deck to hull seam construction-opinions?

OK, so some companies like Swift and Current design like to use whats called extruded vinyl H channels to join the upperdeck to the lower hull ,glue it closed and then apply tape seams over it with glue on the inside and outside.Others like QCC like to use the two hulls overlapping at the joinery about 2" claiming this make sthe strongest joinery. Still others like Seda or Mariner just butt join the two edges and tape seal them inside and out.Im looking at 3 differant companys kayaks to choose my next kayak .Which of these designs really does make the best seam for strength?(ps- Im not going off cliffs and waterfalls)Anyone know of a failure of one of these designs?

I’ve seen the H channel fail alot. so much that we no longer use it in composite construction. the channel can break, come un-glued, etc.

I’ve seen butted joints fail, usually either a bad joint to start with OR a devastating blow where anything would fail. Dry layup or poor sanding between layers will cause this to fail BUT if done right this is an awesome system.

Not real familiar with overlapping but assume this would be quite strong.


The overlapping seam
on a QCC is quite strong, I have had mine for 6 years and been in pretty rough water/hard landings with no failure…wouldn’t worry about QCC at all there. I highly recommend them for flatwater anyway…they are pretty good in the waves, but very little rocker so are slower to turn. Not a “playboat”, but an excellent mile eatin’ boat

Have you considered Prijion?
Prijon used a HPT that is hemetricaly sealed.

Strong enough Vs strongest…
I believe the strongest seam I’ve ever seen is overlapped, bonded, and taped and epoxied inside AND outside.

QCC’s are well done but nowhere near the “strongest”. They use Plexus on a lapped joint and it’s plenty tough.

Prijon also uses
foam bulk heads in some of their composite kayaks.

Needless to say that I have removed a few of those (on friend’s kayaks) and replaced with REAL fibreglass bulkheads because they leaked dangerously too much!

There is something that I just don’t trust with Prijon composite boats…

is tricky stuff in production. It’s got to be ‘right’ every time or failure can (and usually IS) catastrophic!


Thanks for the reply

QCC seams can fail.
My 400X seam failed when the boat fell about 4’ off the rack onto the concrete garage floor. It appeared that the Plexus had only bonded with the edges of the overlapped hull and deck. The overlapped areas were still smooth and shiny along 18" split, which was from the bow tip and back on one side. The edges were jagged. Of course, the seam is covered under the lifetime warranty, but I did repair it myself.

So, don’t drop your QCC 4’ onto a concrete floor.

needless to say
that the same QCC that fell on the concrete floor would not have faired very well in a bit of a surf landing. Admittedly most “sea kayaks” see very little action and that’s why the manufacturers go away with constructing fragile kayaks to meet the demands of the buyers obsessed with unreasonable weights

That one no, but on one that did not …

– Last Updated: Dec-22-08 5:52 PM EST –

... have that rare assembly/glue you can bet the layup adjacent along their seams would give way before that seam ever would. It is a very strong seam method. Double hull material plus super insane adhesive. Seen any stronger seam joints? May exist, in form Salty describes, but would likely be even more overkill than QCC's.

Let's keep this in context folks. Besides, the seam on QCC's is guaranteed against failure from defect (kayak's, not paddlers!).

The seam I’m describing is
overkill. Overlapped and bonded with Sikaforce two part urethane. Taped inside AND outside and Epoxy post cured glass or glass carbon matrix. Can and has taken hammer blows from a steel ball-peen hammer.

In testing the lapped bonded seam withstood deck / hull crushing under vacuum. That’s before the inside and outside full length glass tape and epoxy!

Such a lay-up is designed to be expedition strong to withstand the worst imagineable paddling scenarios. Overkill for many, but not rock gardeners of expeditioners.

I think the QCC situation described above was a rare case of bad prep and inadequate distribution of the Plexus. Of the methacrylates it seems Plexus is the best. Many yacht and boat builders tout it.

The QCC I saw recently was a beautifully made kayak. I’d like to get one one day for a speedy tourer.