A permanent patch applied to a board, to repair an elognated knothole, or an area of shallow rot in an otherwise sound board.

One of the trickiest aspects of planking a boat is finding wood to cut the planks out of. Trees grow these annoying things called 'branches' which result in the great bane of the boatbuilder, knots. Knots interrupt the continuous surface desired of a plank, weakening the plank and causing a potential for leakage when made part of a boat. Now, if your great-grandafther had been supplied a board that was full of knots, he probably would have thrown it in the fireplace. But as forests become depleted, it is becoming more and more difficult to find long, clear boards from which to cut our planks. These can be found mostly in old growth forests, or in tropical rain forests, and you don't want to be cutting those, now, do you? Also, a board may have only one or two knots, and such a board shouldn't be thrown away. So, you'll have to live with some knots.

Knots come in varying degrees of severity. One type of knot is the "black knot", so called because of the dark ring of bark between the knot (a disconnected segment of branch) and the rest of the plank. This bark will inevitably rot away and the knot will fall out. Obviously, it's bad if this happens when the boat is in the water. You must fix the problem BEFORE shaping the plank.

Black knots have to be prepared by knocking out the knot, and then scraping the remaining bark out of the hole with a penknife. Many knotholes can then be repaired by gluing in a section of dowel.

Unfortunately some knotholes can't be fixed this way, because the hole isn't cylindrical, or because an area around the hole is damaged. Sometimes, the bark has already begun to rot, and the rot has spread between the annual rings that make up the board's grain. Other times, you will find bark growing betwen the grain lines on either side of a knot:

_________________________________________
- - - - - - - -   - - -  -  -  -- -  -
- - - - - --  - --- - - - - - - - - - - 
 - - - - - - - -___  - - - - -   - - - -
 - - - - -  -- /   \- -  - -  - - --  - -
- -  - - - =###     ######= -- - - -- - - 
- - - - -- -   \___/ -- - - - -   - - - - 
- - - -   - - - - - -- -  -  - - - - - - 
- - - - - - - - - - - - - - - - - - - - 
------- - - - -- - -  - -- - - -  --  - -
 - - - - - - ---- --- - - - - - -  - - - -
 - - - - - - - ---- -- -- - - - - - - - -

The only solution to this problem is a permanent patch, known as a 'dutchman'. Begin the repair by making the hole bigger! Scribe out a symmetrical quatrilateral around the hole, resembling an elongated diamond aligned with the grain. Then, use a chisel or a jigsaw to cut out the inside of the hole:


_________________________________________
- - - - - - - -   - - -  -  -  -- -  -
- - - - - --  -.'`-._ - - - - - - - - - 
 - - - - - - .'      `-._- - -   - - - -
 - - - - - .'            `-._ - - --  - -
- -  - - -<                  >- - - -- - - 
- - - - -- `.            _.-' -   - - - - 
- - - -   - -`.      _.-' -  - - - - - - 
------- - - - -`._.-' - -- - - -  --  - -
 - - - - - - ---- --- - - - - - -  - - - -
 - - - - - - - ---- -- -- - - - - - - - -

The shape is very important -- the hole has regular, straight sides, and removes as little wood from the board as necessary.

Next, make the patch. Get a scrap section of board and put it under the hole you just cut out. Use a pencil to trace the inside of the hole on the bottom board. The bottom piece will now have a shape identical to the hole drawn on it. Cut out the patch with a saw or chisel, cutting to the line. You may have to try the patch a few times before deciding it's going to fit well enough.

Finally, cover the outside edges of the patch with epoxy, and insert it into the hole. As with other epoxy repairs, you should put wax paper underneath the board to keep from gluing it to your workbench. After the epoxy has dried, smooth out the board with a file or a plane.

To fix an area of rot, make the patch first. Lay out a symmetrical elongated diamond on a piece of scrap wood. You should be able to make one that covers the rot area by eyesight alone, but use dividers if you want. Cut the patch out, then lay it on top of the board, covering the rotted area. Trace the edges of the patch onto the board. Next, cut out the area inside the diamond (including all of the rot. It's important to make the bottom perfectly flat, so you may want to use a router. If you're a purist, however, go ahead and use a chisel. Finally, glue the patch into the resulting diamond-shaped hole, which should match your patch perfectly. After the epoxy has dried, plane the excess off.

A dutchman makes a strong, watertight repair to a board. The use of epoxy ensures that the repair is stronger than the actual board. But be warned: If you're planning to bright finish your hull, the dutchman will stand out like a sore thumb. Of course, if you're the type of person who varnishes a boat hull, you can probably afford to make your boat out of old-growth tropical hardwood anyway, and throw away a $50 board because of one knothole. Knock yourself out.

Dutch"man (?), n.; pl. Dutchmen ().

A native, or one of the people, of Holland.

Dutchman's breeches Bot., a perennial American herb (Dicentra cucullaria), with peculiar double-spurred flowers. See Illust. of Dicentra. -- Dutchman's laudanum Bot., a West Indian passion flower (Passiflora Murucuja); also, its fruit. -- Dutchman's pipe Bot., an American twining shrub (Aristolochia Sipho). Its flowers have their calyx tubes curved like a tobacco pipe.

 

© Webster 1913.

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