Installing d-rings to a Royalex hull with adhesive

D-Rings are commonly applied to the inside of canoe hulls to be used as tie-down points for gear, flotation, thigh-straps, etc.  

They consist of a metal D-Ring fastened to a vinyl patch with a piece of webbing.

The outer layer of Royalex is a sheet of vinyl.  The adhesives generally used to adhere the vinyl patch of the D-Ring to the vinyl skin of the Royalex are:

 

  • Waterproof Contact Cement
  • Vinyl Adhesive

In either case, the approach to use is as follows:

  • Mark the position of the D-Ring by drawing around it on the surface of the canoe
  • Sand the surface of the canoe and the underside of the vinyl patch on the D-Ring
  • Sand only enough to roughen the surfaces of both the patch and the canoe hull.  
  • The webbing holding the D-Ring to the vinyl patch is stitched in place.  If you sand too vigorously, you can break or weaken this stitching and the D-Ring will eventually pull loose.  Sand ONLY the vinyl surface, not the stitching.
  • Remove the sanding residue and wipe both surfaces clean with denatured alcohol
  • Apply a LIGHT coating of the adhesive to both surfaces (hull and patch) and allow to dry until it barely feels tacky
  • Apply a second thin coat to one of the surfaces and allow to dry completely
  • Roll the edges of the patch up and begin to stick it to the hull from the centre outwards
  • Align carefully before you touch the patch to the hull.  There's no second chance here.
  • Maintain pressure until the bond is secure.
  • Wait 24 hours before applying any load to the D-Ring

Caution

The two most important things to remember are:  

  • Apply the adhesive as a THIN layer
  • Allow the adhesive to dry before sticking the patch to the hull.

Adhesives in general, and contact cement specifically, emit styrene as they cure.  If you place a thick coat on the hull, then cover it up with a patch, the styrene will migrate into the foam core of the Royalex and partially dissolve the hull material.  This can result in a soft, spongy spot in the hull.


Disclaimer

These instructions are general recommendations.  You should consult with your boat manufacturer to ensure they agree with this technique before starting.

Applying too much adhesive; or applying the wrong type of adhesive can result in a permanent soft spot on the hull.