Shearwater hatch seal

My wife and I have 2 Shearwaters (The boats are awesome).  

We have not been able to get the hatches to be fully waterproof.  They are fine for calm conditions but not in rough wind and waves.  We built them with all of the materials in the kit.  Recently, we tried ordering some hatch seal material off of the internet.  It turned out to be very thin... too thin.  Used it on my wife's rear hatch.  A recent crossing of Lake Champlain go somewhat scary with her read hatch filling completely with water from large waves.  Our front hatches that used the CLC material faired better, but each had atleast a gallon of water.  For some reason my rear hatch seems to be watertight, or atleast close to it.

I am looking for a serious fix that is waterproof.  My current thoughts are:


  1. Add external webbing straps to increase and better spread the downward pressure.
  2. Making the channel form fit the hatch cover by using silicone or thickened epoxy and then pressing the hatch cover (sans foam) covered with plastic (so it won't stick) to create a perfect fit.  Then add thin foam to the hatch cover.  Has anyone actually tried and fully tested this?
  3. Find some magic hatch tape (I say magic because I think the CLC stuff is as good as anyone elses).
  4. Buy flotation bags and admit defeat.
Some of the problem may be from a lack of precision on our part.
I plan to call CLC as well and see if they have other advice.  The way we built them works fine on calm lakes, but for overnight trips with the possibilities of big waves, it is just not safe currently.
 - Josh 


9 replies:

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RE: Shearwater hatch seal


On my SW17 I originally used the CLC foam seal on the hatch and had installed the thin lip on the hatch rim. The seal slipped on me in the heat. I removed it and ripped some minicel foam on my band saw and glued it to the hatch with 3m weather strip adhesive (the brushable kind)


On my wife's sw16 I did not us the thin lip and glued minicel foam right to the rim.


In both cases they have been very water tight. Not 100%, but dang good.


RE: Shearwater hatch seal

Hey Dan,

I'd guess it's your internal bungee system. In my mind, there's no way it could be as effective as the toggles. I built 2 SH boats, too. On the first one, I experienced a lot of springback in the hatch cover from the stiffener trying to revert back it's natural flat shape. Definitely affected the fit of the cover, but the toggles are pretty effective at countering that because they're far enough apart.

On my 2nd boat, I used strips to stiffen the hatch cover. This worked much better.

I've seen boats that use the strap hold-downs, but for them to be effective, the hatch covers have to be significantly proud of the deck. Not a fan of how they look. Not crazy about toggles, either, but it was a lesser-evil type of thing.

Cheers, Pat

RE: Shearwater hatch seal


You may be confusing me with Josh...

I had less stpringback on the rear hatch on the 2nd boat because I scored the plywood before I glued it on and the method I used gluing the seal to the rim has worked very well. This is the way Eric Schade suggested doing it.


RE: Shearwater hatch seal

Oops. Sorry, Dan (and Josh).

Josh, are you using toggles or internal bungees? Also, make sure the seam where the 2 ends of the weatherstripping come together is fairly smooth with no gaps. I've had better luck with the thick weatherstripping. It's a pain at first, but once it compresses, it's fine.


RE: Shearwater hatch seal

Thank you for the detailed responses!

John from CLC also sent a note (Thanks!)


    We are using the toggles, and I overlapped the weatherstripping to allow no gaps as per the instructions.  

 I redid the hatch seal on my wife's boat with material from a local hardware store... similar to CLC's material.  So far it seems ok.  I think our problem stems from some slight warping in the hatch covers.  Despite this, the toggles create enough pressure that it is working ok, but not great.  This weekend we went kayak camping in two days of perfectly glassy water (incredible!).  The only chance to test the kayak hatches was when I accidently flipped the boat getting out on a slippery rock.  The hatchs didn't have a drop in them.  I am convinced that the problem only occurs from repeated waves over an extended period.  I now feel confident that both boats won't sink full of water in the waves, but that they might pick up a gallon or two in heavy waves.

  John Harris suggested a garden hose for testing and this seems to be the best approach...  Our apartment lacks one, so I will track down a friends and do some experimenting before doing any radical fixes.  I think we have this under control, we just need the time to do some testing and tweaking. 

 Thanks all!

- Josh

RE: Shearwater hatch seal

What about a raised hatch configuration? 


RE: Shearwater hatch seal

RE: Shearwater hatch seal

A pic. of the underside of the hatch...

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