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Re: Wood for strips: either will do
By:Paul G. Jacobson
Date: 7/7/1999, 3:43 am
In Response To: Wood for strips: Low weigth or rings close togethr (Jan Gunnar Moe)

> When choosing wood to make strips:

> Do you pick the ligtest board or the board with the rings closest together
> for strength? let us assume that direction of grain is as good in one
> board as on the other. I am to use spruce, but I guess that this will be
> the same decision whatever wood to be used. (Implicit belief on my part:
> Rings closer together means more strength AND more weigth. If the last
> assumption is wrong, then everything will be easier...)

> Jan Gunnar

It is not critical. However, if you are trying to create a light boat then you can save the most weight if you start by selecing the lightest wood, or making thin strips. If the final weight is not a major concern, and we may be talking about a difference of only a couple of kilograms, give or take, in the total weight of the boat, then get what ever is reasonably priced and looks good.

Size for size most pine and spruce have seemed stronger to me than cedar. Oak is stronger still. Yet I've been building with cedar, and it is certainly strong enough for this job. You will probably choose spruce or pine. If you find some lighter pieces of those species they should work just fine.

The fiberglass coverings add a tremendous amount to the strength. This contribution seems to make grain direction and ring density irrelevant.

Strip construction allows two good strips to sandwich a 'poorer' strip and reinforce it. Just picking and applying strips at random you are unlikely to build in any areas of great weakness. Consider that the worst case might be if you used 4 or 5 really weak and awful strips side by side. they would not be as week as the cockpit area, which is cut open, and does not have ANY strips over it's length and width. It is a big hole in the center of the boat, yet the boat floats nicely. If you had a similar hole that big the boat would be jsut fine as long as you could keep the water out. That is another thing that the fiberglass fabric and resin do well.

I think that once you actually get started putting strips on your forms you will gain a great respect for the inherent strenght of strip construction.

Best of luck on your project.

Paul G. Jacobson

Messages In This Thread

Wood for strips: Low weigth or rings close togethr
Jan Gunnar Moe -- 7/6/1999, 10:47 am
Re: Wood for strips: either will do
Paul G. Jacobson -- 7/7/1999, 3:43 am
Re: Wood for strips: Low weigth or rings close tog
Hans Friedel -- 7/6/1999, 6:02 pm