The 2016 Gumotex Seawave has had the stern slightly adapted to take an optional rudder kit. They’ve also improved the velcro bands for the optional deck by using Nitrilon, but it’s the rudder that’s the interesting development.
Coincidentally, I was halfway through adapting a cheap SoT rudder for my Seawave (left) and the factory version (going for £200) gave me some good ideas. The Gumotex rudder kit could be easily fitted to first-model Seawaves, and possibly to other Gumboats with similar triangular stern decks.
For the time it took to make mine I could have fitted a Gumotex kit ten times over but with only these pictures I was unsure exactly how it was secured. I suspect there’s an additional unseen plate underneath the stern decking to help jam the whole set up securely into the back triangle of the boat.
Otherwise the plate would be prone to distortion under rudder forces, giving a mushy response. I got that on my prototype version.
The Gumo’s rudder’s retraction method seems to be pull-up-and-in, (left) whereas my SoT example above is a more conventional swing-up-and-over which puts the rudder right out of the way over the back of the boat. IMO this is better for negotiating tight turns in narrow sea chasms where an unexpected swell could crunch your protruding rudder blade.
At the pointy end the pedal board looks reassuringly basic (and easy to copy) and the only obvious difference between an old Seawave are the two line guides on the stern deck (right) which I added to my boat to make a straighter, drag-free pull on the lines.