OK folks. I'm back to wanting a below-deck autopilot ram onto my steering quadrant again. Taking the wheel off to fit the emergency steering is a pain and it's hard work handling the boat in the marina with the tiller setup.

Here's the thing. I have the world's largest stainless steel steering wheel on my boat, so the moment of inertia is huge (according to wikipedia the inertia is proportional to the square of the radius!) so the pilot ram is going to have to do a MASSIVE amount of work to turn the wheel. Probably more work turning the wheel than steering the boat.

This must be a solved problem. Is it feasible to remove the spline key and rely on tightening the locking bolt (it has a winch-handle head) to engage wheel?

This is close to what I have except the wheel goes where the Lewmar labelled brake knob is, and a locking nut follows it. On mine the brake knob is on the other end.

You may find that without the key the wheel nut may loosen when turning to the left especially if you come up against the rudder stop or weather helm or aggressive avasive manoeuvres. Could be scary.
You really need some sort of spring loaded dog clutch that is that disengages when the nut is loosened .
A piece of key steel that fits the length of the keyway of the shaft but modified to only engage in a portion of the wheel key slot may work with a coil compression spring pushing the wheel off when the nut is loosened 3 or 4 turns,,,but you may run into problems with that approach if the large wheel leverage shears off the small portion of key.
It looks to be a taper on the shaft which could make things difficult for ease of intended modified function.

smaller steering wheel maybe?

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cammd said..
smaller steering wheel maybe?

Given a wheel with half the radius would have less than 1/4 the inertia it's definitely a consideration.

I might start keeping an eye out for a carbon wheel on Aussie yachties on FB.

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cammd said..
smaller steering wheel maybe?

This?

I get that they are not cheap, but if it is that heavy you are going to hammer your power budget let alone the extra loads. IMHO, your autpilot is one of those areas where its worth investing in. An autopilot that you don't want to use because (insert reason here) is a major PITA.
I destroyed one of my 900mm wheels. A carbon fibre replacement was $2000, a GRP replacement was $600. I opted for the GRP one, it looked very bit as good and was still super light. I had a Lecomble and Schmitt actuator, properly trimmed I could get it below 1 amp current draw on a max draw of 20amps. Big difference in power budget, so it's worth trying to get all of your components right.
Cheers!
.

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shaggybaxter said..

cammd said..
smaller steering wheel maybe?

This?

I get that they are not cheap, but if it is that heavy you are going to hammer your power budget let alone the extra loads. IMHO, your autpilot is one of those areas where its worth investing in. An autopilot that you don't want to use because (insert reason here) is a major PITA.
I destroyed one of my 900mm wheels. A carbon fibre replacement was $2000, a GRP replacement was $600. I opted for the GRP one, it looked very bit as good and was still super light. I had a Lecomble and Schmitt actuator, properly trimmed I could get it below 1 amp current draw on a max draw of 20amps. Big difference in power budget, so it's worth trying to get all of your components right.
Cheers!
.

Putting a smaller lighter wheel on would be a good solution, because if I sell the boat I can always put the bigger wheel back on it.

I'd be keen to know where to go for the wheel.

Hi John,
I had Carbonautica wheels originally, then went to GS Composites. GS Composites were sold through a mob on the Gold Coast but I'm sorry, I can't remember their name. For reference, my wheel diameter was 900 mm which was pretty common.

www.jefa.com/News/dis_steerer/dis_steer.htm

Suspect this won't be compatible, but a great solution.