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George.
09-11-2004, 04:08 PM
Dalia has a strip-planked hull, 5cm by 5cm strips, epoxy made in Brazil - most of you guys wouldn't know the manufacturer. I did my best to do it right, even though she was built outdoors.

She was launched three years ago in August. On launch day, one of the cranes broke a fitting and she DROPPED (gasp!) two and a half meters onto hard-packed earth. The hull weighted 18 tons at the time. No damage, no leaks.

To this day she has not leaked a drop. She rolls quite a bit at her moorings (not as protected as I'd like), and we have been sailing almost every weekend for a year now - have had a few rail-down hard beats to windward.

The nightmare: some dark night in the rough open sea in a future dreamed-of cruise, one or more of the strips will spring catastrophically, and she will go down like the Edmond Fitzgerald. No rational reason, just basic insecurity, born of inexperience.

Is this a reasonable fear? When, if ever, can you consider a strip-planked boat "tested and approved?"

Ross M
09-11-2004, 04:22 PM
Was she nailed during construction? If so, I think you can rest easy... somewhere in the archives is a link to a webpage detailing the results of a nailed strip plank boat that beat against the rocks for several days. The reinforcement provided by the nails impressed the author, and me.

Ross

Tonyr
09-11-2004, 04:25 PM
George, what a story, with a good ending - so far! Did you have any fasteners between the strips? If you did, then it seems to me that catastrophic failure of any one strip is pretty unlikely. Was the hull fibreglass/epoxy coated after stripping? One, slightly heroic, possibility if you remain really worried would be to fibreglass the bottom up to the waterline stripe, perhaps two coats of 15 oz. fabric or so. On the other hand, if you have good bulkheads and watertight compartments inside, perhaps you don't need anything extra, since a failure (if one occurs) would be well enough contained to get you home safely, if a bit wet.

Tony.

George.
09-11-2004, 05:14 PM
She is nailed with 10 cm copper nails, one every 10 cm, and she has five structural bulkheads in addition to 36 frames. But only one of the bulkheads (the forward one) is watertight, and if there is a leak behind it, down we go. I messed with the original 1903 "plans" (really just line drawings by Howard Chapelle) by strip planking, so I got a bit paranoid at some point and decided to do frames AND bulkheads.

But still, though I realize she won't actually spit out a plank, if the seams crack she could still lose watertightness and fill up, couldn't she? Is there a point where you figure that the epoxying was successful and will not fail, like with concrete, or can it always delaminate on you on some dark night, like the traditional-caulking advocates say?

http://www.imagestation.com/picture/sraid139/pd427d84d46321161a1886a69c1c3cf6b/f70d30e5.jpg

[ 09-11-2004, 06:19 PM: Message edited by: George. ]

paladin
09-11-2004, 05:31 PM
george,...
Tana Mari was built strip planked with two veneers over and two layers of Xynole to the gunnel and an extra layer from above the waterline around the bottom of the boat....she has been repeatedly slammed in offshore nasties, spent three nights during a monsoon in water that wasn't deep enough, pounding in the sand bottom...and still went around the world.....no nails..strips were epoxied...and the boat ain't broke yet...bilge izz dry as Sahara in summer....

Zane Lewis
09-12-2004, 02:52 PM
At risk of being flamed I have not heard of any correctly built wood epoxy boats failing just for the hell of it. Obviously you could hit something, or in racing boats use a grade of construction that was just a little too lite.

Anyway even traditional built boats have documented evidence that the springing of a plank or losing caulking could and has caused sinkings.

You have both glue and nails.

Scroll through the attached link and at the end you can see how a strip plank hull even with almost every plank and rib broken can still stay afoat. Admittable with regular pumping.

http://www.woodenboat.net.nz/Boats/boatmischief/boatmischief.html

This was my Dads H28 Strip planked and nailed built in the 1960's in New Zealand wrecked in the late 1980's when she came off her mooring and went up under an over hanging cliff for 12-24 hours. The pics where taken when the sea had droped and people could to board her to start salvaging what we could.
Zane

Tom Robb
09-12-2004, 05:48 PM
Or you could carry a good quality life raft & EPRIB and hope for the best.
Some might recomend drowning with quiet dignity like a gentleman, but that isn't a popular notion these days. :D

PaulC
09-12-2004, 06:01 PM
Or you could keep a tarp in a locker. If you spring a leak thats not quite catastophic (ie. if you have time), you can slip the tarp over the failing section and pretty well stem the leak.

Henning 4148
09-13-2004, 01:15 PM
If you're unsure whether your build matches standards, get a surveyer / designer to survey her (or your building plans) and you will know.

If you just want to be extra carefull for the sake of it, the glassing sounds like a good idea.

Or just give her away for a few dollars and go for an Etap, they are unsinkable. I happen to know someone who might be interested ...

As even with the best workmanship and adhering to striktest standards you can not rule out all causes of hull damage (collisions etc.), it's a sensible precaution to be prepared
-to seal damaged areas quickly while underway
-to get water out of the boat quickly
-to have something like a liferaft
-to have means of calling for help

Another point is, that as far as I think I remember more boats have to be abondoned due to fire than due to sinking, so the sinking is not the only problem to worry about.

To summarizy: You got a mighty fine looking boat there representing a very substantial value. I guess it's natural that you worry a bit. If you really worry about springing a plank, I would ask a real professional.

[ 09-13-2004, 02:26 PM: Message edited by: Henning 4148 ]

Phil Young
09-14-2004, 10:22 PM
be unlikely for the plank to pop right off. Damn near impossible. At most you might get a crack between 2 planks. An dthey are still held against each other pretty tight by the whole structure. if its right near the keel maybe you need to go on the other tack to get the keel pulling the right way. At worst you've got a small, slow leak, and chances are as the offending plank get swet it soaks up some water and swells pretty tight. Relax, she must be atough boat given the history, she'll not let you down. (I used to have a steel boat, and always worried about rust in some dark invisible recess, finally popping through from the inside and sinking her. Never happened though.)

Hwyl
09-15-2004, 07:18 PM
George, you delibrately overbuilt the boat 2" strip planking on frames is incredibly strong. If it was a traditional planked boat, inch and a half planking would be heavy.

You should think "glass half full". Every time she falls off a wave, you should say to yourself "this is the boat that survived dropping 2.5 Meters onto concrete--she can take anything".

George.
09-16-2004, 05:54 AM
Thanks to all for the encouraging responses. I really exposed my deepest insecurities here, as we are about to start on open-sea passages. As for Dalia being overbuilt, gulty as charged. She displaces 35 tons, so I could go with a 10-ton hull, and I believe that for an amateur, thicker wood is more mistake-proof, and redundancy in structural items is advisable. It cost more, but that was spread over three and a half years of hull construction (plus two years saving up before that).

On the one hand, the epoxy manufacturer (who died three years ago) assured me that once it sets right it is set for life - any mistakes show up soon or not at all.

On the other, there was a WB article a while back talking about a delaminating stem that came apart five years after launch, and I have heard other "rumours" about "time-bomb epoxy."

I was wondering if, from a chemical-bond point of view, it is true that an apparently well-set epoxy bond can eventually come apart. Also, what is the life expectancy of a well-made epoxy bonds?

sdowney717
09-16-2004, 06:06 AM
instead of the epoxy wood bond failure I would think more of a wood cracking crushing spliting failure from that drop. And that energy would have been concentrated in the area where it hit the ground. The epoxy joint is stronger than the wood itself.

sdowney717
09-16-2004, 06:08 AM
Epoxy joints could fail and separate if the surfaces to be joined were covered with amine blush.

Russell Sova
09-16-2004, 06:12 AM
I just can't picture that happening. Haven't heard of it happening and you have a fantastic boat there George. At some point you may get a leak, but wood, once it's bent and stays bent for some time, like three years, is hard to bend back the other direction. Do you inspect her annually?