rudder control with severe heel

[cpthook]

As a novice I've heard that at severe angles of heel the rudder stops responding.
I was wondering about the sort of heel angle at which this starts to occur? Last year
I had water up to the lee rail and was a little worried about this. Presumably the
best way of avoiding is to reef early but what happens if you get caught out
heading for a shoal? Do you ease the sheet on the genoa (the boat I use warns
against furling the main unless head into wind)?

 

[Guest]

>As a novice I've heard that at severe angles of heel the rudder stops responding.
I was wondering about the sort of heel angle at which this starts to occur?


Depends on your boat. The rudder will stop responding when it is either no longer in the water or is too shallow to grip properly.


> Last year
I had water up to the lee rail and was a little worried about this.

Nothing much to worry about, when the rudder loses grip the boat will naturally round up head to wind.

>Presumably the
best way of avoiding is to reef early but what happens if you get caught out
heading for a shoal? Do you ease the sheet on the genoa (the boat I use warns
against furling the main unless head into wind)?

If you need to lose heel quickly drop the main sheet, this will lose all power from the main. If you want to prevent a lot of heel reef the main early and then take a couple of rolls in the Genoa if necessary. Also watch you aren't sheeting in your sails too much, this will cause heel. When the wind gets a bit fresh you can also tighten up your halyards and kicking strap to flatten and depower your sails.




Regards,

Peter
http://www.mistressofmourne.com

 

[AndrewB]

This tendancy to lose rudder control is called 'broaching', and ends with you rounding up into the wind with the sails shaking. It happens to all yachts, though some are worse than others. If the spinnaker is up it can cause all sorts of chaos.

Four things may cause the rudder to stop responding when you are over on an extreme heel.

1. The rudder may be mostly out of the water, or in very turbulent water near the surface.

2. The rudder may 'stall out' and be ineffective, particularly if it is long and thin, and turned to a considerable angle.

3. The hull shape may promote uncontrollable weather helm at extreme angles.

4. The sail plan is unbalanced with heavy weather helm, which is most noticeable when close reaching in strong winds, when you would be over at an angle anyway.

Correcting by hauling the helm hard over is never a good solution, as it tends to brake the yacht and may stall out anyway. The quick way to restore control from a mild broach is to let out the main sheet, NOT the genoa.

The real answer is not to sail at extreme angles of heel. This is a matter of technique. Few yachts sail well with water coming over the lee rail. As many books on racing point out, one of the key differences between the guys at the front of the fleet and those at the back is that those at the back are invariably over at a larger angle of heel.

For cruising, as you suggest by far the best thing is to reef down, striking a balance between the sails to reduce this tendancy to round up. The amounts to reduce each sail is a matter of experimentation. Against the text-book theory, it often helps to take a bit off the genoa first, as this is more effective at bringing the yacht upright.

Although most mainsail reefing systems do need you to turn up to wind, you do not necessarily need to turn right head-to-wind. It is usually possible to reef from a close-hauled position, with the main eased off but the yacht still sailing on the genoa. Its worth practicing this manoever as the ability to shorten (and restore) sail quickly is very confidence-building.

 

[Chris_Stannard]

Agree with feathering the main in an emergency. Another way to depower the main is to take the traveller up the track and ease the sheet and kicker. The bottom half of the sail will be working but the top half will not, which reduces the angle of heel. In the same way moving the genoa cars farther aft will depower the top of the genoa.

The problem is that as you heel the underwater shape of the boat changes and it requires more rudder to keep on course. The rudder also causes the boat to heel towards it, so that for example on a starboard tack with ten degrees of weather helm some of the heel wii be caused by the rudder. If a gust now hits you you heel more and you need more rudder to correct the situation, but this in turn adds to the heel, changing the under water shape still further so the boat has a greater tendency to heel. At extreme angles, 30 degrees plus the rudder is beoming less effective due the angle it is at, and if you put more rudder on it stalls and then you have a broach.

The answer is of course to balance the boat with a small angle of weather helm.

A further indication of this can be seen on racing yachts when spinnaker reaching, which is usually when the most spectacular broaches occur. You would think that, with all the power in the spinnaker, that this was the sail to let off. In fact the way to stop a boat broaching in this situation is to let the kicker off the main, this depowers the main immediatley and the boat comes more upright and does not broach. You can try this for yourself on a windy day on a broad reach. Pull the kicker down hard to set the main correctly then let it go and see how the boat becomes more upright and requires less weather helm.

Because of the power in the main I do not agree with rolling in the genoa before you reef the main, I usually have two reefs in before I start to roll mine. But you have to experiment to find waht suits your boat best.

Good sailing

Chris Stannard

 

[oldharry]

Dont worry about it. As others have pointed out, once the boat is lee rail under she will be slowing down anyway, and its time to reduce sail. Rudders dont suddenly stop functioning because of the angle of heel. What can happen if you have too much sail up when sailing downwind is that the pressure of wind on the sail overpowers the rudder and the boat swings round out of control. The same can happen with a big following sea. Its called broaching, and is spectacular and scary, but not often particularly dangerous except that you are out of control and the unexpected can happen to you, the boat or your crew so is best avoided.

The boat will tell you she is unhappy long before you lose control altogether, by heeling over too far, slowing down, griping up to windward and so on, long before you lose control. As soon as you notice that sort of thing happening its time to reduce sail - and many boats go noticeably faster reefed down and sailing comfortably than trying to force them along under full sail and silly angles of heel.

Even in the broaching situation the boat will have been complaining for some time that you are overpressing her, by becoming increasingly difficult to steer and maintain a straight course.

There are, at sea, of course exceptions to every rule - and even those of us who have spent a lifetime afloat can get caught out from time to time. Thats part of the fun of it!

 

[Twister_Ken]

What is said below is good advice, but there's another factor which is particularly a problem with boats with very broad transoms. As the boat heels the downhill side goes down but doesn't sink very far into the water, while the uphill side climbs high into the air. Because high topsides often go hand in hand with broad transoms, this can happen well before the lee rail gets near the water. This heel lifts a large amount of rudder out of the water, making it next to useless. In a steady breeze you can reef to avoid this, but in a gusty breeze you may have the sails reefed to average windspeeds, not peak ones. In which case, gust = heel = broach unless you're staffed-up to dump mainsheet, traveller, kicker etc as the gust comes in. That's one reason why on some of the more extreme short-handed racing boats they have twin rudders, so that one is pointing pretty much straight down from the downhill side when the boat is beating.

The gust,heel, broach sequence happened to a Bavaria we were following last weekend, three times in a row. V. spectacular.

 

[cpthook]

broach downwind

hi

I think I've got my head round a broach to windward - yacht comes head to wind,
sails flog and I imagine you get thrown around a bit as the heel disappears and
she thrashes about a little?

How about a broach downwind? Will she gybe? Will she come about and end up
head to wind and if so, which way? Presumably it's a lot more dangerous? I
remember gybing with main sheeted in hard and it was still an agitating
experience in moderate wind for a novice. Presumably an unexpected broach
will cause a gybe, the boom will swing and there will be more potential chaos?

 

[AndrewB]

Re: broach downwind

Yachts don't usually broach going to windward, it usually happens on a reach.

The mechanics of a broach on a run are a bit different, and generally more spectacular. One cause is where the the yacht trips over the keel, as a result of being lifted by a following wave and not being corrected quick enough by the helmsman. The yacht comes hurtling around like a water-ski, practically dipping the mast in the water. No gybe, but in big seas there is a risk of being thrown right over by a breaking wave.

Another scenario is the 'death roll', usually initiated by sailing by the lee, specially with the spinnaker up. The yacht starts rolling from side to side uncontrollably. If the helmsman cannot ease the boat back up-wind in time, this is highly likely to end in a crash gybe followed by a broach on the other tack.

That's why running in strong wind is considered tricky!

 

[Twister_Ken]

Re: broach downwind

You're right - an upwind broach is usually not too much of a problem, except for lost places if you're racing. But it can get expensive if you broach into someone, or in front of someone. A sunsail yacht managed to ram and sink a motorboat near Lee-on-Solent last season doing this.

Downwind broaches can hurt. Conversely to an upwind broach, the modern broad beamed broad transomed hull shape seems to perform rather better downwind in boisterous conditions than narrower designs. But in all those Beken type pix, you still see any spare crew clustered in the upwind aft quarter, trying to keep the nose up, the stern down and the rudder in the water.

The primary secret of avoiding a downwind broach is to sail a broad reach-gybe-broad reach course, rather than close to a dead run. If you do have to go more or less straight downwind the helmsperson steers the boat to keep it under the masthead, while the trimmers stay awake and are ready to dump as soon as the helm feels he or she is losing it.

On the 41 footer I used to race, we knew we had three leeward-windward rolls before we broached. As the third roll developed I would dump spinny sheet which generally stopped the rocking unless a particularly unfriendly wave came along at the wrong time. If I didn't the next roll to windward would usually see us wipe out.

Dumping mainsheet has little effect because the main is usually squared away against the shrouds and can't be let go any further to lose drive.

I've got a picture at home of the boat where the spinnaker seems unnaturally big. It takes a little whiile for the casual viewer to work out why. Its because Keith Beken was using a wide angle lens and the masthead was more or less directly above his dory. It's only when you realise you are looking at the tops of three sets of spreaders that you appreciate how far we've rolled to windward.

For the average crusing sailor, though a downwind broach would be a rare beast because you're not forced by some race committee to sail dead downwind with loads of sail up. My advice, if you do find yourself in a hatful of wind going close to dead downwind, would be to round up for long enough to drop the main, then continue downwind under foresail alone.

For the ultimate downwind horror see Silk II on http://www.beken.co.uk/posters2.htm

 

[Guest]

Re: broach downwind

>For the ultimate downwind horror see Silk II on http://www.beken.co.uk/posters2.htm

Is that the one with about 8ft of bow buried in the water and the boat doing a headstand?

Regards,

Peter
http://www.mistressofmourne.com

 

[Twister_Ken]

Re: broach downwind

That's about the size of it.