Hobie Sport tracking

Customizing your rudder is one of the easiest mods. As Bob says, you can simply cut the bottom tip off with a hack saw if you want it shorter -- All the rudders shown in the pic below work essentially as well as the uncut sailing rudder (except the one on the far left which still has about twice the authority as the small rudder).


These have been modified to retain rudder authority while minimizing drag, not with the intent of making them shallower.
Left rudder good for all functions but a little small for sailing
Second rudder good combination of sensitivity, authority and efficiency. Works well with any boat up to Island size (early models)
Third rudder -- best combination of all the above, this is my "racing rudder". Excellent performance with boat wakes and usable with older AIs
Fourth rudder has winglet -- has greatest authority in all cases with all boats
Fifth rudder old style sailing rudder (not fully "balanced") with standard rudder overlay for comparison (about 1/2 the area, 1/3 the authority).

Here are a few things about rudders you might like to know:
1. The sailing rudder is no deeper in the water than standard fins; obviously shallower than Turbos. So there is no need to cut it down as long as you are taking full strokes with your fins
2. Even when locked down, Hobie rudders are designed to kick up rather than break when they get grounded.
3. Different parts of the rudder are best at different things -- things you would keep in mind when modding.
-- the lower part (below keel level) is important because it is in relatively clear slipstream -- this area gives you the most sensitivity to small corrections. It also keeps the rudder engaged best in rough water.
-- Width of the rudder gives you more authority, especially at small speeds.

So carve away on the large rudder without concern that you'll ruin anything and customize to your heart's content! (Best not to cut the small rudder though, as it is too small IMO for any trimming.) Or just leave the large rudder as it comes without concerning yourself about depth. Regardless, the large rudder upgrade gives you the best handling upgrade for the buck by far!

I doubt anyone else will do this, but I like it a lot. I bought the sailing rudder and installed it. Then I bolted the regular rudder to the sailing rudder to add depth. So I get about an additional 4 inches of bite in the water. The ONLY draw back is I will not use the rudder lines to raise the rudder. I simply stop short of were I need to go. Get out and hand raise the rudder. Works for me. I saw some other home made rudders for the outback and decided I was not the fixer upper builder like other so I just bolted the other on the yak..

I never thought to do this. I am genuinely tempted now. I think I would like to try the style of the 2nd rudder for my Revo11; should work well under mirage drive or sail power.

Tell me more about the one with the winglets though? What was the logic behind it and what kayak did you intend to use it on? Also are the winglets designed to be parallel to the plane of the water surface or set to an incline for some reason?

That's an interesting thought. If the winglets are set at a slight angle to the flow of water — such as sloping down from front to rear — could that negate, to some degree, the rudder cinching we have to do when engaging the rudder? I ask this because sometimes, when I am traversing water that I know might have tree limbs just below the surface, I uncinch my rudder so as to not break the rudder line or rudder pin. But that uncinching can screw up rudder authority if you add a little too much speed to your paddling — causing a sudden veer to your left as the rudder lifts up.

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Absolute kayaking corrupts absolutely.

Winglets are not uncommon among surf ski rudders and are designed to enhance the authority. They do this by helping keep the slipstream perpendicular to the rudder. I borrowed this concept to enhance the large rudder's bite when riding boat wakes at an angle. It also works well on the AIs especially when tacking. Below are a couple of close ups.



I set them up parallel to the horizontal. This actually provides a small amount of lift to the stern at higher speeds because the slipstream is angling up to fill the void behind the boat. When we were experimenting with these I sent one to yakaholic and he felt that his enhanced the speed of his AI in match racing with his wife.

It is notched in the front and held slightly back from the leading edge of the rudder so as not to snag debris. It is held slightly off the rudder bottom to protect it if the rudder bottoms out. Once tacked in place, the full contact surface is epoxied and shaped to strengthen the attachment. I posted a "How To" several years ago but the accompanying pics have been removed by the hosting service unfortunately.

Alternatively my friend Mike has been experimenting with a different rudder attachment. It is set at a small positive angle of attack and designed to stay above the water line at slower speeds and engage the water at higher speeds as the stern "squats" (see pics).



This is an alternative to putting weight in the bow to keep the boat on its lines at higher speeds. It has a lifting action on the stern proportional to boat speed. This in turn allows the boat to achieve a faster fast cruise. Very clever idea!