whattodo?glue?

[werner]

Hello,
I supose this problem is not exactly new;
A mahogany 35 ft, beam 5ft, yacht carvel planked ( no brewing)
planks 13 to 14 mm, original 16mm( 5/8")completly
refastened (rove)good frames, wood is very dry (years on land),
few planks show openings 1 to max 2.5mm but not all,
inside the wood is coated with epoxy, not happy with this but that's the way it is(=epoxy ran between frame and planks).
former owners planned to epoxy and glas cover the hull. I am not fund about that because I realise the possible problems of encapsulating the wood.
I do not think I can "throw" her in the water and hope the planks will swell enough.

An architect said I should spline the hull. another Wharf sugested to put in thin splines glued to one side only. and ofcourse another profesional said the best way to go is to epoxysheat ( two or three layers cloth)....

Shoud I consider wood veneer as better (except for the work involved and a "thicker" hull?

If I were to use only splines, ? possibly only between planks showing openings?(read somewhere splining is not a good idea for a mahogany boat)

If I have to choose for epoxy is splining necessary or just glueing between planks ( good enough to stiffen the hull)

Kind regards ,
Werner

[Dan McCosh]

This doesn't sound like anything more than the usual drying out that will return when the hull is wet. The epoxy on the inside is not critical, as the wood will take up water where it can get it. Splining with the hull dry is a big guess as to how much it will swell when wet. I'd launch her, maybe with soft seam compound in the seams, and see how much it swells. From your description, it isn't a loose as my hull gets most springs.

[Bob Smalser]

The good news is that epoxy slopped on the inside of the frame-plank joint isn't a vapor barrier. More good news is that quartersawn H. Mahogany isn't as athletic as some woods like cedar...and epoxy is pretty flexible.

The bad news is that if it's adhesive epoxy as opposed to thinned CPES or some other light "fairing" epoxy...something will give with great force in the cross-grain glueing...hopefully the glue bond...but you may have a plank crack.

I'd think long and hard about sticking anything hard in those plank gaps....that wood's gonna move regardless of how many splines and how much fabric and epoxy is applied...the fabric merely evens out the stresses....for a while, anyway.

Problem with splines is that those planks were attached tightly edge-to-edge, at moisture equilibrium with the air when the boat was built...and the first and subsequent swellings and shrinkings were against cotton caulking and seam compound. Add splines now after what appears to be a normal shrink cycle, and the edges of the planks will crush cell walls when they swell...which will work, but shorten the wood's useful life considerably....and also making the next shrink cycle even worse. The fabric/veneer and flexible epoxy applied to the exterior will likely hold it together, but those relatively-thick planks are eating themselves up straining against glue, splines, fabric/veneer and frame with each future cycle.

And it'll swell in your damp season regardless of the outside epoxied fabric. Now at the end of my dry season, the covered, quartersawn DF 2X6's in my lumberyard in stacks sitting outside measure 5 and 7/16"...by the end of December they'll measure almost 5 and 5/8". Multiply that by the number of strakes per side on your yacht and you get an idea of the forces involved....and remember you're also throwing your wood in the water.

Also beware of the "Full Employment for the Boatyard Industry" syndrom when getting advice from parties with a built-in conflict of interest.....even surveyors...."Sure Mr Yachtsman, here's what it needs..."

[ 10-04-2003, 01:36 AM: Message edited by: Bob Smalser ]

[Buddy]

Would it not be a drop in the bucket of some future huge time and materials investment to have her launched and monitored withan electric bilge pump and see just in what state your hull condition equalises? As we say down South, "IF IT AIN'T BROKE, DON'T FIX IT?
How else can you more quickly, reliably and inexpensively determine if indeed anything's amiss? Sounds like a lovely old traditionally built wood boat, not a newer tech composite, behaving just like a boat too dried out from being out of the water too long. Give the craftsmanship and materials that built her a chance to remedy themselves

[Popeye]

epoxy only in seams, no splines... no.

a technique to renew plank edges is to epoxy in splines and cut new seams over again to accept traditional caulking.

I (wood) splined my seams with great success. why? the planks are old and lack cellulose and are not likely to move as much as in younger days. Plus, the climate my boat is in is moderate and humid, so no real hot hot summer, nor cold cold dry winter, just moderate temps and humidity, so planks are more stable.

One huge advantage in using splines is the amazing hull stiffness created. you will have a monocoque hull that makes frame redundant. May consider a 'softer' wood material for spline, eg research suitable cedars.

Spline dry with accurate machining, swell and keep planks stable in compression. sheath if desired, epoxy moisture barrier coat is essential.

[ 10-06-2003, 02:20 PM: Message edited by: popeye ]

[Bob Smalser]

"....you will have a monocoque hull that makes frames redundant....

And that's good, because do it on a relatively tight boat whose planking hasn't already broken down, and you'll put one helluva strain on those plank-to-frame fasteners.

Something is likely to give.

[Popeye]

Agreed. I have read about this and similar techniques for plank edge gluing. The two primary caveats for success are the planks are tired and the climate for the boat is moderate. Attention to these two trite but important details is essential. Neither should the rest of the research be ignored to refine the technique. New wood plank boats are similarly built without caulking seams, but suspect under professional opinion.

So like Bob sez, you may have high structural stresses to deal with.