What's so special about marine ply?

[Wanderer138]

I was at the local lumber yard yesterday shopping for some 3/4-inch plywood to repair a chainplate bulkhead. They had marine ply at $56 a sheet (4x8) and oak plywood at $48 a sheet. They also had something called Para-ply. It had nine plies (the other two were 5-ply) and seemed to have a much closer grain and it was noticeably denser. The pieces I saw were made in Paraguay (hence the name?) although the guy at the yard said a lot of it also comes from Brazil. A 2x4 sheet (more than enough for what I need) was $13.Has anybody ever used Para-ply for marine work? What makes marine ply "marine"? Is it the type of glue used to bond the sheets? Does it get some kind of water-repellent treatment? What kind of wood is used to make marine ply? Thanks in advance.PeterH23 "Raven"

 

[F rank]

Link to Plywood info

Here is a link to the plywood association definition

 

[Brian Stevenson]

marine ply

My old dingy was constucted with marine mahogany plywood. I was always told that "marine Plywood" was manufactured completely free of any voids and that the glue for bonding the plys was Resourcinal- a truly waterproof glue. Glues may have changed to a more modern product now. I learned that "exterior grade" fir plywood would delaminate, and there were voids in the plys, when I worked in the housing industry.I think that this is truly a case where quality products cost more. Hope this helps.

 

[Wanderer138]

Thanks for you responses

I'm sure they may be a few more but I'm leaving on a business trip and won't be back til Friday and I didn't want to wait until then to say thanks. Have a good week.PeterH23 "Raven"

 

[Alan Barone]

Marine Plywood

I've repaired many boats and was a cabinet builder for over 20 years Marine plywood is submersable Where other plywoods my resist moisture but will delaminate if it gets wet often for internal boat parts can use anything as long as you seal bolth sides and the edges if you only seal one side the plywood will warp. The glue used with exterior plywood is similar and would have to be sealed with epoxy to be submerged goodluck with your project. littlemermaid@prodigy.net if you need any techinal assistance

 

[Bob Camarena]

Search Google

I did a search on Google for "para ply" and came up with a number of hits, including some boat building oriented discussions. A quick read tells me that it shouldn't be used as a substitute for marine ply, but seems to be pretty good otherwise.