Flying Canting Keel-Extraordinary Innovation!

Paul B

Take it easy on bashing Doug on this subject. He does have experience with moving ballast systems. Small yes, but the physics of small and big are not so much different in this case.

As an engineer, I can say that moving weight around is really not that hard if you go at it correctly.

It took me next to no effort to think through a fast system that would take minimal effort during a tack.

Design a plank that translates side to side, similar to the International Canoe, only add rollers to make it low friction and let it “tilt” as controlled by stays off of the mast. Place the plank just ahead of the mast & put the pivot point say 2' above the deck.

Mount a ballast on the plank that translates on low a low friction wheel system. A cable drive that automatically extends the ballast to the end of the plank is simple.

As you are making headway between tacks, a crew member operates a pedal/grinder system to slowly elevate the extended weight that is locked fully extended to the windward side.

As the boat tacks, a separate pedal/grinder is operated to reposition the plank/ballast to the opposite side. Since the plank was elevated to an angle that makes this a “downhill” move, this is both easy & fast.

Paul Flados

 

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Paul, the beauty of my system is that the load is 100% supported by trapeze wires-makes it very easy to move. Check out the "Ballast Mover" in post 169..

 

Doug,

I never bothered to study you stuff in detail, the concept is pretty obvious and has the potential to generate all the righting moment you want. I am actually surprised that there has not been more activity with the concept in full scale.

My suggestion was an adaptation to add a “tilting” aspect that would make "easy to move" even "easier" as you arrange to have help from gravity.

On a small scale, batteries & motors do the job.

If you want to go big, you can still get what you want, it is just a question of choosing either brute force to go fast and uphill, or finding a way around doing it the hard way.

 

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Paul, I missed where you said stays-sounds like we're talking about the same thing-the "tilting" function is a critical part of my system as well. When the wing is centered, the trapeze wires support it with shock cord; as the weight moves inside the wing the shock cord stretches allowing the wing to tilt as much as you want it to. See the model picture below showing the tilt:

 

It's not proven to be that easy in real life. To use a real-life example, in 18 Foot Skiffs it was found that you could not normally use unlimited wingspan, despite the fact that the 30' wide wings used in the Brisbane "worlds" by Brownie worked in that very special environment. This is partly because as leverage increases, so does the penalty for the normal problems of making an error when trying to judge exactly how far you have to move across the span of the righting-moment lever.

This sort of thing repeats in many scales in many classes; it's why a crew-weight stuffup in Etchells is less important than in J/24s, or the main reason why it's so much easier to tack a Laser than an International Canoe which has a much wider righting-moment lever, or why it's harder to use a 12m windsurfer sail than a 6m sail in shifty winds, or why the later Bethwaite HSPs were more conventional than the earlier ones. The problem is not getting the forces in balance in a steady state, the problem is that a steady state is very rare in most sailing locations, and in many high-performance classes the critical area is not the straight-line stuff but getting around the corners.

Funny thing is, the people (like Paul B) who query the claims of posters who are very short of hands-on experience in fast boats and offshore races then get abused by other posters who imply that you need lots of hands-on experience in fast boats and offshore races to be able to judge this sort of stuff! That's exactly the point that Paul keeps on trying to make!

If you did need experience on cats, skiffs and other dinghies, ULD monos and long ocean races to judge this stuff, then it's pretty obvious who would and would not qualify.

 

From Julian Bethwaite on the subject of on-deck movable ballast:

Picture: 18' Trapwing model showing tip pods and wing:

 

Herreshoff on-deck movable ballast

From the 1800's:

 

That video does not show a real CFD simulation. It is a very bad Saturday morning cartoon.

The simulation shows a boat that does not pitch or heave an inch as it goes over a row of ridiculously high/closely spaced waves.

That video could never prove anything one way or another.

 

As an engineer have you considered the spreadsheet Doug has posted as "proof" of his ability to move x weight y distance in z time?

Go ahead and take a look at it. It is a power comsumption study tool. It does not prove the activity can be performed.

Go ahead and plug in something unrealistic for a ballast system, like moving 1000 kg 100 meters in 1.5 sec. The formula gives you a result.

It is simply calculating the power required to perform the work. It is not proving the work can be done.

 

The ballast mover gives an idea of how big a battery would be required to move the ballast within the constraints of a 20% grade and start stop acceleration/deceleration for any times over 1.5 seconds. Any time can be chosen by the designer from one tack every 12 seconds , one tack every 2 minutes or whatever for 8, 10 12 hours or more. Ricks work in creating the spreadsheet allows a target speed to be chosen and the power requirements to be assessed( and therefore the weight of the battery, size of the motor etc.). Of course there will be development challenges-but they can be solved. Ricks work has shown that the power required for even the fastest times is practical and he is 100% convinced that he can design a system to work for any parameters I choose. The speed of the system can easily be greater than that of a crew moving side to side-thats just a fact. Any speed can be designed for-the weight (which is also variable) would be able to be moved using a similar small joystick to the ones used for the radio controlled test models which were loads of fun to sail with extremely quick power ballast systems.
Smaller systems like for a 14 footer can be moved manually though it might be more fun to use a very minimal joystick controlled electrical system. Every electrical system would have manual backup.
This kind of system would revolutinize small singlehanded, high performance planing monohulls in terms of access for disabled and physically constrained people.
See post 169 for the "Ballast Mover" spreadsheet & measured times for full out to full out tacking of a number of existing boats.
See post 180 for RC test models using a version of the system.

 

So, all you need do to prove the efficacy of the system is to build it full size, and show that the system can work as advertised. Everything else, aside from the needed proof, is pure speculation and nothing more.

I would love to see the system work, but I have more than a few passing doubts.

 

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Well, everything else is part and parcel of the design process and is as important in its own right as the full size boat. Everything is step by step...

 

There's no proof that it would work?

 

I emphatically disagree.
1) I proved it in numerous test models over 10 years.
2) Charles Herreshoff proved on-deck movable ballast works on racing boats in the 1870's.
3) Julian Bethwaite believes the concept has merit as do many other experienced sailors.

 

There is more to it than just proving it will work.

When the discussion is simply moving weights around, it is just physics and engineering. Where the discussion is about max speed, hanging a heavy weight off to the side of a monohull does have quite a bit of potential.

My comments were just for moving weights in the quest of a high top speed for good conditions. If these were the only parameters involved, a moving ballast system would be high on the list of things to try.

Much of the reason that moving ballast rare is that real world boat racing is much more. To be able to be worth the effort, a "sliding ballast on a sliding plank" would probably need to generate the equivalent righting moment of least two or three crew members (or more for a larger boat) on a trap or rack. A good traditional layout can handle light, shifty or unsteady winds without any real problems. Think of the heavy ballast off to the sideof a boat and the way it would respond to a sudden lull or wind shift that unloads the sail.

Again, for a top speed special, all sorts of "weird" stuff can work. If someone is going for this, I recommend we cut them slack and cheer them on. Just do not mix this up with a discussion of what will work for a more general purpose boat.