Anonymous wrote:

[...] use my vane turret to drive an aux rudder (probably with a bigger vane) [...]

This topic got me interested in studying your vane design. After some time looking at the photos over and over I think I understand how it would operate with an aux rudder. I have two questions that I hope you would be willing to answer.

If your vane was used to drive an auxiliary rudder in place of a pendulum is there some way to adjust the ratio of vane deflection to rudder deflection? It seems like the quadrant and the fairlead taking the lines to the quadrant would need to move with respect to the aux rudder pivot. Is there some other way this ratio could be tuned after the gear is installed? 

I was also wondering what you use to allow the turret to rotate freely when setting the course. Is there a plastic bushing or is it all plywood riding directly on plywood?

It's difficult to say too much without any drawings to look at, only small photos which aren't good enough to work from. It's complicated, with one more crank and push rod than strictly necessary. It takes more engineering and metal work to make these crank and push rod gears than the drum, cord and sheave gears. There doesn't seem to be any remote course setting. He seems not to have taken it any further than just "around the bay".

He's got some things right: the vane axis is inclinable from 0˚ to 30˚ for example (but in practice you find the angle that works best on average, and fix it there - generally 15˚ to 20˚). 

I think you'd find it easier to work from my drawings, Jami. Either use my vane turret to drive an aux rudder (probably with a bigger vane) or build the whole pendulum gear. I've deliberately designed it for construction with the least skills and facilities.

I can't see, but I suspect that this 32ft boat has wheel steering, and clamping the main rudder is done with a screw mechanism in the pedestal. I don't buy the "no lines across the cockpit" argument with tiller steering, as this is the easiest way to fix the main rudder when using an aux rudder.

This looks good, Jami
Belcher also describes a con-rod-version of his OGT MkII. In the end it depends on what material you prefer to work with. If you have tools and skills to work with metal on that level, go ahead. Personally I am more a wood, plywood, canvas and string kind of guy, so prefer the ‘Otto’ version. These days we have Dyneema line which will improve precision in the link between the vane and the tiller. Moreover, today's wood epoxy makes building the wooden structure very simple.

 

Arne

PS: The conrod version has the advantage that you can swing the course around as much as you like. That is; you can sail in several circles  just by turning the vane around more and more. With Otto, the string version, I have to wind the course-setting table back 360 degrees after each gybing. Personally I didn't find that difficult. I just locked the tiller for a second with the  vane's lines still attached, then swung the course-setting wheel and finally freed the tiller lock to let the vane take over.

Jami.

That OGT MkII vane may look awfully big and bulky. So it did to me while I was building it. However, on the boat it looked OK, and my Malena was after all only 1ft bigger than your Galion. Besides, the all-wood construction made it quite light. A smaller vane will be just as vulnerable to the sheet in a gybe, so I guess some sort of fence or arc would be needed, anyway.

I can see your point with starting with an autopilot. With the AUX-rudder connected to the main rudder, you should hopefully solve the weather helm problem.

Below is a quick sketch showing how the classic pushrod link can be adapted to connect the two rudders. The pushrod should be made so that it can quickly be fitted and removed, while the ‘elbows’ will be ‘permanent’.

Remember, since the AUX rudder has been given almost 22% balance, the forces on the pushrod and elbows will be quite light, even with only 150mm elbows.

Have a look.

Arne

PS: The gearing between the OGT MkII vane and the tiller is adjustable simply by having several screws to choose from on the tiller (note how that brass chain is connected to the tiller on the photo in that article). The default gearing is 3:1, so that 15° vane movement gives 5° tiller movement.

 

Yes, it would, actually, Jami. My pendulum is very powerful, but because I've inclined its power axis, it has a relatively small arc of movement compared with a horizontal power axis. That doesn't matter, because you operate it in a similar manner to the aux rudder/fixed main rudder. You shorten in on the line that's pulling the main rudder's tiller to weather, so that the pendulum is staying within its central arc of movement but the main rudder is at an angle of weather helm. This is similar to setting to fixing the main rudder at an angle of weather helm so that the smaller aux rudder is able to stay within a small angle of incidence and not stall out. That's the story upwind.

Downwind, it's a different story. A fixed main rudder is giving you passive resistance to yawing, like a skeg, as the aux rudder is making course corrections as the swells roll underneath. Whereas a pendulum is actively sensing the yawing, and making the main rudder actively fight against a yaw. In both cases, though, there is no biassing applied on the main rudder or the steering lines - they are both centralised.

Note how the Hydrovane has a knob for adjusting the ratio of vane angle/rudder angle movement. This will be for tuning the performance for different conditions, and is probably the reason why the Hydrovane is liked and preferred to the pendulum gears by some sailors, but it would be difficult to steal that idea and apply it to a home made gear. The Hydrovane scores most highly over the pendulums with wheel steering, which cripples a pendulum's performance, whereas an aux rudder is unaffected. With tiller steering, I reckon the pendulums to have the edge.

All in all, my money's on a pendulum like mine as the best bet for your particular configuration of stern and rudder, but I have had (in the dim and distant past, so I don't remember it well) "good enough" performance from an aux rudder and inclined axis vane.

Note what I've described here about a peculiar effect that I found with insufficient inclination of the vane axis, or none - if the boat rolls to windward, the vane axis can actually go negative, and then the vane can go unstable and throw from full angle one way to full angle the other way, with chaotic results. Stick with an inclined angle vane axis, not a Belcher-style horizontal axis.