Why is the rudder ineffective in steering the boat?

[Snowpetrel]

I guess you have the main up as well as the jib, if it was just the jib then thats likely the issue. Other than that I can only think that the CB is jambed and was never down properly as I dont think a ballasted board like the sonata would raise itself underway.

[roland stockham]

How broad is the transom and how much heel are you getting. Some lightweight broad stern boats with a single rudder can have this problem at 15-20 deg heel. Basically the rudder comes out of the water so no steering

[Learning Curve]

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

Its a swing keel. Lead I presume. Boat spec says 409kgs with a adraft of 1.5mtrs once down. Having just looked that up I now realise the swing keel can go much lower than it is so I'll have to see if it's stuck. If it's not down all the way this could be the problem.

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? Not sure what the tiller would do if I let go I'll test that out this weekend.

This info will help diagnose the situation

[Learning Curve]

Originally Posted by 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.

Thanks Don, No unusual noises. Jib only sailing for now whilst awaiting the main to be repaired. No heeling at that speed. I will be checking the keel is fully down and also trying with the main up in case it's a sail balance issue as well. It's got me buggered why it's happening! It may not be so much the rudder isn't working as apposed to the boat getting pushed away from th ewind from the bow with just jib up, keel not fully down and being so light.

[Learning Curve]

Thanks for the eadvice and links. My keel has a winch and gravity keeps it down being 407kgs. it does however only look to go down about 45degrees so may be stuck.

[Jim Cate]

Jib alone? I didn't pick that up in your earlier posts. That could indeed cause inherent lee helm... but it would be the same on both tacks, so I'm still a bit perplexed.

Jim

[thomm225]

Originally Posted by 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

You probably have just forgotten what it's like to be totally new at sailing.

It's like magic at first when you sheet in the sail a bit and the boat actually starts to move .....

[Snowpetrel]

Originally Posted by Learning Curve

Thanks Don, No unusual noises. Jib only sailing for now whilst awaiting the main to be repaired. No heeling at that speed. I will be checking the keel is fully down and also trying with the main up in case it's a sail balance issue as well. It's got me buggered why it's happening! It may not be so much the rudder isn't working as apposed to the boat getting pushed away from th ewind from the bow with just jib up, keel not fully down and being so light.

Jib only is almost certainly the major cause of the lee helm, prehaps made worse by the keel not being fully down.

Jib only sailing can work in steady condtions, but in gusty stuff the boat can get unmanageable when boatspeed drops. And then a puff comes through especially if the headsail is sheeted in too tight.

[Kudu]

Jib only is 95% sure your problem. Sailing with jib alone only works well with fixed keel boats and large,overlapping jibs. More than likely your jib is not of the overlapping or "Genoa" size.

Wait till you get your main on, and all will be well.

In the meanwhile do some research on "sail balance", which really means aligning the air side forces with the underwater side forces. The rudder is only a trimming device, you have to get the main forces lined up first.

[Don C L]

All well and good but it still doesn't account for what sounds like it happening suddenly on port tack only. Maybe when it is that on port tack all the crew goes forward to get in the shade of the sail on the foredeck on a sunny afternoon and the rudder lifts out of the water.

[messias]

Originally Posted by Snowpetrel

Jib only sailing can work in steady condtions, but in gusty stuff the boat can get unmanageable when boatspeed drops. And then a puff comes through especially if the headsail is sheeted in too tight.

+1 here.

That situation used to happen with my previous boat (and was a fin, not swing)
First time it happened I even thought I had lost the rudder to the bottom, as it suddenly had no pressure at all (it was a pierced through rudder, so I was not able to check if it was still there until it got a grip again )

I honestly think it will happen on both tacks... just didn´t happen yet.

[boatman61]

I do a lot of jib only sailing and I have never experienced this phenomena.. even less so just on one tack.
I would be looking more at the keel for the solution.. does it come all the way up, is it all the way down.. is there a deformation in it.. is the pivot bolt hole worn on one side causing it to twist just one way under load.
How does the boat behave with the board all the way up.. apart from not pointing as high.

[thomm225]

Originally Posted by Learning Curve

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? Not sure what the tiller would do if I let go I'll test that out this weekend.

You shouldn't have to let go of the tiller.

You should always be pulling the tiller toward you a bit when sailing upwind (or on a beam reach) to compensate for a bit of weather helm which is what you want

If you don't have weather helm, then your mast is probably leaning forward too much and/or your rig is way out of adjustment.

The problem though is most likely sail trim......especially since it's only on one tack

[chris95040]

Well, the OP said they've observed this on a port tack, not that it definitively *only* happens on a port tack, right? So I'm going to assume that aspect of this was a red herring.

Learning Curve, at some point in the near future, with a little more experience, I think you'll chuckle that you left out the fact that only had the jib up!

Keep in mind that with just the jib the boat is going to want to rotate off the wind. (The bow is being pushed sideways. ). Also keep in mind the rudder's effectiveness is dramatically impacted by the boats speed through the water. If you get a little too close to the wind, you'll lose your speed, your rudder will be ineffective, and with jib only the boat will fall off the wind.

If its really just happening on one tack, take a careful look at what might be asymmetrical- how tight you are sheeting the jib, the location of the jib blocks/cars, the water current?

[thomm225]

Looks like that "small" detail about sailing with jib alone was left out of the opening post.

This pretty much answers the question.

And it goes back to the fact that you can drive/steer the boat with sails alone with proper sail trim especially on a small light boat like the OP's