View Full Version : Cracked plank at stem
06-13-2003, 07:01 AM
I am building a small dinghy with 1/2" white cedar over steam bent white oak frames with a white oak backbone. The plank is fastened to the frames using copper nails and roves. At the stem I am using 1" #8 silicon bronze screws. The plank is now fully fastened and once complete I noticed that a screw at the stem was not quite in enough so I gave her another turn while applying pressure to the plank pushing it into the stem only to see the plank crack a good 3 inches starting at the screw and heading fore and aft.
Is there a way I can fix this without removing the entire plank? This is my first boat so I hope there is a work around as removing all those
rivets will certainly be a chore.
Thanks in advance for any assistance...
06-13-2003, 07:50 AM
Hey Glenn. I've had this happen several times when building and boy does it suck. Really all you can do is remove it, make a new plank(you've got a template for it), and then re-attach. You might want to boil or steam that plank end before you attach it. It also might help if you plane the end down to a little less than 1/2 inch, especially if it the garboard plank.
Best O luck.
[ 06-13-2003, 08:52 AM: Message edited by: Chadd Hamilton ]
06-13-2003, 09:09 AM
Glenn, tried to email you but Juno kicked the email back to me. Your rivet removal technique should work fine.
Post some pics of the boat to the forum-sounds like a nice little boat.
06-13-2003, 01:26 PM
Yea, you gotta do it over. Keep in mind that if the plank is not SOLIDLY clamped against the frame, trying to get a screw to draw it tight will almost always split the plank.
06-14-2003, 08:08 AM
Yes, if you're trying to draw a plank in with a screw, without clamping, it would be better to use a flat-head screw and a washer to draw it in until the glue is quite dry. Then back the screw out, countersink, and replace it with a proper wood screw.
The head of a wood screw is a wedge, after all.
06-14-2003, 08:19 AM
Glenn: If you can get the screw out and the split closed, you should be able to glue it closed and attach the plank with additional screws. You will be the only one that will notice it, especially if you paint. I split the outwale on my skiff, and so far no one else has seen it or at least said anyting about it.
Ditto the comments about drawing in the parts.
Also, is a 1 inch #8 enough for a 1/2 inch plank ?
06-16-2003, 03:04 PM
Is the hood end held with just one screw? Or two? Is it to be glued to the stem rabbet (which it shouldn't be)? If held with one or two screws and not glued, I would unscrew the hood end and pull it out so you can get at both sides. This may or may not require removing rivets at the first frame.
Drill a small hole at the after end of the split. Separate the split carefully with a putty knife or small hardwood wedge so you can squeeze some resorcinol or (second best) thickened epoxy from both sides into the split. Take out the wedge, clamp the hood end vertically and let the glue set up at least 24 hours.
Unless there is room for a new screw hole, drill out the old screw hole. In either case, drill with a bit the same diameter as the screw's shank. Countersink the hole just a tad larger than the screw head (flathead). Renew appropriate bedding compound, clamp the hood end to the rabbet, and sink the screw carefully just enough to hold the hood end in and squeeze the bedding. 1" seems a bit short for this job; put in a 1-1/4". Finish by filling the small hole and over the screw, sand and paint.
An alternative to a flathead screw is to use a pan-head, although you would have to use stainless since they don't come in bronze. Bore through the repaired hood end the same diameter as the outside of the threads. Counterbore just enough so the screw head can be covered with putty. A pan-head will not try to expand the wood and make a split.
Alan D. Hyde
06-16-2003, 03:13 PM
A good explanation, Bayboat.
06-16-2003, 07:46 PM
When glueing add 2 cleats across the plank either side of the screw, this will help protect the glued split till after the screw is in place. Then carefully plane or sand away the cleats.
06-19-2003, 01:17 AM
Ken: Good idea. How about glueing a cleat on just the outside? That would reinforce the hood end enough until it is refastened. Then as you say the cleat would be easily removed. I think it might be difficult to have an inside cleat near the hood end. Wouldn't it get in the way of the hood end-rabbet joint?
Glenn: Of course the dyed-in-the-wool perfectionist might tear off the plank and make a new one. But if you look closely at a perfectionist's work, no doubt you'll find a few places where an inconsequential adjustment or repair has been done. Yours is a case in point. It's just not worth the time and expense to replace the whole plank. Especially when a slight accident is so easily well hidden. Mending the hood end as described is only a venal sin, not a cardinal one.
06-19-2003, 06:49 AM
Both cleats on the outside was what I meant, sorry I wasn't clear enough. Just enough space between to access the screw. I have done this with success.
06-19-2003, 08:45 AM
I'll vouch for Bayboat's method, having thought that that extra quarter turn on that screw "wouldn't hurt". :( The drilled hole at the end of the split will stop the split from propagating, so definitely drill it. A 1/16" bit should do fine. Be sure you're really at the end of the split (or even a tad beyond it) or else the split will just keep on opening up when you start filling the crack and/or bending the plank back into place. Steaming the plank probably isn't necessary since the plank didn't break the first time you pushed it to the stem. (Yep, done that one too :D )
Remember, it's only a boat, not a piece of fine furniture. (Unless you plan on varnishing the whole thing and keeping it in your living room. :D )
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