Tag Archive: adhesive for kayaks

Adhesive used for repairing and outfitting kayaks

Watertight riveting in kayaks and boats

Updated October 6, 2017

Pop rivets are widely used in the construction of boats, canoes, and kayaks.
Sealing rivets can be useful as a measure of extra precaution in case they come in contact with the water through which your kayak or boat goes.

How to better seal the rivets

Here are some tips for watertight riveting of kayaks and small boats made from Polyethylene –

  1. Polyethylene is the most widely used polymer resin (namely “plastic”) in kayaks, and it’s softer than aluminum and fiberglass used to produce other small boats. For this reason, it is recommended to use special aluminum rivets designed for riveting jobs in kayaks. These special rivets split in three, which increases their grip on the surface around the rivet. You can get these rivets in outfitters stores, and online.
  2. Drill holes of exactly the same diameter of the rivet that you use (3/16″), and preferably slightly smaller holes (5/32″).
  3. Apply a dub of Goop adhesive on the hole, and push the Goop into the hole. Goop is a powerful watertight adhesive used for plumbing and marine projects. The Goop you squeeze into the hole will coat its sides, and come out on the other side.
  4. Before you insert the rivet into the hole, coat its end with Goop. As you push the rivet into the hole, its tip will come out on the other side, and it will be coated with a thick layer of Goop. The sides of the rivet will be coated with Goop as well.

    A rivet dipped in Goop watertight adhesive

    As you pull the rivet’s mandrel, the rivet will split in three and it will attach the two plastic walls while being coated with Goop. Excess Goop that will not come out on the other side or coat the sides of the hole, will remain on the outer surface and get squeezed by the rivet’s head. This way, the rivet’s parts that come in contact with the plastic will be coated with Goop, which will make them watertight.

  5. After you’re done riveting, coat the rivet’s head and the surface area around it with a generous amount of Goop. This will prevent water from touching the rivet, and in case of saltwater, it will prevent corrosion.

3M 4693 Scotch Grip TM H Plastic Adhesive – Good for Use in Polyethylene Kayaks?

‘Plastic’ kayaks is a term that refers in most cases to rotationally molded Polyethylene kayaks.
Polyethylene (HDPE, MDPE, LDPE and various commercial names) is by far the preferred resin in the kayak industry because of its superior performance when it comes to shock resistance, durability and overall reliability, but it is known to be quasi impossible to bond. This is because Polyethylene’s surface tension is low, which doesn’t allow for significant chemical reactions to occur, including bonding. The upside of this feature is that Polyethylene has superior resistance to strong solvents, acids, radiation etc., and indeed it is used for making fuel tanks and containers for active chemicals.

When an adhesive’s label says it bonds plastics it normally doesn’t mean Polyethylene.

3M is offering a an adhesive called 3M Scotch-Grip TM 4693 H Plastic Adhesive, and the company states it works for various plastic materials, Polyethylene included.

We tested this product and found that indeed it bonds with Polyethylene, and apparently a little better than other adhesives we know.
However, in our opinion the bonding is not sufficiently strong to allow use in structural repairs or for attaching accessories to a Polyethylene kayak, except maybe a fish finder, a decal etc., which are not required to support weight or resist even weak pulling forces at any time.

This adhesive could be used to seal rivet and bolt holes above waterline (E.G. with carry handles, rod holders, eyelets etc.). We would not recommend using it for sealing holes below waterline because we’re against drilling holes in kayak hulls below waterline in any case…

We would not recommend to use it for fixing cracks anywhere in the hull, and as far as filling gashes (such as those created by oysters) we don’t see the benefit of it, and we don’t see how the adhesive would stay in its place if it had to resist abrasive forces.

All in all, we found that common, general purpose adhesives such as the popular ‘Goop’ perform reasonably well too in such light duty tasks.

In sum, this adhesive cannot replace ‘hard’ methods such welding, riveting and bolting, but it can be useful in other ways.