Earlier this year, I purchased a used 2001 NDK Romany sea kayak. The front hatch rim was cracked all the way through on both sides where screws had been placed to help hold the rim on the deck. The holes that were drilled through the rim to accommodate the screws weaken the rim, so this is a common problem with those boats that have screws or rivets through the rim.
The front hatch leaked a small amount as a result of the cracked rim and my attempt to seal the cracks with a urethane sealant had not really worked to my satisfaction so I ordered a replacement rim. I began the repair this afternoon and made significantly more progress than I expected to for the first day. Over the course of several posts, I will be sharing the techniques that I am using to replace one of the standard 10″ plastic hatch rims found on many of the NDK kayaks. While these hatch rims are also found on many other composite kayaks, I will caution you that many of the manufacturers are installing these rims using 3M 5200 adhesive which cannot be removed if there is a problem with the rim. The NDK kayaks used Sikaflex 221 adhesive which can be softened with heat allowing the old rim to be removed. Before attempting this repair on other brands of kayaks, I would check with the manufacturer.
Tools Needed: Dremel tool with #409 cutting wheel and #428 wire brush attachments, 1/4″ chisel, 1-1/2″ wide putty knife/scraper, heat gun, allen wrench, pliers, hack saw, 60-100 grit sandpaper, acetone, rags.
Step 1: Remove the screws or rivets. Luckily, my kayak had screws which I was able to easily remove with an allen wrench and pliers. Rivets would have to be drilled out.
Step 2: Using a Dremel tool with a cutting wheel, I cut through the upright lip of the old hatch rim to get it out of the way and to make it easier to pry up the base of the rim later. Buy several of the cutting wheels. I broke about four of the discs in the process of removing the rim.
Step 3: While the cracks on each side of the rim had already completely separated the rim into two pieces, the crack was not quite wide enough to easily insert the chisel between the rim and the deck of the kayak. I took my Dremel tool with the cutting wheel and carefully sliced down into the base of the rim along one of the cracks to widen the opening about 1/4″ so I could insert the chisel.
Step 4: Slide the putty knife around the outside of the hatch rim between the rim and the kayak deck to cut through as much of the adhesive as possible. Breaking this seal with a knife reduces the chances that you will accidentally chip the gelcoat as you are removing pieces of the rim.
Step 5: Use the heat gun only as much as necessary to warm and soften the old hatch rim and underlying adhesive. Try not to overheat the fiberglass as this will cause it to get brittle and and can also damage the gelcoat. Carefully use the chisel to pry up the end of the rim. I tended to insert the chisel from the outside edge of the rim and slowly levered the rim up using the raised areas of the deck as the fulcrum rather than trying to pry up the rim from the cut edge which I felt might be more likely to cause damage to the fiberglass edge under the rim.
Step 6: After prying up about 2-3″ of the rim (which also had a tendency to deform due to the heat), I slid the putty knife as far as I could between the rim and deck and then used a hack saw to cut off the small section of the rim that was loose. Having the putty knife directly below the saw blade prevented me from accidentally cutting into the fiberglass of the deck. Continue this process carefully working all the way around the rim.
I had pretty good success in removing sections of the old rim until I got to the last 4″ or so. The fiberglass deck in that area was too flexible and I couldn’t get the adhesive to release. In order to avoid causing excess damage to the underlying fiberglass, I used the Dremel tool with the cutting wheel to very carefully cut away the inside edge of the remaining piece of the old rim until I could just begin to see the fiberglass deck edge below the hatch rim. Once I could see the fiberglass, I was able to insert the blade of my putty knife between the fiberglass and the hatch rim and cut through some of the adhesive. By cutting through the adhesive on both the inside and outside edges of the old rim, I was finally able to pop off the final piece of the rim.
Step 7: Once the old rim was completely off, I first used my putty knife to slice off the thicker sections of the old adhesive.
Step 8: To remove the remaining adhesive, I used a wire brush wheel on the Dremel tool to abrade the adhesive down to the gelcoat. According to instructions I received from Sea Kayaking UK (the new name for NDK), it is not necessary to remove absolutely all of the old adhesive. However, with the wire wheel, I was able to get most of it off. I did wear out one brand new wire brush wheel in the process and had to run out to get another one at the hardware store to complete the process to my satisfaction.
Step 9: Once I had most of the adhesive removed using the wire brush, I had to remove some of the adhesive from the inside edge of the hatch opening so that it would not interfere with the fiberglass repair that I needed to do before installing the new rim. I used some large grit sandpaper followed by acetone on a rag to remove the small amount of adhesive that was in the area where I would be applying fiberglass cloth and epoxy.
In next installment of this blog, I will talk about doing the fiberglass and gelcoat repairs that needed to be made before attaching the new hatch rim.
I’d also like to acknowledge all the helpful advice that I received from several sources before beginning this repair, but I don’t like to name people on the internet unless I have their prior permission, so suffice it to say that I didn’t invent these techniques by myself. I accumulated a lot of wisdom from others who have already done this repair in the past. I must say that so far it is going even better than I had hoped!