Kayaks and ultra lightweight boats such as the S4 are molded from Polyethylene (PE), which is a relatively soft but very strong material. In order to reduce both weight and cost, the walls of these small craft are made thin, which presents a challenge as far as permanently attaching objects to them. Such object can be carry handles, rod holders, seats, etc. Screws don’t work in such cases due to the thinness of the walls, and bolts don’t work if there is no access to the other side of the wall, in order to apply the nut in its place on the tip of the bolt.
The typical solution, which works in most cases, is to use special rivets that were developed for soft walls. These rivets split into three arms that fold back into the surface of the other side of the wall, and they are the standard rivets used in kayaks and small craft.
See article on watertight riveting »
But these rivets are relatively small, and sometimes they’re not enough. In such cases, Toggle Bolts provide a sturdy and easy to apply solution – Toggle Bolts were initially developed for hollow gypsum drywall. Gypsum boards are thick, but gypsum is a very soft, brittle and weak material, too weak to resist pull from screws. The problem of softness and lack of access to the other side of the wall required an ingenious solution, and toggle bolts are without any doubt a most ingenious invention.
A toggle bolt is a two-piece, steel fastener. Its two parts are a bolt and a spring-loaded pair of steel wings that fit on it –
You just drill a hole in the wall in the diameter indicated by the toggle bolt manufacturer, and push the bolt in with its wings folded. After the wings are forced all the way through the hole, they will open up by the action of the spring. Rotating the bolt will cause the wings to get drawn back towards the bolt’s head, and against the wall. Once the wings are pressed tightly against the other side of the wall, they will provide enough support to the equipment that you want to attach to the boat’s wall.
Waterproofing the hole in your boat or kayak can be done by using a generous amount of Goop, which is a watertight adhesive that adheres sufficiently well to Polyethylene walls, enough for such a light duty application. This said, we recommend not to drill holes below waterline, or even close to it. Any hole in the boat should be only drilled only at a safe location.