff

Then I tabed everything in real good with csm and woven....
actually as I see! This is a good way of fastining wood to existing hull leaves a nice hard rubber like substance all around for no hard spot

Wait, are you saying that I could use PL Premium to actually adhere the wood to the existing fiberglass skin?

That could prove to be very interesting, and potentially save me a lot of trouble, as I need to ship in most of my supplies. Anything that can save me resin interests me.

I am restoring a Powercat. Rather than stringers, the boat has a thin layer of plywood attached to the bottom of each of three sponsons, and then glassed in. So, I could clean and prep the surface, cut new plywood, PL the pieces down! Let it cure for 72 hours, and then simply glass over top? And the same for the transom? Prep the glass, glue the transom with PL, and then glass over top?

The extra working time seems like it would also be a big advantage to the first timer such as me. Is this something a lot of people do?

 

[mxcobra]

Re: PB vs CSM For Gluing Wood To Fiberglass

The only problem I had is PL must cure 1000 percant first or it will cause a reaction with the polly and bubble up and mess up the bond.

You really need to let the pl cure for a week or more and in some spots if you have the pl on real thick stab it with a knife.
After a day or two. As to let air get doun in there it wil cure better this way