Thread: Crooks for Knees and Stems

When I was a youngster, I remember the old blokes talking about jumping out of a boat into the swamps to retrieve just the right shaped mangrove stumps for similar applications. They did this a kids and were rewarded by way of the boat trip by a well known boat builder in Port Adelaide.

Also as a youngster, I remember gathering bent tea tree branches with my father, to make knees for "flatties". These were boats made from two 12 x 1" boards bent to shape, with 4" x 1" solid bottom. The bottom was nailed onto the sides with square twisted copper nails. My job was to keep the potatoe sacks spread on the bottom, wet, to keep the boards tight. The pine used was kauri or hoop pine.
Jim

Interesting stories! Now, when I go for my morning walk through our local patch of bush, I am constantly on the lookout for 'crooks'. Surprisingly few around.

I am wondering af anyone has ideas about how much bigger the raw crook must be than the stem or knee. What are the considerations?

I can think of -

1. basic dimensions
2. matching the grain to the required bend
3. avoid sap wood
4. any others?

make a template of the knee and take it with you... find a likely candidate lay your template against it see the way it goes... you will know mate

The template can be made of any light timber ply mdf whatever cut to shape required... you could make the entire thing including the thickness by layering the ply templates together that way you could hold the now full size template to the crook check that way then hold it to the other side check that way... know pretty chop chop if it would be good to go Id think eh?

Well the template is the only way I know to go... so if others have other ways bring em on!!

Dingo's right on the money with a pattern.

Generally I look for a piece that has the required bend (or approximate)first. Once I have the required bend, I mill the piece up to the required thickness.

If I was doing say quarter knees on a small boat, I would mill up at double the final thickness of the knee plus around 1/2" for dressing. I say double if you are going to split the stock and bookmatch the knees.

Once milled, sand/plane/scrape the surface until you can see the grain direction and lay on your pattern. I try and get as many as I can out of the larger crooks even if the grain is not a 100% match for the curve but is pretty close. Make sure you consider both sides of the slab as it may look great on one side but have a defect on the other.

Sometimes, a larger crook will only yield a single piece due to funky grain but the remainder can be used for all sorts of pieces in the boat like rowlock blocks etc. Piece below is a classic example.



I also used solid stock for 1/2 lapped knees where the join is not viewable ( say a stern knee with the join under a thwart) and it is a good utilisation of the resource and just as strong as a grown one.

With larger crooks for stems, consider using a solid piece of the crook for the outer stem and process it to final shape and laminate an inner stem using the outer as a jig. Cut the rabbet on each piece individually then glue/fasten together. This will give you two beautiful outer stems instead of one solid one if you are short on stock.

Cutting larger cooks requires a decent drying time. I also try to cut in cooler months to reduce rapid drying and use some timber grease on the exposed ends/sides to reduce checking.


regards,

AD