Grapeview Point Boat Works

81 E Grapeview Point Rd + Allyn, WA 98524 + 360-277-9015 + boat_works@yahoo.com

Building a Glued Lapstrake Rangeley Lake Boat

Page 6: Scarfing Planking Material and Hanging Garboards

Planking material - 5mm Shelman Shelmarine® Okoume marine plywood
Planking material - 5mm Shelman Shelmarine® Okoume marine plywood

We are using Shelman's Shelmarine® 5mm Okoume marine plywood for this project. We have begun scarfing the plywood for the planking. The panels are just over eight feet long (metric) so we are joining two full length panels and one additional half panel to make a twenty foot long panel. This will allow us to shift the location of the scarfs a few feet apart on alternate strakes, which might not be really necessary, given the high strength of the joints, but it can't hurt.

Planking scarf
Planking scarf

The plywood is okoume, an African hardwood, a distant cousin to mahogany. It is commonly used in lightweight boats. The 5mm thickness has five plies, bonded with an exclusive fungicidal glue, which makes the Shelman "Shelmarine®" product the highest rated okoume available. Lloyds rates Shelmarine®" as “moderately durable” which is more favorable than it might sound.

The bevels for the scarfs are planed to a 10:1 slope. You can get away with 8:1, but we have plenty of length available, and it really isn't much more work. The longer scarfs will be bit stronger, and might bend a little more fairly. As with all glue joints, epoxy resin with the appropriate thickener is used as the adhesive.

Twenty foot plywood plank
Twenty foot plywood plank

The keelson and stems are beveled so that the planking lies flush. The ribbands are a big help in establishing the correct angles. This is slow work, since the bevel changes constantly down the length of the hull and up the stems. Except the scarfs, all the bevels on board are "rolling" bevels. Maybe that's why it takes so long to build one of these wooden boats...

Checking stem bevel
Checking stem bevel

We use door skin to test the fit of the planking on the keelson and stems. The photo shows an interior view of the aft inner stem and keelson. It just about fits, we'll need to shave a bit more off the "knee" of the stem.

Installing the port garboard
Installing the port garboard

Planking up is always interesting, since the hull shape is finally fully revealed. The garboards (planks nearest the keel) are always the toughest, especially on boats with flat bottoms like this. The poor garboard has to turn through nearly 90 degrees as it approaches the stems. Fortunately, on a boat this size it has a long distance to do it. The tubby little eight foot dinghies with a four foot beam are the tough ones. The rest of the planks get easier, since there is less twist to them.




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