Custom, Larger Under Stern Rudder for K1

Last fall I bought a used Knysna Stiletto X K1 kayak. It’s an older kevlar marathon kayak. I had moved up a couple of tiers of kayaks last year and my other kayak is a 16’ Dagger Seeker (older poly).

I probably averaged 5, hour long outings per week on a lake last summer/fall. I’ve never had to put much thought into balance. I thought the Knysna might be a fun challenge. A local rowing club has lanes on the lake too. I tried the kayak a couple of times last fall and I appear to be completely out of my depth with respect to balance.

I was thinking if I installed a bigger under stern rudder it might add stability and help me develop adequate balancing skills sooner. The rod on the rudder has a square section near the top for the pulley (for the t bar steering system) to slide into to and a threaded section on top of that to hold it in place.

Is there a solution someone can suggest? Eg. Are there any say larger rudders for wavey sea conditions from other manufacturers that might work? I saw a DIY article about making a rudder, but I don’t know how to find a compatible rudder rod without using the rod from the existing rudder.

I paid $400 US / $550 Can for the kayak, so I’m also not looking for a terribly expensive solution

Find out if there is a way to add more “plastic” (assuming it is made of plastic) to the one you have, by gluing probably.

I’m skeptical how much a larger rudder would help since it would be quite close to the center of rotation.

I’d add weight in the bottom of the kayak until you gain more confidence. Weight will lower your center of gravity in the water and provide inertia to counter act a rolling motion. I’ve used dry bags filled with water to improve my stability when photographing from a kayak. The trades offs are slower acceleration and increase resistance if you have to roll back up after going inverted. It is a cheap and easy thing to try before delving into a rudder modification.

I bought an add on 7" understern rudder for my flat bottomed ski. I don’t like the way it catches current. I’m going to cut it down to 3".

StrayedAfar - I’ve read the rudder can help with stability. I was thinking of how a keel on a sailboat and how it helps prevent tipping? Am I off base?

I’m a bit heavier than I’d like a the moment. I was thinking about removing the seat and sitting on the bottom to lower the center of gravity by say 2". Do you think that would help?

If I understand, your issue is balance? That doesn’t sound like something a larger rudder would help in any meaningful way.

A racing K1 is a very unstable feeling boat as compared to a sea kayak.

Getting a significant weigh (10s of pounds) in the bottom center of the kayak in a position where can’t move could help.

Or you could make (or buy) something like the Huki Gull Wings

Peter-CA - Yes balance is the issue. I was certainty expecting it to be tippy, but I couldn’t really use it. I’d let go of the dock and immediately fall into the water.

I don’t see how a larger rudder would improve stability in any meaningful way. Yes it would take a tiny bit more effort to push the larger rudder through the water but that’s it. The keel on a sailboat is ballasted, which is what provides the stability (although note that the stability provided by a ballast keel only starts working when the boat leans (heels) to one side).

There are removable sponsons or floats that can be added to a kayak to provide stability - training wheels in a sense. I think that’s the route I would try.

Edit: from a naval architecture perspective, “stability is righting moment”. There needs to be some force trying to right the boat. Rudders don’t provide the necessary force.

I took the seat out of the K-1 I tried to figure out. Sitting on the bottom lowered the center of gravity considerably.

A longer rudder might give the bare minimum of extra stability, but why go custom? A surfski rudder will probably work, as there are only a couple of ways to hook up an under the hull rudder.

A sailboat keel increases stability due to the weight at the bottom - it lowers the CG of the boat, enhancing its primary stability. Comments above re adding weight do the same thing.

Rudders don’t weigh much, so won’t change the CG. Their lateral area will add drag while capsizing (rolling about the longitudinal axis). So, while it will slow down the capsize, it won’t make the boat more stable.

Adding an outrigger or sponsons would add stability, but it won’t look much like a kayak anymore. Sometimes sponsons are located just above the water, so they have no effect until you start to roll.

PS I posted before I saw Brodie’s post - he covered what I just said, a little better, I think.

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Yes, lowering the seat would certainly help since it lowers your center of gravity.

Lots of good responses on how a sailboat keel works.

The answer is probably more seat time to improve your balance. Many surfskis and racing kayaks are very unstable when not moving. Ironically the company says this is their most stable kayak and is recommended for beginners.

A bigger rudder may slightly improve stability when moving at a good pace, but will probably add almost nothing when standing still.

Lowering the seat or adding ballast that cannot move can help.

Thanks all, really appreciate all of the feedback.

Do the cheap inflatable outriggers (possibly with some diy adjustments) seem like a reasonable set of training wheels?

rstevens15 - Are you suggesting my Stiletto X is the most stable Knysna K1? Google searches to learn more about it have been kind of fruitless, so I’m curious if you know something that’s been otherwise lost to the ages?

I was looking at a different model. The Stiletto is discontinued but has been listed in the third least stable class of racing kayak, 2 on a scale from 0-10. It is tied with several other Knysna boats in this class. There are no models of Knysna boats that are less stable, although there are many boats that are of equal or less stability made by other manufacturers.