A few questions about hull alignment after stitching

So, I finished stitching this afternoon, and now the fun part... how to get everything fair and true.  I utilized the CLC recommended method of doing 3 or so stitches per side in order to maintain evenness along the length of the boat.  I can honestly say that the chines and keel look pretty darn straight fore and aft (i'm going to run a laser-level down the keel just to make sure).  There are still two big issues, however.  I have two pretty decent sized-hollows along the keel, with a raised area between them.  What's the best way to get these out and get the keel in a smooth line (if you're looking down it at an angle)?  


The other big issue is that my keel pieces must have shifted forward after the first dozen or so stitches, and are now positioned about 3/16" too far foward of the stem and stern, so they don't line up perfectly.  The way I see it, I can do one of a few things:

 1)  Take out all the stitches, realign keel panels, drill new holes, and re-stitch.

 2)  Leave the way it is and plane off the excess into the right alignment/shape.

 3)  Fill in the hollows in the bow and stern with epoxy/glass and paint the hull instead of varnish.   



8 replies:

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RE: A few questions about hull alignment after stitching

If it's going into a museum, take apart and start over.

If not, ignore the 3/16" problem and trim the ends.  For the hollows:  loosen the stitches through the hollow areas to let the panels bend out and fill the hollows.  Use small slivers of wood or toothpics to force the panels apart if needed.  When happy with the fairness of the keel, retighten the wires with slivers/toothpics at each stitch to hold the shape.  Cut the small wood inserts off when you are close to fair to make sighting along the keel easier.  Also consider running a saw blade through the raised area between the hollows if needed.  Your call.

If this doesn't help and you're still not happy with the hull's fairness, take apart hull and buy more stitch wire.  Bevel the panel edges where they join (remember how they fit before taking apart -you can put blue painter's tape along the panel edges and write on the tape) and then put back together, carefully.

Good luck and be patient.  This is a critical step.

RE: A few questions about hull alignment after stitching

Thanks for the response.  You've confirmed what I was thinking was the best way to proceed.  Although I like museum quality woodwork, I understand that this is a kayak, and will be beat up on beaches over the years... so having to fudge things a bit here and there in the building process doesn't bother me that much. 

 Next question... is the spreading of the keel panels best done with the hull inverted or upright?  Sighting is certainly easier with things inverted, since the keel is at eye level... but I can see how having gravity work for you with the boat upright would be advantagous.   


RE: A few questions about hull alignment after stitching

Inverted.  It would be hard to check for fairness through your hull supports when upright. 

RE: A few questions about hull alignment after stitching

Great advice thus far.  Thanks! 

 Could someone take a moment to describe the progression of the keel line from bow to stern?  I'm looking for info as to when the keel flattens out to assume a straight line before continuing its slope at the stern (does this happen 3 feet, 5 feet (etc) aft of the bow, or even further aft?).  I would take a ride to Mystic this weekend to take a peek at a completed boat, but we're moving tomorrow and simply can't take the time to head down there. 

 So far the toothpicks have worked to level out most of the keel, but I need to get an idea of the finished shape before tying it back together.


RE: A few questions about hull alignment after stitching

Not enough info.  We don't know what you are building.  Each kayak design has its own rocker (curve of the keel).  Look at your plans, the side view of the hull.  If you need to, draw a straight line on the plans, under or tangent to the keel.  mark off stations along that line in some units of your choice (12", 100mm, ...) starting near the bow or where you want to start making measurements.  Then measure up from that line to an edge of the thick black line of the keel (try to be reasonably consistent).  Convert your measurements to full scale and compare to your hull.  Put blue painter's tape along the keel line and transfer your station marks to the tape, that'll help keep track of things.

Don't get caught up in perfection, errors will creep up when scaling.  You want a fair curve for the keel line, not a level one.  If all your seams and panels are 3-D fair, but slightly off your scale measurements, epoxy it.  Without a lot of experience you're likely to mess up your fair shape by trying to reach a perfect curve in one plane.

Good luck with your move.


RE: A few questions about hull alignment after stitching

Thanks again!  The boat is a Chesapeake 16.  I was thinking about using the profile drawing from the plans, but didn't know to best utilize it.  Now I can give it a go.  The rocker is certainly getting better since I snipped the stitches and started adding wedges... now its just trying to fair things out.  Theoretically, the area of maximum rocker should be at or just forward of the beam, or at the CG of the displacement (but my experience is with full displacement sailboats, not kayaks). 

 As you can tell, this is my first time building one of these beauties!

RE: A few questions about hull alignment after stitching

Ok, so this process is pretty darn frustrating...

I almost think I've got the correct shape now, after inserting numerous cedar shakes into the keel chine the .  I still have my doubts however, and am almost thinking that I put too much rocker into the keel.  In some areas, I put in upwards of 3/16" additional spacing between panels.  I think I'm becoming pretty darn paranoid about permanently glassing the wrong shape into the boat, and am almost tempted to put it back to the way I started just to make sure... 

I think I need a support group...    

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