Plywood questions

[Joel B]

Back to the old Meranti/hydrotec vs. okuome question.

I know Wes put Meranti on the bottom of his hull because it is tougher and more rot resistant.  Has anyone built an entire CS 20 out of meranti?  will the extra weight of meranti make a difference is a CS 20?

What is the difference in BS 6566 Okoume and 1088 and Joubert

I'm excited to finally be underway

Joel

[Joel B]

I weigh 240 I could make the 50lb up with diet and exercise

Does that 50lb make a difference?  are there other considerations with the meranti other than the weight?  I've also read in previous threads that meranti isn't as easy to work with.  Is the $500 price difference worth it?

[Joe Nelson CS#35]

I built my entire CS20 with Aquatek, except for the deck and coamings...they are BS1088 Okoume.  My boat has been used for 5 years without any problems.  I did fiberglass most everything except for the deck.  I am happy with it.  As far as rot resistance goes, they both mold in humid conditions if not protected with epoxy at about the same rate.

[Joel B]

Joe

Why did you go with Okuome on the deck?  is there a differnce between aquatek and hydrotek besides the brand name?

[Joel B]

I think I found the answer to my own question.  Aquatek is BS 6566 rated and Hydrotek is BS 1088 rated.  However I don't know what the ratings mean other than the 1088 seems to be a higher rating. can anyone enlighten me?

[Hirilonde]

I found this article to be a pretty good explanation of plywood standards of interest to boat building.

[Joel B]

that article was very helpful.  It sounds like no matter if I choose okuome or meranti I want to use the 1088 standard for the wood.  The question that remains is okuome or meranti. 

Is there a design consideration other than weight?

[Peter HK]

As I understand it meranti is a little heavier, stronger, less flexible, more impact resistant, more rot resistant and cheaper. Okoume is a little lighter, more flexible, less rot resistant and more expensive. There's probably not much between them overall except in price.

I had the option (here in Australia, from a specific, reputable Asian maker) of a slightly thinner meranti sheet (at about 5.7-5.8mm) which was designed to be as strong as 6mm Okoume and minimize the weight difference and was significantly cheaper. When I weighed the sheets they were 5-10% heavier than Okoume. I thought it a good compromise.

If money is no object go for the best. Meranti will produce a fine boat if you want to save a little- but at a B&B regatta with a serious race you may not come first  :'(

Peter HK

[Hirilonde]

And Merranit splinters really burn under the skin and will fester if left there for a day or two.

That's the truth!!  I used to manage a shop building garden furniture out of Meranti, and know from frequent experience.  If you get one, remove it right away even if it is painful to do so.

[Howard]

Is there a design consideration other than weight?

I have some samples of both. My concern was about durability. Not only rot, but the ability to take a hit. I whacked both samples with a ball peen hammer. The meranti still dented, just not as much. Another consideration would be the color of the wood finished bright. Meranti finishes dark, almost like a walnut. Okume is lighter......in color and in weight. An Okume deck finished bright would look better, and put a little less weight up on top, lowering the center of gravity....although that would be very slight. If a deck is going to have much curve, Okume would bend easier.

[John Burritt]

Graham advocates Okoumi, saying it has the best strength to weight ratio.  Aside from the weight issue, the real concern is ply thickness.  I've seen "1088" Okoumi where the outside veneers were significantly thinner than the inner plys.  The might have been the same when they were glued up, but at the end of the sanding process, they were a bit lacking.  They will be more apt to split on the exterior face when bent across the grain of the outside veneer - a bit disconcerting.  This can usually be avoided by presoaking the outside veneers w/ hot water.  This is helpful even w/ "balanced" layers which have been stored in a real dry environment.  Comparatively, Okoumi is more bendable than Meranti or Sapelle (mentioned in the article reference above.

[Greg Luckett]

My Spindrift 12 is made from Okume 6mm sheet stock, while the lumber used is either White Oak or Sassafras. The gunwhales (to be finished bright) are White Oak with an Okume cap, all stained "gunstock" and looking really good.  I have applied several coats of the stain, the last being this afternoon, and will wait a week or so to apply the epoxy and the varnish. The Okume cap blends in really well with the oak.  I expect to make the tiller from white oak too and also finish it the same was as the gunwhales.

If I ever build the Princess Sharpie 26, it will have Merianti on the hull and any place structural panels will be installed, and Okume anyplace else that it can be used...maybe.

[Joel B]

Will using meranti affect its ability to plane?

Thanks for all the replies. 

[Greg Luckett]

Will using meranti affect its ability to plane?

Thanks for all the replies. 

No.

[Guest LeeH]

I would think any excess weight would delay the planing effect to some extent, ie requiring more breeze (power) to get her up on it.

[Greg Luckett]

I would think any excess weight would delay the planing effect to some extent, ie requiring more breeze (power) to get her up on it.

I believe planing is a function of the hull design and the amount of power applied via the engine, or on a good sailing day and with the waves just right, the sails.  I use to plane with my Lightning under full sail with following seas.  It was more like surfing.

[PAR]

If the whole boat was made of Meranti, you have about 60 more pounds on your build, which isn't enough to get excited about.

[Joel B]

I was just on Noah's web site and they have Okuome BS 1088 listed for $49 and Joubert BS 1088 for 75.  Whats the difference? both are 6mm

[Greg Luckett]

I was just on Noah's web site and they have Okuome BS 1088 listed for $49 and Joubert BS 1088 for 75.  Whats the difference? both are 6mm

Joel, what was the quantity that had to be purchased to get those prices?  Boat builders around here buy from Noah's but only when getting 20 or more sheets as the shipping/packaging cost tends to double the price per sheet with lesser volumes.

I think that Joubert is just a manufacturer of the plywood. It is still BS1088 Okume.

http://alliedveneer.com/marine_plywood/Joubert_Okoume_BS1088_Marine_Plywood-p-16133.html

[Oyster]

The 49 buck stuff is chinese through and through. It can be good and it can be iffy. In layered boat construction thats not a real problem. Single sheet construction and lapstrake contruction in today's world spend more for the Occume or like types.