pivot keel mechanism

[gja]

I am working with a french architect on a 36´aluminium fast cruiser.Hull lines are drawn,sailplan is drawn and interior is on its way.I have decided to fit a pivot keel which allows me to bring the draft from 2,80m to about 1m,being able to rest the boat on its keel and stabilize it with the two rudders.the first drawing had 1500kg lead at the bottom.lifting keel will have probably the same weight.question is:does anyone have a drawing of the mechanism used?I know the way it works (pulleys or screw)but would like to find something that is safer in case of impact.usually the screw bends and you end up having the keel blocked half lifted and loose stability.I doubt pulleys would work with such a load.I am not sure pivot keel is the correct word.to make things clear:the same as on class 8´s or first 27 (beneteau) but just bigger.boat will be 36´,3m80 wide,aprox.displacement 5000kgs.42sqm mainsail,38sqm genoa,100sqm spinnaker.arquitect is www.rolland-archi.com.you´ll see on the main page the outlines of the boat.

[ted655]

"swing keel"... US term
I'd have a redundent system. A cable with eye I could attach a ratchet lift (come-along) to & an overhead hook point. If keel screw fails, then attach the backup to the eye, disconnect the upper screw pin & and hoist up the keel, & bent mechanism.
If all this was to fit inside a seachest, then the cover could be removed and a repaired screw could be replaced back without hauling the boat.
But what do I know1 Just a thought.

[gja]

SWING KEEL...thanks for the tip.that was the idea I had.I would even think of a system where you disconnect the screw as soon as the keel is in position,fixing it with some kind of pin calculated to be cut with a given load(impact).

[ted655]

+++"some kind of pin calculated to be cut with a given load(impact)."++++
A "shear pin" much like the old outboard props used.
Another design might be a method where the top attachment of the screw wold "slide" through the hole of the attachment point, IF the keel were to hit & lift up when it hit an obstruction.