h23 RUDDER

[RichB]

Has anyone tried changing the h23 rudder from its traditional form to an inboard style. Would a 12" move forward positively effect performance.

As I am laying on my back scraping the bottom for new antifouling, I can't help but think how easy this modification might be. It would penetrate the hull and actually go right up through the scupper hole. Of course the original scupper is just short of a joke. The new rudder shaft would terminate in a stainless sleeve which accommodates the rudder blade in a similar way as the original aluminum sleeve. If the blade can be shortened to keel depth, it might not have to be removed for trailering.

The scupper then becomes a horizontal rectangular passage out the transom.
It could be a 2" x 4" stainless sleeve with seals at each end. The scupper is a mod which the factory should participate in.

The swim platform now can be wider.
The old thru-hull can be used by a bilge pump.

 

[peptobysmol]

Sounds very interesting. I like the idea of having a "free" transom. It would allow for a swim ladder there or to move the motor over to the midline with its balancing benefits (of course now where do you put your battery if you moved it from the lazarette to the starboard setee? LOL).

Points to consider of course are how much rudder do you "do away with"? I'd like to think that you keep the same rudder draft as the original to maintain stability and control - but that is just an assumption. The only potential problem that I could foresee is the horizontal and vertical forces that may act on the cockpit floor where the new rudder post emerges and the bottom of the hull. I would imagine that some fiberglass over wood/stainless steel backing to reinforcing would be mandatory for structural integrity.

All things aside as long as there isn't a significant increase in the amount of turbulence generated by the keel by moving the leading edge of the rudder about 12 inches foreward it would be OK. It would also have a quicker turning moment as well I would think.

Hey, if you do it... take a bunch of pics! I might follow ur lead!

--Edit. I have a 1985 and was thinking that you'd use the cockpit drain to the through hull. So if your's isn't like mine sorry for the long unnecessary post.

 

[Jim Kolstoe]

First off, I will admit that I have neither tried nor contemplated the change you're proposing - nor would I. The first thing that comes to mind is that by by moving the rudder forward you're changing the location of your center of lateral resistance forward, which I think gives you more windward helm. You then increase this this by reducing the blade area substantially when you cut a very deep rudder to "keel depth." My guess is that you net out a significant windward helm. Because you have a much smaller rudder with the same sail plan, your ability to resist rounding up will be greatly diminished. I assume that you have considered the impact on usable space in the cockpit and feel it is acceptable.
Having said all that, I suggest you try two experiments. First, build a temporary rudder the size you're considering and try it hung from the existing pintels on the transom, then sail it under differing conditions and see what happens. Obviously it will not exactly duplicate your proposed change, but its a cheap, easily reversed test. Second, put a mock-up of the proposed rudder sleeve, any needed bracing and the tiller in and spend some time working with it in the cockpit to see how it affects your use of that space.
Jim Kolstoe, h23 Kara's Boo

 

[Mark Major]

An interesting experiment. The only modification I've contemplated is what the effect would be of a more "balanced" rudder. I don't know much about these things but understand ours is unbalanced because the force applied for steering is aft of the pivot point. I thought that perhaps extending the leading edge forward toward a more balanced design might create some interesting changes in performance. Taking your proposal and consdering a balanced rudder design would allow you to increase total surface area despite a shallower cut. I think maybe you might need a slide rule on this one, or just be willing to make a lot of trials/errors. Sounds like fun, though. At worst even if nothing turns out satisfactory the modifications you would be making are reversible. I'd like to participate (if not only simply observe) if you do undertake this.

 

[RichB]

Thanks for all three comments. Pull out the slide rule? The lateness of my reply is due to family visiting. I have been known to get into the numbers but spend much more time in the envelope of intuition and trial & error.

My 1989 h23 is basically unaltered. The original owner gave her the tapered mast and some nice racing hardware. She has a nice quick response. 6 winches is definitely overkill. Weather helm is minimized by keeping the mast firmly forward in the step. A small angle aft and it gets out of control. So balance would be critical to a rudder redesign.

This years most pressing issue is the main sail. I ripped it on a marker coming into port in a t-storm. It is repaired and it's old. It could be blown out far enough to contribute to a balance problem. But the main balance problem is sailing quality vs the wallet quantity.

Jim's consideration of Lateral resistance will definitely require a wider blade and a healthy pinch of Mark's balancing. I think there will be a benefit from it being more vertical than it is hanging off the stern at an angle.
My crew seems to think it already tacks plenty fast. I am always having to wait on the sheet tailing. She might want to sail under Peptobysmol's command for a while.

Trial and Error - Several test blades can come from a sheet of 3/4" plywood attached to a slotted, (reusable) head. I have come to appreciate the additional 11" of draft the existing rudder gives. It has saved several groundings in west coast Florida. The reason for wanting to shorten it is laziness. The list of tasks to launch and unlaunch could be shortened by simply to leaving the rudder in place for trailering.

I really should mention that my wildest dream (for the transom) is to add a full width swim platform and if I can say it ..... a walk thru. Giving all due respect to its simple and thoughtful design, the rudder flopping thru its arc back there takes up so much space, and occasionally fights with the propeller.
Gotta cut and run, they are short handed at work.
Best regards .... Rich
Sorry for the lack of editing.



the mock-up idea for the tiller. I had planned to use a strap or a pintle to keep it rigid and aligned. This would also reduce stress on the short distance from hull to cockpit floor.

 

[Brian M H23]

Here is a better idea for you.
Leave the rudder where it is, and build your swim platform out back.
Make a new rudder such that the tiller is at floor level.
Done