Friction is a function of surface contact area, force and the coefficient of friction. When I car-top my kayaks, these three variables are what I have to work with.
Ratcheting up the force is the simplest way to increase the holding friction. However, this can strain and stress a boat, an expensive investment to damage!
Commercial racks increase the surface contact area with special cradles. Unfortunately, these are expensive and reduce the general function of the rack.
Sleeves of non-slip rubber to augment the friction easily secure my boats. It's cheap and general, rather than brute force or elaborate racks. A more simple solution.
Step 1: Materials and Tools
Step 2: Construction
- Unroll the non-slip material and cut in 12" sections.
- Lay out sections on top of non-permeable paper.
- Apply a thick bead of epoxy in a 2" wide - zig-zag along on edge.
- Fold non-slip material over, onto the epoxy.
- Use a spatula to press the flaps together and keep your fingers clean.
- Let cure per the epoxy's instructions, outdoors preferably.
Step 3: Wrap-up!
I've also found that there is no longer any need to ensure my tie-down straps lay flat across my kayak. In fact, when the sleeves bunch up, and twist around the straps, I get the best holding power. An awesome tertiary advantage, I can throw the straps on sloppy and quick- with better performance!