Marine ply lamina question: Whats up with my ply!?

[matnoo]

I have bought some panels of marine ply to make an outboard transom on my boat. Its a lot heavier than normal ply and a curious thing, it has a 1mm horizontal lamina layer then a 3mm thick vertical layer, and then a 1mm layer and a 3mm layer and so on.

The 3mm layers look less 'quality', or less dense than the 1mm layers, apparently this was decent ply bought from a good wood merchants a while ago (graham cant remember exactly where though so i cant ask them!!!)...

So why have different thickness layers, i thought the whole idea of ply is that is has equal lamina to stop distortion? This has 3/4 of it horizontal, surely that cant be good?

Whys my marine ply like this!?

Mat

 

[boatmike]

The "marine" grade of ply can in fact be any wood and any number of laminates. The standard refers to the glue it is put together with more than the wood. There are good, bad, and indifferent standards of MP just like anything else.

 

[clyst]

Because its probably of far eastern origin . If you want equal thickness laminates you wil need Brunzeel or a decent Anchor ply . Either will be expensive .

 

[oldsaltoz]

G'day Mat (matnoo),

Just for the record; 'some' ply is made to flex more in one direction than the other, this applies to the cheap and very expensive marine ply.

So your application would need the 3mm end grain to be vertical.

Avagoodweekend......

 

[Lakesailor]

MP also has a guarantee against voids in the glue. I bought some cheap 6mm ply to extend a thwart on my tender. When I cut into it there were some air pockets in the glue. I'm not bothered as it only cost £1 and is held on with just 2 bolts. If it ever rots I'll splash out on another £1's worth.

 

[matnoo]

like your pic! I presume its on a trailer, but it looks like the dinghys got wheels!

hehe


Cheersguys, have found some more stuff anyway!! But ill be getting some more ply in over the next week, and the info is much appreciated


Mat