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SoFastSoSlow

Super Theoretical... Replace keel ballast possible?

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Newb question...

Isn't it theoretically possible to completely replace keel ballast with windward water ballast?

I know I know, you would loose the ability to self right, and you would have to make sure you have the windward ballast filled...

But, theoretically, can't the righting moment created by the lead ballast be more than offset by some water ballast?

Perhaps a compromise can be made to keep just enough keel ballast to self right, but use adjustable ballast (water or otherwise) for righting moment when sailing?

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lots of boats use water ballast for righting moment, generally to replace crew on the rail. Most boats still have enough ballast in the keel to right the boat in a full knock down. 

Now many boat classes prohibit any moveable ballast except for crew weight, and all ratings penalize water ballast unless you certify you will not be using it when full crewed.

See Riptide boats, quest and aerodynes, madrona,, older open 60s open 40s etc.  

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G32, has no lead only water, and she is self-righting.  It was great fun to yell to my son "empty the tanks", when tourists became pesky at the launching ramps.  Cleared out those not in the know.  Aloha, Guerdon.

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9 hours ago, SoFastSoSlow said:

Newb question...

Isn't it theoretically possible to completely replace keel ballast with windward water ballast?

I know I know, you would loose the ability to self right, and you would have to make sure you have the windward ballast filled...

But, theoretically, can't the righting moment created by the lead ballast be more than offset by some water ballast?

Perhaps a compromise can be made to keep just enough keel ballast to self right, but use adjustable ballast (water or otherwise) for righting moment when sailing?

Keel bulb ballast and water (windward) ballast serve 2 different purposes on a sportboat.  water ballast serve the same purpose as crew - trying to keep the boat flat.

Keel ballast keep the boat from falling over at the dock and keeping the boat from turtling in a knock-down.  If you are sailing the boat right (very flat) the keel ballast wont ever help you with speed - at the low heeling angles you sail the righting moment gained from the keel is minimal

 

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you can replace all the keel ballast, hell, the keel itself, for another hull, paralell to the first one and connected to it by beams - it's called a catamaran, but  then you'd have to move this thread to multihull anarchy..;):P

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On 11/25/2017 at 6:45 AM, Trovão said:

you can replace all the keel ballast, hell, the keel itself, for another hull, paralell to the first one and connected to it by beams - it's called a catamaran, but  then you'd have to move this thread to multihull anarchy..;):P

Hahahah of course of course but then I wouldn't be a proper sailor! :lol:

 

On 11/24/2017 at 8:38 PM, Christian said:

Keel bulb ballast and water (windward) ballast serve 2 different purposes on a sportboat.  water ballast serve the same purpose as crew - trying to keep the boat flat.

Keel ballast keep the boat from falling over at the dock and keeping the boat from turtling in a knock-down.  If you are sailing the boat right (very flat) the keel ballast wont ever help you with speed - at the low heeling angles you sail the righting moment gained from the keel is minimal

 

So that's my point right there, keel ballast does nothing for righting moment when flat, hence why sailboats NEED to heel.

Instead, why not have 100% righting moment at 0 degrees of heel, with windward water ballast? (never mind multihulls of course...).

I ask because you can make a monohull much lighter, cheaper, and trailerable compared to a multihull... if you could only get rid of the damn lead!

P.S. Foils, like the new AC boats, are for another discussion of course (another form or righting moment, "dynamic RM" if you will.)

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16 hours ago, SoFastSoSlow said:

Hahahah of course of course but then I wouldn't be a proper sailor! :lol:

 

So that's my point right there, keel ballast does nothing for righting moment when flat, hence why sailboats NEED to heel.

Instead, why not have 100% righting moment at 0 degrees of heel, with windward water ballast? (never mind multihulls of course...).

I ask because you can make a monohull much lighter, cheaper, and trailerable compared to a multihull... if you could only get rid of the damn lead!

P.S. Foils, like the new AC boats, are for another discussion of course (another form or righting moment, "dynamic RM" if you will.)

 

define "proper" ;)

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Just enough lead in the keel to right from a knockdown and DSS foils* for tremendous additional righting moment--much lighter than water or lead........

* 1- DSS 1=foil assist

2- DSS-2 = full flying on the right boat

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