Sealing leaks in the fiberglass Tempest.

-- Last Updated: Jun-04-07 8:04 PM EST --

I know there’s been a couple good threads on this topic. I’ve written up here details on sealing the seam between the hatch cover sleeves and the fiberglass, from the underside of the deck. I want to acknowledge Steve Sheerer and Dennis H for excellent general advice on this topic. I’m not sure if anyone had written about sealing the hatch sleeves from the inside, and it seems to have worked pretty well so far, so I thought I would write it up. Questions, corrections, suggestions, are welcomed. This information may also apply to other kayak makes/models.

* Reference threads.

Soapy bubble test for leaking compartments, Steve Scherrer:

* Problem statement.

When I leave my 2006 Tempest (Tempest hatch covers, versus Kajak Sport) on top of my car in the rain during the day, I will get 1-3 cups of water in the compartments. I will similarly get a few cups of water in the front compartment if in waves for an extended period of time with water washing on to the bow.

* Related observations.

The hatch covers for my boat are pretty tight. I always make sure they are on well. Especially during the rain situation, it seems unlikely that much water is getting in past the hatch covers. It is more likely getting in through the seam between the hatch sleeve and the fiberglass. Performing the bubble test as described by Steve (see reference thread, link above) confirmed leaks around the hatch sleeves. Also, in an early 2007 Tempest with KS covers, Dennis H observed that he was getting water into the compartments from around the sleeves and not past the covers. Sealing the sleeves from the outside with 4200, re-sealing the bulkheads (for good measure) with 5200, and sealing around the skeg tube passing through the bulkheads with 5200, gave him dry compartments.

During roll sessions I get between just droplets and about a quarter cup of water in the compartments. The exception is the day compartment which can sometimes get about a half cup of water. A known additional leak point for the day compartment and rear compartment is the skeg cable tube passing through the bulkheads. The tube is not sealed around the bulkhead. Any water in the cockpit can leak into the day compartment through the space between the tube and the hole in the bulkhead, especially when the boat is upside down (during rolling or wet exits.) Similarly, water can leak from the day compartment to the rear compartment.

* Results after sealing the hatch sleeves.

After one pool roll session, the front compartment was bone dry. Not one drop. The day compartment still gets a quarter cup of water. (I may not have got the skeg tube sealed completely.) The rear compartment had just droplets, no collected water.

After a couple days of several hours in 1-2 ft wind waves with water washing on to the front deck, there was no collected water at all in the front compartment, only dampness on the float bag. Same for the rear compartment. There was still the quarter cup or less in the day compartment. This is a huge improvement over the past in the front compartment in rough water. (Just in time for my Gulf Islands trip. No coincidence there.)

* Solution.

3M 4200 regular or quick cure can be used to seal the interface between the hatch sleeve and fiberglass on the outside of the boat. It adheres well to gel coat. Dennis H successfully used this method. Alternatively, 3M 5200 can be used to seal on the inside. It adheres well to fiberglass. I chose to try sealing on the inside as I already had the 5200 to seal a small leak in a bulkhead. Also an inside job wouldn’t show on the outside. 3M marine seal is very viscous and sticky and would be impossible, for me at least, to do a nice neat job on the outside. I figured if the 5200 didn’t hold on the inside, I could always come back later with 4200 on the outside.

* Tools and materials.

- 120 –150 grit sand paper.
- Air source. (To blow off the sanded area. I used a hand pump, the type used for blowing up inflatable boats.)
- Rubber gloves that fit tight on the fingers, such as surgical gloves.
- Optionally a spare set of gloves. (To change to clean gloves part way through the job. This marine seal is incredibly sticky.)
- A hand mirror. (for viewing up under the deck around the sleeves on the inside of the compartments.)
- 3M 5200 in the squeeze tube or calking tube. Either regular or quick cure. (I used one squeeze tube of the quick cure. It was just enough, using sparingly but making sure to get a good continuous coat, for the three hatch sleeves, a small spot on a bulkhead, and the keg tube. If I had it to do over again I would have bought the calking tube, which is larger volume, so that I would feel free to use it very liberally and it would have been easier to squeeze out. It might have helped to put a lot more around the skeg tube as it’s tough to see up under there to make sure it’s sealed all the way around.)
- Caulking gun. (If you choose the caulking tube of sealer.)
- Razor blade or sharp knife (for cutting the nozzle on the sealer.)
- Paper towels (for cleanup.)
- Acetone or other solvent. (for clean up. Acetone worked well.)
- Saw horses (or something to place your boat on.)
- A table (or something to place the tools and materials on.)

* Procedure

1. You may wish to do a thorough leak test on the boat before you start, in case you want to seal some other leaks from the inside at the same time. Note, 5200 does not stick well to gel coat. You will need 4200 if sealing from the outside on the gel coat surface.

2. Get everything set up ahead of time. Once you open the tube of 5200, you have about an hour to work with it before it hardens too much to be workable. You may possibly have longer, but I wouldn’t count on it. Read the directions on the tube. Working time probably varies with temperature, too. Was about 55F and dry when I did the job. It took me about 45 minutes.

3. Leave your boat right side up. The sealer is plenty thick enough that it will not drip at all. Any stringers of the sealer will fall by gravity down into the compartment. If upside down, any stringers will fall trough the hatch sleeve, and stick to the rim of the hatch sleeve, or swing onto the outside surface of your boat. I found out the hard way. Also, it’s more difficult to work from under your boat. You will probably get some sealer on the rim of the hatch sleeve and outside of your boat anyway, from your gloves, but not as much as if working with the boat upside down.

4. Take the hand mirror and look inside your hatch cover on the under side of the deck to see the seam between the black hatch sleeve, and brownish fiberglass (or yellowish Kevlar) to see what you will be sealing.

5. Remove the hatch covers. Remove the black retainer lines from the covers by undoing the knot at the cover and tucking the line into the compartment, out of the way of the job. For reference in re-tying, the knot is the same type as used to terminate the bungee lines on the deck.

6. If sealing areas around the seat, like around the skeg tube where it passes through the bulkhead between the cockpit and the day hatch, or around the skeg slider box from the inside, consider covering or removing the seat and back band. (I just unclipped the two rear retainer straps on the back band, and moved the straps and back band out of the way for sealing around the skeg tube.)

(I forgot all about the skeg slider box at the time. Didn’t have enough extra 5200 anyway. Also, on later inspection I couldn’t see a clearly defined interface between the skeg slider box and the fiberglass on the inside. I would have had to just goop the ever-loving out of the area. This is the one spot where I think the 4200 on the outside might be a better solution. Also, the leak around the skeg slider box, even if leaning a lot or in rough water, may be negligible since the cockpit will always have some amount of water via drag in from legs and feet, and leakage around the spray skirt tunnel if no dry suit/top overskirt.)

7. Lightly sand the surface to be sealed. Sand from the inside edge of the underside of the hatch sleeve, to about an inch inward, overlapping well with the fiberglass surface. Blow off with air. (IMO the best prep for glue jobs is usually sanding, as it gives you roughened and clean surfaces.)

8. Put on the gloves.

9. Cut the applicator nozzle on the tube of sealer. Cut well down on the nozzle for a large diameter opening, especially if using the squeeze tube. This stuff is viscous and not easy to squeeze out.

10. Squeeze the sealer onto your index finger, and run your index finger with sealer along the area to be sealed. Do this around the inside of the hatch sleeve, until you can run your finger all the way around the perimeter of the sleeve and feel a continuous coat of the sealer from the edge of the opening on the underside of the deck and inward at least an inch. The sealer is sufficiently sticky and viscous that you can feel it very well through the elastic rubber gloves. Finally, inspect with the hand mirror. If in doubt, add more.

11. Clean up as necessary, as you go along or at the end of the job, with acetone and paper towels. Any 5200 in unwanted places on your gel coat, or on you, should wipe up pretty well with acetone as long as it hasn’t yet cured. It wipes up so-so on the inside of the plastic hatch cover sleeves, and of course won’t wipe up well on the seat or back band cloth.

12. Let cure. When dry, the 5200 has a feel like tough rubber. It feels like it will stick well and last.

13. After the sealer is cured, re-attach the hatch covers and back band (and seat if it had been removed.)


Paul S.

I would like to add to Pauls post.

In using 3M 4200 to adhear to gel coat the gel coat just needs to be clean, I wipe it down with isopropyl alcohol and let dry, you do not need to sand as 4200 is made to ahear to a slick surface. Yep messy to work with and hard to get a neat job.

By the way both my and my wifes tempest hatches are totally dry after sealing the hatch rims and the skeg cable.And believe me the kayaks have been upside down a lot while learning to roll. Thanks to Paul mission acomplished on the rolling for me, wifes still learning.

Thanks Paul


I finally got my Kokatat GMER dry suit with overskirt. (Before that I was using a loaner with no overskirt.) Now very little water gets into the cockpit. Also, now, the day hatch stays dry. On closer inspection, and given the above observation, I’m sure I hadn’t completely sealed the skeg tube where it passes through the bulkhead. I’ll get another tube of 5200 and seal it soon.

I’ve since been on the Hood Canal rolling and horsing around for two days, and in wind and waves one day, and on the lower Columbia in wind and waves. Everything dry. Very good.


Tempest KS hatch covers
What is different about these hatches that makes them more desirable? What does KS stand for?

Thanks, Art