Swing Keel for 26M

[Chopper Pilot]

https://www.youtube.com/watch?v=S3mQNLTuJRI

Imagine swinging this either from a hinge at the bottom of a modified dagger board! hull, you could even connect it to the base of the mast. Then a short section to swing to either side. Then plug in the longer section from outside the rail. Instead of lead, i would use a water ballast so it would be light until filled and if it contacts the water, it would have zero weight applied thus no rolling moment to it. If hung on the dagger board, and you wanted to swing it, undo the halyard that is supporting the weight, run the rope under the front side of the boat, to the other side and reattach that rope to the halyard again. Then use your winch to raise it to the level you like. You could get some serious speed out of this pig. But it has to be a water ballast though. And the halyard off of the mast must be able to support the weight. Think of it like a spinnaker pole holding it out, and the mast and winches supporting the load.

If mounted underneath, swung out to the side, and left in the water while at anchore, it could act as a stabilizing bar to keep the boat from rocking in one direction. If it had a pole coming off of one of the rails, it could stabilize in both directions.

[dlandersson]

So the idea is to move the ballast above the water to reduce drag - like a Cat.

https://www.youtube.com/watch?v=S3mQNLTuJRI

Imagine swinging this either from a hinge at the bottom of a modified dagger board! hull, you could even connect it to the base of the mast. Then a short section to swing to either side. Then plug in the longer section from outside the rail. Instead of lead, i would use a water ballast so it would be light until filled and if it contacts the water, it would have zero weight applied thus no rolling moment to it. If hung on the dagger board, and you wanted to swing it, undo the halyard that is supporting the weight, run the rope under the front side of the boat, to the other side and reattach that rope to the halyard again. Then use your winch to raise it to the level you like. You could get some serious speed out of this pig. But it has to be a water ballast though. And the halyard off of the mast must be able to support the weight. Think of it like a spinnaker pole holding it out, and the mast and winches supporting the load.

If mounted underneath, swung out to the side, and left in the water while at anchore, it could act as a stabilizing bar to keep the boat from rocking in one direction. If it had a pole coming off of one of the rails, it could stabilize in both directions.

[Obelix]

What's not shown is the means to apply the internal force to keep the swing keel suspended. This force has to be applied to the inside swinging part (is it a counterweight?) and must be at least equal to the weight difference between the extended and the internal weight. This internal counterpart and the mechanics and space it requires would prohibit this technology in a cabin cruiser.

Obelix

[Russ]

Interesting.

But we didn't buy a Mac to race it. That's a different boat.

[Chopper Pilot]

It wouldn't take much weight from a water ballasted counter weight suspended from the top of the mast and held outward with a simple pole just to see if it increases speed

But if there is no advantage to speed, maybe we should tow sea anchored!

[Norca]

The lifting foil is also interesting idea, it creates lift on the leeward side to stabilize the boat,
It also adds very little weight. If it was designed in from the beginning, one could reduce the fixed ballast to compensate so the trailerweight would be the same.
and it could fit righ under the floor Tthe boat in this video is erally flying:
https://www.youtube.com/watch?v=MTZKBZTm04A

I would love to pass my friend on his stiletto catamaran with my mac

[jimbo]

There was a discussion some time back on this topic. Build a variable aerofoil dagger board. A deformable skin controlled by mechanical cams. Same effect I think.

[kurz]

well I like very much the hydrofoil idea. Even if we do not have details...

But in the every day use I think it is the most simple system of the three: swing keel, hydrofoil, of like macgregors 70 the waterbalast system to move.

Not to forget: What to do if the system breaks down...

[Ixneigh]

I ll let you guys work on all these fascinating new mods while I cruise around at 3.5 knots letting the dogs sail the boat. They can do this quite well if I set the sails and lock the helm for them.
Ix

[dlandersson]

Ditto.

I ll let you guys work on all these fascinating new mods while I cruise around at 3.5 knots letting the dogs sail the boat. They can do this quite well if I set the sails and lock the helm for them.
Ix

[Norca]

We can always dream
But probably a ballast-tank on each side under the settees would be more practical, and easier to install.
I think it could be fairly efficient to increase righting-moment, but it would take up a lot of room, and make the boat less
practical for cruising. maybe some flexible and removable tank that could be used when day-sailing, and removed when cruising?
Then the rigging would have to be strengthened to take the extra load due to higher righting moment, and here we go again, one thing leads to another.
Probably 200 liter of water on the side is OK, it is the same weight as two of my friends sitting in the same location.. It would give a little more stability when sailing
in high winds.
Contrary to what most people think, it will not increase the risk of capsize if the tanks are low enough, once the boat is over on its side, the ballast will become
efficient even if it is on the wrong side.

[Russ]

Ditto.

I ll let you guys work on all these fascinating new mods while I cruise around at 3.5 knots letting the dogs sail the boat. They can do this quite well if I set the sails and lock the helm for them.
Ix

+1

[Highlander]

Ditto.

I ll let you guys work on all these fascinating new mods while I cruise around at 3.5 knots letting the dogs sail the boat. They can do this quite well if I set the sails and lock the helm for them.
Ix

+1

U - Guy,s need to get Motivation

J

[Chopper Pilot]

Law of diffusion of innovation for sure

[Ixneigh]

I love innovation. But I spent all day sailing today. Wind was 10-15. The boat was perfectly balanced, no matter where the board was. We sailed around four knots, didn't heel too much, I went nearly out of sight of land and didn't get a drop of water on me. She'll sail herself for hours if you are just out for larks. In the weather and areas I prefer to sail, the boat is a delight. Sure it's not the fastest thing out there but if I wanted speed a used F-9A tri would have been possibly affordable. That doesn't have enough room to live on half the year, for me. If the object in question already does what you want , my motivation is much lessened to change it. I do change it though. I put those skegs on. I want to strongerfy the edges of the hull where they meet the deck. That will involve several thousand dollars of materials and labor. It will make the boat stiffer and stronger for the type of sailing I plan to do with it. I'll fix that ballast valve once and for all full stop soon. Already figured out a way to do it. The sun shade does everything I wanted. Doubt highly there is another like it on the forum.
I put a lot of thought into the hull of this boat when I got it, and am amazed it sails and motors as well as it does. The only way I can think of to maybe improve it , and it's a big maybe, would be to relocate my 350 pounds of extra lead to the outside, in a type of shoe just aft of the dagger board, where the hull begins to slope up. This would carry the deepest draft part, currently just forward of the dagger board, aft for four feet. The shoe would have a nicely feathered trailing end. But vertical. Now that's a ton of effort plus now the trailer won't work. All for marginal improvements. The rig, in my opinion, is an easier, more cost effective way to look for speed. The new Hyde sails i bought were worth ever cent. Carbon fiber spreader tubes might save a pound or two, 12 feet up. How about a tapered carbon spar? Pitch that roller furler and have three sizes of hank on headsails. Don't add the mast slot slides to your main, just use the rope luff.
Fix those rudder brackets to eliminate the slop and flex. Upgrade to Ida rudders. Tattoo just ought to make those standard equipment.
Ix