Caledonia yawl project: Making more sawdust

The process of cutting thin strips for laminations is a reductive one. As I don’t have a band saw, I’m using a table saw with a blade that is just shy of 1/8 thick. So for every 1/8″ thick strip I cut, I loose as much in sawdust.



I have just two more 2×3 boards to rip and I’ll have everything I need to glue up the bow and stern apron and stem.

Caledonia yawl project: Ripping Jig and other preparations for the stem and apron

To be able to get the 2″x 1/8″ thin strips needed to laminate the apron and stem I need nice clear (knot free) vertical grain wood. In my case that will be Douglas fir.

Last weekend I was able to find several 2×3 lengths that if ripped on its edge will give me 2.5″ wide strips that will give me the margin to plane down to the 2″ width specified. To do this you need to rip accurately, and the solution I found is to make a little jig that attaches to the table saw that should help yield consistent strips throughout the 8″ lenth. After each cut you move the fence over until the board stock rests against the jig guide wheel & repeat.

ripping jig
simple ripping jig with roller

I also went back to the lumberyard to get western red cedar to build up my centerboard and rudder. I’m doing this while the strongback is free of the boat and I have a nice flat surface. That way I’ll get all my laminations done at the same time.

I’ve borrowed from the Gougeon Brothers and tu Gurit Embh. publications on wood foil construction.  Ian Oughtred’s plans and instructions in “Clinker Plywood Boatbuilding Manual” are good but basic and as water is so dense small improvements in execution should have dramatic impacts in performance.

lamination plan for rudder and centerboars
Centerboard stringer design in “How to build rudder blades & centerboards” by J.R. Watson
Gurit instructions for cutting a Naca profile for a centerboard

Gurit’s guide also suggests that in testing stiffness western red cedar sheathed with three layers of unidirectional carbon fiber had a 67% gain in stiffness over just using mahogany.

Last scarf, moving on to the aprons and stems.

This weekend I was able to get back up to speed on my Caledonia yawl project after missing a week. I glued one of the two scarfs on strake 2 and will leave the other to do when I’ve got the station molds up as there is the most twist in the forefoot of strake 2 and it will be easier apparently to glue it down first and then do the scarfs.

IMG_9316
Scarf clamping mechanism. the 2×4 is screwed to the 3/4″ plywood to keep it from warping.

 

It was then time to tackle the apron and stems of this Caledonia Yawl. I’ve decided to try the method of laminating thin strips 1/8″ of Douglas fir with epoxy and West system 403 microfibre additive. The part I’ve been struggling with is that in Ian Oughtred’s plans the apron is 2″ wide. So I need to find a stock of wood that is at least 2.25 or 2.5 inches wide so that after it is laminated I have a little margin to plane it down and fair it.

Punching through the plans to create a pattern for the mould that will be used for the lamination.

 

But all the standar lumber jumps from 1.75″ to 3.5″ and it seems wasteful to rip down a 4×4 timber just to get something 2.5″ wide. After a visit to a couple lumber yards I decided to get a few vertical grain clear 2×3’s and rip them along the wide edge to get the width of strips I need.

The stems are only specified to be 1.75″ wide and so I am able to use rough fir 2x4s to cut the lamination strips and I’ll have 1/4 inch of material to plane off and to keep it true.

Transcribing the bow apron and stem pattern.

After using my full sized plans of the bow and stern apron and stem to punch through all the reference points onto my pattern board. I traced it all out again.

laying out the blocks I will use to clamp the laminated wood. Note that I’ve also put down packing tape to make sure the epoxy won’t stick to the pattern.