Tag Archives: rudder for Gumotex Seawave

Seawave Rudder MkII tested

Gumotex Seawave main page

Rudder rationale discussed
Gumotex’s 2016 factory version
Making the prototype rudder
Testing the prototype

Update 2019:
I’ve not used my MYO rudder since I made it in 2016. Partly because I’ve only done day trips predicated on nice weather, but also it’s all just more faff and clutter, not least the lines and footboard. As explained earlier, for multi-day trips where you must deal with the winds you’re given, it’s a good idea. But even then, you only notice your relative lack of speed alongside others. Alone, you’re as fast as you are.
Rudders are not about steering or tracking as they are on powered boats; in a kayak they’re about enabling a more efficient, balanced paddling effort on both arms by compensating for the boat’s deflection for side winds. In a way the simple stock skeg-shifter (right) will do as well with much less clutter and weight. Or, use this rudder, but locked in position as an ‘articulated skeg’ in place of the Gumotex skeg for shallows and beach parking. That is handy to avoid stressing the stock skeg, especially when the boat is loaded.

While waiting for rudder bits to turn up, we went out for an evening paddle round Eilean Mullagrach. It was pretty calm but at no point did I think, ‘Darn, I wish I had a rudder’. When it came to turning corners we just paddled hard or dragged a blade and round we came.
But the Seawave rudder project carries on like a supertanker with a jammed… rudder, if for no other reason than it’s fun to experiment and a rudder can also work as an articulated skeg when locked out – something I may look into when it’s all done.
Ironing out the flaws with the prototype added up to attaching it more securely at the back and making the pedal board out of something more responsive and durable. By coincidence, all these components can be sawn from a single piece of 450 x 300 x 12mm LDPE chopping board (left) which costs from £8 on ebay in a range of colours. This is 50% thicker than the smaller board I used on the prototype plate so doesn’t need doubling up and gluing to make it rigid.
At the back I slimmed the rudder plate right down to a simple strip of 65mm x 450mm, glued a block on the end to better support the gudgeon swivel pivot sleeve and added the crucial second fixing under the portaging handle (left). I also added a triangularish screw plate underneath (left, with red cord) so it all sits snug in the stern. With the hardware and saddle strap that now adds up to 306g (the rudder unit weighs 450g with its running lines). Even though it’s slimmer than the proto plate, it weighs about the same because it’s now 12 mil. But looks a whole lot neater.
The pedal board is from the same slab but uses stainless hinges, not zip ties. I’m reminded, you’re constantly making small adjustments as you paddle so pedals need to be as taut and responsive as possible. Once I’d trimmed the board and pedals a bit (left), with hinges it came in at 660g.
The board and maybe the pedals could have been made from 8mm if there was some to spare – but an 8mm board wants to be ~450mm wide to sit snugly in the boat’s side channels. Like the rudder, the pedal board will be subject to strong forces in heavy seas so also needs to be solidly jammed in. Meanwhile, I noticed the floor-laminate prototype board (right) gained nearly 15% in weight after getting wet – a sign it won’t last long. Still, it made a good template.
I do wonder if something like the Grabner rudder pedal bar (left, similar to Gael’s old H2) would be much lighter, as solid and as effective as my board. It costs €70 plus €30 for a pair of Zoelzer pedals.
I can’t really see how I could replicate that alloy footrest bar – out of copper tube filled with resin perhaps (like this motorbike rack)? It’s held securely in place without fittings by being jammed in the channel cavity between the floor and the sides (like my board), but a check with Gael advised me against it. As it happened, I’d pretty much decided the same mid test run (below). A sliding ally bar plus sea water isn’t a great combination and might bend or break, or the pedals snap. I know the ally backrest bar on my Amigo wasn’t up to it and Gael’s backrest broke (though it was ancient). My plastic version may weigh double but should be solid. Interestingly, just as a bag of clam cleats turned up make a quicker way of fine-tuning the rudder pedal lines from the cockpit, I see left that Grabner use them – a good sign.

The weather here’s about to crack and then we’re moving south, so in a rush I took the revised rudder plate out for a test with the creaky waterlogged pedal board. Heading towards Horse Island tidal passage, I didn’t need a weatherman to know which way the wind blew: from the WNW at about 12mph. Initially the boat needed constant small corrections to maintain a course, and there was some stiction, hopefully down to the zip ties on the soggy pedal board. I tried a few tight turns and marvelled at the control and how sharply the boat swung round like a pedalo. The rudder plate is now as rock solid as anything fitted to an IK can be. Again, I consciously tried not to correct with my arms, just my feet, which were twitching regularly.
At Horse Island I was way too early to run the passage, but as it was probably my last paddle here till next year, I decided to head for Badentarbet. Turning north, closer into the wind the micro corrections were no longer needed and the boat ran as if on a skeg, but without arm corrections. I’m pretty sure paddling 20–30° off the wind would have required arm steering, but I just hacked away towards Rubha Dunan on the mainland as the wind increased. When I tried a bit of downwinding protracted rudder juggling was needed to keep the back-end in line.
I passed through a channel on the headland and the NW wind got steadily stronger so crossing the bay to the beach seemed to take ages of effort. By now the small corrections I’d been making were no longer necessary, perhaps something had bedded in, the knots had tightened up or like riding a bike I’d just got the knack of minimal rudder movement to keep the boat on track. But upwind paddling is comparatively easy so I tried across the wind, now running over 15mph, and a bit more downwinding which gave me that unsettling Ningaloo feeling. This must be the weak point of a buoyant, windprone IK (especially when unloaded), and maybe all kayaks and canoes too. The chop was only a foot high, but were there a swell of a metre or more, the rudder would be briefly lifting and the stern sliding. I wonder if in a such conditions a combination of rudder and skeg (which is always submerged) might be a way of limiting weathercocking? Or perhaps just more practice is required. There’s also another solution that might arrive here in time to try out.
As I neared the beach the wind was hard in my face but I realised I was actually on good form, unlike on the Tanera run with the prototype. So I hammered away with all I had until my strake hissed onto the sands. Paddling hard is all helped by my brilliant, bent-shaft Werner Camano paddle, no less than ten years old this summer. It still clips together with a satisfyingly ‘clunk’ and has very little play. If it ever got lost or abducted by aliens I’d buy another without hesitation.
I was glad I’d got stuck into a longer test run than planned, and am now confident my MYO Seawave rudder is in the ball park. Hopefully the new pedal board will complete the job.

Total weight: 300g rudder plate + 450g rudder + 660g pedal board + ~100g rigging = 1.51kg (3.3lbs), or < 10% of the boat’s weight
Total cost MkII version: £20 rudder + £15 rigging + £8 LDPE board + £10 hinges + £2 fittings = £55

For about £200 posted I could have installed a 2016 Seawave rudder kit, but from all the images I could find at the time it was unclear exactly how it secured at the back – there must be their version of an unseen triangular underplate, but even then it’s still a stressed-out single point attachment. My additional under-handle fixture eliminates pivoting. And the plywood Gumotex footboard (right) appears to sit loose and seemingly will also pivot on that single strap. Production versions may differ and let’s not forget that adding all this complexity also adds a risk of breakage or damage. The simplest solution is usually the best, but the 160-g skeg will always be clipped in the boat as a back-up and a Seawave is controllable (if much slower) with no tracking aids at all. It’s worth remembering: a rudder isn’t about day-to-day tracking, it’s about maintaining a course when the boat gets pushed about in stronger winds. In such conditions a skeg is essential and a rudder is an improvement, as explained here.
On the beach, prior to lugging the boat over seaweed-clad boulders, it took only 30 seconds to unclip the rudder mechanism from the plate to pre-empt stumbling and damaging it. Since then I changed the rudder plate mounts with tool-free knobs and an eyelet (left). When rolling the boat up it was best to pivot the rudder plate around the drain hole 90° to pack better.

Gumotex Seawave – MYO rudder

Seawave main page

Refining and testing prototype rudder
Making and testing MkII version

Update 2019:
I’ve not used my MYO rudder since I made it in 2016. Partly because I’ve only done day trips predicated on nice weather, but also it’s all just more faff and clutter, not least the lines and footboard. As explained earlier, for multi-day trips where you must deal with the winds you’re given, it’s a good idea. But even then, you only notice your relative lack of speed alongside others. Alone, you’re as fast as you are.
Rudders are not about steering or tracking as they are on powered boats; in a kayak they’re about enabling a more efficient, balanced paddling effort on both arms by compensating for the boat’s deflection for side winds. In a way the simple stock skeg-shifter (right) will do as well with much less clutter and weight. Or, use the MYP rudder, but locked-out as a lifting skeg in place of the Gumotex skeg for shallows and beach parking. That is handy to avoid stressing the stock skeg, especially when the boat is loaded.

After writing this a few weeks back I decided to try and fit a rudder onto my Seawave. On that breezy Mull trip Gael, in the ruddered Incept K40 (right), seemed a little faster than me and the penny finally dropped as to why.
A rudder can compensate for winds pushing the boat off course while you power on as normal. Without one you’re pulling harm with just one arm in an effort to keep on course – that explained why I was a bit slower. Rudders have nothing to do with improving tracking which the Seawave does fine with the help of the skeg (though fitting a rudder means you won’t need a skeg). And unlike a ship, rudders have little use in ‘steering’ which a kayak does easily enough by dragging or drawing a paddle blade.
As mentioned elsewhere, another benefit of using a rudder instead of a skeg means that you can park the boat on flat ground without it pressing on the skeg – particularly useful when the boat is loaded and heavy (left). I’ve often thought about fitting a hinged skeg at the back of the boat to enable this. It’s a way of avoiding the complexity of a rudder but with the benefits of solid tracking which is useful at sea.
It helped that I found SoT rudders from Hong Kong on ebay for 20 quid. For that price it was worth experimenting, just like it was for a knock-off disc sail. Here in the UK a proper sea kayak rudder costs around £200 for a full kit with pedals. I also learned that Gumotex had introduced a Seawave rudder kit on their 2016 model as I was halfway through this project. I’m glad I spotted it as it gave me some good ideas, while the cost and certain features of the Gumotex rudder reassured me that my MYO was a better way to do it.

Does an IK need a rudder?
Most of the time on calm day trips a skeged Seawave manages fine without a rudder. But on a longer multi-day trip, or a scheduled one like Mull, you have to deal with the weather you’re given, or sit it out. As it is, unlike hardshells, IKs are innately more windprone as they’re lighter and sit higher on the water.
I paddled with a ten-ton hardshell once in Australia with my old K40 (left). Where we could, we both had sails (right) and the hardshell flew along (a rudder makes kayak sailing much easier). But me, I had to give up on day two; I couldn’t control my kayak in the 20-30-knot backwinds, and that was with a rudder. On another earlier paddle in Ozzie in my Sunny I remember pulling hard on one arm for hours and days to counteract the crosswinds. I ended up with arms like a fiddler crab.
So with an IK the window of rudder usefulness – when winds are strong enough to require rudder correction, but before they’re too strong for all except short, white-knuckle crossings – is actually quite narrow. Say, between 10 and 20mph.
This’s why I’d sooner not spend £200 finding out if a rudder suits my sort of paddling. A rudder isn’t going to transform my Seawave and I may end up not using it much, as I’ve done with my disc sail (though having a rudder again may encourage me to give sailing another go). But a rudder will slightly extend my boat’s paddlability. When a brisk quarter wind blows from front or rear I’ll be able to set the rudder against it and power away with equal effort on both arms. Anatomical consequences? More Popeye, less Fiddler crab.
Gumotex’s old Helios ran a crude rudder using the stern seam flap to pivot the rudder with very basic stirrups. The sea-slick Seawave isn’t made like that so needs some sort of fitting. Bodging etiquette requires that costs, effort if not time taken must be a practical minimum – and all additions must be reversible with minimum alternations to the craft. What I’ve made here is only a prototype which I’m calling Mk1. As you’ll read, i found many ways to improve it.
The Chinese SoT item (left and right) has a 16″ blade, minimal blade breadth, can be quickly removed on the pivot pin and can be both retracted completely from the water and dropped back in, using control lines. And better still, the retraction sweep comes right out and drops over the back of the deck, not sticking out vulnerably like the Incept rudder (right) or the Gumotex kit.

MYO
While the rudder inched its way here from Hong Kong I came up with a rough idea to mount it on a chopped up kitchen chopping board held in place by straps or similar off the rearmost deck line sleeves, then cinched down with an extra D-ring glued under the stern – the only mod permanently added to the actual boat.
On the end of the board some sort of gudgeon pivot swivel bracket device was needed – either a proper stainless steel bracket from SeaLect (right), or a block of whatever fixed to the board plus a ⅜” hole drilled through it to take the rudder pin. Rigidity, or minimal flex is important if the rudder is to feel responsive – another flaw I recall from the Incept. Mounting something rigidly on the end of an IK is tricky, but if my first ideas aren’t good enough, there’ll be other ways of doing it.
The way I chopped my 8mm board up and glued on the off-cuts for added stiffness produced about an inch of thickness at the back (right). And when the rudder turned up with a gudgeon pivot swivel sleeve, I decided it could be jammed into the back end of my board to provide a solid enough pivot.
This kitchen plastic is a dream to work with: it cuts easily, melts readily (no need for a drill) but is fairly light, stiff and rot proof. I mounted a clamp through the boat’s drain hole – copied from the Gumotex kit – and used an off-cut with a melted-in M6 nut (right) to grip the top plate under the deck. With a strap threaded through the rearmost deckline sleeves, this triangulated the mounting to reduce but not totally eliminate sideways pivoting. When it turns up a ‘saddle strap’ through the under-stern D-ring will hold the board down to reduce movement some more.

Control lines
Having owned a ruddered IK helped with setting up the control lines. The pulley threading of the rudder lifting/dropping line pulley is fairly obvious – the goal is to create as little drag as possible and the many fixtures on the Seawave make this easy. I used bits of yellow fuel line (above right) to make runners for the line which is more or less a closed loop from the rudder sliding through a karabiner hooked to a deckline sleeve left of the cockpit and knotted up to a plastic knob (above left). Haul back to lift the rudder; pull forward to drop. The trick is the get the length right before cutting off the excess cord. I might have done better using zero-stretch Dyneema cord here rather than cheaper paracord, but that’s easily changed if need be.
One thing the rudder needed to improve the lifting line’s angle was a smooth shafted M5 bolt running through it as shown left. The holes are already there – maybe it’s supposed to be like that (no instructions with rudder, but you do get 4m of paracord). I originally used a zip tie (above right) until I realised it was squeezing the rudder plates together and cramping the swing of the blade. The bolt isn’t tightened and rolls as the red udder lifting cord passes under it.
The rudder pivot lines run smoothly through more fuel line slipped unobtrusively under the redundant splash deck tabs on the hull top (right and left).
At the foot end attaching pedals to my big footrest tube (right) wasn’t going to work. I thought about using a smaller bit of tube but then decided a plain board with pedals pivoting on it at floor level works best – as Gumotex below right.
I found a plank of laminate flooring in the barn, sawed it into the right shapes and attached the pedals to the plate with zip-tie hinges so the thing would pack flat when not in use but makes the pedals stand up which is handy. This floor laminate was what I found lying around wanting to get the job done, but another slab of kitchen chopping board will be a better long-term solution. At least I have a template just as long as the pedal board doesn’t dissolve at the first splash of seawater.
The pedal board is moveable front and back same as my foot tube was (for different length paddlers or two-up) but I need to find some way of fine tuning the 2mm Dyneema rudder line lengths to match. Something more than a spring cinch lock like you get on a stuff sack that will actually lock the slippery Dyneema cord, but not need tension like the cam lock cleats I used on my V-Sail. I ordered the wheel locks on the right which should work.
The whole thing took a couple of days to work out using a jigsaw, a drill and a camping stove plus a skewer. If I had to do it all again and had all the bits and pieces at hand and a better idea of what I was doing (ie; this again but better) I reckon it would all take me 4–5 hours. Total weight added is 1.85kg, but I saved 450g by ditching my drainpipe footrest with a thinner version at a quarter of the weight.

The costs were:
• Rudder £19
• Chopping board £2
• 5m of 2mm Dyneema and paracord £11
• Five mini karabiners £2
• Two cord locks £1.50
Other bits and pieces I already had or found lying around might add up to another tenner.
Lessons learned: it pays to think it over: first ideas may give the impression of momentum coupled with intuitive brilliance, but are not always the best.

Next instalment: Oh rudder, how art thou?

2016 Seawave with rudder option

Seawave main page

My MYO rudder (MkII)

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 (right) and the factory version (going for £150 from bluewatersports on ebay.uk) 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, like the Sunny and 410C.
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, (right) 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.