Keel Placement

[usa2]

why would you want to move your ballast fore-and after though. The only reason i would see fit to do it is you are building a downwind flyer to lift the bow up. there usually isnt any reason to move it for and aft.

[Alixander Beck]

Originally Posted by Tim B

Basically, it's the first place the boat will leak. being as it is, pretty much at the deepest point.Tim B.

Im thinking of something on a 5 meter or smaller with a fin keel and ballast in soemthing similar to a centreboard trunk, enabling the keel it move forward and aft but without pivot.

I dont think this will cause leaking as there are thousands of boats with centreboard trunks.

[Alixander Beck]

Originally Posted by usa2

why would you want to move your ballast fore-and after though. The only reason i would see fit to do it is you are building a downwind flyer to lift the bow up. there usually isnt any reason to move it for and aft.

Thats essentially what I was asking.
Is there a practical use to a keel that can move forward or aft? I think the use could be to balance the boat in terms of CE and CLR instead of using only the mast rake and rigging to correct/induce this. Additionally it would be easy to remove the fin keel for trailering and more importantly to change keels to compensate for weather or crew ballast for example.

[Karsten]

On a boat smaller than 5m you wouldn't need a keel. The weight of the crew is more than enough to keep it upright. You can also move the crew weight aft for downwind sailing. The weight of the keel is only going to slow you down.

[SuperPiper]

Moving keels forward and aft is common in the Mini TransAt class. Nothing is taboo to these guys.

http://boatdesign.net/forums/attachm...achmentid=2385

[tspeer]

Originally Posted by Alixander Beck

Thanks for all the input and ideas.
...
I am working on a design that would allow a high aspect keel to be moved forward and aft on the hull and as I have not seen this design before I wonder why? ...

It's been done on Mini Transat's. There are designs that allow the keel to articulate side to side and also move fore and aft.

[Alixander Beck]

So would the benefit of a sliding keel be that it could be moved forward and aft to trim the Helm while under sail instead of trimming the rig to acheive the same result?

Also I assume it would be moved to its aft position on runs and conversly moved forward when beating, finally being moved finely to find the right Helm groove in any point of sail.

Are there any other advantages that I am missing?