View Full Version : split plank

09-13-2006, 04:41 PM
I've made a 16' Swampscott Dory, cedar planked, lapstrake, DF frames and bottom. I found a very small crack below water line between the last aft frame and an intermediate frame (rib) which was oozing water. I didn't care about the water but didn't want the crack to grow so I took off the old rivets, overlayed another 20" peice of cedar on top of the cracked portion and glued it good with Gorilla Glue and repainted the outside portion. It leaks a little bit more than it did before. My main concerns are to stableize the crack so it doesn't get worse and to keep out water from between the old and new planks so it doesn't rot in there. I'm willing to do the whole repair over if anyone can recomment a better method. Thanks in advance guys.

Vincent Serio III
09-13-2006, 06:12 PM
For a small crack, routing out the crack and epoxying in a spline (cedar) may do the trick.

Take a straightedge and lay it along the crack to get the best average of a straight line that will run through the crack. Get the radius of your router and make a spacer block to use as a template for laying out a straight line upon which you tack a batten. Use the batten as a guide for the router. Rout a 1/4-3/8 groove with a straight bit over the crack, extending slightly into the good wood at both ends. The groove should not extend through the thickness of the plank, but leave about 1/16-1/8 as a base for gluing in the spline.

Set the blade of the tablesaw at 5 degrees and rip a spline at the width of the groove. This will provide a good gluing surface for the v shaped spline in the rectangular groove.

Mix epoxy with silica thickener or plastic minifibers (wood flour would probably work) to mayonnaise consistently. Fill the groove with the mixture and put your spline in. When dry, plane to the surface of the plank.

See my album, last few pics for a pictorial depiction.


Can't guarantee that new cracks won't appear, so inspect your plank for other defects.

09-13-2006, 07:53 PM
What if I want to reinforce the hell out of it with no thought of how it will look?

Vincent Serio III
09-13-2006, 08:10 PM
Splining would be a strong repair with added advantage of good looks--if the planks are painted, you probably won't notice. Bright-finished--probably wouldn't look too bad.

By reinforcing I assume you mean preventing the crack from propagating. Splining will do that. If reinforcing means preventing new cracks from forming, that's a different story.

Your wood may be too dry, or goes through seasonal or wet/dry expansion contraction. The wood may be too stressed, etc. Proper selection of materials from the get go is the only way to prevent this--the old timers knew this, and the selection of proper plank stock was part of the art and alchemy of wooden boatbuilding.

A pic of your boat and the problem area would help to answer this further. There are also other threads--use the search function and type in "cracked planks". I'm sure this thread will light up soon as there are many opinions on this topic out there!

09-13-2006, 08:31 PM
Bringing boat onto trailer, big wave, boat hit side of trailer. That type of crack propagation.

09-13-2006, 09:16 PM
The other aspect of this is whether the Gorilla Glue will keep out the water. I read the other threads Vincent. Thanks for the help. I'd still like more ideas before I route. Anyone else care to venture an opinion?

09-14-2006, 09:24 AM
Bart, can you get any pictures of the current repair? Love to help, but It's hard to visualize the problem. - Norm

09-14-2006, 10:15 AM
Bringing boat onto trailer, big wave, boat hit side of trailer. That type of crack propagation.

Well, assuming the big wave is a boat wake -- I'd say the only way is to angrily wave a flare pistol around and use larger fenders...

;0 )

Seriously, unless you want to glass the outside with Kevlar or other high-tech fabric, I can't think of any way to protect a solid-plank boat from hard impact damage.

And even the Kevlar glass may not really do much more than provide *abrasion* resistance -- some questions have been raised on some of the Yahoo boatbuilding groups about the amount of impact resistance gained by glassing this way.

I've seen fore and aft rubrail-like strips of wood used on some boats for protection, but they were usually carvel-planked. Still, something like that would be preferable to glomming on blocks of wood inside or out, which would limit the flex of your damaged plank and perhaps result in more splitting.

Splines are the way to go!

Eric D
09-14-2006, 02:58 PM
gorilla glue is NOT a suitable answer IMHO. Spline is more permanent.

Quick fix seems to be what you want. Some will plug the very ends of the crack taking care to get the grain in the correct direction and then epoxy the whole thing, crack and all. Then paint with UV stabilizer, and then pray.

The response you got above by Vincent was a very sound answer for a lasting repair.

Steve O'Connell
09-14-2006, 07:11 PM
I had the same problem with my swampscott (cedar on oak). The crack had been plugged at either end by a previous owner, but the crack worked its way around the plugs and kept running. I tried opening the crack with a hacksaw blade and then epoxying it. BAD idea. Last year I finally decided to tackle it with a bit more care and thought. From the outside I routed about half way through the plank an inch either side of the crack and a little beyond the ends. Then I epoxied a piece of cedar into the void. It seems solid and the crack has stopped running. Perhaps not the end of the problem, but so far so good.

09-15-2006, 01:16 AM
There seems to be at least two misunderstandings. First, protecting the boat against damage is not the problem, accidents happen. Secondly, I hope you're not thinking that I used glue only to fix a cracked plank. I built the thing in the first place so give me a little credit here. I want to fix the problem so that it will be bombproof husky and I'm not concerned with how it looks. The idea was to glue in a new peice of planking on top of the cracked one that would run about 5" beyond the crack on each end. Think of this kind of like a butt block only it's 20" long. Also, the problem isn't leaking because the water was barely oozing through- until I glued the new plank on. Now it's oozing quite a bit more and I don't like the idea of water getting between two peices of wood. Routing in a new peice is a good idea. Does anyone have another option? I realize now I should have used epoxy instead of Gorilla Glue but I've never had a problem with water getting through the glue before.

09-15-2006, 02:54 PM
Thought Iíd add my two bits worth, not to offer any solution but as another way of looking at a common problem. I have an 18 foot double ender, yellow cedar on oak (number 3286 in My Wooden Boat, this site) with a similar problem effecting three planks; checks spanning several ribs and all underwater; the longest is over five feet in length.

Iíve owned the boat (Northern Star) for nearly thirty years, and it happened the first time I pulled her out for winter storage. When the boat goes back in the water in the spring the checks leak at an alarming rate, saved only by a good bilge pump, for about 24 hours and then tighten up completely. Iíve never done anything about the cracks, believing that since they do tighten up, anything I put into or around the wood will simply cause the wood to either crack somewhere else or force a rivet as the wood expands. Iíve also never thought it weakens the integrity of the planks in question. Iíve always considered it as a minor irritant more than outweighed by the pleasures of owning a fine wooden boat.

Incidentally, Iím a long time reader of WB and decided it was time to come aboard this forum.

Cheers Colin.

09-15-2006, 08:24 PM
Good point Colin. Initially I could have done nothing about it and now wish that I had done nothing. Now though, I have more of a leak from under the patch (the water is leaking out the bottom of the patch) and I'm concerned about having water trapped between the two. I'm pretty certain the plank is much stronger than it was before.

09-15-2006, 09:02 PM
Bart, if it was up to mee, I'd make 1 of 2 choices. One's been mentioned, one has not:

1 - strip off the repair and start over by routing the crack and gluing in a spline of the same material, in the same grain orientation as the plank. You could use either PL Premium (good) or epoxy (better), but not GG.


2 - With the boat out of the water leave the repair as is until it's pretty well dried out. Then saturate the area with CPES, which as I understand it, will penetrate anywhwere water would get to and seal up those surfaces. Keep pouring it in till it won't take no more.

The only other choice would be to pull the plank and replace it entirely. It doesn't sound like that's necessary.

- Norm

09-15-2006, 09:06 PM
Bart, one question just occurred to me that nobody asked - is your repair on the inside of the boat where it backs up the crack, or on the outside where it covers it up?

09-15-2006, 11:59 PM
It's on the inside. I mentioned that it's like a butt block in function. If your planking material is short you have to put two short peices together to make 1 full sized plank. On my boat I put them together with longassed scarfs but you can butt two peices together and glue and screw a block of wood on the inside of the boat to hold the butt joint together. What I did was similar only I glued and riveted 20" of planking material to the inside of the cracked plank. I should put up a picture maybe.

09-16-2006, 10:35 AM
Yeah Bart, I know what a butt block is. I understood your earlier post to mean that you had used the overlay plank as a "tingle" , which is a temporary patch on the outside of a crack. Used to be done all the time to keep working boats afloat during a season. Temporary is a relative thing of course. I put a tingle on a failed glue seam 15 years ago and only just removed it for real repair in 2005. Robin Knox-Johnson sailed his Suhaili three quarters of the way around the globe with a tingle on her bottom (that he put on in the middle of the Atlantic, BTW).

I'd say the problem on your dory is that the bond between your repair piece and the plank has failed, and the split isn't closing up no matter how wet it gets. So your best bet is to strip off the repair and fix the split as Vincent suggested above. Since the split was caused by impact, not by stress from wood movement, splining will work perfectly, so long as you choose the material and grain orientation well.

- Norm

09-16-2006, 11:57 PM
Anyone ever try splining from the outside? If I see that the split has gone under the frame where I can't get to it I might have to consider it.

09-18-2006, 05:55 PM
From the outside is the only practical way to do it. That's where the water is. Never seen it done any other way.