mahogany marine plywood structure?

[blackspot]

Let me introduce myself first.
My name is Goran Catic and I`m from Belgrade, Serbia.
I`m planning on building Sea mini sailboat designed by Van de Stadt.
http://www.stadtdesign.com/products/vds311.htm

Constructor suggests using mahogany marine plywood 5 and 10mm as well as okume 10mm marine plywood for some less water-exposed areas.

Unfortunately, material availability here in Serbia is very poor. Best offer, that is, closest to what the constructor suggests is 10mm mahogany marine plywood manufactured by slovenian wood factory www.javor.sl

Aside from their very high price [which is a smaller problem] I am confused by the following:
Their mahogany marine plywood consists only of external layers from mahogany while other inside layers are made from poplar wood. [willow family of trees]

I am relatively inexperienced and don`t know much about standards for mahogany marine plywood structure, types and subtypes...

I was wondering if you could advise me if this particular kind of `mixed` plywood should be used for building Sea Mini sailboat?

Other essential parts that are supposed to be made from okume plywood and other are not a problem as I`ve found suppliers that could provide these other materials.

So the only problem appears to be mahogany marine plywood. It it very hard to find in Serbia.


Any suggestions?

[Not A Guest]

I would expect any marine plywood would be suitable. If the okume plywood is marine grade, it should be suitable for all parts of the boat.

[blackspot]

ok, but doesn`t it make a difference if inside layers are made of some wood that absorbs water for example beech or oak?

in that case if a small crack occurs below the waterline soon it will become swallowed up and create even more damage to the surface...

these are all just guesses from an amateur so I would like to ask someone really experienced to be `the judge`...

BTW, in some books I`ve read that okume marine plywood isn`t very suitable for all parts of the hull because of their not-that-good stiffness...

[gonzo]

Poplar would not comply with marine plywood specs. However, if it is all you can get, try to seal really well.

[blackspot]

well, that`s what I thought when I found out about poplar inside...

even so, that plywood costs twice as much than what some other small dealer is offering me. `his` plywood is made of unknown exotic wood he calls `amesla`

I have one book about exotic types of wood and all their alternate names in different countries but I couldn`t find `amesla` anywhere, not even on the net...

anybody heard of it?

gonzo, I`m actually closer to ordering adequate marine plywood from abroad or even traveling to Hungary, Poland etc than making such compromise right from the start...

[blackspot]

if there are users of this forum who live in central/eastern europe who know of a quality marine plywood supplier PLEASE let me know about it!

any info would be helpful, phone number, email addresses, anything...

I`ve bought construction plans two weeks ago and so far I haven`t found a decent marine plywood supplier...I`m getting nervous if you know what I mean......

[Whanton]

Hi Blackspot ,I buy 3/8 Marine plywood in Detroit area $50.00 / sheet and I'm told it comes from Russia . Its high quatity and all the glues are same as used in the US. Douglas fir and Mahogany are more expensive and are a special order in this size. $80/sheet.

[blackspot]

Originally Posted by Whanton

Hi Blackspot ,I buy 3/8 Marine plywood in Detroit area $50.00 / sheet and I'm told it comes from Russia . Its high quatity and all the glues are same as used in the US. Douglas fir and Mahogany are more expensive and are a special order in this size. $80/sheet.

well, all things considered, I think I`m going to import one older sailboat from sweden later this year or next spring. importing plywood without knowing anybody in russia would be too much for me...

I`ve found out that used sailboats in sweden are really affordable compared to other W european countries since there are mcuh more of them `per person`.

thanks anyway!

[PAR]

What marine grading system are they using? British Standard (1088 typically), France CTBX, Japan JPIC, Dutch Komo class A, I know the Polish have some pretty good stuff, but don't know what their marine standard is. Have you tried to call, email or other wise contact some builders in your area and see what kind and where they're getting plywood?

[amitk]

Originally Posted by blackspot

well, that`s what I thought when I found out about poplar inside...

even so, that plywood costs twice as much than what some other small dealer is offering me. `his` plywood is made of unknown exotic wood he calls `amesla`

I have one book about exotic types of wood and all their alternate names in different countries but I couldn`t find `amesla` anywhere, not even on the net...

anybody heard of it?

gonzo, I`m actually closer to ordering adequate marine plywood from abroad or even traveling to Hungary, Poland etc than making such compromise right from the start...

Amesla is not a wood specie. The plywood factories that buy a mixture of tropical veneers are calling it "Mesla". I don't know the marine plywood specs, but if it is WBP with minimum of 99% wood failor (after 4 cycles of boiling and drying), have no voids and is from a durable specie (like copaiba, tauari, amapa, andiroba... Copaiba and Andiroba are the best, but it is a very havy plywood 750 kg/m^3) you can use it as marine plywood

[vladimin]

[quote=blackspot]Let me introduce myself first.
My name is Goran Catic and I`m from Belgrade, Serbia.
I`m planning on building Sea mini sailboat designed by Van de Stadt.
http://www.stadtdesign.com/products/vds311.htm

Constructor suggests using mahogany marine plywood 5 and 10mm as well as okume 10mm marine plywood for some less water-exposed areas.

Unfortunately, material availability here in Serbia is very poor. Best offer, that is, closest to what the constructor suggests is 10mm mahogany marine plywood manufactured by slovenian wood factory www.javor.sl

Aside from their very high price [which is a smaller problem] I am confused by the following:
Their mahogany marine plywood consists only of external layers from mahogany while other inside layers are made from poplar wood. [willow family of trees]

I am relatively inexperienced and don`t know much about standards for mahogany marine plywood structure, types and subtypes...

I was wondering if you could advise me if this particular kind of `mixed` plywood should be used for building Sea Mini sailboat?

Other essential parts that are supposed to be made from okume plywood and other are not a problem as I`ve found suppliers that could provide these other materials.

So the only problem appears to be mahogany marine plywood. It it very hard to find in Serbia.


Any

[vladimin]

Cao moje ime je Vladimir, iz Beograda.Takodje se zanimam za sea mini.moja adresa je vladimin@verat.net .ostavi e-mail

[blackspot]

Originally Posted by PAR

What marine grading system are they using? British Standard (1088 typically), France CTBX, Japan JPIC, Dutch Komo class A, I know the Polish have some pretty good stuff, but don't know what their marine standard is. Have you tried to call, email or other wise contact some builders in your area and see what kind and where they're getting plywood?

well I dont think any boatbuilding company uses plywood anymore.

nowadays that is left for enthusisasts only...

people I`ve talked to told me to give up on building and rather save money and buy a used sailboat.

it appears as if i`ll do just that though Ive already bought plans for Sea mini...

[amitk]

It seem like there is lack of information about tropical wood species. While the Mahogany had very good publication at the last centuries, there are a lot of better wood species for naval construction (that why in Brazil no one uses mahogany for naval construction). Since my business is plywood, I will revise the most common species which are adequate for plywood manufacturing.
Louro Vermelho – completely rot resistant; has constant red color.
Andiroba – used for plywood just if been ordered; very high rot resistant; has constant red color.
Copaiba – very high to high rot resistant; has beautiful esthetic appearance; very flexible; very high physical resistant; the preferred plywood for local furniture manufacturer.
Roxinho – very high rot resistant; very high physical resistant; light to dark purple color.
All the species above has better rot resistance than mahogany (high rot resistance), similar to better physical resistance, and weight a little beat more (copaiba specific weight is 750 kg / cubic meter).
More information for the other specs:
All the exterior plywood should be glued with WBP glue (phenol formaldehyde).
Delamination should not have to happen. All exterior plywood are tested in boiling test to verify the gluing quality. If one found delaminated panel, he should return the all lot back to the manufacturer.
Voids in the plywood can be eliminated by using big veneers (130 cm X 260 cm) or more attention in the assembly. I think your preferred solution is the firs one, which means using better wood. I looking for marine plywood manufacturing to receive better price for plywood produced from better logs, and using the worst logs for regular exterior plywood.

Amit Kenny
amitk@brascompdobrasil.com.br