Cobra Hatch Seal - Frogs Butt Upgrade

I came up with this seal upgrade for the Cobra hatches that I've shared with a couple others, and finally have field tested it a couple times to the point where I'm confident it's the way to go.  I call it the Frogs butt upgrade.  (Is a frog's butt water tight?)

First, the narrow rubber seals on Cobra hatches are not all that robust.  In my experience, you will have some small amount of leakage on most kayaks like the Marauder given the number of hatches involved.  They just don't provide a whole lot of extra room for error in making contact with the hatch covers.  The upgrade will be a vast improvement in the water-tightness of the hatches. 

After ordering samples of several types of material, I arrived at the following selection.

The material:  3/8" Santoprene Foam Cord
Supplier:  McMaster Carr
Part Number: 6322K13
Cost: $0.55 per foot
Link:   http://www.mcmaster.com/asp/enter.asp?partnum=6322K13

Santoprene cord is very compressible but seems to be quite durable at the same time.  Excellent weatherability. Material is closed cell, which means each cell is completely closed, restricting water, air, and gas from passing through.  Excellent recovery from compression. 

How to install:   Simply pull out the old gasket material and push this 3/8" cord into the seam along the hatches.  It'll sort of pinch itself in the seam and anchor just fine without any adhesives.  I used a flat piece of plastic to gently push the cord into the seam as I went.  More than half of the material should stay above the surface of the hatch rim and will compress into your hatch as you seal it up.  Very easy install.

You'll find that after several hours of the hatch being in place, the seal will form to your lid.  The material will expand back to shape again if the hatch is removed for a period of time.  I have gotten into the practice of loosening my hatch covers when my yak is in storage just to keep the seals  in good shape.  I really don't think this stuff takes a permanent memory though, it should be an improvement even if you leave your hatches buttoned down all the time.

In my two times out with these new seals, hatch leakage has been reduced virtually to zero.  Now I just have a couple of rivets to seal and I'll truly be as tight as a frog's butt.

Photos below.

Erik

Nice one Erik! Do you have any idea how many feet you ended up using?

Nice post Erik!

Nice one Erik! Do you have any idea how many feet you ended up using?

I used just shy of 15 feet for the three hatches on my Marauder.