New Boom for an Old Finn

[UCanoe_2]

There seems to be a lot of spar making on the forum these days. Here is mine.

When I acquired my mid-60s Finn a couple years ago, the boom was in pretty bad shape. The forward end of the boom was abraded from contact with the mast, and the glue joint was split.

http://pic90.picturetrail.com/VOL2300/10706129/19088927/305029352.jpg

http://pic90.picturetrail.com/VOL2300/10706129/19088927/305029349.jpg

This boat does not have a conventional gooseneck. The boom just goes into a mortise on the mast, and is secured with a wedge.

http://pic90.picturetrail.com/VOL2300/10706129/19088927/305029342.jpg

The forward 16" or so is hardwood, and the rest is spruce, joined with a scarf.

http://pic90.picturetrail.com/VOL2300/10706129/19088927/305029347.jpg

The hardwood part was also beginning to rot. It broke earlier this summer.

[UCanoe_2]

I made a jig using a 2 x 6 for a base, and scrap lumber for cleats.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/371073317.jpg

I got Douglas fir 1 x 4s from the local lumber yard, and some rough cut ash from the sawmill nearby. The building trades students at work dressed the ash to the same dimensions as the spruce.

I roughed out the scarf joints with this ca. 1957 Shopsmith bandsaw, and did final shaping with a belt sander. I used a router to cut the bolt rope grooves before assembling the boom halves.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/370849931.jpg

Here the halves are glued up and secured in the jig. I used MAS epoxy thickened with milled glass fibers. I'm fortunate to have friends who will work for beer; several helped with this operation.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/370832691.jpg
http://pic90.picturetrail.com/VOL2300/10706129/22354643/370849944.jpg

The boom was held in the jig with wooden wedges. I made lots of mistakes cutting the scarfs, so I created plenty of wedges.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/370832489.jpg

http://pic90.picturetrail.com/VOL2300/10706129/22354643/370849921.jpg

[UCanoe_2]

I cut the bolt rope slot too short, and had to extend it.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/370849969.jpg

You can see some of my mistakes in this photo. The slot is a bit too wide, and the halves are not perfectly aligned.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/371073259.jpg

Trial fitting the sail.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/370850010.jpg

[UCanoe_2]

Roughing out the tenon on the forward end of the boom.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/371769316.jpg

Dressing the boom to finished thickness with the 1950s Shopsmith jointer. I used a 2 x 6 supported on two step ladders as an outfeed table.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/371073298.jpg

[UCanoe_2]

Fitting the boom tenon to the mast mortise. The wedge holds the boom in place, and can be pulled tighter to serve as a primitive boom vang.

http://pic90.picturetrail.com/VOL2300/10706129/22354643/371769322.jpg

http://pic90.picturetrail.com/VOL2300/10706129/22354643/371769319.jpg

Varnishing, with a sign to warn SWMBO. The twine runs through a piece of hollow fiberglass tent pole, wrapped with plastic tape. How does anybody achieve a dust-free and bug-free shop?

http://pic90.picturetrail.com/VOL2300/10706129/22354643/371769302.jpg

I'll install the hardware this evening and go sailing tomorrow.