How to make the dry hatch dry

[Jaytee]

I know it won't be a substitute for properly packing things in dry bags and whatnot, but I'd at least like to achieve a semblance of water resistence in the dry hatch on my Dagger Blackwater.

Got swamped by standing waves a bit a few weeks ago when the Buffalo was high, and I was surprised how much water was in the dry hatch (and thus slightly more work to empty). I'm thinking some kinda silicone or something around the seal?

PS, the issue isn't the lid/hatch, which seals fine. It is the bulkhead (if that's the right word) between the dry hatch and the rest of the boat.

[Eric Esche]

Stand boat on end and seal bulkhead with 100% silicone, NOT latex caulk. Use a spatula or a squeegee to smooth into a 1/4" to 1/2" bead along the edges. Let cure 48 hours, and then turn boat on other end and repeat on the other side of the bulkhead and wait another 48 hours.

May not be what instructions, on Silicone caulk reads but this is in a confined space and unless you put a fan in the boat to accelerate curing, you probably need to wait 48 hours on the cure for each layer, or at least that's been my experience.

Done maybe 40 boats this way and no leaks afterwards. In the "old" days with composite kayaks, if we couldn't afford float bags, we sometimes put in bulkheads to do the same thing, but we also but in a drain plug as nothing is perfect.

If it is the hatch seal, you can get some very thin sheet 1-2mm neoprene and make a secondary seal to go under the hatch seal.

Eric

[Jim Krueger]

Jaytee,

The advice Eric has offered is spot on to what I'd also recommend. However, since little of anything sticks very permanently to the plastic sides and bottom of the kayak, you may need to repeat the process frequently. In the time's in between repairs, the action of a persons weight getting in and out of the boat , as well as the ups&downs of going over rocks,etc., the bottom will flex enough to tear the bond and again allow some leakage. It seems contact cement, and glues and caulks of all sorts stick like 'Elephant Glue' to the foam material of the bulkhead, but not so to the Polyethylene. But, it's an easy fix every now and then when the boat is clean and dry. .02cents worth.

Best Regards
Jim

[Jaytee]

Thanks guys! You rock!

[Eric Esche]

Couple of other things you might try before you apply anything.

1. Make sure the surfaces to be bonded are both clean and bone dry. Vacuum out any debris like sand leaves, mold, slime. Run a soft white paper towel along all the surfaces to be bonded when you think it is prepped and do that with a bright light. You find things that you might not find otherwise.

2. On the polyethylene surface, you can burr up the suface with the end of a file with scratching parralel to the bulkhead or with crosshatching. This helps the adhesive or sealent bond better mechanically to the polyethylene. These scratches should not be deep - no more than 1/16th of an inch if possible, but 1/32nd is better. Don't sand off the groove tops. They help with more surface area to bond to.

3. You can also accelerate curing by using a hair dryer, but do not concentrate on any one area for more than 30 deconds if you can. Remember that you are dealing with a confined space and do not get knocked out by fumes if you are using using glues and that some of them are flammable.

4. You can also preheat an area to be sealed or bonded by preheating it lightly before the application. Again - not too much heat and do not use a blow torch - you just want to warm it, NOTmelt it. Polymers do not like added thermal history, and boats have been burned up this way. (but never by me so far.) Preheating an area to be bonded or sealed also has the effect of reducing your working time of the glue or sealant. This is a trick that is better used by those used to working with the glues or sealants on the substrate involved. A faster cure might get you on the water faster, but it also might not be as strong with some glues and sealants. Some commercial glues, sealants, and resins are designed to have a short working time, but a longer working time is usually more desireable when making repairs and it tends to be stronger. If in doubt or a lack of experience, read the instructions.

If any of these steps sound familiar and similar to raft patching, if you think about it, they are all composite structures made of disimilar polymer materials.

Also note that when using most contact glues, it is generally preferrable to use 2 thin coats, rather than one thick one. On expanding glues, one thin layer of glue is usually best but read the instructions supplied with the glue and follow them.

Eric Esche

[Jim Krueger]

Again, I concur with Eric. Even more so with his thorough recommendations for the preparations, it makes all the difference in the longevity of the seal, and it can mean the difference of only having to reseal the bulkhead once in a great while versus much too often. I especially think the thorough cleaning, and scoring of the plastic material of the kayak is just the very best. I think you can actually achieve a better seal than the kayak came from the factory with.
Well said Eric!

Best Regards
Jim