Shearwater Double woes

I have a couple of problems that I think may be specific to this design, so any specific experience will be welcome.

Woe 1: misfitting mid-deck.

I have assembled the deck parts of my Shearwater Double kit, but they don't fit very well. I'm having trouble getting the edges of the rear deck and front cockpit parts to line up with the adjacent mid-deck, and there are gaps of 1/8" between the edges, only 6" from places where the same two edges are tight.

What can I do to correct this?  Should I take the parts apart and plane to fit?

Woe 2: unfair keel

The deadrise on this design is pretty flat in the after part of the boat, so the #1 hull panels don't have a lot of curvature; this has resulted in an unfair keel line, with some unsightly (and hydrodynamically suboptimal) bumps and hollows.

Any suggestions on how to fair this up?

 


6 replies:

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RE: Shearwater Double woes

can you confirm if you have just stitched the parts together or have you already epoxied or glued the parts.   this will make a difference in how you approach it.

that said, in general you want at least all the fairness issues worked out prior to glueing anything up.  some of the fit issues are natural and it is not uncommon to not have things lined up perfectly....but they can generally be addressed with some pressure to bring things into alignment. 

lots of good experienced people on this site who have built this boat so i expect you will hear from others soon.

h  

RE: Shearwater Double woes

Stitched, not yet glued.  And I do want to get it fair before I glue.

 

RE: Shearwater Double woes

   Just brainstorming. I'd try systematic tightening and loosening of stitches to try to improve fairness. If that failed, I'd try inserting shims wherever possible to improve things. If that failed, I'd make some temporary forms to push the hull into shape and then use epoxy to lock it in place.

I would not worry about tiny gaps or overlaps in seams. That can be fixed with peanut butter putty and/ or sand paper.

RE: Shearwater Double woes

Howdy, 

a frequent forum contributor, Mark Nye, has built a really nice shearwater double and i expect will  comment....maybe he is on holiday or away for a bit.

i have had similar issues on some longer kayaks with little rocker and relatively long flat sections.

a couple things i have found helpful in addition to tightening/loosening the stitching....

in supporting the boat, suspend it so that the weight is carried by the side panels....vs on top of a saw horse where the weight of the hull on the sawhorse can distort the hull.

use packing tape and/or spreaderstick (to pull together or spread apart) the side panels to the design width at the shear.  sometimes on a long hull, this will not be acheived naturally without some help.  by doing this, you often introduce some tension into the structure that then starts to pull the panel fare that would not occur otherwise.  temporarily stitching a buklhead into place can also help with shaping.

h

RE: Shearwater Double woes

Another source of unfairness in broad, flat panels can sometimes come from the plywood itself. 4mm okoume is a 3-layer construction, so oddities in just one layer can't be overcome by the higher veneer count in thicker sheets with 5 plies or more.

On one of my builds, the bottom panel had a big (visually interesting!) swirl in the grain on the outer face. This swirl put different tension in that face layer, causing about 1/4" of hollow over a 12" circular area. We tried heroic measures- wetting and adding pressure while it dried, and then stitching a temporary batten inside while the outside was glassed. The guy building the boat with me wanted a varnish finish, so putty was out. By tilting the boat so the dish in the panel was horizontal, we could flood clear epoxy in the area to try to bring up the level to blend with the rest. It mostly worked, but it was a huge ordeal, with multiple coats, sanding/fairing the raw epoxy, and dealing with drips and runs.

Sometimes, natural materials are just showing their variability!

RE: Shearwater Double woes

Roger and I have been communicating via email thanks to the builders club. 

The SWD is not the easiest of S&G builds.  I wrote this just after completion: .  From a technical perspective, there is nothing difficult about this build, the only real issue is size.  The long panels are fragile during assembly and a second set of hands really helps.  With 400+ (I lost count) wire stitches, it takes a while get everything lined up and tight.  There are nine full length (18.5’) filets, filets around both sides of the four bulkheads and the two cockpit recesses.  Glassing, sanding and varnishing are all marathons.  This is a build that takes some patience, and probably not the best first build.

My biggest advice for this or any of the other CLC kits is to trust that the CNC panels are cut correctly, and the boat will take the correct shape if wired correctly.  The SWD hull build over four bulkheads and another two internal forms, so the  "big puzzle" will only fit together one way. 

    

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