veneer vs balsa

[cshelden]

After almost a year, i'm almost to the point of decking my 12. The local wood shop caries veneers of all types of wood, mahogony (three types) teak you name it. While I love the look, they seem much thinner than the 1/16" balsa sheeting as called for to use as decking. I read Doug's post on useing veneer as well. My question is this:
1. do I use veneer the same as I would the 1/16 balsa, or do i sheet it with balso then veneer over that?

2. are there various thickness of veneer or is all veneer the same thickness.

3. if i go with the veneer/glass solution, does the thinner venner cause an issue with structural integrity?

Thanks for the help, hope these are not simpleton questions.

Charlie
OKC, OK

[Gene Rosson]

Charlie;
Deck construction is a hot topic about which you can get numerous opinions. I'll describe my position as follows.

The deck <b>is</b> a structural member. The rigidity of the deck is not quite as important on a light boat, say a US one meter. In fact some boats use Monocoat, the stuff model plane wings are covered with. Some marbleheads for example. A heavy boat like a 12 needs more stiffness.

You can add stiffness with deck beams. Several of them, especially where the hatch perimeters are located. The deck beams will not weigh much if you use cedar or spruce or some other light weight wood. I dont think balsa is appropiate here.

Yes, veneer is made in more than one thickness. The thin stuff is going to need some glass on both sides. If I was using thin veneer
I'd probably put sixteenth inch balsa on the bottom and glass both sides. That will make a four ply laminate. The trick in controlling weight is to be sure the glass laminate is not resin rich. Use one and one half ounce glass on the bottom and three quarter ounce glass on the top. Try to persuade yourself not to use teak. Teak is likely to be oily, heavy, and tends to dull cutting tools. Don't give polyester resin a second thought. Use a good epoxy and the whole thing will stay together with more certainty than polyester.

I have seen some very nice decks made from balsa without a top veneer. It still has glass both sides. If you select the balsa carefully you can find some with pleasing grain patterns. It looks good thhrough the top layer of glass. If you intend to paint the deck, then grain pattern does not matter.

The strength of a plate structure such as a deck is determined by two basic things. First by thickness, not necessarily the strength of the core material, and next by the strength of the inner and outer surface. Glass over balsa will do that very nicely. Extra core thickness increases stiffness exponentially. By the third power actually. So three thirty second balsa core is way more than one and one half times stiffer than sixteenth balsa.

Your questions are by no means simpleton.

I expect several others to jump on this , so you'll have plenty of input. I think Jim Linville and perhaps other builders use foam sheet for decks...Light, strong, nice.

[cshelden]

Gene,
Thank you for the input, I should have said in my earlier post I do have beams or a structured deck per say. I pretty much followed what was lined out on the ec12.info website as well as the plans I downloaded. So the structure is in place for that part of it. Thanks again for the input, it gives me some options to mull over.

charlie

[Doug Wotring]

Hi Charlie,

I forget the thickness of the Veneer I used. It was eassily 1/2 as thick as the Balsa that was used on the other boats being buit alongside mine.

I used Teak Veneer which was paper backed (thin venner tends to want to come apart otherwise) I beleive it was a door skin as I was able to get 3 decks out of it.




We cut the deck to basic shape (perhaps 1/2-1/4" oversized, vacume bagged glass on the paper side which increased the strength considerably.....fixed it to the deck, trimmed then glassed the top with very light glass and to the hull itself. slightly heavier than the Balsa Counterparts that were built in the same shop, but it is very strong and you can't beat the look of a nicely grained wood on the classic lines of a 12

[cshelden]

Thanks for the info Doug, what is available locally is about 1/2 as thick as well maybe not that much as compared to 1/16 balsa so I guess 1/32. It comes in 24" x 48 and 24" x 96. I've not decided a wood just yet, it will be either red mahogony or teak. I just got a vacume food sealer for Christmas, so maybe I can try some vac. bagging with that. I'll try on some scraps first though.

Thanks again.

Charlie

[cshelden]

Thanks Skip,
But that would require me to go in and strip out all my handy work so I have some sweat equity at this point. The structural ribs and I have a relationship now after crafting each piece...besides...i'd have to tell my wife I didn't really need that 3" belt/disk sander for my work bench haha.

Charlie

[MichaelJ2K]

Ray Ozmun used to sell hulls with either a 1/16th inch aircraft grade mahogony ply deck or a two layer glass laminate with support ribs molded in to the bottom. With aircraft grade mahogony prices out of site, he dropped that option. My first Ozmun hull had mahogony and my second has glass. Either way his workmanship was excellent.

[Gene Rosson]

Charlie;
Two days and several replies already. I told you this was a hot topic. I concur with those who suggested a Zellnack deck. He does superb work.

You are certainly right about the deck beams. They are complex little critters. If the deck centerline is to be straight, as per convention, then the deck skin is a double conic section. That means that every deck beam will have a different radius of curvature.

I am into self flagellation so I built my deck in strip fashion with a mixture of wood coloration. Sitka spruce and western red cedar with glass top and bottom. Vacuum bagged. Starting with strip thickness of 0.150" more or less. Apply glass to bottom. Sand the top to about 0.090' or thereabout then glass the top. It is remarkably light, wicked strong, and looks pretty too. If you do it this way you can fully justify the acquisition of the new sander. The only problem is that your wife, having viewed the scrumptious deck job, may require you to build to build some pretty table tops or something.

Fair winds and calm seas.

[Matthew Houghton]

Here's my answer to your specific questions...

Charlie, get a thicker veneer and glass it on the bottom. Glue it onto the boat but don't use as much weight as the building site shows with the balsa. Don't deck the boat with balsa. Glass it on top and seal it to the hull. Sand and polish. You shouldn't have a structural integrity issue due to the strength of the veneer itself.

Looks good too.

We've used it here in Central PA. We have a rather hard-hitting club sometimes and Doug's boat has held up quite well. Looks distinctive too.

Your idea is great Charlie. Adds a fantastic personal touch too.

Take care.

Matt

[kahle67]

"Just a thought. Leave the handy work and check Mikes deck.
Good sailing"
[/quote]

Those decks are actually made by Bob Dudinsky of RMD Marine (see suppliers) and he does do excellent work. They are fiberglass with a foam core and a gelcoat finish. No wood in the deck and no frames equals a deck for life.

However, this is a builders class and no one should discourage a skipper from doing his own "handy work" (This coming from a commissioned builder). Wood decks a very attractive too.

Good luck with it, Charlie. What Matt has posted makes sense to me. There is no need for balsa if you glass the underside of the veneer and then again on top once the deck is on the hull.



Reichard Kahle
Charleston, SC

[Paul Fixx]

I'm a bit late getting in on this thread, but the following might be interesting to you. I built my EC-12 after a bad experience with the deck of a borrowed one getting speared by a port tacker's bow while it was rail down. I didn't want that to happen again so I was looking for something stronger than glass over balsa, but as light as possible. I tested many options by dropping a 1/4 pound pocket knife onto sample pieces of decking supported on a 6" square frame to simulate the ribs. In the end I settled on 1/16" birch plywood with 3/4 oz cloth on top and .5 oz tissue on the bottom, all vacuum bagged while setting. That was about 25% lighter than 1/8" balsa in the same glass sandwick. The knife bounced off when it was dropped from up to 18 inches and then started sticking and the blade didn't fully penetrate until it was dropped from over 2 feet. The balsa was punctured at 9 inches and penetrated at 12.

While I was messing with sandwiches I made deck beams from 1/8" balsa sandwiched in 1/64" plywood. It's s lot lighter than basswood and far stronger.

-Paul Fixx

[MichaelJ2K]

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by pfixx</i>

<SNIP> In the end I settled on 1/16" birch plywood with 3/4 oz cloth on top and .5 oz tissue on the bottom, all vacuum bagged while setting. <SNIP>
-Paul Fixx
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Paul,
Can you elaborate on the .5 oz tissue? Thanks.

[greerdr]

Paul,
Great to see you in the EC-12 discussion!Will you be comming down for the 1st Fl. EC-12 regatta in Palm Beach Gardens?Do not bring that knife!

R.C.Greer

[Paul Fixx]

It's pretty much like a nose-blowing tissue; thin with a tighter weave than cloth. It gives a little structure for the epoxy to hang on to. I must have read about it in some EC-12 info, maybe on Rick's building site? The stuff I used came from http://www.cstsales.com. It's on the last page in their fiberglass section.

-Paul

Paul,
Can you elaborate on the .5 oz tissue? Thanks.
[/quote]

Paul Fixx
EC-12 #1621
Stowe Yacht Club

[E Artz]

Paul,

what adhesive and technique do you use to create your ply/balsa sandwich?

Earl

Earl