Just a note: It took me 2-3 hours to stitch the deck and hull together initially, but this was because I moved slowly when I added the "tack welds" with thickened epoxy and also had to locate a 2nd pair of hands to bring them together initially (w/ putty knife and stretch wrap).  I didn't stop working on it during that time.  Just a slow rookie.

Hi HerbieRidesAgain, 

i am a big fan of fibreglass reinforced strapping tape to handle the toughest of 'muscling' the parts back into alignment.  

its a little hard to see, but in the picture below, i had a deck with a similar problem and i went so far as to use the strapping tape on the deck (just behind the forward hatch) to pull the sides of the deck in towards one another (you see the strapping tape on the deck....but it actually is running under the deck pulling the sides in).

i then glued the hull to the deck (just glued around the strapping tape) and when the glue had cured, i then cut it with a scissors on the inside, pulled the tape out, and finished it up the glueing process.

anyway, that is an approach that has gotten me out of a lot of jambs.  if that doesn't do it, drilling more wire holes will not likely be any more successful.  if the pieces are glues so far out of alignment that this would not pull it together, i would just carefully recut the glue seams in the offending location and re-align and reglue.

fwiw, you will get drift in shape with time....so its helpul when things are not attached for any length of time to temporarily tape or otherwise hold them in shape.

h

h,

Thanks for the suggestion.  I was surprised at how well masking tape held the deck/hull together with a small strip across the interface when I was trying to pull them together, but it hadn't occurred to me to use stronger tape like this and use the tape's tension to keep the deck pulled together on the bottom - great idea and seems less risky/frustrating than trying to close such a big gap with a handful of copper wires.

It seems like the tape might lift off a decent amount of wood on the un-epoxied outside of the deck/hull, but the same was true of masking tape, and I'm pretty sure I can still get a nice bright finish despite that (though I'll test on a few scraps before putting the tape on the kayak).

as long as you don't leave the tape on there for weeks you should be fine.  most of the tension is where it takes the corner from the top of the deck to the underside....but becuase the tape is 2 inches wide, it spreads the load evenly..so i have never had a problem.

i would, fwiw, stick with a good brand like 3m.  i was trying to save some money on tape on my last build and bought some no-brand stuff that left residue (it had a very stick/mushy adhesive) that was a hassle to clean up.  my experience with 3m is no residue, and comes off cleanly.

h   

That strapping tapoe idea for pulling hull edges into alignment's a good'n. Being wider - 1" or 2" - will tend to be more effective than individual point-load wires, unless you want to bother with a bunch of the latter at close intervals, then deal with all those holes later on.

If you want to minimize pulling wood fibers off perhaps a layer of packing tape along the panel edges adjacent to the seam being glued would work? Placed between plywood veneer before strapping tape is deployed it ought to offer a better surface (smooth, non-porous) than the raw plywood veneer and - in my experience - doesn't do much at all to pull fibers off when being removed if you're careful to pull it off by pulling the stuff back at 180° rather than perpendicularly.

This ought to minimize issues resulting from excess epoxy squeeze-out too as 'pox just doesn't bond to the packing (polyester) well tape at all. 

 Sorry that I didn't see this earlier, but you can avoid the issues with adhesive residue in the future by using shrink wrap instead.

It comes on a roll on a stick (visible to the right of the epoxy behind the boat), sticks to itself without adhesive, is enormously strong in tension (TV and movie villains love the stuff for immobilizing their victims) but is easily removed with a razor blade or just unwrapping. In the picture it's reinforcing the epoxy tacks after I removed the wires but before I finally attached the deck.

If I remember correctly it was $10 for 1,000 feet at my local UPS store (office supply stores might have it in their shipping section). I've used it on 5 boats over 16 years and still have over half the roll left.

Have fun,

Laszlo

Slightly different reshaping question ---

Having installed the hatch sills, when I went to see if the hatch cover would fit, I discovered that one of the hatch covers is slightly warped --- a bit of a saddle shape where two diagonal corrners are higher than the opposite two.  What's the best way to flatten it out?  It's got one layer of fiberglass and epoxy on it now, but I haven't filled the weave yet.

Dang, Laszlo, Mother said I'd learn somethin' new every day if I just paid attention to smart people!  You mean something like this:

Amazon.com : uBoxes Mini Stretch Wrap 5" x 1000' 80 Gauge Stretch wrap : Stretch Film : Office Products  ?

Just pull, stretch round and round, and, Bob's your uncle, fugitive boat pieces secured?  Spanish windlass on a stick, for all love.  <;-)

.....Michael

h,

thanks for the details on the fiberglass strapping tape you used (and tip to avoid leaving it on for weeks).  I wanted to ask but figured it probably wasn't important.  I'll stil with 3M.

spclark,

Appreciate the tip on using packing tape to avoid tearing out plywood fibers (and letting glue seep through).

Laszlo and Gramps,

I have been using stretch wrap since I first brought the deck/hull together (and have stretch wrap holding the middle of the kayak together right now), but I think the stretch wrap I'm using now is thinner than what I used when I first brought the deck/hull together.  Either way, I've been unable to squeeze the deck in at the edges enough while wrapping the stretch wrap to get it to hold shape.  Unfortunately my stretch wrap roll is unmarked and I don't have the packaging, so I'm not sure of its thickness.  I'll pick up some 80 gauge as Gramps suggested (thanks) in case that will help.

I did some sleuth work and determined that the stretch wrap I brought (Duck Brand 5" x 1000', 285849) was 40 gauge - doh!  I should have been more careful when I bought it.  I will pick up some 80 gauge and try some combination of that and fiberglass tape.

I see a light at the end of the tunnel now, folks.  Thanks!

 a couple additional notes from experience. 

if you take a long length of fibre reinforced tape and loop it all the way around so it is attached to itself, you don't need to push it hard into the wood surface so less risk of taking any wood with it when you remove it.  i do recommend testing with any tape, i just have not found the glass reinforced packing tape particularly aggressive pulling wood up with it....the 3m has more of a blue tape stickiness to it and has typically come off very clean.

the big advantage of the fibre reinforced tape is it has truly almost no detectable stretch.  so if you secure it, the pieces is not going to drift from the shape.  so it's a bit of a different animal than stretch wrap.  since you are using it like straps, you can easily see if you have the piece positioned correctly.

the last thought is that i recommend, when there is a lot of misalignment, that you use the glass tape on either the deck or hull only(pulling across the inside side of the piece) to get the alignment (step one) and then another piece to hold the deck/down onto the deck (step two).  so i approach it as two seperate (but related) problems. if everything is very closely aligned and pliant, you can combine the steps.

h

ELB,

I had some warp in my hatch cover on my WD12. Here's how I fixed it:

The hatch cover was clamped to the workbench with enough pressure to flatten it. Then the doubler was cut, but not the cover. The big fat kerf was filled with epoxy/woodflour, a longitudinal stiffener was attached and the whole thing allowed to sit for a few days to cure good and hard. The hatch was now flat.

Then I rounded the corners on the stiffener. I ended up with basically a t-beam assembly for my hatch cover.

Not only does it fit well, it's strong enough to sit on. That, along with the internal invisible hold-downs, makes wet re-entries from the back easier and safer since I don't have to worry about snagging a hold-down or bending/breaking the cover.

Have fun,

Laszlo

I don't use the shrink tape to pull in the parts, just to hold them. In fact, for the WD12 I had some springback that had the deck and hull out of alignment so I used a screwdriver to lever the pieces back into alignment and secured them with the shrink tape. The nature of that tape is that it's great for applying a constant pressure but not so good for increasing it. It's for keeping pieces in alignment, not for getting them there. For that a utensil is required.

The nice thing was that the shrink tape could stay on after all the wires were out and not interfere with gluing the deck on since it was on the outside.

Laszlo

This had turned into quite a thread thanks to generous and detailed contributions from forum sages!  I feel like I'm benefitting from a winter lull in boatbuilding forum traffic.  ;-)

h,

It seems like a full loop where I need it most to pull the edges in (just fore of the cockpit) might work against itself in a way since it would apply downward (compressive) force at the center of the deck, where the deck seems to need to move outward (upward) as the sides are pulled in.  One advantage using fiberglass tape only on the deck edges and bottom as you showed in the picture upthread (as opposed to looping it fully around) might be that the center of the deck would be free to flex upward.  Then again, it's possible that outward hull flexure is way more important than inward deck flexure.  I'll consider both full-loop and edge+bottom strategies.

Laszlo,

I hear what you're saying about stretch wrap being a shape-holding tool rather than a shaping tool.  I've been using a couple of putty knives (1" wide and 6" wide) to lever the hull out to align with the deck before applying stretch wrap.  I think the thinner (40 gauge) stretch wrap is so thin that it stretches too easily and lets the parts slip out of position on the far side when I try to align the 2nd side.  Maybe the thicker stretch wrap will solve that problem (I'll re-post after giving it a shot this weekend).

I also have a mildly janky hatch, so I'm happy to see discussion of that in the thread.

has* turned into quite a thread.  I didn't mean to imply that I'm bitterly disappointed at recent contributions.

Hi Herbie, 

in answer to your concern, as i mentioned, the tape has no stretch.  so i actually pull it across the bottom first to pull it into shape.  once i have it in shape, to ensure it stays put, i then take the extra tape from the ends (or a third piece of tape) and overlap them on the deck (or hull).   at this point the deck is sprung into shape and tape is not exerting any signifcant pressure on the deck.  if i only leave a short amount of extra tape on, i have found that it sometimes peels off the wood...(unless i really press it into the wood).  but it will never peel off if i overlap even the tiniest bit of it onto the tape itself.  

i hope that addresses your concern.

h

Hatch warp seems to be an inevitability.

I had the same thing happen with the compartment hatch on my Waterlust canoe early this year. Solved it in exactly the manner described though I used two stringers rather than just one as this hatch is a trapezoid rather than round / oval. So there's a reinforcing stringer set a couple inches in from the front and back edges, each profiled to match the deck camber of the frames in front and back.

The six toggles set three to a side are fully up to the task of holding it flush to the deck and tight aginst the foam sealing material underneath.

h,

Good point.  The tape is also just a shape holder rather than a shape definer.  It shouldn't constrain reshaping since that the deck should be re-shaped by the time the top of the deck gets taped.  Makes sense.

I just realized that I misspelled the subject of this thread ("stiches").  I put a lot of thought into what I'm going to post but seem to post carelessly (and usually verbosely) when the mood strikes - hehe.

   Thanks for the advice on the hatch cover warping -- and the reassurance that it happens commonly.  It's not very far off, so I think my plan is to try using a heat gun to soften the epoxy and clamping the cover into a flat position while it cools.  If not, I'll see what I can do with cutting the doubler and crossbracing.  It's the big trapezoidal rear hatch, and it looks like only one corner is off, so I'm not sure how much a brace in the middle will help.