Water-ballasted multihulls

Vulgivagus

Well, the person who conceived of the tubes used by T. Jones [one Leo Surtees] wanted to add mass opposing the direction of mast movement thereby preventing a capsize and [having looked at the patent] uses butterfly valves an' linking rods, all possbily electrically automated. Too late, generally.
As a single hander in a small boat there just ain't always room and power for the system - yours or his - and no one wants to wake out of a nap and start leaping around for levers just as the hull starts lifting.
Personally, I consider self orientation [wha' happening?] and boat maneuvering at the top of my list of priorities and I want a static preventative - either water ballast or a sheet tripping mechanism to allow the sails to lose pressure. The latter is iffy and the system proposed by L.S. is attached to the keel fin permitting the windward ama to lift clear of the water before it automatically activates [if the battery is flat then, whoops, over you go. See USA patent 4,541,356 for detail]. As mentioned, sometimes there just ain't time for manual actuation.
I must hasten to add, when racing, water transfer systems ae wonderful and are really worth their weight penalty!
If no one has done this before then what I need to do is place a reservior [open to the water at the base of each ama] with a small entry and drainage hole.
The more the ama lifts the more effective the mass of the water in this reservior so slowing or negating the consequence of a sudden squall. Then there is time to lash the tiller an' let sheets fly.
Does this sound dumb?
Plastic/polypro/fiberglass has roughly the same density as water, hence when a container made of any of the above is filled with water and then immersed in water it then has neutral buoyancy. But start lifting it out of the water then it becomes heavier as the lift progresses.
Anyway, you’all were discussing a similar topic so I thought I’d seek some well thought out advice.

 

Only in Monohulls! Like I asked before, and you just said, better dump or scoop separately in each hull for multihulls

 

Actually, some bluewater multi-hulls also transfer internal ballast water when making passage across oceans. I've always considered this an unnecessary penalty in the smaller boats and Surtees, Jones et al recognized this. The venturi/butterfly question is relatively high on maintenance and eventually degrades into uselessness.
I also got to thinking ‘bout the maintenance of the “tubes”/reservoirs and concluded that, in the long term, there is no simple way of clearing them of sea growth - barnacles, weed and the like - which would cause them to be less efficient and thus negate their designed purpose. But using water as ballast is still a good idea but a such a latent/dormant system should require little maintenance.
And, I think, the only answer to those specifications is a horizontal stabilizer placed on the port side of the starboard ama and a horizontal stabilizer placed on the starboard side of the port ama. The stabilizer would run along about a third of the length of the ama, be fairly narrow in width and be located halfway ’tween the keel and the waterline. In the event of a unexpected squall the affected stabilizer would need to shift 200 to 300 kg water [± 1.5 tons force at the masthead] while on its way to the surface, more than enough to do the job. And it wouldn’t restrict any crew wishing to fly a hull or get in the way of mooring in very shallow water.
Would you care to comment on this please?
Ciao.

 

Hmm - I dont get it myself. I dont see stabilisers providing a lot of capsize resistance, they just dampen hull motion.

You would be better off with some kind of mainsheet release gizmo when a gust hits.

 

All waterborne craft make use of water resistance in some form or other. This is the art of sailing, whether wind or power is used. Indeed, without this resistance life on water would be very very difficult indeed, and as we currently use it, impossible!
Oars use resistance, keel fins use resistance, leeboards use resistance, sea anchors use resistance, rudders use resistance, propellers use resistance, waves use resistance. Without this effect parachutes wouldn’t work, birds couldn’t fly and fish would be unable to swim!
Vehicle oscillation dampers [shock absorbers to you!] are nothing more than circular bi-directional horizontal stabilisers.
This is all terribly tedious!
In truth, I lack patience for this type of nonsense.
Please get y’self a really good starter book on physics [Rr.
All this correspondence is terminated forthwith.
vulgivagus