should be used on poly boats? I have read in posts not to use silicone adheasive on poly boats because it does not adhere well and will leave something behind when removed so that no other sealant will stick. The hatches on my son’s Old Town Castine leak like a sieve. I want to replace the gaskets between the boat and the hatch rims with some sort of a sealant. The gaskets are way to thin and that’s where the water leaks in.
What do you paddlers recomend? Thanks to all that respond!
P.S. Also what adheasive is recomended for mini cell and neoprene to glue it to a kevlar interior for heal pads and ect?
Contact Cement
Contact Cement works well for minicell to kevlar or glass. It will probably work for a limited time on the poly…but there isn;t much that sticks to Tupperware… but try the contact cement for the gaskets…I’ve had pretty good luck with it.
Nothing
There are no adhesives or sealants available at the consumer level that adhere well to polyethylene. The best I’ve found is Lexel by Sashco—it is very stretchy when cured, so it’s less likely to pull off the plastic under stress. The 5200 marine sealant from 3M sticks tolerably well if the parts won’t be moving.
For gluing foam, use a contact cement like Weldwood or DAP floor cement. You can get it in a spray can now, which can be easier for large areas. Make sure it is NOT the Californicated water-soluble type—beware of green cans. Speaking of contact cement, an alternate way of sealing plastic bulkheads is to glue strips of neoprene or inner tube rubber over the seam with contact cement.
Marine Goop has worked very well
for me a couple of times. At Home Depot.
Flame
– Last Updated: Jul-16-04 8:50 AM EST –
Flame treatment may improve the bond, as described here:
http://www.westsystem.com/webpages/epoxyworks/16/bondingskeg.html
I'd think that epoxy would be too rigid for most joints on a polyethylene kayak.
WW boaters have plastic boats
and we glue stuff to them all the time. For things like hip pads (minicel) most people use the red can of Weldwood contact cement as suggested above. It lasts for a reasonable time but will eventually pull loose. When that starts I just put in some more cement and press it together again. For other stuff many people use one of the following: marine goop, aquaseal, or shoe goo. They are just different names for essentially the same thing. You can get aquaseal with an accelerator that speeds up drying as well as acts as a thinner/solvent. It sticks to neoprene very well and is flexible.
marine goop works pretty well
for the mini-cell a product called barge cement is tough,and is used to repair inflatable boats
Nothing II
LesG is right: Polyethylene has a very low surface tension and doesn’t bond well with anything.
The bond lasts even less in changing temperatures and mechanical stress that are characteristic of a small boat’s hull.
If sealing these hatches is critical to you don’t think glue but rather welding- Very carefully of course 
Oh…hatches
For some reason I was thinking bulkheads the first time I answered. Are your hatch rims held to the deck with bolts? If so, it doesn’t really matter if the sealant adheres to the plastic or not since the pressure from the bolts will hold it together. Use any outdoor or marine sealant, or cut rings of neoprene to make thicker gaskets.
adheasive
I had leaking bulkheads in my Current Designs kayak. The factory send me a product called Kopper Lastic.This seems to work very well. The product is made in Canada. Good luck.
Lexel
I have used Lexel to install and seal bulkheads in Dagger boats. They recommended it.
Polyurethane caulk/adhesive
Its available at Home Depot and similar stores. The main problem is it takes a week to dry. I used it to mount my transducer inside my hull and it has held for several years.