Tacking in light winds?

[Don C L]

Originally Posted by Stu Jackson

Since I sailed on SF Bay I rarely had 5 kt winds.

There is some good advice here. I'd add, most new sailors tend to sheet in the sails too tight in light air at first since sheeting in is usually associated with more heeling and a greater feeling of speed. In light air you must start out after the tack not pointing so high and not sheeted in so tight. Better to have big curves (more camber) in the wings (sails) to gain power (lift) and build speed. (And release the outhaul on the main a bit too. Many folks have the main too flat in light air because the outhaul is too tight.) As the boat accelerates you can point higher and bring in the sheets. If you sheet in too tight too soon, the flat sails just drive the boat sideways (leeway) more than forward (headway). Many racers also sheet in too tight too soon after a tack too, so don't feel bad.

[s/v Jedi]

Originally Posted by Don C L

There is some good advice here. I'd add, most new sailors tend to sheet in the sails too tight in light air at first since sheeting in is usually associated with more heeling and a greater feeling of speed. In light air you must start out after the tack not pointing so high and not sheeted in so tight. Better to have big curves (more camber) in the wings (sails) to gain power (lift) and build speed. (And release the outhaul on the main a bit too. Many folks have the main too flat in light air because the outhaul is too tight.) As the boat accelerates you can point higher and bring in the sheets. If you sheet in too tight too soon, the flat sails just drive the boat sideways (leeway) more than forward (headway). Many racers also sheet in too tight too soon after a tack too, so don't feel bad.

Ahhhh I’m not alone

[wholybee]

Originally Posted by Don C L

There is some good advice here. I'd add, most new sailors tend to sheet in the sails too tight in light air at first since sheeting in is usually associated with more heeling and a greater feeling of speed. In light air you must start out after the tack not pointing so high and not sheeted in so tight. Better to have big curves (more camber) in the wings (sails) to gain power (lift) and build speed. (And release the outhaul on the main a bit too. Many folks have the main too flat in light air because the outhaul is too tight.) As the boat accelerates you can point higher and bring in the sheets. If you sheet in too tight too soon, the flat sails just drive the boat sideways (leeway) more than forward (headway). Many racers also sheet in too tight too soon after a tack too, so don't feel bad.

Many sailors think of this as "gears." In first gear the sails are eased and you are pointing a few degrees lower. You have more power and better acceleration, but not the high speed. As speed builds, you "change gears" trim in, and point higher.

[thomm225]

Originally Posted by ChrisJHC

Many boats (including mine) can point higher than 45 degrees. For example, mine starts to luff significantly at 35 degrees.

When I’m tacking, I find it best to do a 90 degree tack and then, when the boat picks up speed, gradually bring her to around 40 degrees.

The actual angle to the wind I can hold depends on a range of things, including how much sailing into the swell slows me down.

And one final thing to confuse the OP: many boats find they can hold a closer angle to the wind on one tack rather than the other!

As many have said, you’re always learning, particularly heading upwind in light airs.

Info like this for a beginner which the OP appears to be will just confuse him more.

My racing boats (beach cats) the best of which could sail almost 30 degrees off the wind. (the one that was mainsail and spinnaker only was best of the 4 I raced as far as pointing high)

The Bristol 27 I have now is lucky to get 65-70 degrees off when the wind is up.

In light winds, it's fine.

To sail closer to the wind rake your mast more. If you have the adjustable mast rake slam it tight.

When the wind is up stiffer battens in the main can help you point higher.

You also have to find the sweet spot which might not be when the tell tales are flowing straight back.

Of course we went by feel ...as in feeling when the boat sped up,

Downhull tight when the wind is up but in 5 knots or so main luff a bit loose.

Sail sheeting ease. No where near as tight as heavy air sailing

Best way to learn this is racing one design because when you are going to windward with 15-30 boats off the starting line exactly like yours you find out real fast if you know how to sail close to the wind or not. First leg in most buoy races is an upwind leg.

A cruiser that has never lined up with boats like his and sailed upwind is just guessing as to how well he is trimming his sails and setting up his boat as there is no other boat to compare his settings to.

In the light air photo tell tales are normal but when the wind gets up near 17-20 knots many times I have the tell tales pointing way higher sometimes close to straight up.

I had different battens for light and heavy air.

Mast prebend was cranked on much more in heavy air also

You could get apparent wind from your face and your wind indicator combined which ever was easiest at the moment.

Sometimes in heavy air you had to derotate the mast to depower or over rotate.

[Dave_S]

Originally Posted by Dockhead

You're leaving out leeway, and difference between true and apparent wind - there are a few more vectors.

Another important factor is optimum VMG to windward, which does not occur at the closest possible angle to the wind. VMG to windward is the direct measure of your success in getting up to windward, not indeed any angle.

90 degrees over ground, the angle between COG on one tack to COG on the other, so taking account of all the vectors, and at optimal VMG to windward (i.e. not pinching) is just about as good as it gets with a really good sailing boat sailed really well in ideal conditions. 100 degrees is already really good. 120 may be all you can get in an average boat in less than ideal conditions, or even more. I am assuming zero currents; a tide running greatly comicates this.

Since you are sailing in waters without currents, I would suggest cracking this with your instruments. You should be able to get them to read VMG to windward. If not, you can set a waypoint directly upwind and look at VMG to that. Play around and find that angle and that sail trim which gives you the highest reading.

Speed is your friend going upwind - all other things being equal, the faster you go, the less leeway. Sail on a close reach, trim well, and check your speed. Then head up gradually, trim the sails, and stop heading up before the speed falls off dramatically. That should be somewhere not too far from your best VMG.

Sail trim - and sails with good shape - are key to getting upwind. That is because upwind, your sails are acting purely in lift mode - so available power is the sum of lift minus drag, so you have to be able to trim to minimize drag. Baggy sails will kill your upwind ability.

Good luck! Sailing upwind is hard but fun - really separates the sailor-men from the sailor-boys.

I don't believe reduced tacking angles are a measure of the boats or skippers performance, counter intuitively, I believe in working to increase them.

Any boat has an optimum AWA upwind, while maintaining this angle I work on pushing the true wind back (widen the angle). VMG improves by pushing out your tacking angles to a point. Listed below.

Note the VMG expressed as a % of wind speed does not take into account windage.

Target values.

AWA of 25° your best VMG will be TWA @ 57.4° (68.3% of TWS)

AWA of 30° your best VMG will be TWA @ 60° (50% of TWS)

AWA of 35° your best VMG will be TWA @ 62.5° (37.1% of TWS)

AWA of 40° your best VMG will be TWA @ 65° (27.8% of TWS)

AWA of 45° your best VMG will be TWA @ 67.5° (20.7% of TWS)

Any TWA above or below these angles while maintaining the corresponding AWA will reduce the VMG.

All these values will give you wider than 120° tacking angles (windage included).

[wingssail]

Originally Posted by Dave_S

I don't believe reduced tacking angles are a measure of the boats or skippers performance, counter intuitively, I believe in working to increase them.

Any boat has an optimum AWA upwind, while maintaining this angle I work on pushing the true wind back (widen the angle). VMG improves by pushing out your tacking angles to a point. Listed below.

Note the VMG expressed as a % of wind speed does not take into account windage.

Target values.

AWA of 25° your best VMG will be TWA @ 57.4° (68.3% of TWS)

AWA of 30° your best VMG will be TWA @ 60° (50% of TWS)

AWA of 35° your best VMG will be TWA @ 62.5° (37.1% of TWS)

AWA of 40° your best VMG will be TWA @ 65° (27.8% of TWS)

AWA of 45° your best VMG will be TWA @ 67.5° (20.7% of TWS)

Any TWA above or below these angles while maintaining the corresponding AWA will reduce the VMG.

All these values will give you wider than 120° tacking angles (windage included).

I cannot quite reconcile these numbers with my observations and the VPP program I have.

For any monohull I can model, over wind strengths from TWS 6-20, at no time does a AWA of 40 or 45 result in the best VMG.

I found that true wind angles (TWA) of 40-45, which produced AWA of 25-31 resulted in tacking angles of 90deg and the best VMG.

[Dave_S]

Originally Posted by wingssail

I cannot quite reconcile these numbers with my observations and the VPP program I have.

For any monohull I can model, over wind strengths from TWS 6-20, at no time does a AWA of 40 or 45 result in the best VMG.

I found that true wind angles (TWA) of 40-45, which produced AWA of 25-31 resulted in tacking angles of 90deg and the best VMG.

In the figures I've shown the AWA are for boats that sail best with that AWA as the optimum for that particular boat. So a boat that has strong performance might manage an optimal AWA of 25° without pinching, lesser performance boats might only achieve 30°, 40°, or 45° on a sliding scale based their performance level. So if the best you can achieve is 30° without pinching then the fastest you can travel upwind is if you can run at 30°A and 60°T simultaneously irrespective of wind speed you will have a VMG of 50% of the true wind speed.

My figures are a bit misleading because if you can just sail with an AWA of 30° and 60°T your optimum AWA is probably 27°ish and you should always sail close to the optimum for best VMG. If you sail at 27 your target TWA should be around 58° which you won't achieve but that's the goal.

If your boats polars or your experience show the best apparent wind angle for your boat upwind is 25°, then while sailing at that angle to the apparent wind the best angle for your TWA is 57.4° this will give you a speed upwind (not boat speed) of 68.3% of the true wind speed.

If in your example you have AWA of 25° with a TWA of 40° you will be making 46.6% of the true wind speed.

In your example if in 10kn of breeze you will be 2kn faster at the wider angles to your destination.

[s/v Jedi]

We’re long and narrow but we’re a ketch so no upwind machine. In light airs 10kts wind our best VMG is at 45 degrees true wind. In 20kts it is at 50 degrees to true wind, mostly due to better taking on the waves.

For the Windex up the mast: I think they have two positions for the indicators: 45 degrees and 30 degrees? Before out Windex was ripped off by a hawk, ithas the indicators at 30% and that apparent wind angle was just a bit too much for us… 35 degrees our vmg went up a little bit.

For real data you need electronics that have your polar diagram and it will simply show you a percentage of how good you are doing.

[Dockhead]

Originally Posted by Dave_S

I don't believe reduced tacking angles are a measure of the boats or skippers performance, counter intuitively, I believe in working to increase them.

Any boat has an optimum AWA upwind, while maintaining this angle I work on pushing the true wind back (widen the angle). VMG improves by pushing out your tacking angles to a point. Listed below.

Note the VMG expressed as a % of wind speed does not take into account windage.

Target values.

AWA of 25° your best VMG will be TWA @ 57.4° (68.3% of TWS)

AWA of 30° your best VMG will be TWA @ 60° (50% of TWS)

AWA of 35° your best VMG will be TWA @ 62.5° (37.1% of TWS)

AWA of 40° your best VMG will be TWA @ 65° (27.8% of TWS)

AWA of 45° your best VMG will be TWA @ 67.5° (20.7% of TWS)

Any TWA above or below these angles while maintaining the corresponding AWA will reduce the VMG.

All these values will give you wider than 120° tacking angles (windage included).

Yes, of course, this is correct, but especially with a catamaran.


The direct measure of your progress upwind is VMG to windward, as I wrote. This will not -- also as I wrote -- occur at the narrowest angle to the apparent wind, nor will it occur at the narrowest possible tacking angle over ground.



But tacking angle over ground is still pretty important, as the geometry of going upwind rapidly deteriorates over about 100 degrees.


Tacking 90 degrees over ground, one mile upwind takes only 1.4 miles of sailing

For 100 degrees, 1.55 miles

For 110 degrees, 1.75 miles

For 120 degrees, one mile upwind takes two miles of sailing


So you'll need a whole lot of extra speed to make up for the geometry, sailing that low on your tacks. The target speeds and angles in your table are something like what you would expect to find in a performance catamaran; monos are different. Best VMG on my boat, for example, is achieved at different angles depending on the sea state and wind force, but it's normally about a 100 to 105 degree tack over ground. In dead flat sea with 15 knots of wind, it might be as little as 90 - 95 degrees. In rough seas and strong wind, might be much more, 110 to 120.


Racing really helps to understand this.

[Dave_S]

Originally Posted by Dockhead

Yes, of course, this is correct, but especially with a catamaran.


The direct measure of your progress upwind is VMG to windward, as I wrote. This will not -- also as I wrote -- occur at the narrowest angle to the apparent wind, nor will it occur at the narrowest possible tacking angle over ground.



But tacking angle over ground is still pretty important, as the geometry of going upwind rapidly deteriorates over about 100 degrees.


Tacking 90 degrees over ground, one mile upwind takes only 1.4 miles of sailing

For 100 degrees, 1.55 miles

For 110 degrees, 1.75 miles

For 120 degrees, one mile upwind takes two miles of sailing


So you'll need a whole lot of extra speed to make up for the geometry, sailing that low on your tacks. The target speeds and angles in your table are something like what you would expect to find in a performance catamaran; monos are different. Best VMG on my boat, for example, is achieved at different angles depending on the sea state and wind force, but it's normally about a 100 to 105 degree tack over ground. In dead flat sea with 15 knots of wind, it might be as little as 90 - 95 degrees. In rough seas and strong wind, might be much more, 110 to 120.


Racing really helps to understand this.

I think we may be talking about 2 different scenarios. I am saying, 2 boats with the same AWA, the boat with the widest TWA will always have a better VMG upwind. (Unless the boat is exceeding the figures quoted in my previous posts)

Tacking 90 degrees over ground, one mile upwind takes only 1.4 miles of sailing

For 100 degrees, 1.55 miles (if you are maintaining 30°AWA and you have improved your TWA out another 5° you must have improved your boat speed by a value higher than the extra distance travelled and therefore improved your VMG you can't achieve that extra 5° while holding 30°AWA without increasing your speed by more than the 10-11% additional distance).

If your AWA also increases then that is a different conversation.

For 110 degrees, 1.75 miles
(if you are maintaining 30°AWA and you have improved your TWA out another 10° you have improved your VMG)
For 120 degrees, one mile upwind takes two miles of sailing (if you are maintaining 30°AWA and you have improved your TWA out another 15° you have improved your VMG) NOTE: You are almost at your maximum VMG at this point.

I do relate it to my boat and a couple of others I've been on. They are all catamarans.

The maths holds true regardless of the boat.

I still believe....
Sail to your optimum AWA then work to widen your TWA regardless of the numbers.

Where I see we could have issues agreeing is what constitutes "optimum AWA" it is particularly obvious on my boat, it may be less obvious on others ?

[JC Reefer]

Light wind sailing tactics are different and less forgiving then normal conditions. You really need to maintain sail shape.

To do this you might need to sit on the low side of the vessel so that you create a slight heel. This allows gravity to keep the sail (think foil) fixed in the correct position.

Sail shape is real important in light wind, and you want a more pronounced foil. The image below shows an airplane wing extended for lower speeds. They do this at landing.


So, like the plane, you want the sails to have a more pronounced foil shape. For the main, this means easing up on the Outhaul and vang a bit. For the jib, you like can not crank it in all the way because that flattens the sail. You want your sails to have shape.

Instead of 45 degrees to the wind think 55 from tack to tack. Once you have moment the you start come me up closer to the wind.

Besides sail shape, the movements onboard should become smoother, smaller and with intent. It’s all about being efficient. Moving the tiller causes drag, so sit it straight for a bit and let the vessel settle through the tack.

Weight should go more inboard and center. Become more one with the boat.

There is more to it but that’s a good start. I raced in college and my team train on a rather small lake.

Good luck, sail fast.

[Tupaia]

Originally Posted by JC Reefer

Light wind sailing tactics are different and less forgiving then normal conditions. You really need to maintain sail shape.

For the main, this means easing up on the Outhaul.
Good luck, sail fast.

One of the most effective sail controls for light winds and many sailors never adjust it, or can even see it hidden in their Stak-packs.

[Ivanvet]

Originally Posted by catsketcher

When I coach or take new crew out I tell them of the four gears of sailing upwind.

Nothing new to add to this conversation, but I always learn more visualizing the discussion. Here is a video of the 'gears of sailing upwind' to complement Catsketcher's great explanation.

https://www.youtube.com/watch?v=AaUR...SailingPodcast

[danstanford]

Originally Posted by Dave_S

I think we may be talking about 2 different scenarios. I am saying, 2 boats with the same AWA, the boat with the widest TWA will always have a better VMG upwind. (Unless the boat is exceeding the figures quoted in my previous posts)

Tacking 90 degrees over ground, one mile upwind takes only 1.4 miles of sailing

For 100 degrees, 1.55 miles (if you are maintaining 30°AWA and you have improved your TWA out another 5° you must have improved your boat speed by a value higher than the extra distance travelled and therefore improved your VMG you can't achieve that extra 5° while holding 30°AWA without increasing your speed by more than the 10-11% additional distance).

If your AWA also increases then that is a different conversation.

For 110 degrees, 1.75 miles
(if you are maintaining 30°AWA and you have improved your TWA out another 10° you have improved your VMG)
For 120 degrees, one mile upwind takes two miles of sailing (if you are maintaining 30°AWA and you have improved your TWA out another 15° you have improved your VMG) NOTE: You are almost at your maximum VMG at this point.

I do relate it to my boat and a couple of others I've been on. They are all catamarans.

The maths holds true regardless of the boat.

I still believe....
Sail to your optimum AWA then work to widen your TWA regardless of the numbers.

Where I see we could have issues agreeing is what constitutes "optimum AWA" it is particularly obvious on my boat, it may be less obvious on others ?

After thinking about it a lot, since it is backward to everything I have been taught, I think I grasp what you are saying. However I think the concept if flawed by the fact that your boat, given good trim for the angles, will only sail one speed at one wind speed and AWA. It is true that perhaps your optimum AWA for best VMG is fairly constant at different wind speeds giving you higher VMG's with constant AWA, but the variable is the true wind speed available to you.

If you are trying to maximize your VMG, the standard practice is to establish a best boat speed through the water for a given wind speed and to enhance your VMG by finding ways to reduce your TWA (tacking angle) not widen it.

I tried to attach the polar for my boat here but it was too high a resolution so the file was too big, but look at any polar chart to get the concept. Mine happens to also show AWA mirrored on the chart and you can see that for any wind speed there will be an optimum TWA for best VMG.

[wholybee]

Originally Posted by danstanford

After thinking about it a lot, since it is backward to everything I have been taught, I think I grasp what you are saying. However I think the concept if flawed by the fact that your boat, given good trim for the angles, will only sail one speed at one wind speed and AWA. It is true that perhaps your optimum AWA for best VMG is fairly constant at different wind speeds giving you higher VMG's with constant AWA, but the variable is the true wind speed available to you.

If you are trying to maximize your VMG, the standard practice is to establish a best boat speed through the water for a given wind speed and to enhance your VMG by finding ways to reduce your TWA (tacking angle) not widen it.

I tried to attach the polar for my boat here but it was too high a resolution so the file was too big, but look at any polar chart to get the concept. Mine happens to also show AWA mirrored on the chart and you can see that for any wind speed there will be an optimum TWA for best VMG.

To make it more complicated, you also have to account for leeway, which most polars do not. On my boat, as I sail higher than 45 deg AWA, my leeway increases as well. My theoretical max VMG is about 33 degrees AWA (with TWA varying quite a bit based on windspeed, but always very close to 33 AWA). But, at 33 degrees AWA, I have so much leeway, that isn't really my best VMG. I need to head off a bit, pickup some speed, and reduce my leeway.