Lee-ving

[Bertil Rafting]

I am counting and thinking of installing a lee-ving as described on the web-site "Dynamic stability systems". It will increase righting moment when needed with 250-300 kgm. Thats an increase with about 50% with extra weight only 40-50 kg
on the rigth/downside of VCG(vertical center of gravity). Are someone of you interested doing the same so we could lower the production cost?

[tewharaunz]

Maybe I'm a bit cynical, but those look very high tech. Isn't putting one on a Mac like putting a Formula 1 spoiler on a minivan? Of course, if you do it, I'd love to read about it

[Dragos Filimon]

what is a lee-ving ??

[NiceAft]

what is a lee-ving ??

Here you go Dragos.
http://www.dynamicstabilitysystems.com/

All power to the internet and Google search.

Hey, my initial response to Bertil Rafting's post was WTF is a lee-ving


Ray

[grady]

I has to be fast look at that spoiler1

[Dragos Filimon]

They fit better on the car then on a mac. They should put a lot of stress on the hull.

[Max Entropy]

looks like it would have to be built into the hull, which would need significant reinforcement. A Mac's hull is way too lightly built to stand those loads, and there's no easy way to reinforce it either.

[Jimmyt]

Lee-ving : what you're doing after you've been there long enough...

I guess "water wing for your boat" didn't have a marketing ring to it. Really an interesting idea - an invisible outrigger that appears to slide back and forth through the boat to give lift on the leeward side. I'd have to sail with one before I would think on it much. Very invasive mod with moving parts. Appears to add overall width - which for me is a deal breaker as I trailer to the water every time.

Have you seen one on a 26 foot boat? The site shows some larger boats. More importantly, have you sailed on one?

[grady]

They are starting to put a lot of foils even on monohuls. However they are racing boats and go 20 to 30 kts where a foil can realy start producing a lot of forces and provide more lift than drag. Not saying it won't improve performance but at 5kts it is going to be marginal. Below is a picture of what they did to Wild Oats.

[BOAT]

Ok, I get it now - it's a "wing" that goes on the "Lee" side of the boat. A "Lee" "Wing".

Yes, if you put in another daggerboard trunk in the MAC it's doable. The reason the Vertical Daggerboard Trunk is so great on the MAC M boat is because it's completely water proof - you can turn the boat upside down or any which way and the Dagger Board Trunk does not let any water into the boat. All of us that sail the M boat understand that concept - it's a great peice of simplicity that improves the M boat over the X boat by eliminating metal parts, holes in the hull, maintenence, and is completly safe.

Take the same concept - the Vertical Daggerboard Trunk, and just TURN IT SIDEWAYS - the HORIZONTAL Daggerboard Trunk - and now your talking about the concept of a "Wing" on the "Lee" side of the boat.

Because the trunk is totally water proof just like a vertical trunk - it's safe, but also VERY STRONG. Just the concept of building a vertical trunk that goes from port to starboard instead of from top to bottom, would make it very strong.

Then you add the simple idea of a "wing" (a daggerboard) that slides back and forth in that trunk and you have a really nice way to control the degree of heel on a sailboat - it's a great idea. Imagine the lift it could add to the lee side too - pretty incredible gadget. As the boat tries to lean over the wing is pushing the boat back up right by actually lifting the low side of the boat into the air!

If you did this on a M boat the "horizontal" trunk would need to be part of the ballast tank about two feed behind the daggerboard. The M boat hull is actually one of the strongest hulls in production below the waterline because of the ballast tank - this actually would work on the M boat.

[Highlander]

ok Boat so when r u gonna make me one !!

J

[Ixneigh]

I don't think those are a good idea on a Mac.
If you want that speed get a pogo thirty.

More foils collect more seaweed. Performance ends up in the basement.
Those foils aren't just done by eye. They are very precise. And they don't like seaweed. I found this out with the Ida rudders quickly. How are you going to clean off the seaweed?


Retractable foils will cost more then the boat if installed correctly. Plus they will intrude on living space.
Fix foils will require a nasa approved study to see how they will impact boat handling under various engine and trim settings. Perhaps the pentagon has a set of hydrolic adjustable foils they will sell you for a billion or so.

Fixed foils will also require a custom built trailer.

The boat will need to be rerigged once the safety factor of heeling is changed. The macgregor system is such that no part is stronger then it needs to be, once you change something, other things are going to be impacted. Don't forget new chainplates, and thickening the hull in that area.

Ix

[BOAT]

The wing is the same length as the width of the trunk it sits in. That means the wing fits completely inside the horizontal trunk - there is nothing sticking out at all until you slide the wing to the port or the starboard - then you have SOME of the wing sticking out of the side - but MOST of the wing is still inside the trunk. It works the same way our daggerboard trunk works. Our daggerboards fit completely inside the trunk when retracted. The wing will clear seaweed just like the daggerboard does - you just retract it. I would only expect about 24 inches of the wing to be exposed for a boat as light as the MAC.

I don't think this would be a gadget for speed on a MAC - I think it's more of a gadget to improve the heeling and keeping the sail plan more upright to allow better pointing and so forth. There may be some speed added in high winds but that would mostly be from upward lift - and that is really the weak link in the design - the wing could break under the load of trying to lift one side of the entire boat up higher in the water - it's like as if you put a stick in the side of the boat and tried to lift - the hull would not break - the hull is more than able to handle it's own weight at any single point - trailering the boat on only two trailer bunks is more than proof the hull is plenty strong enough - the problem is not the hull - it's the wing - under such a heavy load it may break. And in regards to trailering it makes no difference to the trailer anymore than our daggerboards - when fully retracted in the trunk there is no hindrance to trailering. The wing would be too weak to damage the hull.

And that is the only weakness actually mentioned in the website by the designers - they say that IF it breaks you are just back to a normal boat with no wing. (But that means they have probably already experienced a break). I suspect they mention it because they already know.

The freeboard is so high on the MAC that to get the wing down in the water where it needs to be you need to mount it nearly right on the bottom of the boat. The wing would go under your feet inside the ballast tank - there would be no change to the headroom or any room in the boat - but I think you would loose about 40 gallons of ballast.

I'm not suggesting that we modify the MAC for a wing I'm just saying that if this were part of the original factory configuration I think it would have worked. The idea seems sound to me. The only way would indeed require a full factory redesign - but if Roger were a young man of say 45 and still building boats - it might be something to consider in his next model.

[Jimmyt]

Ok - maybe it will fit in the boat width. Look at the curve at the end (to get the lift). Makes for an interesting trunk design.

[Bertil Rafting]

Thanks for all your comments. I will try to give some answers:
-"BROR" understand how it works. Except he had not said anything of the weigth of the boat that is also seemingly decreased when using the wing. Some of the power lifts the boat.
-The wing is sitting in a casette aboat 2 inch high and about 1,5 foot wide on the floor after the center board, so it would not take much space.
-When the wing not in use it is in the casette. Length of the wing is the same as the Mac is wide where the wing sits.
-On the website dynamicstabilitysystems.com you you can videos from small boats (26 feet and more) using the wing. I have never sailed one with the wing. There isn't any here in Sweden.
-The boat stops leaning with 10-15 degrees and is going smoother in waves.
-The mast on Mac is overstrong, Mac is very weak with only a little more than 500 kgm RM30 so I do not think I have to change it, but i am not ready yet with my calculations.
-When the wing is in action it is about 1 m(40 inch) outside the hull.
-I will come back to the forum as things develops.