Gumotex inflatable kayak tracking fin

When my newly purchased Gumotex Sunny inflatable kayak arrived I was surprised to find that there was no tracking fin included in the package. I phoned the supplier and was told that the fin was an optional extra and it was not really required. Initial trials on a calm river showed the tracking was not a problem, but when it was used on the sea the kayak would constantly turn broad side on to the waves. At its worst, 2 up with a following wind, the only way to keep straight was to have the back person steering and the front person paddling. A fin was definitely required.

The canoe has some tough rubber straps for attaching the fin so it was quite easy to cut a fin with attachment lugs from a piece of 2mm aluminium sheet. This was slid under the rubber attachment straps from the front so any forward impact would push the fin on.

This was tried on a windy day in Poole harbour and worked well. The constant swinging broadside to the waves had disappeared and it was easy to explore the shallows around the islands. On the way back the canoe had, however, developed a distinct tendency to turn right and when the fin was removed it had been bent sideways, probably from hitting the bottom. The fin had more than enough grip on the water so I chopped a few centimetres off the end, however, the fin was always going to be strained when the canoe was on the ground as it tended to flop sideways.

The second attempt was a double (bilge keel?) fin. This was similar construction but with an additional fin the other side of the attachment lugs. The fins were splayed out slightly to give a stable base and also toed out to take account of the slight angle of the back of the canoe. When the canoe sits on the ground the fins sit upright and the attachment and fins are not stressed. The double fin can also be made shallower. It is now possible to slide the canoe out of the water on the fin and avoid scraping the fabric, although I'm not sure the attachment would survive too much of this treatment.

The tracking seems to be fine and the fin has so far survived several trips, being bounced on beaches, groundings and general abuse. The only downside is that the fin is more difficult to pack than a flat item.