Two Questions Regarding Draft and Stability

[boatman61]

Originally Posted by barnakiel

Hmmmm...

Just asking.

Downwind the board is up but maybe not all the way up?

I can remember my Finn broaching wildly with the board fully up. Lowering the board a bit helped a lot.

Hove to the board will have to be down perhaps?

I mean - if you keep it up then how do you keep the boat hove-to? Will she not bear off?

barnie

The only 'planing hull' drop keeler I've sailed is the Oceanis Clipper and she hove to keel up just fine... the ballast wing keel and balanced sails kept her pointed ok, apart from when the odd wave from another angle would knock her of a bit... but that happens in most every boat....
Running before the wind with the board up is actually recommended by Beneteau... the owner, who crewed on this delivery trip decided to drop the board without telling me... we were running East before a F6 NW along the Algarve towards Faro under full main and Genny.... next thing I knew a quarter wave had lifted the stern and she just pivoted... nothing I could do in spite of rapid opposite lock.... luckily the waves were only about a metre high and no damage was caused but from running at 8+ knots to caught in the irons in less than a minute is not an experience I care to repeat...
EVER.
After some slightly undiplomatic language from me... and the board back up we resumed the last leg with no further incident...
The older conventional designs are pretty much similar in many ways but a bit more forgiving

[Adelie]

Originally Posted by barnakiel

Downwind the board is up but maybe not all the way up?

I can remember my Finn broaching wildly with the board fully up. Lowering the board a bit helped a lot.

I assume you are referring to the Finn dinghy. The hull on the Finn is very rounded and smooth. With board up there is almost no 'bite' on the water in the foreward half of the hull. Board down a bit cures that for downwind sailing.

In a centerboard keelboat, there is a keel under the boat which is generally a bit shallower than a comparable full keel boat, say 4' draft instead of 5' for a 35' long vessel. That keel provides enough 'bite' for good steering from downwind up to a reach. For a high close reach or close hauled it wouldn't be as efficient as the deeper hull except for the centerboard which generally is better upwind than the comparable regular full keel boat. On the other hand the higher placement of ballast in the centerboarder means you need to start reefing earlier than the comparable fixed-keel boat. My guess if performance is probably similar averaged over the whole range of possible conditions. Individual boats may vary

Originally Posted by barnakiel

Hove to the board will have to be down perhaps?

I mean - if you keep it up then how do you keep the boat hove-to? Will she not bear off?

Hove to I would imagine the board all the way up is probably best, a wave hitting the boat side on would skid her more easily across the water with the board up. With the board down the boat would roll farther before starting to skid.

As far as directional stability while hove to, remember there is a keel foreward, it's just not as deep as a regular boat would have.

Check out the underbody in the line drawing for the Tartan 34C, you can see that there is a shallow keel that the centerboard pulls up into. A headon view would show it better, alas.
TARTAN 34 C Sailboat details on sailboatdata.com

[wolfenzee]

What you seem to be looking for pretty well describes my boat, 30'LOA/25' LWL/8'9" beam/ 5' draft weighing in at around 17,000lbs. She is quick in a light air while solid in nasty seas, designed to be easily single handed. (The rig has been modified: foot of main was shortened to 15', jib boom removed and forestay moved aft of windlass to allow for a cutter rig.)

[beau]

A friend of mine who has circumnavigated three times has his solution to bad weather.
Now he does have a tried and tested, Roberts 43 steel mono.
He just pulls down all sails, goes below, closes the hatch pulls out a bottle of rum and a good women and goes to bed until it is over.
Works for him

[NotQuiteLost]

Originally Posted by beau

A friend of mine who has circumnavigated three times has his solution to bad weather.
Now he does have a tried and tested, Roberts 43 steel mono.
He just pulls down all sails, goes below, closes the hatch pulls out a bottle of rum and a good women and goes to bed until it is over.
Works for him

It doesn't get much better than that I love having a ketch rig, because I can 'heave to' with just the main and mizzen, making it much quicker, simpler and easier to adjust since I never have to leave the cockpit for anything. My standing rigging would chafe my headsail sheet anyways.

I recently installed some heavy stainless eyes on the deck to attach my cutter blocks to, for optimal shape and angle, so that might be a way to go in the future. I really wanted to hold out for matching car tracks to put up there, but one of the great things about steel is you can modify it pretty much however, and whenever you want to. And I couldn't afford the wait on the tracks.

[barnakiel]

Adelie _ THX for explaining the issues. Yes, I think in the broad context of many different hulls it is all true.

Originally Posted by Adelie

In a centerboard keelboat, there is a keel under the boat which is generally a bit shallower than a comparable full keel boat.

You are right. I think, however, that some hulls do not have the false/half keel - e.g. Ovni or Southerly.

Originally Posted by Adelie

Hove to I would imagine the board all the way up is probably best, a wave hitting the boat side on would skid her more easily across the water with the board up. With the board down the boat would roll farther before starting to skid.

Yes. But I think when the waves are already breaking (they have to be, if the boat is skidding) it is no longer time to be hove to. I think when hove to, the major danger is if at any point the boat is beams on to the waves - exposing all the topside to the full energy of the white water.

I agree that the skidding or sliding plays a role in dissipating the energy, but given the fact that the momentary velocities of water in the rolling crest can easily exceed 2x the wave speed (which can be easily well above 20 knots in a good blow), it does not sound like the best storm tactics to get hit by a mass of water traveling at up to 50 knots.

And it only takes one wave. Do not ask me how I know ...

barnie

[barnakiel]

Originally Posted by wolfenzee

What you seem to be looking for pretty well describes my boat ...

Beauty!

b.

[barnakiel]

The boat,... ;-)))

b.