Why is the rudder ineffective in steering the boat?

[Learning Curve]

Hi All,

We are having problems understanding why, when under sail on a port tack doing about 4-5kt in a 10-15kt wind... on a beam reach then all of a sudden we can't hold a bearing, the bow turns off the wind and puts us in a broad reach. I don't get it. We cant hold positon or steer closer to the wind aiming to be close hauled

I'm suspecting my swing keel is either riding up, the boat is just too light or I haven't got the swing keel all the way down making me lose that counter force of the keel?

Thoughts as to why this is happening?

It's happened twice now and left us precariously close to a lee shore needing to then start the engine for maneuvering, then of course she steers beautifully.

(It's a 23ft Southern Cross/Sonata 7)

Thanks

[malbert73]

If happens all of a sudden it’s almost certainly due to your centerboard/swing keel stalling. So yes, if not down all of the way this could happen, or if it rides up. Or if you’re trying to pinch too close to wind (although if you’re doing 4-5 knots that’s less likely. Do you have a clamp to hold down the keel?

[deltaten]

Speed falling off during tack,with little water movement over the rudder = no"bite"? I've found tacking wit the tidal flow/current ; even at reasonable speed results in same. Takes a few moments to recover (relative) speed and gain steerage.

[Jim Cate]

Couple of additional questions:

Does this only happen on port tack as you seem to indicate? That's really odd if so!

Is this a swing ballast keel or a swing unballasted centerboard?

When sailing along under these conditions, BEFORE the loss of control, what happens if you let go the tiller? Does she go straight, turn upwind or turn downwind?

This info will help diagnose the situation.

Jim

[fatherchronica]

It is not quite the same thing, but I once traded some stuff for some other new to me stuff which included a little fiberglass dinghy. It was impossible to point on one tack and wanted to broad reach. It turned out on closer examination, the first day I sailed it, that the centerboard trunk was about 3/4 of an inch ( that is some unknown amout of millimeters in Northern California) out of alignment with the centerline. Being young and not having learned how easy fiberglassing is, I built a new centerboard that was shaped to nearly compensate for the flaw, if you put it in correctly.

[Cheechako]

I had this problem with a 31 foot boat I spent 2.5 years building from a hull and deck. When new, I actually broke the steering cable/clamp trying to turn the boat. It would not turn. To this day I do not know how it could have been solved. I rigged a bowsprit thinking it was a sail balance issue., it didnt help. The boat had wide flat aft sections and a deep sharp V forward of the keel. In the end I figured it was a hull shape issue.

[Don C L]

Very odd. I am going to assume this is for real, but what you describe doesn’t fit the description of a rudder stalling. First of all do you hear any clunking in the keel, is it riding up at all and how is the rigging tension? Whether the keel is all the way down or not does not affect the rudder, but it does affect leeway. So I am wondering about the “4 to 5” knot speed. The rudder will do its job if it has water flowing over it and the boat is not heeling more than 35 degrees or so. Perhaps you have 1 knot of headway and 3 knots of leeway, if the keel is riding up, and especially if the main sheet car on the traveller is pinned to the port side and the main is sheeted in tight and flat on the beam reach. On stbd tack it will sail better than port if that is the case but still not well.

[Cadence]

Is it possible you has a sail trimming problem? at times sheets are better than a tiller.

[FabioC]

You must be experiencing increasing lee helm (the boat has a tendency to bear away, and you need to correct it with the tiller) before this happens.
This happens when the rudder eventually stalls. The Center of Resistance (CR) is more astern than the Center of Force (CF) and the boat pivots around the CR and bears away. The momentum becomes too strong to counteract with just the rudder.
You should be able to correct it with a combination of controls: 1. lower the centerboard (which should move the CR forward), 2. ease the jib, 3. trim the main, 4. power up the main by cranking the vang, trimming the outhaul, etc. (depends on the boat).
If this happens on one tack only, one should also check the tuning of the rigging. It may be that the mast bends much more on one tack than on the other (for example, one of the shrouds is tighter than the other) and depowers the main on one side much more than on the other (or depowers the jib on one side more than on the other, so you only notice it on one side).

[swampbush]

Originally Posted by Learning Curve

Hi All,

We are having problems understanding why, when under sail on a port tack doing about 4-5kt in a 10-15kt wind... on a beam reach then all of a sudden we can't hold a bearing, the bow turns off the wind and puts us in a broad reach. I don't get it. We cant hold positon or steer closer to the wind aiming to be close hauled

I'm suspecting my swing keel is either riding up, the boat is just too light or I haven't got the swing keel all the way down making me lose that counter force of the keel?

Thoughts as to why this is happening?

It's happened twice now and left us precariously close to a lee shore needing to then start the engine for maneuvering, then of course she steers beautifully.

(It's a 23ft Southern Cross/Sonata 7)

Thanks

We used to have a Sonata 7 just up the road from you at Lake Macquarie. It always seemed better balanced with our jib rather than a genoa up. Our keel had a rope that helped lock it down. Sometimes the rudder would also come up if it slipped on the rope jammer that held it down. There are also two rudder lengths on Sonatas. I was told ours was the longer racing one. Talk to the sonata association http://www.sonatayacht.com or ring or join the Newcastle and Hunter Trailer Yacht club up the road from you. People there know huge amounts about this popular boat and are willing to help. http://www.trailersailer.org

[catsketcher]

IIRC the Sonata needs a winch to get the keel up, but it does pivot. It is not a daggerboard style keel.

It seems as though you are losing flow over the keel. The only time I have had a boat do what you state is when we have broken a board. I can't see how the keel is riding up on its own. But the boat will be old now and may have had some work done on it. The board may be damaged and ventilate, but it shouldn't really do this in 10-15 on a reach.

If your board is unballasted it may be riding up. Is it easy to wind the winch to raise it? I have some friends with a Sonate 7 and they have sailed it around the Whitsundays fine - the design seems fine.

Jump in the water when the keel is down and have a look. Check that it can't swing aft. The Sonata should have a fair bit of weather helm and not massive lee helm. You can talk about them here

Newcastle Hunter Trailer Yacht Association

and here

trailersailerplace.com.au

cheers

Phil

[Stu Jackson]

Originally Posted by Cadence

Is it possible you has a sail trimming problem? at times sheets are better than a tiller.

My first thought, too. Often skippers will move to a beam reach and not realize just how much their sails need to be let out. I've been [repeatedly!!!] guilty of this!

Good luck.

Jim's questions are very pertinent, too.

Edit: My reading comprehension 101 is poor today, sorry, you were on a beam reach already. Doh!

[thomm225]

Originally Posted by Cadence

Is it possible you has a sail trimming problem? at times sheets are better than a tiller.

I'd say most all the time the sheets are better than the tiller......

If it's not a centerboard problem, it definitely could be sail trim. He may not have sheeted in his main enough

Also, he doesn't say whether or not he has lee helm under normal circumstances.

His rig and mast could be way out of alignment, but since he mentioned 'on port tack' I'm thinking he may have not trimmed the sails properly

This is where beach cat racing helps you better understand how sail trim affects the boat because on a crowded starting line you have to hold your boat pretty much still mainly using sails only without going over the line sometimes for a minute or two depending on how early you arrive to claim your spot

[ZULU40]

Originally Posted by Cadence

Is it possible you has a sail trimming problem? at times sheets are better than a tiller.

balance between centre of effort and centre of balance
sailing overpowered

[Jim Cate]

I'm having a very hard time imagining what possible error in trim can cause uncontrollable lee helm when reaching in 10-15 knots of breeze. Further, it's hard to imagine why one would only make this error on port tack. Finally, it's hard to imagine a rig being so badly tuned that it would cause such a dramatic failure of control... and only occasionally at that.

Perhaps my imagination is lacking...

Jim