Broad Reaching vs Sailing Wing on Wing

[Dockhead]

I am getting near the end of my fourth annual 1500 mile trip from the UK to Finland. The perverted East winds I was struggling with finally went away and the prevailing SW S and W flows have come back.

As a result I have had to do a few hundred miles of sailing dead downwind.

I am single handed at this point, so have not been able to change headsails from my blade jib, used mostly for upwind work and strong conditions, to my regular 120% yankee.

I know race boats rarely sail dead downwind, preferring to broad reach and gybe. Since I expected poor performance dead downwind with my small jib (and on top of that, my pole is out of action due to a problem with the track), I have been experimenting with broad reaching and gybing. I thought VMG downwind should have been optimal at just that angle where both sails are drawing on the same side of the boat.

But that has not been the case! I don't understand why, but sailing wing on wing, even with the small jib, even without a pole, has been much faster. To such an extent that sailing DDW is giving me higher VMG towards points even 20 or 25 degrees off of DDW, than heading up directly towards the destination.

I am really puzzled by this. The only thought I have is that the blade jib must work poorly on a broad reach. It is working surprisingly well DDW -- I guess it needs the pole less than the yankee would. I would be interested if anyone has any insight, or experience, to share on this.



On another topic, I had a cracking sail on Monday from Gotland (the Swedish island in the middle of the Central Baltic) to the Estonian islands in a F6 from NNW, so a slightly broad reach, veering N for a slightly close reach later in the day. The sea was inexplicably calm -- almost flat -- which is beyond my understanding how. The wind was close enough to the beam for me to get good drive out of my staysail, so I went under all plain sail, mostly at 9 to 10 knots, making good 105 miles before cocktail hour, in less than 12 hours, almost effortlessly, despite fighting a slightly adverse current. The sea started to get a little rough only in the last few hours. I was seeing apparent wind in the upper 20's by the end of the day, but instead of reefing, I flattened and slightly feathered the main (boom out slightly further than where it should have normally been). I am getting terrific results with this technique in stronger conditions, which is allowing me to carry full sail without reefing anything up to about 30 knots apparent on most points of sail (not hard on the wind), producing a lot of speed and minimal heeling.


But it was not technique, but the gorgeous day, which produced the cracking sail. I was somewhat dreading what I expected to be fairly rough conditions when I headed out under an iron-gray sky at dawn, and was amazed and gratified how the day turned out, with bright sunshine and almost flat water. I guess it goes to show that if you go out often enough, and stay out long enough, you will sooner or later meet perfect sailing conditions

[JPA Cate]

What a lovely post! Yes, sometimes those mischievous thugs, the weather gods, conspire to give you wonderful conditions, and then, one must thank them, but not forget their basic nature!

What really works, is paying attention to VMG. It doesn't lie. Even when/if we don't understand quite why it is the way it is, the VMG is reliable.

All the best,

Ann

[thinwater]

Originally Posted by Dockhead

...I know race boats rarely sail dead downwind, preferring to broad reach and gybe.... I thought VMG downwind should have been optimal at just that angle where both sails are drawing on the same side of the boat.

But that has not been the case! I don't understand why, but sailing wing on wing, even with the small jib, even without a pole, has been much faster. To such an extent that sailing DDW is giving me higher VMG towards points even 20 or 25 degrees off of DDW, than heading up directly towards the destination.

I am really puzzled by this....

The reason for your puzzlement is your assumption that racers always reach down wind. In fact, for many classes, it is faster (VMG) to sail wing and wing.

Wing on Wing and Win! | jworldannapolis.com

As for why sailing 20-25 degrees to one side might be faster, the answer is in your speed polar. There is generally a dead zone somewhere between DDW with both sails drawing and broad reaching with the wind a little after of the beam. In this zone the jib collapses or at least generates so little power it might as well be rolled up. Thus, If I have a destination 20 degrees to one side of DDW, I generally alternate between wing and wing and a good broad reach, as you have described.

Hoisting a spinnaker changes all of this, depending on the hull and the cut. Deep reaching courses become faster and DDW is no longer attractive. But that is a different case.

[Dockhead]

Originally Posted by thinwater

The reason for your puzzlement is your assumption that racers always reach down wind. In fact, for many classes, it is faster (VMG) to sail wing and wing.

Wing on Wing and Win! | jworldannapolis.com

As for why sailing 20-25 degrees to one side might be faster, the answer is in your speed polar. There is generally a dead zone somewhere between DDW with both sails drawing and broad reaching with the wind a little after of the beam. In this zone the jib collapses or at least generates so little power it might as well be rolled up. Thus, If I have a destination 20 degrees to one side of DDW, I generally alternate between wing and wing and a good broad reach, as you have described.

Hoisting a spinnaker changes all of this, depending on the hull and the cut. Deep reaching courses become faster and DDW is no longer attractive. But that is a different case.

Thank you for these very useful insights.

Another example of how much insight into sailing can come from racing experience. My racing days are too far in the past and too poorly remembered to help much, plus I didn't stick with it long enough to ever be very good at it. We didn't have polars or even wind instruments -- just a windex.


I have always been aware, of course, of the "dead zone" between DDW +/- 5 degrees, or so, where you can go wing on wing, and more than that, where you can't go wing on wing, but you can't get both sails to draw on the same side of the boat. But I had always thought that once the jib could draw, you'd already be going much faster. I'm still puzzled by why that has not been the case. Either I was fantasizing all along, or this particular headsail just doesn't produce much drive at those angles. I will change to the yankee when I have crew and continue these experiments.

[thinwater]

Originally Posted by Dockhead

... But I had always thought that once the jib could draw, you'd already be going much faster. I'm still puzzled by why that has not been the case....

The reason is that the sails remained stalled until the apparent wind angle is nearly on the beam (about 40-60 degrees above DDW, depending on the boat and rig). Speed is all about how much air the sails can turn, and without attached flow, they turn less air through a smaller angle. But by the time you heat the angle up that much, you are sailing 30% farther, though not going 30% faster.

Obviously, the exact angles are boat-specific. My last cat would tack down wind and never sailed W&W. My current cat is slower and W&W is often the right answer.

[Joli]

Look at your polars, if they are flat on the bottom you gain nothing by reaching up. If they look like an inverted heart ❤️ you should be mindful of your angles. And remember to always sail the favored board unless new wind or sea state dictates otherwise.

[Dockhead]

Originally Posted by thinwater

The reason is that the sails remained stalled until the apparent wind angle is nearly on the beam (about 40-60 degrees above DDW, depending on the boat and rig). Speed is all about how much air the sails can turn, and without attached flow, they turn less air through a smaller angle. But by the time you heat the angle up that much, you are sailing 30% farther, though not going 30% faster.

Obviously, the exact angles are boat-specific. My last cat would tack down wind and never sailed W&W. My current cat is slower and W&W is often the right answer.

OK.

I think you're saying that the sails are acting to produce drag only, and no lift, until the wind is nearly on the beam, correct? That corresponds to my understanding.

But white sails on a fore and aft rigged vessel, especially one with aft-swept spreaders, will have greater projected area and will work better even in drag-only mode, with the wind not directly aft, won't they? If that's the case, then why wouldn't I be getting at least as much drive out of the rig with both sails filled on one side, as I would wing and wing?

Maybe the answer is the jib only LOOKS filled on a very deep reach? Maybe the aft part of the jib is still blanketed by the main at very deep angles, even though the jib appears to be filling and drawing?

Just throwing out ideas here. And if that's the case, I wonder if it makes sense to haul in the boom a little to let air circulate better to the jib?

Sailing DDW or on a very deep reach, I typically put on a fair amount of of vang and pull the boom out with the preventer until the sail nearly touches the spreaders -- figuring I want to maximize projected area. But this might not be right when we consider what's going on with the jib. Hmmmm.

[Dockhead]

Originally Posted by Joli

Look at your polars, if they are flat on the bottom you gain nothing by reaching up. If they look like an inverted heart ❤️ you should be mindful of your angles. And remember to always sail the favored board unless new wind or sea state dictates otherwise.

If I only HAD polars :headbang: They don't exist for my boat as far as I know, and in any case I have non-standard sails (95% blade headsail, and carbon laminate straight leech main with vertical battens instead of Dacron hollow leech).

It might be worth trying to make some myself.

Concerning the favored board -- this is rather off topic, but it's SO ture and SO important. I wish I had understood that a decade or two earlier :headbang:

[thinwater]

Originally Posted by Dockhead

OK.

I think you're saying that the sails are acting to produce drag only, and no lift, until the wind is nearly on the beam, correct? That corresponds to my understanding.

But white sails on a fore and aft rigged vessel, especially one with aft-swept spreaders, will have greater projected area and will work better even in drag-only mode, with the wind not directly aft, won't they? If that's the case, then why wouldn't I be getting at least as much drive out of the rig with both sails filled on one side, as I would wing and wing?

Maybe the answer is the jib only LOOKS filled on a very deep reach? Maybe the aft part of the jib is still blanketed by the main at very deep angles, even though the jib appears to be filling and drawing?

Just throwing out ideas here. And if that's the case, I wonder if it makes sense to haul in the boom a little to let air circulate better to the jib?

Sailing DDW or on a very deep reach, I typically put on a fair amount of of vang and pull the boom out with the preventer until the sail nearly touches the spreaders -- figuring I want to maximize projected area. But this might not be right when we consider what's going on with the jib. Hmmmm.

Now we are getting complicated.

Yes, it can actually increase the drive to haul the main in just a little, depending on the sail design. Specifically, full batten sails can often get reverse flow on the back side, driving more air into the genoa.

However, the risk of an accidental jibe goes up fast, so this is a bad idea in waves. However, I often do this for two reasons. First, my boat is a cat and it tracks very well down wind. Second, with aft swept shrouds, I don't have much choice. I always set a preventer when sailing W&W.

[Livia]

We had a tall skinny main (short boom) and with our preventer on, we were able to sail wing on wing slightly by the lee on passage. In fact, by the lee was often faster than DDW. I wouldn't want to try that with a long boom and a lot of sail area hanging far away from the mast but for us it worked.

[Dockhead]

Originally Posted by thinwater

Now we are getting complicated.

Yes, it can actually increase the drive to haul the main in just a little, depending on the sail design. Specifically, full batten sails can often get reverse flow on the back side, driving more air into the genoa.

However, the risk of an accidental jibe goes up fast, so this is a bad idea in waves. However, I often do this for two reasons. First, my boat is a cat and it tracks very well down wind. Second, with aft swept shrouds, I don't have much choice. I always set a preventer when sailing W&W.

OK, I'll try it.

I'm fanatical about boom control and ALWAYS have a dyneema preventer on whenever the boom get beyond the rail - so even when reaching.

[Dockhead]

Originally Posted by Livia

We had a tall skinny main (short boom) and with our preventer on, we were able to sail wing on wing slightly by the lee on passage. In fact, by the lee was often faster than DDW. I wouldn't want to try that with a long boom and a lot of sail area hanging far away from the mast but for us it worked.

Yes, I think everyone sails the main slightly by the lee when going wing on wing, don't they? Since the unpoled headsail won't tolerate even one degree of it? Might be worth trying going further in that direction. Despite aft -swept spreaders, my main seems to work ok up to about 20 degrees by the lee.

[thinwater]

Originally Posted by Dockhead

OK, I'll try it.

I'm fanatical about boom control and ALWAYS have a dyneema preventer on whenever the boom get beyond the rail - so even when reaching.

I agree with Livia re. sailing slightly by the lee being faster. It increases flow on the lee side of the main and keeps the genoa full. Obviously, you have to watch out for yawing.

I have mixed feelings on a Dyneema preventer. On one hand, if the control line is long (to the bow and back to the cockpit) and the boom is back a little, even a little stretch can permit a jibe. There is an up-coming PS article on jibe controlers that covers this. On the other hand, if you stuff the boom in the water, Dyneema is unforgiving. I use polyester, but I've got a lot of beam and the preventer is rigged to the midships cleat. If I ever dip the boom in the water, it will be because I am upside down.

Either way, make certain you can release the preventer in a controlled manner if (when?) the main is backed. S__t happens and you need a plan.

[Dockhead]

Originally Posted by thinwater

I agree with Livia re. sailing slightly by the lee being faster. It increases flow on the lee side of the main and keeps the genoa full. Obviously, you have to watch out for yawing.

I have mixed feelings on a Dyneema preventer. On one hand, if the control line is long (to the bow and back to the cockpit) and the boom is back a little, even a little stretch can permit a jibe. There is an up-coming PS article on jibe controlers that covers this. On the other hand, if you stuff the boom in the water, Dyneema is unforgiving. I use polyester, but I've got a lot of beam and the preventer is rigged to the midships cleat. If I ever dip the boom in the water, it will be because I am upside down.

Either way, make certain you can release the preventer in a controlled manner if (when?) the main is backed. S__t happens and you need a plan.

Thread drift, but interesting.

How can a preventer rigged to midship cleat prevent a jibe? Won't the main force vector be DOWN? I rig mine to bow cleats, although this is a PITA and requires long lines.

I chose dyneema because I needed the long lines (45 meters long) to be practical to handle, and so I wanted to use smaller diameter rope. I think that if the boom goes in the water at speed -- and I may be making 10+ knots in strong weather -- I am totally screwed no matter what -- no preventer will keep things together. So the design brief for my preventers did not include surviving that. I take great care not to risk getting the boom in the water. That means getting rid of the mainsail altogether sailing downwind in big sea conditions, which I do religiously. Headsail alone for such conditions, and boom safely raised, centered, and out of the way. But getting the boom in the water is unlikely on this boat in any case, as she has a fairly short boom, only 6 something meters (high aspect main), and fairly high (I guess 3 meters above the unheeled waterline).


I actually don't think the preventer needs to be all that strong. It works by preventing snatch loads on the boom, and there won't be any if the preventer is kept taught. The total force which the backed main can exert on the end of the boom is rather small compared to the strength of ropes of this size. The big caveat to this is that the preventer is often working at an angle which magnifies the loads, so this has to be taken into account.


As to being able to quickly blow the preventer -- I completely agree with you. Mine are always kept on a secondary winch, the one normally used for a running back stay, but not needed for that on the lee side. Also, you have to be able to constantly adjust them so that they are always taught, another reason why I keep them on a winch. Fortunately I have enough winches (10x) on this boat to make that work.

[Pete7]

So what happens if you use the Genoa and the Yankee as twin head sails without the main DDW? Appreciate the pole is out of action so you might need to use the blade instead.

Is the blade more stable and less likely to collapse DDW +-25 deg because it's a tall skinny sail perhaps?

Pete