Tag Archives: kayak rudders

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, a rudder is a good idea. But even then, you only notice your relative lack of speed (due to sidewind paddling correction) alongside others. Alone, you’re as fast as you are [grasshopper].
Rudders are not primarily about steering or tracking as they are on powered boats; in a kayak they’re about enabling an efficient, balanced paddling effort on both arms by compensating for the boat’s deflection from side winds. In a way the simple stock skeg-shifter (left) will do as well with much less clutter and weight. Or, use the MYP rudder (below), 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. 


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 (above 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 seawater 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 to 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 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 ballpark. 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 vs Incept K40

Seawave main page
Home-made rudder tested

gumk44I owned a Gumotex Seawave and a few years ago had the Incept K40 for a year or more. IMO these were two of the best IKs around for sea kayaking and touring. Fast stable and form.
Like my paddle with my former Grabner Amigo, a longer trip with a K40 also gave me a chance to reappraise the pros and cons of these two IKs. Gael’s red K40 is the same one I tested in 2012.


As you can see in the table below, the Nitrilon Seawave is a little longer, quite a lot wider but less spacious inside. It claims a much greater payload, has space for up to 2.5 paddlers as well as fitting an optional fully removable deck and a fixed skeg.
The K40 is made from a stiffer ‘PVC-urethane alloy’ fabric, has a zip-up/roll-back deck, a rudder and a single seat. The twin side-beam hull explains its slimness as well as the greater internal width. Both these IKs weigh around 17kg.
New Zealand-made Incepts are hard to find in Europe or the US. One price in Germany today quotes €2500, while a Seawave with an optional deck comes in at £995 in the UK or from less than £700 when boatpark.cz were having a sale.Out of the bag the Incept runs PRVs rated at 5 psi or 0.34 bar on all three chambers, with inflation valves handily located around the cockpit. I’ve adapted my Seawave to run all-round PRVs too, all rated at 4.78 psi or 0.33 bar. Even then, loaded up I could feel my kayak flexing a little in the briny swell bouncing off the Ross of Mull.
Paddling with the K40 for a couple of days, I got the feeling it was a little faster than my Seawave. Gael’s K40 was loaded a little more heavily than my boat, but my added weight easily exceeded that. Both boats run similar pressures but the slimmer, stiffer fabric’d K40 has the advantage, even though it’s a little shorter. Gael may also have a more efficient paddling technique, but overall we agreed that in the windy conditions we were experiencing, it was his rudder which made the difference when it came to maintaining a steady speed, despite its slight drag deficit. (Good page explaining sea kayak rudders).


Simply put, with a bit of rudder correction to compensate for winds pushing the boat off course, Gael could carry on paddling full steam ahead. At the same time I had to correct my steering by yanking hard on the upwind arm and trailing the other to maintain a given course, so I was only powering with one and a bit arms. This gave the K40 the edge – say 5–10 minutes over an hour.


Running a Grabner Holiday Gael is a rudder fan and thinks adding one to a Seawave would make it a perfect IK. Me, I’m not so sure the added complexity and risk of breakage is worth the ease of balanced paddling, but I think I’m talking myself into it. As long as my system is not like the Incept’s horribly mushy rudder actuation. It felt less effort to paddle Gael’s K40 than my wider Gumboat, but pushing hard on the inflatable pedals was a bit like using a cushion for a steering wheel.

A great way to improve the K40 would be to be to fit something like a Grabner rudder (left): hard plastic pedals pivoting on a rigid bar. The actual pivoting- and rudder-lifting mechanism at the back looks like a standard sea kayak arrangement with a rudder pin. We both agreed the K40’s generic hardshell rudder blade is too small for this boat when the seas get lumpy or the winds exceed F4. A longer blade is needed, but that creates more drag. Better just to accept an IK limitations and not go out in those conditions, as I found once, though I’ve just remembered the skeg-steering idea a visitor suggested to me last year: pivoting the half inserted Gumotex skeg using cords (left) to fix an angle against a steady wind.

Especially when loaded, my Seawave’s fixed skeg can be a bit of a pain at the shore. You need to drag the boat in on a flowing tide but I don’t like the idea of the heavy IK pressing on the skeg unless it can gradually sink into the sand on an ebb. At other times I needed to find a rock, use my Pelicase or lean on the K40. But that’s all a small price to pay for the benefits the skeg brings at sea. I’ve thought of fitting a retracting/trailing skeg to get round this, but if I go that far I may as well try and install a rudder. Chinese SoT ones on ebay go for just 20 quid and it could help review my dormant sailing experiments which I recalling during the backwinds of Mull.


The other impression was the initial tippiness of the K40 – yikes, it’s been a while since I’ve experienced that. In fact it soon went away and anyway was helped by the thigh straps which again, I’m reminded don’t snag the knees as securely as my set ups in the Amigo and Seawave – possibly because the front mount is too far forward (using the rudder pedal mounts). But then again, I should have bothered to adjust the rudder-footrest towards me a good few inches. just as Gael moved my footrest tube away to suit his longer legs when we swapped boats.

As well as being narrower, the K40 gives the impression of a more box-like hull (left) with more prominent chines which aid edging. On a proper hardshell sea kayak edging can be used to turn the boat (lean right to turn left – no, I never got the hang of it either) but I doubt the K40’s hull was designed that precisely. A hardshell’s retractable skeg (where present) is used to carefully counteract the kayak’s weathercocking rather like a rudder.

I don’t recall steering using the K40’s edge (with the rudder up), edging was more a way to keep the boat level with the help of the thigh straps when riding up side waves and to limit swamping. The rounded Seawave is more raft-like in its stability, as Gael soon noticed, but gets there in the end thanks to high pressures and a long waterline.
The Incept was also much more roomy thanks to the slim side tubes. That makes the thigh straps more important and I actually missed the packraft-like jammed-in feeling between my Gumotex’s fat side tubes. The seat didn’t feel as comfy and secure as the packraft/SoT set up on my Seawave and all-in-all, I felt a bit out of sorts in the Incept which helped me realise how well my Seawave is suited to my sort of paddling. About time – it’s taken a few IKs to get there.