31 January 2012

SHOP: repairing a leaky hatch

We all love a sea kayak with dry hatches but rarely that is the case.
After owning numerous kayaks I only had two that had consistently dry hatches.
Kayak hatches leak for a lot of reasons: poor design and materials seems to be the most common but often even a great hatch design can leak on one boat and be dry on the next one.
So what causes hatches to leak?
Hatch cover_ VCP

I found that the type of hatches using a neoprene cover seal under a fiberglass lid work well when new but after a few years deteriorate and start to let water in.
Of course, let's not forget that  most kayak hatches will remain dry if the kayak is used in calm conditions and the water does not reach the lid.
Some hatches seal extremely well and seem totally leak proof, to then let water in when the kayak is inverted (rolled) on a hot day. Drilling a very small hole into the bulkhead usually solves the problem because it helps to equalize the expanding and contracting air when heated and cooled during rolling.
As air heats up in the sun it expands and when the kayak is suddenly inverted into the cold water, the cooling effect contracts the air inside the hatch resulting in suction. The lid might seal enough to prevent water splashes intrude the hatch space, when paddled right side up, but not enough to prevent the force of suction when submerged (inverted)
But what to do when you know that you have a very good seal with the lid (and there is a breather hole to let the expanding/contracting air in-out) and your hatch area is wet after even a non rolling kayak session?
I had a few cases of hatch covers rims leaking.

The (usually) black rim is cemented to the deck of the kayak by a bonding agent. In quality boats that happens to be an epoxy type glue and in some other kayaks is just simple "goop", ranging from silicon to polyurethane.
Either epoxy type glue or goop bonding can perform the task of keeping those rims attached as long as there is a solid continuous bead around the whole perimeter of the rim.
It does not matter how expensive my kayaks are and from what reputable brand; leaking hatch rims are not uncommon.
I have removed a badly sealed rim: I found the caulking under the rim made very poor contact and looked like the factory worker forgot to press-in the rim firmly enough against the deck. I cleaned up the bad silicon and re-seated the rim with polyurethane.
In an other case the epoxy glue did not make it all around the rim leaving a section without a proper seal. I could not remove the rim (the bond is seriously strong) but I mixed-up some epoxy glue of my own and poured/forced it into the section where there was none.

Last but no least: even with the rim seated well and the lid being positively waterproof in one case a hatch was still leaking despite the best efforts in finding the problem.
On a friend's kayak a hairline crack was eventually noticed on the gelcoat close to the rim after doing the test (below). A bit of poking revealed that the gel coat was all there was keeping the water out. There was a large air bubble in the lay-up where the reputable manufacturer did not fill; just fiber and no resin, letting water seep in.

The repair involved him removing away all the gelcoat above the void, remove loose fibers and clean the area with acetone.
Several solid layers of new cloth and epoxy were laid (inside the hatch) over the repair. Gelcoat had to be matched to the existing color to make the repair invisible.

While performing this repair on the deck the cable for the skeg needed some attention too. It used to be very sticky when trying to deploy it: the housing would flex and bind under pressure. Glassing a long unsecured section of the cable housing to the under deck solved the poor performance.

While some hatch lids will seal really well others will only seal sometimes.
I found that the kayaks with the new Kajak-Sport lids (dual density) work well in winter but poorly in summer. What gives?
I have the mandatory vent holes in the bulkheads but when I go for a rolling session in the summer warm waters it seems that the new lids (softer rubber on the edge, stiff plastic in the center) leak about a cup after an hour or so. I am not the only person that has this problem since others have revealed me to experience the same.

in this video light vaccum was applied to test if water would seep past the lid's lip

A friend of mine solved his case with the dealer promptly shipping him the older style round lids that are made entirely from soft rubber (non floating type): now they seals 100%.
Worth mentioning that after precise measurements of the roundness of the hatch rim, he found it to be 1mm out; would that effect the sealing of the dual density hatches?
However to solve my problem, I am unsure if I will be able to source the old large oval Kajak-Sport lid to address my summer paddling leaks.

PS: The key to these repairs was placing a small waterproof camera inside the hatch and film the source of the leak. I recommend trying it if your hatches are suspect.

PS AUG2012 If you are not happy with the performance of your hatch covers have a look at Sea-Lect Design ones. Review here


  1. Try to install goretex vents to the bulkheads. http://www.gore.com/en_xx/products/venting/protective/products/screw-in_holder.html . Glueing a piece of goretex fabric over small
    drilled hole in bulkhead works as well IMO.
    I have installed those vents to my Tahe kayak, and never seen water
    inside hatches. Inside and outside pressure differencies equalize quite fast.
    Those new Kayaksport hatches are also ok, when there's no sand or securing string between hatch and rim. But yes, this goretex vent stuff is the key to not having vacuum inside hatch.
    Toomas Tikenberg

  2. Toomas, I always wondered if Gore-Tex would work as breathable material for hatch ventilation but I wonder how big is the patch of fabric that you are using? and how do you fix it to the bulkhead?
    What annoys me with the Kajak Sport hatch covers is that they only leak in summer (25C plus air temperatures) despite having breather holes in the bulkheads.

  3. Hi,
    I installed those vents. Here is datasheet info:

    I can't check right now, what type of vent it exactly was ( too much snow on top of kayak :)
    but seems that all those plastic vents have similar dimensions. I guess that 10mm hole covered
    vith goretex fabric works well. Placement of the hole should be in place where it cant be penetrated
    accidentally, or covered with some protection. And of course glue should be applied only to the rims
    of goretex patch...

    1. Strange, datasheet link lost somewhere...

      And maybe in summer, when air is warmer than water, then cold water causes vacuum in hatches...

    2. I have no doubt that from the hot air to the colder water transition (like a roll) there would be some vacuum occuring.
      Maybe the KS hatch covers don't seal all that well in warmer climates? I don't seem to be the only one...
      I will try to get the older style rubber ones, used by SKUK (Nigel Dennis) kayaks for example.

    3. Toomas, I had a look at your link: I like those GoreTex vents.
      And I can source them locally too. Will give them a try.

      I appreciate when readers share tips and knowledge with others. Thank you for your info; very valuable.

  4. Gnarly, do you mean these hatches?

    A friend of mine had problem with leakage on the oval hatch on her Zegul 520. The old version of the hatch solved the problem. The klick-on hatch was also extremely difficult to remove or put on in lower temperatures (<5 degrees celsius). One reason can be that they must aligned correctly, a small difference of only one or two mm makes a big difference. A problem I´ve never had with the round hatches on my Greenland.

    1. Henrik, that's the exact same kayak I have trouble with: the Zegul520.
      Same here: the big oval hatch cover is a bit hard to put on (needs a lot of attention to get the lip on the rim) and it leaks.
      Well, it looks like I will have to source some Kajak Sport "old school" hatch covers for my warm climate paddling conditions.

  5. Hi Gnarlydog, long-time reader but a first-time commenter. I'm one of the owners of Walrus Kayaks, a smallish manufacturer in Vermont, USA. We use the kajaksport oval hatches on several of our boats and haven't encountered the same issues regarding leaks. We've repaired/destroyed/dissected many kayaks built by other manufacturers and found that, when the leak is between the rim and the lid, a distorted mating surface for the hatch rim is often the culprit. Since both you and Henrik are experiencing the same problem on the same model, I'd guess that the Zegul520 mold has a slight distortion in the flatness of the surface on which the rim sits. When the rim is clamped down, it'll assume the same distortion and the hatch cover will, in turn, not create an even seal all the way around. One trick that often works well is to try a bead of vaseline or drysuit gasket conditioner (essentially an oil for preserving rubber) on the inside of the hatch lid. This usually will take up the slight space left between the rim and the cover by the distortion in the rim, in-turn plugging the leak. If this isn't enough, I'd recommend going to the old-style (all rubber) covers like you said. Kajaksport makes a total of four cover styles, with the old-style rubber covers being the most waterproof and the new-style "click-on" being the least. The other two hybrid covers may be better than the click-on cover, but generally aren't as good as the all-rubber covers. If you decide to switch to the old hatch covers, feel free to send me an email (mark@walruskayaks.com) and I can source you some at our cost (probably a bunch lower than you'll find them anywhere else). Keep up the great posts and I hope we can arrange a way for you to try out our boats sometime in the future!

    1. Mark, thank you for your comment. You seem to confirm my friend's findings on the leaky hatch of his Tahe Greenland that had the dual density lid's rim out of round; the rubber hatches solved the problem there.
      While the Vaseline could seal the gap I believe it would a poor solution for my paddling environment of sandy shores. I will try the rubber hatches solution.
      From the images on your site the Jaeger seems like a fine playboat suited to my weight. I used to live in the Berkshires for a while, a few years back, and would have loved the opportunity to test your offerings. Being on the other side of the world right now, I think it would be difficult to get the hands on a test sample :-)

  6. We're sorry we missed you while you lived nearby, but we've been hoping to make it to your side of the world in the not-so-distant future. I'll, of course, let you know if/when we do. Given a sandy paddling environment, you're definitely right that Vaseline would be a terribly sticky and ineffective mess. Good luck with the other style of hatches and let me know if you have trouble getting your hands on one.

  7. an interesting study, I found the same re the kajaksport hatches - hard vs soft rubber on my Greenland also,,, but not on my Tiderace. I had a Valley Nordkapp Lv briefly that leaked like a sieve everywhere, a case of very poor manufacture quality. Having sent it back for repair Valley seemed incapable of fixing it so I took my money back.

  8. Update.
    Kajak-Sport sent me replacement hatch covers for my Zegul, they are the rubber ones.
    While they are slightly heavier they fit very snug, no matter how hot the weather.
    After a recent paddle in rough conditions and an hour of rolling the hatches remained totally dry.
    The Kajak-Sport rubber hatch covers solved my problem. I am now a happy paddler again :-)


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