Pivotable Ballast Systems for Cruisers

[Bahama]

I've read about pitotable ballast systems and found them to be very interesting; but the systems that I've seen were complex and required hydraulics to move the ballast band forth.

For cruisers (NOT racers) that don't tack back and forth as much, wouldn't it make sense to move the ballast back and forth using gravity, momentum and friction from the water. Just before changing tack you would release a locking mechanism, which would make the ballast swing naturally down toward the other side (possibly all the way over) but to get that extra force needed to lock it into place on the other side you could simply use rotating fins on the ballast or the support arms temporarily to add the force needed until it gets lock into place--at that point change tack.

What I like about this idea is that you don't have to cut through your hull to move this back and forth, it can all be done externally; the only potential hole drilled would be for the fin movement, and that would be vastly smaller than what is needed for ballast arm(s) support.

I thought this looked like a nice poor man's way to break into this; it certainly offers some advantages.

Also, I was curious about using 2 arms rather than one large one; one fore and aft of the keel, and the ballast would just pivot below the keel's lowest point. It would be made to lock in place in the middle as well.

And lastly on this idea, would you want the ability to lock in place somewhere in between for storm conditions and the smaller sails. So 5 pivot points in total for this idea.

I really like the idea of using gravity and potentially fins to swing the ballast back and forth. Again, I just wanted to toss this idea out for public domain to see what people thought about it.

To make it short:

forget about it.

No, no, it was worth to be discussed, and it was to the very extreme end here....

It still is not worth talking for a homebuilder.

Regards
richard

[Bahama]

Originally Posted by apex1

To make it short:

forget about it.

No, no, it was worth to be discussed, and it was to the very extreme end here....

It still is not worth talking for a homebuilder.

Regards
richard

Odd, I read what I thought were all the posts regarding the subject here and did not see a single reference to using what I described, especially temporarily using a fin rather than hydraulics or other mechanical means to move the pivot. What I thought was novel about the idea is that it does lose some power, but that's not of much concern to the cruiser who doesn't tack much and the time lost would be gained back and then some or the pivot concept wouldn't even be invented.

If you can point me to those numerous discussions that I missed regarding my fin design, I'd love to read them so that I don't waste the time of you fine folks here. I did do some more looking around and all i can find is some discussion called "Automatic keel trim tab?". Is there anything more? Or any keyword suggestions would be appreciated as well... canter I suppose, I didn't use that as a search term, I'll try that word next.

Welcome mate,

you do not waste our time! And if, then it would be our decision to stay on what you (or we) started.

The complication of so named (in reality they ALL fail) advanced systems is so far away from the dreams of the inventors, and has so absolutely nothing in common with going to sea, that it would waste your and my time to go deeper into it.

Talking long range cruisers (and nothing else is affordable by a homebuilder), the epitome we have seen a hundred years ago, the rest was drivel and marketing.

Regards
Richard

[Bahama]

Originally Posted by apex1

Welcome mate,

you do not waste our time! And if, then it would be our decision to stay on what you (or we) started.

The complication of so named (in reality they ALL fail) advanced systems is so far away from the dreams of the inventors, and has so absolutely nothing in common with going to sea, that it would waste your and my time to go deeper into it.

Talking long range cruisers (and nothing else is affordable by a homebuilder), the epitome we have seen a hundred years ago, the rest was drivel and marketing.

Regards
Richard

So the pivot ballast concept is mainly for the racers with the time and money to tinker; but too problematic for casual maintenance free use?

I can buy into that; I think you can see that my goal was to try and hit someting closer to maintenance free by tossing out the motors and gizmos and just use gravity alone if possible, and otherwise just a nudge more using a small fin for that extra push during the downward swing to the other side... kind of like how we give a little push to swing a child in a swing... the the fin would just go straight again.

I started to ask about a scissor type idea... but when I drew it out more I realized that it would not work. So I give up and I'll leave this to the racers!

[Perm Stress]

Originally Posted by Bahama

So the pivot ballast concept is mainly for the racers with the time and money to tinker; but too problematic for casual maintenance free use?

I can buy into that; I think you can see that my goal was to try and hit someting closer to maintenance free by tossing out the motors and gizmos and just use gravity alone if possible, and otherwise just a nudge more using a small fin for that extra push during the downward swing to the other side... kind of like how we give a little push to swing a child in a swing... the the fin would just go straight again.

I started to ask about a scissor type idea... but when I drew it out more I realized that it would not work. So I give up and I'll leave this to the racers!

In mini 650 they use mutlipart tackle sometimes instead of hydraulics (have seen a photo somewhere). it is possible because the keel and boat are really small.

As to using hydrodynamic forces to finish the cant of keel to leeward just before tacking, leeway of boat will try to exactly the opposite. So, in order to finish the cant, you would need to over-rotate the keel profile so much that it will pull all your boat to leeward; all the rest of your foils will work at much greater angle of attack to compensate for it and create lots of drag, slowing the in least desirable moment -just before the tack; and so on and so on... nobody know where this spiral would end.
Here we even do not mention how much area and angle of attack of canting keel profile would be necessary to create enough "canting force" at few knot forward speed.

[Squidly-Diddly]

CAD/CAM parts for cheap that only aero-space companies could make just 20 years ago for millions.

You can also do your own computer stress analysis with student versions of SolidWorks, etc.


But I still like the idea of water storage/ballast/flotation tanks positioned as far apart as possible and pumping/draining water to either side.

I'd like fresh water to be stored in bladders inside Water(sea-water) Ballast tanks, with the option of quickly "blowing all tanks" with low pressure air to create massive flotation.