Split stringer on kayak - repair

[NY_Rocking_Chairs]

Though my wife denies it she must have dropped the boat or rolled over hard into the dock or something.  The stringer is split enough that there is a slight bend. 

 

Opinions on repairing without taking the skin off and replacing the entire stringer?  Already going to be difficult as it's the section just forward of the cockpit.

[Hirilonde]

I can't see the damage well enough to evaluate.

[andy00]

Looks like it could be repaired with a butt block. The two butt blocks shown were used in the original construction in lieu of scarf joints. They are the same scantlings as the stringers they are joining. 

 

[Kudzu]

Can't really tell but that looks like a nasty break. If it were mine I would take it apart and reskin but I know you don't want too.

 

Without seeing a better photo I am not sure the best way. But a block might work but it will flatten out the curve the wood has taken.  But the problem there is there no way to clamp the block tight to the stringer. 

 

I can't think of an easy and safe way to fix it.

[andy00]

Dear Mr. Chair:

If causing an unfair curve is a concern, you can carve a little curve into the butt block. But I think that you will find that less curve is needed than you might think. As far as clamping, consider lashing, cable ties, and/or screws. If you use epoxy glue, you don't need a tightly clamped joint, as the glue will fill the gaps. Remember to put some plastic sheet (e.g. plastic bag) between the stringer and the skin to avoid gluing them together. Have fun!

[NY_Rocking_Chairs]

Thanks! 

 

Apologies for the poor pic, boat was on the rack and I was using a head-lamp to illuminate the interior while trying to use my camera phone, etc.

 

A butt-block is good idea! I can use two, one on the side and one on the top, that would push the curve out.  I have some pretty thin clamps and should be able to get between the skin and stringer with some pressure.

 

Thanks all.

[Hirilonde]

23 hours ago, andy00 said:

Dear Mr. Chair:

If causing an unfair curve is a concern, you can carve a little curve into the butt block. But I think that you will find that less curve is needed than you might think. As far as clamping, consider lashing, cable ties, and/or screws. If you use epoxy glue, you don't need a tightly clamped joint, as the glue will fill the gaps. Remember to put some plastic sheet (e.g. plastic bag) between the stringer and the skin to avoid gluing them together. Have fun!

 

Yes.  Yes to epoxy for the reasons stated. Yes to clamping methods and that snug is all you need with epoxy. Yes to protection.  Epoxy messes don't clean up later.

 

All I would add is to use some filler to thicken the epoxy.  I would use wood flour with a little coloidal silica aka Cabosil and West System 406.

[NY_Rocking_Chairs]

Ended up de-skinning it and replacing the stringer.  Once removed it turned out to be much more than just a split, was broken in two.  New fabric should be here by the end of the week.

[andy00]

So, what's the result of the failure analysis? Was there a knot or odd grain where the stringer failed? Any other evidence that could help prevent such an incident in future projects?

[NY_Rocking_Chairs]

On 6/16/2020 at 9:01 AM, andy00 said:

So, what's the result of the failure analysis? Was there a knot or odd grain where the stringer failed? Any other evidence that could help prevent such an incident in future projects?

 

Unfortunately I was not there when it was broken and she doesn't remember doing anything that could have broken it.  Our thought is that when she strapped it to the top of the van it was tightened too much or something.  This trip it is riding on the boat trailer so easier to secure and strap down.

 

Definitely wasn't a knot, I always cut and scarf around those.

 

We started sewing yesterday afternoon (thanks Jeff for quick turn around and the extra screw).  She's a quilter and is doing the bow, night and day difference to my stitches and her stitches, anyone want to hire her to sew your boat(s)?

[Hirilonde]

The only other thing I would add is that there may have been some grain run out. Though the failure from that often occurs during the bending into place.