Stringer Grain Orientation - Core Sound Mark III

[don6558]

I've started to cut out the parts for my Core Sound Mark III build.

Already it's been a learning experience. I had cut out 1 shear strake and was using it as a template to cut the second shear strake.  I did not realize how flexible Okume is. I had clamped the 2 pieces together with 4 clamps and proceeded to cut with my router. The rotation of the cutting bit caused the piece being cut to pull out from under the template causing it to be miss cut. I will add plywood using tape and epoxy and recut. Fortunately,  this is along the joint lines and will be covered up by the joint treatment. This time though, I will use double sided tape to hold the pieces together.

 

I'm using Fir for the stringers. Does anyone know if I should be using quarter sawn lumber or does it matter since it will be sheathed in fiberglass?

 

Once I get all the pieces cut, I will start posting my progress. Unfortunately this will take a while as I'm a long haul truck driver. It's a long time between home/boat builing times.

[AmosSwogger]

Generally speaking, quartersawn lumber is prefered because it is more stable (and it looks better if finished clear since the medullary rays are visible). 

 

It does not expand and contract as much as as flatsawn lumber.  The reason for this is that quartersawn lumber wants to expand and contract along its thickness, while flatsawn lumber wants to expands and contracts along its width.  As a result, quartersawn lumber moves less, and is therefore less prone to cupping and cracking if its moisture content changes.

 

The wider the wood, the more advantageous it is to use quartersawn.

 

Since stringers are not wide, and they will be coated with expoxy and paint, these wood movement issues that make quartersawn lumber more desireable are not applicable here in my opinion.  I would just make sure they are knot free.

 

I would try to select quartersawn or riftsawn for wider pieces however (the tabnernacle for example).

 

EDIT:  as I recall, I did make sure my port and starboard hull panel stringer grain orientation matched in hopes that they would bend equally as the hull was unfolded.  I also made sure that when scarfing stringers togethers I matched the grain orientation (I didn't glue a quartersawn piece to a flatsawn piece).  I'm not sure if any of this really matters that much.  

 

Edited September 21, 2018 by AmosSwogger

[don6558]

Thanks.

This is the type of answer I love. Not just yes or no but a clear and concise explanation so that I can make the informed decision based on my needs.

 

Thank you again.