Tag Archive: fish scale

Aluminum rivets in fishing kayaks and boats

You may have an outfitting project in mind, such as attaching a rod holder to your kayak, or you may just wonder how strong are Wavewalk kayaks and boats built.
More generally, how well do aluminum rivets work when used in kayaks?

Before going further, we need to explain that nearly all modern kayaks are made from Polyethylene, a polymer (plastic resin) softer than steel and aluminum, and even softer than fiberglass, which is why it requires the use of special rivets that split in three and provide a better grip over a broader surface.
These rivets go under commercial names such as Tri-Fold, Tribex, etc.

Alumium rivets are used for attaching kayak parts together, such as the 14 rivets that attach the W700 Saddle part to the Twinhull part.
They are also used for attaching accessories such as handles, pad-eyes (eyelets), etc.

Here is a little experiment we did –

We riveted together two pieces of Polyethylene that we cut from a part of a Wavewalk kayak. We used just one rivet for this.
We hung one end of the joint pieces of plastic from a basketball pole, and on the other end we hung a fish scale.
We hung a travel bag from the fish scale, and filled the bag with bricks.
We stopped after ten bricks, because the dial on the fish scale had ran full circle, and stopped at 50 lbs.
At this point, neither the plastic pieces nor the rivet showed any sign of stress.

testing-the-strength-of-riveting

50-lbs-pulling-on-a-rivet

fish-scale-at-51-lbs

Needless to say that the effectiveness of a rivet depends on more than just the force applied on it in lbs, and additional factors are very important, such as the angle of the force (vector), leverage (a critical factor), the temperature of the plastic (hot plastic is softer), etc.
If we had attached the parts in this experiment differently, we would have seen different results.