Questions on sealing bulkheads/hatches

I purchased a used Necky Chatham 16 this past weekend and took it out for an inaugural paddle Sunday morning. Even with a spray skirt and the hatch lids firmly in place, I still had some water inside the bulkhead compartments after my paddling session. So, obviously there is a leak somewhere.

Since this is a used kayak that probably has some deferred maintenance anyway, I decided to forego the usual meticulous testing to pinpoint the actual leak and just reseal all the bulkheads and replace all the hatch gaskets.

Last night, I resealed both sides of all three foam bulkheads using Lexel. The instructions on the tube indicate the sealant requires 1-2 weeks for a full cure, but will skin over in 30 minutes and can be painted after 24-48 hours. My question is how long should I wait before I take my kayak back out on the water? I was hoping to go paddling again this coming weekend, but the instructions indicate a full cure in 1-2 weeks. Do I need to wait that long?

Tonight, I will be replacing the gaskets on the three hatches. I already removed the hatch rims and scraped off the old butyl tape. I have new 1" wide black butyl tape and 3M 5200 sealant being delivered today. My plan is to install the new butyl tape, screw the hatch rims back on (not too tight), and then apply a clean bead of 3M 5200 around the perimeter of the hatch rim where it meets the deck for extra security. Will my planned course of action be sufficient for preventing any hatch rim leaks? How long does the 3M 5200 need to cure before getting back on the water?

Thanks for any advice!

Glass or plastic?
5200 should be all you need for the glass boat, unless there is a leak in the skeg box. But since you said that it’s not just the rear compartment, then bulkheads and hatches would be the most likely causes.

In the glass version, you should be able to paddle it the next day or day after that. The poly version flexes a little more, so letting it sit for a few days is a good idea.

The hatch covers do leak from time to time, depending on age, so resealing them can be a good idea. Stay with what you already did for now, and see if she still leaks.

Sorry, I forgot to mention it is the polyethylene version of the boat.

Another question I have is regarding pressure holes in the bulkheads. In searching Pnet and Google for instructions on resealing bulkheads, I’ve seen many posts stating to make sure there is a pressure hole in the bulkheads. Most of these posts say to simply take one of those small tubes that come with a can of WD40 or compressed air and just push the tube through the foam bulkhead.

Is this necessary? If so, why wouldn’t the manufacturer have installed these pressure holes? Won’t these holes cause leakage into the supposed water-tight bulkhead compartments if you have to do a wet exit? If the pressure hole is necessary/recommended, do you use the WD40 tube only to create the hole by poking it through the bulkhead and then removing the tube? Or do you leave the tube in place?


tube hole is small enough to vent air
but will eventually leak water if it rises to level of puncture. Volume of water will be very small unless cockpit is flooded for some time.

As to why mfg do or do not add hole is likely to let owner decide. I have bored all my bulkheads for decades now.

As a result of your efforts you know it is done and correctly so. Enjoy that sweet boat.


– Last Updated: Apr-27-16 7:09 PM EST –

Determining where leaks occur can take 5 minutes and may eliminate a lot of unnecessary work and goop.

Personally I'd wait a week if your resealing method was a duplication of the original sealant where goop is applied to a smooth hull making a fillet to the exterior of the minicell bulkhead. That method of sealing is easiest for assembly but poor for integrity because there is nothing adhering the bulkhead to the hull at it's largest area of direct contact between hull and bulkhead, instead of sealant/adhesive joining the 2" thickness of the bulkhead there's a variable sized fillet on the outside of the bulkhead.
If you removed the old goop and roughened the plastic hull at the fillet joint and under the minicell then injected the Lexcell about 1/2"-1" between minicell and bulkhead you sealed it 10x better than when it was built at the factory.
The Chatham hulls are fairly flexible and if there isn't a very fat thick fillet of goop especially in the aft bulkheads what happens is the movement gently pulls the sealant away on the inside of the bulkhead which then allows more movement on the opposite inside portion pulling it away. It starts where you can't see it. Without a big fat pile of goop fillet taking up the movement one thin edge of sealant pops away allowing water in which lubricates movement of the bulkhead like crazy and in no time the bulkhead is simply hanging from the deck with thin flaps of sealant doing nothing.
It was really obvious on a 6 month old Chatham 17 that was only used for a few months. The width of the sealant on the hull joining to the bulkhead varied from 1/8" to 1/2" with sealant thickness at the fillet joint varying from 1/16" to 1/8".
There is simply no way a 1/8" piece of goop affixed to a SMOOTH polyethylene hull will stay attached for long when 2" of minicell is being flexed on it. Imagine gluing 2" minicell on a flat piece of plastic but only doing it on one side. It's obvious the glue joint is a hinge. Ok do the same on the other side and it holds on better. Now compress and pull the minicell and you'll see movement pulling and stretching the fillet joint. The connection to smooth poly expects a lot of the sealant/adhesive especially since the minicell is free to move like a hinge on one side then another bit by bit pulling the sealant away. Once a teeny bit of moisture gets between minicell and hull it's pretty much zipper time and the bulkhead pushes to fillet right off the hull. 2" of glued minicell AND exterior fillet will resist movement a lot better than a variable 1/4" - 1/2" fillet outside the minicell.
Sorry for the long winded answer.

Pressure holes
They equalize the air pressure between the cockpit and the compartments. I have a few kayaks, and they’e all drilled. All three have solid bulkheads (Hard plastic, wood, and glass). The hole only needs to be tiny. I used the smallest drill bit I could. My Caribou came already drilled by the manufacturer.

My Betsie Bay has screw-on hatches, and they’ll get stuck closed if there’s no vent hole. Foam bulkheads will move from the difference if it’s big enough, and leak.

And no problem on the long-winded answer. I have a tendency to post long-winded questions! :wink:

Kind of wish I had received your answer before I had actually resealed my bulkheads. Oh well, the next time this kind of maintenance is required, I may very well consider removing the foam bulkheads altogether, clean everything up, rough up the plastic hull, lay down some sealant on the plastic first, shove the bulkheads back in, and then caulk around both sides with a nice, thick fillet of Lexel. Too late now, but good for future reference!

Leave tube in place

– Last Updated: Apr-27-16 2:40 PM EST –

In rough water/rolling/rescue practice more water will enter compartments between oval hatch cover and hatch rim and between sprayskirt and coaming than will enter from a flooded cockpit into the compartments through the a tiny hole. The tiny hole helps to reduce the pumping effect that can occur when a kayak bounces around with water flowing across the hatches. It helps, it doesn't eliminate the effect.

It's a detail paddlers appreciate but a commodity designed to sell to customers seeking lowest price and maximum profit for manufacturers won't appreciate.

In the big picture a tiny hole between bulkheads isn't a necessity compared to bulkheads that remain glued and sealed in place.

Enjoy yourChatham, apparently they aren't being made anymore.

It’ll probably last a good while

– Last Updated: Apr-27-16 3:32 PM EST –

I've tried it different ways. It's not necessary to slide the bulkhead onto a glued hull. I did that a few times and I just ended up wiping away a lot of excess. I think sanding the hull and getting some goop between bulkhead and hull is what makes it last. I haven't seen one of mine become unglued in six years time but have seen a significant number of not so old boats have bulkheads held at the top with water flowing under the bottom with the goop attached to the bulkhead and suspended a fraction of an inch from the bottom.

The other problem with sliding a bulkhead onto goop or injecting a lot of goop under the bulkhead is that the bulkhead simply migrates out of position while drying. This is especially true of the forward bulkhead so you end up grabbing broom handles to hold the bulkhead in place after all that careful work smoothing the fillet.

You can see the problem with manufacturers using this technique on some recreational tandem kayaks like the Wilderness Systems Pamlico tandems where the stern tapers to a wedge shape. The bulkhead is pretty much trying to push forward every time it gets paddled and hull is flexed. After four months of rentals every one of those tandems had a partial or completely detached bulkhead, Every one.

Which 5200 ???
Regular, or fast cure ? Regular takes 5 days. Fast cure is good to go in 24 hrs.

And boy is it a sticky heinous mess
I’ve done fine with neoprene tape, weatherstripping tape, Marine Goop or Lexcel. The trick with using any of the goopy stuff , besides roughening the two plastic surfaces, is to not tighten the screws all the way down. You tighten down about a turn from snug, wipe the excess and let the goop cure then finish tightening. It was funny how Necky kept trying to figure this out for years and they leaked like crazy because the goop would simply pull away from the smooth plastic deck with gaps opening up between the screws. One year it was insufficient goop that didn’t bridge the gaps resulting from the flexible deck and the goop adhered to the hatch but not the deck after regular use. Next year the underside of the hatches were roughed up but not the deck. Still leaked. Then finally they simply used a pile of black goop and it worked.

I don’t see the need for 5200 in this.

Gore vent
I’ve installed Gore screw-in vents in my rigid bulkheads:

These allow air to pass, but not water. Alternatively, and cheaper and simpler, is to glue a piece of Gore-Tex over the pin-hole.


It’s all done and over with now. Well, the resealing part, that is. I resealed the foam bulkheads with Lexel on Tuesday night. And then last night, I resealed the hatches.

For the hatches, I used 1" wide by 1/8" thick black butyl tape and 3M 5200. I lined the bottoms of the hatch rims with the butyl tape and then reattached them back onto the deck. After a good, firm tightening (but not over-tight),I used a razor to trim all the excess butyl tape that squeezed out. I then used painters tape to mask off a 1/4" space of deck all the way around the hatches. Applied a good, thick bead of black 3M 5200 sealant. Smoothed it out and removed the excess. Pulled off the tape and then used my finger again to give it one final smooth-out. Looks pretty good!

Now I just need to let it sit and cure. I was originally hoping to get my yak back out on the river this weekend. However, the weather forecast is looking cold, rainy, and crappy anyway. So, all the goop will most likely get an extra week to cure after all.

Only thing left to do is install the pressure relief holes through my BHs. Picked up a couple extra cans of compressed air on my way into work this morning. I’ve been out of compressed air for a while anyway, and my keyboards are proof of that. Will install the thin tubes through the BHs as relief holes and be done with it!

Thanks all for the replies!

Had to check
This thread caused me to go check my 10 year old CD Sirocco bulkheads. I guess CD did a good job, because all the bulkheads are tight–just like new. I can’t tell if they applied sealant on the edge of the bulkheads, but it does look like they wiped the outside of the seam and left very little to no fillet. That might indicate that they did apply sealant to the edges. How ever they did it, it seems to be working, because I can’t recall ever finding a drop of water in any of the compartments and I’ve certainly had plenty of water in the cockpit a number of times.

The bulkheads are not vented and I guess I’ll leave them that way, because it doesn’t seem to be a problem while on the water. The hatches will puff up in the sun while on land, so I burp them.

CD on the whole
Has a higher QC and design standard than Necky and WS. One can quibble about details but pretty much across the board CD doesn’t have anywhere as many egregious screwups for dealers and customers to discover.

I don’t get it
My NDK is a mess of 1960s manufacturing technology but the hatches are watertight.

That’s the ironic part
Essentially the same hatches. Necky went for an old reliable with the pricey VCP hatches and WS went with their proprietary hatches that had a horrible reputation for popping off easily. All Necky had to do was use a gasket or change the method of assembly and it took years to get it right.