steelespike
Supreme Mariner
- Joined
- Apr 26, 2002
- Messages
- 19,069
I just did a little quick research on pressure treated plywood.Lumber yard PT ply. is not dried thus it is heavy
this can be solved by buying early and letting dry well before useing.In tests for fiberglass bonding to regular dry plywood and PT both wet and dry they determined that there was wood failure before bonding failure for all products.For boat building they reccomend redrying to 18% after treating.That is for building not simple casting decks etc though obviously a good air drying is important for our kind of use..The only fastener reccomendation I found was use that which is appropriate for the application.
I think incapsulating un treated wood in fiberglass/resin etc may help short term but in the end exaserbates the problem of rot.I think every fiberglass boat out there with a rotten transom,floor or stringers proves that.
As i've said many times my PT transom unsealed,unpainted left out year round in the water 7 months a year since about 1985 is still going strong.Original factory transom lasted about 6 years.
My dock planking and staving is about 20 years old unpainted. PT plywood walks to the house about 12 years unpainted.Sure it grays and does need some sealing for asthetics but so far it held up till stained last year.Also painting is ok as long as enough drying time is allowed before doing so.
By the way the galvinized screws in my 8 year old regular ply barn doors corroded to the point of no return
in the weather exposed sections.(central NY)So I think there will be some fastener problems regardless of the wood used and the best stainless/coated etc fasteners are a must.
I think some research with the PT people about compatibility with aluminum may need to be done but my transom still appears to be ok with absolutely no prep in the contact area.
this can be solved by buying early and letting dry well before useing.In tests for fiberglass bonding to regular dry plywood and PT both wet and dry they determined that there was wood failure before bonding failure for all products.For boat building they reccomend redrying to 18% after treating.That is for building not simple casting decks etc though obviously a good air drying is important for our kind of use..The only fastener reccomendation I found was use that which is appropriate for the application.
I think incapsulating un treated wood in fiberglass/resin etc may help short term but in the end exaserbates the problem of rot.I think every fiberglass boat out there with a rotten transom,floor or stringers proves that.
As i've said many times my PT transom unsealed,unpainted left out year round in the water 7 months a year since about 1985 is still going strong.Original factory transom lasted about 6 years.
My dock planking and staving is about 20 years old unpainted. PT plywood walks to the house about 12 years unpainted.Sure it grays and does need some sealing for asthetics but so far it held up till stained last year.Also painting is ok as long as enough drying time is allowed before doing so.
By the way the galvinized screws in my 8 year old regular ply barn doors corroded to the point of no return
in the weather exposed sections.(central NY)So I think there will be some fastener problems regardless of the wood used and the best stainless/coated etc fasteners are a must.
I think some research with the PT people about compatibility with aluminum may need to be done but my transom still appears to be ok with absolutely no prep in the contact area.