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Pawlonia As A Main Material

Submitted by JimD777 on Fri, 05/10/2019 - 08:33

Has anyone built a kayak using pawlonia as the main building material? I found a source here: http://clearwoodpaddleboards.com/surfboard-grade-paulownia-planks/. They have  6 x 3/4 x 8' planks. It appears to be plain-sawed lumber, with various grain.  I know I'll be making a lot of scarf joints on a 15' kayak. How is pawlonia to work with?

DonTaylor1

Fri, 05/10/2019 - 11:31

It is a useable material.  it is stiffer to bend and a little heavier than most cedars.   I have used it in the deck of a boat.  It's slivers are long and painful!

Others will chime in with more info I hope.   

As for the joints.  I would only scarf the joints on the first couple of strips you use at the waterline.  following their installation you can use butt joints placed  on the stations instead of scarfing  in most places.  Sometimes depending on the curve and design you will want to use a scarfed piece as it flows more smoothly.   The butt joints must be spaced at least on strip apart on any given station.

Some folks have scarfed the boards together and cut the strips as one unit.  8 foot material is handled much more easily around the saw  depending on the setup. 

Which design are you considering building?  

Don

JohnAbercrombie

Fri, 05/10/2019 - 19:23

I think it is generally accepted (in traditional boatbuilding) that butt joints in planking should be made between the forms (or frames), not on them.

It's almost impossible to get planking to lay fair if you end the plank/strip at the form.

Better to join between forms - IMO- with a short backing piece of strip if necessary. The backing block /butt block can easily be removed later, before glassing the inside of the hull.

John VanBuren

Sun, 05/12/2019 - 06:42

Hi,

   You caused me to become curious. so I double checked online and I found that WRC has a density of 20 to 23  pounds per cubic foot while Paulownia had a density of 18 pounds per cubic foot. So on average Paulownia is significantly lighter.

John VB

Thanks for replies. I'm pretty experienced at scarf jointing. The boards shown in the website's look really various in color and grain pattern, so it'll be a challenge  to match color & grain with all those scarf joints. I wonder how pawlonia responds to heat bending?

Etienne Muller

Mon, 05/13/2019 - 04:20

If instead of scarfing through the thickness of the strip, you scarf across the width of the strip, you can flip them as you install them and create a subtle zig zag pattern. I have done it. Scarf the plank and then rip the strips.

JohnAbercrombie

Mon, 05/13/2019 - 13:59

I have done as Etienne suggests, and it worked quite well.

If you are worried about colour matching, some planks -ones that are uniform in colour across their width- can be ripped in half and then scarfed.

I mainly use Paulonia for my builds, its available, very light and looks OK.

This Petrel was 13 kg / 28 lbs

Paulownia Petrel

It bends reasonably well with heat, and is easy to plane and sand, although I have found that I need to go one grade finer when sanding, as it can be a bit furry.

It does bruise quite easily under glass, so I recommend using something harder for the stems, and depending on the design the shear as well.

I butt joint everything except the shear.

Justin