On DeckMovable Ballast

But if it is going to be "skiff style" surely having to dump and pump up water will increase the drag by the hull and will compramise speed, or am i just plain wrong here?

 

Here's an idea - as you're going to be filling the same volume everytime rather than trying to pump water exactly, why not use something along the lines of a piston - i.e. the piston retracts and so forces water in by vacuum, rather than having to pump it in. Could conceivably be done by hydraulics (avoiding electrics at all), probably easier, quicker, and more accurate to control, should require less effort. Work done is going to be the same to shift 200lbs of lead as it is to shift the same of water, provided the efficiency is the same, which is the harder bit. As for self righting, I may be wrong but I think the big racing tris (as in the 60 odd foot ones!) use a system to pump water to the top hull to right when they capsize.
JP - dumping water won't add drag as soon as the water has left contact with the boat, as it can't apply any force to the boat. The pickup system could, and as water is added the hull will ride lower in the water (maybe hydrofoils will be needed? this things sounding complex!) but as this is only going to happen when you're overpowered it's probably not going to be too big an issue.

I hope this project works for you Doug but there are a lot of contradicting criterias in your design. For a boat to be fast, it has to be light and dynamic as stated by a few people before. Looking at your RC designs, the equipment you are using on the deck is going to create a lot of drag. Most High performance skiffs are kept as simple as possible to allow for crews to concentrate on sailing the boat as quickly as possible. Reaction times have to be quick too and I don't think its the best idea relying on mechanical equipment to enable a boat to sail effectively and the more complicated that it is, the more prone it will be to failure. If the boat has weight balancing it in a width respective, what sort of method will be implied to balance the boat in a longitudal direction? All high performance boats need continuous adjustments in fore and aft trim to be sailed effectively, if we didn't concentrate on trim on our boat, we'd be stuffed. Using a skiff design with low buoyancy at the front might not be the best option......

There are many modern high performance boats that require mechanical systems to allow them to work properly. I can't see any reason why sliding ballast horizontally wouldn't work assuming it was designed to be a reliable system. And the mechanics-either electrically or human powered are extremely simple-don't see any problem there at all. It's been done on models; Bethwaite's planning on doing it on a large ocean racer. Even if you did it electrically it would require much less power to move a given amount of weight horizontlly as opposed to moving a short lever attached to a long canting keel. Not only that but moving the weight quickly side to side could be done manually with no electric power at all.
I sure don't see the drag you were referring to especially on a 17-18 footer where the weight is enclosed in an aerodynamically shaped wing-it would be far less than a crew on trapeze!
As to moving the weight fore and aft: I think I mentioned earlier that the wing and crew seat would be able to move fore an aft to some degree and the boat would most definitely use a rudder t-foil.In fact experimenting with a retractable forward lifting hydrofoil for partial lift w/o an altitude control system is part of the agenda down the line with this boat.Pitch control should be precise and more than adequate just with the t-foil rudder and fore and aft weight movement.
   I mentioned earlier about the speed the weight could move-either manually or electrically and it would be faster than a crew.
I just got thru doing some research on the water idea brought up earlier and water would simply not be able to be moved fast enough.It would require a 480 gallon per minute pump(!) to have enough speed to move the water as quickly as lead can be moved and you would be just plain out of luck if you lost electrical power because there is no hand pump that could do the job remotely quick enough.
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The question I'm most interested in exploring/solving is whether or not the fixed wing system(side to side-same as Bethwaite/Langman) would be
superior to the original idea where the wing itself along with the ballast moved as well.Like an IC sliding seat. The original rc test moved both the rack and the weight so that there was nothing to leeward at maximum RM. The Bethwaite/ Langman systems are fixed racks with buoyancy pods. The fixed version would seem to be safer from a capsize perspective (for a disabled sailor) but presents a problem in a pitchpole in that it would not recover w/o the active effort of the crew . So either version requires a ballasted daggerboard for the ultimate in safety which would be required if sailed by a disabled crew. And there is no other boat currently being built anywhere that I know of that would offer the combination of self righting safety and high power to carry sail as is represented by this boat(at least in this size range that the crew sits down inside).Not even the new Bethwaite LAS(Lead Assisted Skiff) offers the power to weght ratio this boat potentialy does combined with a selfrighting capability.
   I apprecate everybody's comments and thoughts on the concept; it is a work in progress and I sure don't have all the answers yet but I'm working on it. Please take the time to look seriously at the ideas here and let me know what you think-especially as regards the two different wing systems...

Why not just go for a multi hull Tonns of stability and speed with out the complexity and vast expence that that brings?