Neutrally Bouyant Rudders ?

[Calliste]

What constitutes a "neutrally bouyant" rudder ? Is one perfered or why not ?

What happens on a close reach, with a positively bouyant rudder, to the tiller helm ?

Does anyone balance a rudder to be neutrally bouyant, and if they do, what is the result, and how do they do it ?

Douglas , enquireing minds want to know !

[John B]

I believe Reliance had a hollow steel rudder that was able to be filled with either air or trimmed with water to alter helm balance (primarily).Whether there was a collateral hull trim effect as well I don't know.

[Ian McColgin]

The rudder's shape determines how it will act as a foil. Mass and density are more issues of engineering and perhaps trim.

Sailfish, for example, had completely unballasted rudders and the blade's bouyancy will let it pivot up to horizontal when not locked down. Many smaller boats with outboard hung rudders have a bit of lead to keep them from floating free of the pintel/gudgeon. Sometimes, as with many catboats, the mass of the rudder above the water line does it.

Classic full-keeled boats may have an unballasted rudder of drifted oak. So it exerts a little bouyancy but, held down by the post and tube, it's not about to float off. The weights are small and I've seen some boats go from a traditional oak rudder to some sort of composit that has a little negative bouyancy with no ill effect.

Granuaile's rudder was a beautifully fabricated stainless foil left hollow and empty inside and was very close to neutral bouyancy.

Rudder strains can be large and there's little point to making the rudder needlessly heavy.

G'luck