Light airs sailing

[tyce]

Some advice please,
my boat has a lifting rudder and keel, the rudder pivots through 90 deg so it stands horizontally behind the boat when lifted, if sailing in light airs is it beneficial to lift the keel (going with or against the tide), and then lift the rudder so the leading edge only is in the water which would also i presume increase the water line length by the length of the rudder.
Obviously the rudder is extremely difficult to turn when horizontal like this so we are talking very light airs.
What do yer reckon.

 

[andy_wilson]

The dynamic waterline length is a function of the distance between the bow and stern waves.

Lifting your rudder will have no more effect on that as towing your dinghy has.

 

[NigelBirch]

Obviously you wouldn't want to lift the keel going to windward. I doubt that lifting the keel/rudder would give any increase in speed downwind and wonder whether it might make the boat a little unmanagable. But no harm trying it.

Overall though I think you'd be better of thinking about boat and sail trim....

 

[alistairedw]

Sailing downwind raising the keel and rudder will help boat speed by reducing drag. But upwind you will find that increased leeway offsets any speed gained through the water.

On a beam reach raising keel and rudder halfway will increase speed without a significant increase in leeway.

 

[Skyva_2]

A dinghy sailor will raise the centreboard going downwind to reduce skin friction, but not raise the rudder.

I suppose lifting the keel will have the same effect but it would hardly be noticeable.

 

[jwilson]

Offwind lifting your keel will increase speed in both light and strong winds, to windward you need it fully down even in light airs. On a Parker 27 the keel is not a big part of the ballast, so you don't lose any stability by raising it.

The rudder should be fully down all the time unless you are going into very shallow water. Sailing with it raised is inefficient and puts excessive strain on the rudder cheeks.

 

[Hardley]

Agree with Centerboarder entirely. If you are real keen, moving the crew forward helps as well.
Hardley

 

[moondancer]

On many dinghys the centreboard is lifted downwind as others have said.

I had a lift keel Sonata (it was a swing keel with a stub - very similar to the Jeaneau Sun 2500) and used to lift the keel downwind until my Gps told me it made not a jot of difference to boat speed.

 

[gandy]

In very light winds, waterline length's not an issue because you're only doing a fraction of hull speed. Dinghies would normally be sailed heeled to leeward to reduce wetted surface area and also so that gravity helps retain the sail shape.

 

[Slow_boat]

It makes no difference whether you with or against the tide, either.

 

[Richard10002]

[ QUOTE ]
Sailing downwind raising the keel and rudder will help boat speed by reducing drag. But upwind you will find that increased leeway offsets any speed gained through the water.

On a beam reach raising keel and rudder halfway will increase speed without a significant increase in leeway.

[/ QUOTE ]

On some boats, raising the centreboard/keel all the way downwind can encourage them to roll badly.... a bit, or halfway down, helps combat the roll.

 

[NigelBirch]

Exactly, I sail a dinghy too and the reason I lift the daggerboard downwind is more to do with the fear of accidental gybe, having the board up means the boat is more likely to skid across the surface if it does happen.....

 

[tyce]

i was thinking about the effect of wetted surface area on the keel and rudder, the area of the rudder alone is huge on a p 27 so would it not reduce drag significantly.
I agree entirely about the tide making no difference as to when to raise the keel, but what did cross my mind is if the wind goes altogether and the boat is drifting in the right direction with the tide, would the keel not help speed the boat along abit if it was lowered rather than up thgereby providing more grip on the hull

 

[CliveG]

We found the moving crew forward helped boat speed.

We were running dead downwind with the genoa poled out.
We had a F5/6 up our tail and a 5 ft swell.
When a 3 of us where in the cockpit she was not surfing.
The Son went below to do a log entry and we stared surfing.
(nearly touched 8 knots with a 22' waterline)
As soon as he came back into the cockpit we stopped surfing.

We have not tried lifting the keel down wind.
Must give it a try one flatish day.

 

[EBoat126]

Wouldn't even think about lifting the keel, just move crew weight forward to lift the transom and reduce drag. Not just downwind though upwind too.

 

[William_H]

Ah light wind sailing. We are into our winter sailing season and this is marked by light winds. Our summers are mostly very blowy.

Yes heeling the boat will help at least to keep the sails in shape.

I find more important in racinng is to concentrate on wind shifts.
I always steer from the low side where the jib is clearly seen and you have to be prepared to tack at a moments notice if the wind is knocking you or to turn up to follow a lift.
It is critical just how fast you are going compared to how close to the wind you arer sailing. You can generally sail closer than the tell tails might indicate but be aware of falling boatspeed asyou get too close.

A smaller boat with fin keel is easier quicker to turn so definitely keel down and rudder always down. It is an interesting and different challenge to race in light winds and it takes huge concentration. Get someone else to be responsible as lookout while you concentrate on boat pointing and helming.

Of course luck comes into it and you will always find another competitor just gets a little more wind than you (or less) so you can't take it too seriously.
Tide flow of course even here in Swan River can be significant with little wind so you need to know where the water flows fastest to minimise contrary flow or get help from it. (not that I have ever really figured it out)
Note I have concentrated on windward sailing. Down wind you just look for puffs although it can be detrimental to chase them and hope for a little breeze. good luck olewill

 

[Noddy]

Those of us with multihulls also have to consider whether to raise one or both centre boards or rudders.

Its all a bit much.

I guess its all about reducing wetted surface in light conditions so as much out of the water as you can until leeway or control becomes a problem.

I am definitely going to send the crew (SWMBO) forward next time out in light conditions. (I might even go myself if its not raining). Works in dinghies.

A lot of the multihull literature talks about fore and aft trim with regard to surfing. I think weight forward does help you surf. But with a fast boat the danger then becomes driving into a wave with wind pressing on the top of the sail and pitchpoling. (bad).

 

[Hardley]

But with a fast boat the danger then becomes driving into a wave with wind pressing on the top of the sail and pitchpoling. (bad).

With regard to the above situation, in my dinghy days, I discovered that as the bow was digging into the wave ahead, several vigorous wriggles of the tiller would lift the bow up and you continued planning.
No one has mentioned light air jib sheets, they help the jib to settle much quicker than the weight of normal sheets.