Baltic Birch for transom recore ?

[liki]

Originally Posted by tkk

How come they sell us only the cheap and non-waterproof stuff?

I would suspect the importers to be the culprit here.

[petethai]

I am not American, so I don't know about US crap.
But I am in the process of preparing information about plywood for my new boat. I find this:

http://65.23.157.7/cgi-bin/woodsearc...&comparing=142

and this

http://65.23.157.7/cgi-bin/woodsearc...&comparing=470

it looks good for me, I am talking about birch characteristics.
Also I checked some information about rot resistance for birch , oukume and sapele

"Precise ratings of decay resistance of heartwood of different
species are not possible because of differences within species
and the variety of service conditions to which wood is exposed"

http://www.fs.fed.us/ccrc/topics/urb...0of%20wood.pdf

I don't see any advantage of okoume or sapele.
So what is in the fibers?
If this is not trade secret of professional builders.

"There is no place for opinions or belief in professional boatbuilders statement"
if this true, can somebody show me some test numbers, which say that marine plywood is better as Russian birch plywood.


Regards











'

[tkk]

Birch logs or fallen trees left alone in the forest rot in your eyes. If you are quiet you can hear the hiss as they rot away

This has most probably led to the believe that birch is no good.

I think one of the reasons is that the bark is so effective in keeping all the moisture in and thus promoting growth of all wood-eating organisms.

This guy suspects, that the high pressure and/or high temperature used in plywood manufacturing might change the sugar in birch. Anyway, his experience with birch plywood is very encouraging indeed:

http://koti.kapsi.fi/hvartial/white/white.htm

As you can see here, all plywood manufactured in Finland has been waterproof to the boiling test standard for a long time.

I live and work in Finland and for the forest cluster, although not for plywood producers. You may freely call me a nationalist if you want.

http://www.forestindustries.fi/Infok...ishPlywood.pdf

APEX1: do you know which companies and wher e produces the plywood in Russia that you refer to?

I tend to agree the comment that the exporters/importers are the culprits. Probably they see no market for the higher quality stuff since there is the domestic production, whereas the lower priced interior quality might find some interest in cabinetry.

[quote=petethai;290706]

http://65.23.157.7/cgi-bin/woodsearc...&comparing=142

Also I checked some information about rot resistance for birch , oukume and sapele

That is a very good and reliable database and commonly used by the industry too. It is hard (nearly impossible) to find reliable data on rot resistance. Even the wood explorer shows a too wide range of comments to rely on.
The Okume and Sapeli might not have been the best species to compete but I named them so you are right when you do´nt find a difference worth talking. But there are many species of shorea and other "Mahogany" substitutes used in EU marine ply to get good data any way. Same is valid for the birch ply, many species are used.

When I´m back at my office I´ll dig out the Russian supplier.

[alan white]

Yeah, I have some land in back and I often cut up fallen trees for firewood.
While most other species remain basically sound for up to a few years, birch lasts at most for a few months, if that, when in contact with the ground (and sometimes not even touching the ground).
This isn't scientific; the wood still has bark on it. Still, isn't bark like the fiberglass skin of a transom? Waterproof, like a birchbark canoe.
Maybe we should make boats from the birch bark instead.
I am wiling to accept that different subspecies of the same wood may have very different characteristics.
However, it seems to be the high-tech boys who espouse birch for boats, having read about the strength properties according to engineers, are seeing the more immediate attributes of the wood rather than IF the water gets in and IF it can sit there for a while. I know white oak, cedar, mahogany, yellow pine, and some others do not immediately turn black and mushy when this happens. But I fear birch could. I would only use it in a boat that didn't sit in the water all the time.

[petethai]

"This isn't scientific; the wood still has bark on it. Still, isn't bark like the fiberglass skin of a transom? Waterproof, like a birchbark canoe.
Maybe we should make boats from the birch bark instead."

No epoxy is not like a bark.
When we apply epoxy, we try to protect all surface of plywood (it should be!), even with bark the wood is still exposed to the oxygen, this is why we have rot. But birch bark is waterproof, this is true.
If we cut oxygen, there is not rot.
I am sorry if I am drifting this post in different direction, but in this world, where max.profit is a goal, we have what we have. We have optimum, that means, cheapest product with quality we can accept.
I understand that there is a some marine plywood, which is the best for marine application, but I think, most of plywood which we can buy (not just in US), it is a plywood, not better, or much better as birch plywood. And a lot of the later can be a junk as well.
The reason why I am writing this (in my poor English) is that I like forum like Boat Design Forum. It gives me a lot of information about boats. I am not going to fight with anybody, I just try to tell what I found about this subject. If we exchange our experience our boats will be better.
If we fight, we are not better as "PC contra Apple, digital contra analog..." etc. forums.
Better boat is not just faster, it is safe one.
regards

>>>>If we fight, we are not better as "PC contra Apple, digital contra analog..." etc. forums.<<<<<

There was no fighting here by now!

[tkk]

I think we were only exchanging opinions, yours to mine

Seriously, I think some good points have been expressed by different people.

[petethai]

Originally Posted by tkk

I think we were only exchanging opinions, yours to mine

Seriously, I think some good points have been expressed by different people.

Yes, I agree.

And I didn't say it is fight here, I try to say, I hope this discussion will not end in fight.

Best regards