Muffler Fiberglass Repair - 1986 Ski Nautique 2001

I bought my 1986 SN 2001 five years ago. From day one, it has always taken on some water. Typically, the bilge pump would come on every hour or so. I just assumed this was normal. During my first outing this season, my pump was running almost every 20 minutes. While investigating the issue, I noticed water was leaking from where the port muffler connects to the exhaust hose. Additionally, there was a small crack on the top of the muffler where water was slowly escaping.

My first inclination was to tighten down the two clamps affixing the hose to the muffler. A subsequent water test revealed that tightening the hose clamps did not help the issue at all – in fact it may have made it worse.

Once the muffler was removed, the reason why water was pouring into the bilge was obvious. By tightening the clamps over the years, the fiberglass flange on the muffler had been destroyed.

At this point I wasn’t sure if this could be repaired or if I would be forced to buy a new muffler. I decided to take my first stab at fiberglass work. I picked a modest repair kit from my local West Marine (https://www.westmarine.com/buy/west-system--105-k-fiberglass-boat-repair-kit--12954095?recordNum=1).

My biggest challenge was trying to figure out how to reestablish the round shape of the muffler flange. I tried several sizes of PVC pipes but nothing matched. I took a sip of my beverage to clear my head and it hit me….I immediately began searching my “bottle collection” and finally found one with a “close enough” diameter. The bottle was able to closely restore the original shape of the flange and provide support while I applied the fiberglass. While I was at it, I also patched the smaller cracks on the top of the muffler.

I applied several layers of glass to the outside outside of the muffler flange first and let it cure. I then removed the bottle and applied a couple of layers to the inside of the flange to make it as rigid as possible. Once cured, I sanded it smooth and attempted to reinstall. Despite massive amounts of dishwashing liquid, I could not get it reinstalled. I learned the outside diameter of the muffler flange needs to be fairly accurate in order to be reinserted into wire-reinforced exhaust hose. So little by little, I kept sanding away the newly applied fiberglass until it finally fit. I gingerly tightened the hose clamps and hoped for the best.

An initial check in the driveway was met with virtually no leaks, but I knew the real test would be on the water. The following week, I pulled the kids all over the lake for five hours and…the bilge pump never came on. Hopefully it will continue to hold.

Also, while I had the rear seat removed, I went ahead and touched up the bilge. I used some leftover garage floor epoxy. Before and after photo included.