Big wind continued - centerboard focus

[Brian]

I've always raised CB on downwind to reduce drag when I'm looking for max speed, but kept it full down upwind, thinking this max's the ballast/righting moment, min's the sideways motion thus helps optimize point as well as speed. The Jobson fundamentals book I have has an interesting small boat technique for upwind in heavy weather that I've been wondering about since i got the 240. My interpretation of this is that the CB essentially counters the sideways motion and that this basic resistance factor plays a huge part in how much your boat heels over. He suggests cranking it up a few inches thus reducing the CB area will reduce the heeling and hence the weather helm (keep in mind that he is probably referring to the type of smallboat CB that raises straight up and down and not a swing type CB. I assume the cost of doing this is you will lose more ground to leeward. But, since you can't really reduce 'area' in the same manner with a swing type CB, plus you affect the righting moment, I've always shrugged this off as impractical for my boat's CB - BUT, i've never tested it just to see what happens! Any thoughts? Anybody nuts enuf to try this yet? I'm real curious...Could use a little guidance on your CB trim techniques in general - when do you all play with the CB?Thanks! Brian

 

[Wanderer138]

Swing keel can reduce weather helm

Swing keels have the pivot pin near the leading edge, so as you pull the keel up it also swings aft. The aft movement of the keel shifts the center of lateral resistance of the hull (CLR) aft.Among other things, weather helm is attributed to the center of effort of the sailplan (CE) being aft of the CLR. For various reasons, most sailboats are designed with some weather helm. Most people counteract weather helm by moving the CE forward, e.g. by reefing or luffing the mainsail or reducing mast rake. Moving the CLR aft by pulling the keel up a bit is a simple way to accomplish this result without upsetting the sail trim. As you rightly pointed out, the cost of this move is increased sideslip. It's just a question of how much you can live with.PeterH23 "Raven"

 

[Andy Komorowski]

Try it

I have been sailing my H22 swing keel model with the keel swung up about half-way for about two years now. This started because of the low water level in Lake Erie, and we didn't want grounding around our marina and slip. Later found this to reduce weather helm as well with no noticeable side slipping. On the H22 there's no significant weight to the swing keel for ballast, so no stability is lost either.Andy,S/V Super-K

 

[michael]

racing tricks, centerboards

I've tweaked just about everything to get more speed out any boat I've ever owned and playing with the centerboard is definitely one of them.You're going downwind and a following sea; lower your centerboard a couple of inchs to give it some grab to keep you from sliding off off waves as you surf.Things like that.Play with it. Oil it up and get cranking! Have fun.Good sailing.