Who needs a rudder?

This is just a musing - but…

Windsurfers are very fast. The most important reason for this is that canting the rig over to windward means that what would normally be heeling force is rotated to become vertical lift - bodily lifting the hull out of the water. This means that Archimedes can take honourable retirement. The immersed volume (displacement) is no longer a direct function of weight. For short, fat Footys this should be a godsend. The planing Footy becomes at least conceptually possible.

The other thing is that windsurfers have no rudders. They are steered largely by adjusting the position of the rig relative to the hull. Can we do this with two radio channels? Alternatively, can we multiplex one or both channels to get more functions? I think we can afford to be generous with the electronics: we can eliminate most of the bulb. If the engineering is practical, will it be possible for a mere human 100m away to control the boat?

Answers og the back of a postage stamp please!:graduate::devil3::devil3::devil3::zbeer:

Canting the rig is a very interesting concept A, how it would be practically achieved with the resources we are allowed is a problem that would have to be worked out.

As for steering without a rudder, yes, windsurfers do it, but they can only change heading by moving the rig fore and aft, to actually tack or gybe the sail must be turned, (over the bow in a tack, and across the stern in a gybe) followed quickly by the guy surfing… (this is generally the point that i take a flying header into the water…) grins what would be interesting Angus is if we could come up with a composite method of steering, where for heading change the sail was raked, but to tack or gybe a small trim tab was utilized… it actually could work i think, it would be a touchy thing, but, if tied into the tab it might be effective. (The only issue is that it is most certainly not a light-air setup. Its going to need all the breeze it can get.)

Anyhow, just my .02


It seems that Windsurfing is the extreme in moveable ballast without a trapeze. In my much younger days, laying out horizontal with head dipping in water was possible.

I always though the windsurfers steer by twisting the board with the feet, like a surfer or skateboarding.

A windsurfer steers with both board roll (rail to rail) like a surfer and with the rig. Forward rake to bear away and backward rake to head-up. It’s combinations of rig and board movements which make them so maneuverable and fun…!

Coming from Hawaii, you almost by definition know much more about this than me. Am I not right that rilling the board can (approximately) be mimiced by adjusting the sideways cant on the rig? Remember that whatever’s driving this as a rig on a ball joint with all (?) control applied by (?) underdeck servos.:zbeer::devil3:

You could make a boat sortof like a proa exept instead of an outrigger it could have a keel and instead of tacking it could “Shunt” like a proa. Steering would be achieved by changing the balance using a daggerboard or pivoting centerboard at each end. When Shunting, one board could go down and the other up. with the Up one all the way up, the boat would be balanced to head off the wind. to head back up-wind the up board could be just slightly deployed enough to get the boat heading up.

when floating in dead air, the keel would be pointing straight down, but the rig would be leaning to windward, or perhaps sagging a bit if it isn’t rigid like an airplane wing if you know what I mean. It would probably need to be some sort of swing rig to keep balance close to the middle

The beauty part is, no complicated machinery to make the keel “Cant” and you get the same efficiency.

OR maybe even make some sortof servo activated clutch device that would hold the rig at a steeper angle so that in a stronger wind, the keel itself would be almost out of the water, and the rig would still be “canted” to provide lift.

Problem is, in a lull, the rig would end up flat against the water which would look sortof embarrassing. Hmmm…

How about some sortof counterweight on the heel of the mastso that… gravity… would bring it up again.

I think I just defeated the purpose of my above proa idea.

Its fun to brainstorm

Aloha Angus

I windsurfed obsessively for 16 years and have been working in the industry for over 20. These days a windsurfer is a fully planning hull. The roll or railing of the board from side to side is a very large component of directional control with a modern, fully planing board, and is much like a surfer, wake boarder or snowboarder who does not even have a rig to help steer. In fact the sailor can pretty much steer with his/her feet alone and not move the rig very much at all.

There are very few windsurfers on the water now that are displacement hulls (They were call DIV 2 windsurfers in their day and were used on the race course).The rig cant plays a much larger part of steering with displacement boards that depend almost entirely on the rig for directional control.

If I understand correctly are you planning on a rudderless boat with a rig that pivots in two dimensions, fore/aft and side to side? And as far as I can see it the fore/aft rig cant could work quite well for directional control upwind with sideways cant to windward to add lift & reduce displacement and drag. While side to side cant would give you directional control downwind and fore/aft cant raking the rig rearwards to possibly help stop downwind nose diving?

If this is so you have a very sweet idea that should work really well if the skipper is able to master the coordination of the controls !!

You got it in one! The problem is control by a mere human. By definition we’re in fly by wire territory, but I hink it might be a good idea to give the ‘wire’ a little intelligence of its own.

Damn battery rules - we can get rid of 200+ g of ugly, poisonous, drag induing lead, Any bright engineering student want to give this a go?