REPAIRING PUNCTURED PLANKING

[DOC ZABELKA]

While the boat was laid up for the winter a severe fall windstorm
caused a cradle support to punch a hole through one of the planks
below the waterline. The boat is a 1964 37' Egg Harbor which I
have just acquired and is my first venture into classic wooden boat
ownership or repair. The boat is in good shape and I want to do a
decent repair job. I am thinking of cutting out the damaged plank
and scarfing in a replacement, but don't know whether I should
caulk the seams, epoxy them, or what. Any suggestions would be
appreciated.

[Nicholas Carey]

How many planks are damaged? Is any of the framing damaged?

Assuming no framing is damaged...you probably want to simply remove and replace each damaged plank in its entirety, rather than to try "cutting out the damaged plank and scarfing in a replacement". Replacing a plank is rather easier than it sounds.

The reason is for reasons of strength. If you simply cut out the damaged portions, you're introducing 2 butt blocks in each strake you do this to. This weakens the hull. The usual scantling rule regarding the staggering of butt blocks is a rule of 3:

There should be at least 3 frame bays between butt blocks on a given strake (in the fore-and-aft direction), and within any given frame bay, there should be at least 3 strakes between butt blocks.

This obviously imposes limits on how/where butt blocks can be placed. It also imposes a minimum length to individual planks.

Also, a general rule, you want to avoid "stealers", overly short planks, even if it doesn't violate the butt block staggering rule as the short planks introduce weak spots in the hull.

Here's a couple of books you might want to get that will guide you on your way and describe the spiling process needed to lay out, manufacture and hang a new plank:

Steward, Robert. Boatbuilding Manual, 4th ed. (http://www.woodenboatstore.com/store/prodinfo.asp?number=300-015&variation=&aitem=2&mitem=52).

Taube, Allan.The Boatwright's Companion: Repairs Below the Waterline (http://www.amazon.com/exec/obidos/ASIN/0877421986/kiwianadistribut/002-9183768-8278431).

Once you've hung the new plank and cut its caulking bevels, you'll need to caulk the seams with cotton. You don't want to use modern mystery goo for this. The cotton is actually a structural element in a carvel-planked boat. Caulking, while doable by an amateur, takes a certain amount of skill and specialized tools to do well. If it's only 1 or two planks that need to be repaired, you'd probably do well to hire a good caulker to come in and do the job. Michael Kiefer over in South Haven, MI at Great Lakes Boatbuilding Company (http://www.greatwoodboats.com/), or one of the Michigan Contingent here on the WBF can probably recommend who the good caulkers are in Michigan.

Hope this helps!

[ 01-14-2004, 06:37 PM: Message edited by: Nicholas Carey ]

[Alan D. Hyde]

And, when they say "caulker" it may sound like "corker."

Alan

[Nicholas Carey]

One other thing...before fitting your plank, you might want to consult with your caulker about how tight a seam he wants and what kind of caulking bevel. Your fitting the plank right makes his job easier. Too tight a seam is as bad or worse than too large a seam from the caulker's point of view becasue he might not be able to get cotton in there.

[DOC ZABELKA]

Mr. Carey:

I appreciate the information, but didn't realize that it was such a big job to repair a small puncture. The hole is about 3" by 5" in a single plank. I've built a number of small boats using variations of plywood, fiberglass and foam composite and repairing them is simple. I assume from your message that simply backing up the puncture between frames and fitting a block is not acceptable. Is this because strength and stiffness are compromised or is it because of leakage? Regards...

[Gary E]

Doc,
Since we dont "see" exactly what you see, it's no surprize to me that some people will asssume the worst and think that replacing more than a small section of plank is required, I on the other hand will take your word for it as a 3x5 dammaged spot. If that hole is that small and did not dammage ajacent ribs inside, you may very well be able to either repair just that hole and use a backing block called a but block to reinforce the repair, or as you say replace a short section of plank.

The 37 EggHarbor is a fine boat, I sugest you have someone familiar with EggHarbor construction look at it.

Good luck with it,
G

[Allen Foote]

With 2 holes saws, where 1 fits snuggly inside another, use the smaller 1 to cut a clean round hole and the larger to cut out a snug fitting plug. You may need to do a series of 2 or 3 holes inorder to plug the length. Epoxy in with West System epoxy and epoxy on a cap on the inside of the plank. I would not recommend this on a garboard plank nor anyother close to the keel that might be oil saturated.
If the backside of the plank looks clean and dry then epoxy on a 3/8" to 1/2" piece the width of the plank and extending over the epoxied in plugs by a few inches on each end. Once cured, THEN, epoxy the plugs in, so that the plugs are epoxied to the cap and the sides of the hole. OR you could router a "dutch man" plug and cap that. I am very familiar with these boats.

[ 01-18-2004, 10:00 AM: Message edited by: Allen Foote ]

[Nicholas Carey]

Originally posted by Gary E:
Since we dont "see" exactly what you see, it's no surprize to me that some people will asssume the worst and think that replacing more than a small section of plank is required, I on the other hand will take your word for it as a 3x5 dammaged spot. If that hole is that small and did not dammage ajacent ribs inside, you may very well be able to either repair just that hole and use a backing block called a but block to reinforce the repair, or as you say replace a short section of plank.What he said—There's always the tension between the "Right" way and the expedient way :D Besides....installing a small patch w/a butt block may not even violate the staggering rule.

[ 01-19-2004, 12:45 PM: Message edited by: Nicholas Carey ]