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For a Wharram that uses a Wheel, what diameter do you like looks wise? Not that it needs to be larger diameter to function better, but for looks.

The Narai Mk IV wheel is 23" diameter. If made larger diameter the steering components would need to be adjusted some probably to keep steering forces & throw correct.

I like the looks of a larger diameter steering wheel. Somewhere around 36"-42" depending on size of cockpit.
Dave 'Boatsmith' likes Really large diameter steering wheels. The one they are putting on the glass Ariki is really big. I forgot what size he said it was in the video.

Thoughts on steering wheel diameter preferences for Wharram's? Pics?

Cheers, Allen

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The nice thing about a steering on a Wharram is that you can make the spindle any size you want, or you can do any custom mechanism that suits your fancy. Therefor, you can install whatever sized wheel you like. Even if you use the spindle size in the plans, a larger wheel will give better feel and a tighter response.

I think that the only reason to have a smaller wheel is if you are forced to drive with handcuffs on...

Lol BB what size wheel you planning to use?

Chases, Allen

Whatever I can find closest to free that will readily take an off the shelf autopilot and control lines for self-steering. I try to touch the wheel as little as possible (they are like kitchen sponges: covered in cooties.)

Allen Bosely said:

Lol BB what size wheel you planning to use?

Chases, Allen
I'm going to make mine. Probably out of IPE. It's a bit heavy wood but will feel solid in hand (like a solid core door vs a hollow core door) very strong, it's a pretty wood, not breathing but nice looking.
Just about won't rot even in treated or seed. With nothing on it it greys. But with a little oil rubbed on it every few months will stay nice & natural looking.
A little challenging to glue but not as bad as it reputation.

Will be a 6 spoke with the ring part of wheel pretty close to round cross section.
I found a small diameter splined steering hub with popular 3-bolt pattern for it. So a standard steering shaft can be used.
That way it can be used with drum for rope and/or off the shelf autopilot & control lines.

If you like it when I build it I'll build you one as a gift as appreciation for the forum & all your guidance you have given, and probably will be giving! :-) I'll take care of shipping it to you when finished. That way I get to give something back.
Actually, if you want a real pretty one I can make it out of Monkeypod wood. I'll be cutting & milling it for a lot of the wood on my Narai Mk IV. Monkeypod is really beautiful. To buy it on mainland it's expensive, over here I can get the trees for free & mill the wood.

I decided to cut and mill all my dimensional lumber. I'll be using Albizia Lebbeck and Monkeypod woods. I have been discussing wood choices & options with Paul Riccelli of Riccelli Yaught Design over on boatdesign.net, Paul's been a big help. So have settled on these two for the dimensional lumber. Using Hydrotek Meranti 9mm 7 ply. It's available locally and I can pick & choose my plywood, will use Vertical Grain Douglas-Fir for masts & Gaffs. Can get it local to so can pick my boards. Building them with birds mouth construction.

Cheers, Allen

Cheers, Allen

That is quite gracious of you Allen. I might just take you up on that.

Wheel diameter is an important factor in a steering system. Imagine driving a 40' boat at 22 knots. Would you prefer a 2' tiller or a 4' tiller. The short tiller would not work. With a wheel system it can be set up with any additional leverage you want via the hub cable drum. This can give you 2 turns lock to lock or 4 turns lock to lock or 17. The more turns lock to lock the more leverage (longer tiller). The down side is that the wheel has to turn twice as far (for the 2 vs 4 example) for an equal rudder response. This decreases the helm feel  to the helmsman. Increasing wheel diameter from 2' to 4' doubles the effective tiller length as far as effort to the helmsman is concerned. This allows for better helm feel and a more responsive helm with the the same wheel load.

  Wheel load is influenced by many factors. The Wharram rudders are of the barn door variety. They are aft hung non-counter balanced. Additionally the stock Wharram stern posts are at about a 23* angle. This means that about 1/4 of the energy inflicted by the rudders will be trying to push the sterns down into the water instead of turning the boat. At 5-6 knots this drag induces moderate rudder/tiller loads. At ten knots this load increases exponentially. Even more so at 20 knots. 

  On Brad's Ariki, Bazinga, the boat has been set-up with with a modern marconi full batten main sail with a fat roach, daggerboards, a carbon extendable bow sprit and a set of sails from Dave Calvert of warp drive Spectra material. Brad is a very experienced sailor and a boat that sails well was very high on the priority list. I expect Bazinga to exceed 20 knots commonly. This is fast for a cruising catamaran with a 41.5' LWL even by today's standards. But this is definitely not your grandpa's Wharram.

  On the Ariki 48 I have changed the stern post angle to 5*.

  The steering system on Bazinga is 6mm Dynex Dux that is heat treated and pre-stretched wrapped around a drum on the steering shaft at the helm and routed through the cockpit sole to the aft side of the rear beam where they cross the boat to the other side of the boat where the lash to the tiller bar. The tiller travels about 5 1/2' from lock to lock and we have 2 1/4 turns of the wheel. This would not be feasible with a 2' diameter wheel. 

  Also of concern when considering steering load on these boats is the autopilot steering system. I prefer an electric auto-pilot. These boats change apparent wind angle very quickly due to acceleration fluctuations. Again at low boat speeds this is minor but as the speed goes up the boat will tend to steer a snakey course. Many people are quite content with wind vanes. 

  The rudder loads of a barn door rudder at speed are disproportional to the boats weight and LOA which is how auto-pilots are generally sized. The auto-pilot on Bazinga is a Raymarine EV400  with a Type 2 rotary drive. This drive is rated for a 44,000 pound boat. The auto-pilot does not see any advantage from the larger wheel size. The auto-pilot leverage is determined with chain and sprockets on the steering shaft.

 All of that aside a big wheel feels bitchin when you are in the groove jammin along,,, or not.




BB, I figure you will want to see what quality my work is first. Be a bummer to excited to get a wheel and when you see it think OMG! Not on my boat,I don't care if it was free! lol

Boatsmith, thanks for the wheel size info. Now I know it's OK to have a good size wheel on her. Now you got me thinking 48" wheel sounds pretty nice! :-) What diameter did you settle on for the Ariki that was in your video that had the mockup wheel & you weren't sure what diameter it was going to be at that point?  I enjoy your videos BTW.

Cheers, Allen

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