Why is it so hard for me sail downwind?

[shaant01]

I find that if there isn’t too much wind, it’s much easier to sail in a close haul, whereas if I turn off the wind into a broad reach or even beam reach, the wind seems to die and the boat won’t even move. If there is decent wind, it’s a non-issue. Is it harder to sail downwind when knottage is low?

Thanks!

 

[Davidasailor26]

I don’t know if harder is the right word, but it is definitely slower. When you’re going upwind your own boat speed adds to the apparent wind speed, and the sails are able to act like wings to generate lift and pull the boat forward. When everything is trimmed right it’s not to difficult to sail at or slightly above the true wind speed in that direction. But when you turn downwind you boat speed subtracts from the apparent wind, and the sails usually only provide drag, not lift. Going dead down wind it’s not really possible to go as fast as the wind, and with most non-sport boat hulls quite a bit slower.

Depending on the wind speed you might find it best to go on a broad reach rather than a dead run. At least that way you can try to keep the jib full and not just shadowed by the main. The compromise is that if your target is dead down wind you’ll need to cover more distance reaching and gybing. Racers have polar diagrams that show them the ideal angles for each wind strength, but when cruising it can be just done by feel too. Also if you don’t have a whisker pole you could consider one; that can help the jib pull much better on a run ands even a very broad reach.

 

[BarryL]

Hello,

Youare 100%correct. In moderate or light wind it is difficult to sail downwind. If you really want to sail downwind you really need downwind sails like a spinnaker.
as mentioned, sailing downwind is hard because the apparent wind drops quite a bit as you go for a reach to a run. There is no east to overcome that.

Barry

 

[shaant01]

I don’t know if harder is the right word, but it is definitely slower. When you’re going upwind your own boat speed adds to the apparent wind speed, and the sails are able to act like wings to generate lift and pull the boat forward. When everything is trimmed right it’s not to difficult to sail at or slightly above the true wind speed in that direction. But when you turn downwind you boat speed subtracts from the apparent wind, and the sails usually only provide drag, not lift. Going dead down wind it’s not really possible to go as fast as the wind, and with most non-sport boat hulls quite a bit slower.

Depending on the wind speed you might find it best to go on a broad reach rather than a dead run. At least that way you can try to keep the jib full and not just shadowed by the main. The compromise is that if your target is dead down wind you’ll need to cover more distance reaching and gybing. Racers have polar diagrams that show them the ideal angles for each wind strength, but when cruising it can be just done by feel too. Also if you don’t have a whisker pole you could consider one; that can help the jib pull much better on a run ands even a very broad reach.

Thanks for the clear explanation! It definitely feels slower to sail downwind, but it sometimes feels as if the boat won’t sail at all unless I turn into the wind and tension the sheets. It’s hard to tell. It sounds like more wind is needed to drive the boat on a downwind course. I have a rather small boat (17ft) so there is less sail area overall too. Cheers!

 

[shaant01]

Hello,

Youare 100%correct. In moderate or light wind it is difficult to sail downwind. If you really want to sail downwind you really need downwind sails like a spinnaker.
as mentioned, sailing downwind is hard because the apparent wind drops quite a bit as you go for a reach to a run. There is no east to overcome that.

Barry

Thanks Barry! That is helpful to know. I find it hard to sail even on a reach when there isn’t much wind. I will look into a spinnaker or maybe whisker pole for the jib.

 

[dLj]

Be sure you are actually measuring your speed over water. You may be going faster than you think. As soon as the wind starts getting behind you, you feel slower because you are moving with the wind, not against it.

I few years ago, I went for a day sail where in the morning i was running a close hauled leg and was making about 5 knots. It felt fast. A few hours later i turned around and was heading back on a broad reach and it felt like I was going slow. But when I checked my speed i was running about 9 knots.

dj

 

[shaant01]

Be sure you are actually measuring your speed over water. You may be going faster than you think. As soon as the wind starts getting behind you, you feel slower because you are moving with the wind, not against it.

I few years ago, I went for a day sail where in the morning i was running a close hauled leg and was making about 5 knots. It felt fast. A few hours later i turned around and was heading back on a broad reach and it felt like I was going slow. But when I checked my speed i was running about 9 knots.

dj

Thanks! I don’t have a speedometer on the sailboat, but I know I can’t trust my senses either. Maybe I can find an app for boat speed. You can’t really eyeball it.

 

[dLj]

Thanks! I don’t have a speedometer on the sailboat, but I know I can’t trust my senses either. Maybe I can find an app for boat speed. You can’t really eyeball it.

Actually, yes you can "eyeball" it. Take something that floats and will biodegrade without an issue - like a small piece of white bread - throw it into the water at your bow and count the seconds it takes to pass your stern. Knowing the length of your boat, you then have X feet per Y seconds and it's a simple matter of doing the math.

dj

p.s. even if you aren't totally accurate - it can be a good comparison. However you find it's easier to execute, do it the same way in both directions. Three or four slices of white bread can keep you entertained for hours - and give the local fish population a treat...

 

[Will Gilmore]

Thanks! I don’t have a speedometer on the sailboat, but I know I can’t trust my senses either. Maybe I can find an app for boat speed. You can’t really eyeball it.

I was sailing my windmill with my son. He had almost no experience and we were on a lake with the wind strong in spots, and blocked by the shore in others. We had a nice run out, I was on the jib, my son at the tiller. We turned back to sail DDW. My son said, "We lost the wind." He sounded so disappointed.
I said, No, there's plenty of wind, you just can't feel it because we're sailing with it."

He argued that we weren't going anywhere, so there was no wind.

Being on a lake in the North Woods, I pointed to all the pine needles rushing backwards to illustrate how fast we were going. He was still skeptical until we hit a submerged rock with the daggerboard. I went flying, my shin bruised on the twart as I landed in the bow.

My son looked at the huge black and blue knot distorting on my shin and asked, "Did you break your leg?"

"No, it's just bruised, but now do you see how fast we were going?"

-Will

 

[Joe]

Do you have a sailing instructional book? Now's the time to study up on the nature of true and apparent wind. Remember: True wind data is what we use for navigating, Apparent wind data is what we use to trim our sails.

Downwind sailing will always FEEL slower than sailing to weather. That's because upwind your apparent windspeed is true speed PLUS boat speed. Whereas, going downwind, the boat speed is SUBTRACTED from the true wind.

 

[Will Gilmore]

And don't confuse heeling with power. Just because you aren't heeling, doesn't mean you don't have power driving you. Part of the illusion of sailing is the idea that you are going faster when you are heeling more. That is often not true, and heeling too much can reduce the power driving you forward.

Do you have a sailing instructional book? Now's the time to study up on the nature of true and apparent wind.

-Will

 

[Scott T-Bird]

Just yesterday Sue and I were sailing in light/variable wind, say 5 to 11 knots with main and 135% genoa. On a broad reach, boat speed was 2 to 4 knots. On a close reach, boat speed was 5 to 6 knots. The point of sail absolutely affects boat speed, particularly in light wind. There is no arguing over perception when you are measuring boat speed.

BTW, when on a broad reach, there was no heeling. When on a close reach, we were heeling even in the lighter wind. In gusts approaching 14 knots, we were easing sheets as apparent wind moved back to increase sail efficiency and to prevent excessive heeling and the resultant helm pressure. It's not an illusion that heeling is associated with speed. In this case, it's a fact. Speed increased with associated heeling. Of course, keeping the boat as flat as possible with an increase in wind speed improves speed, but let's not perpetuate a myth that heeling is slow.

 

[SteveHughessails]

When running we push the head sail off to the right and the main to the left or vice versa trying to capture everything.

 

[Scott T-Bird]

When running we push the head sail off to the right and the main to the left or vice versa trying to capture everything.

"Wing on wing" is truly an acquired taste! In light wind, it is difficult to keep the head sail filled without the aid of a whisker pole. In a strong, wind, keeping the head sail is not so problematic but it also becomes less and less for the faint of heart without a boom preventer!

 

[jssailem]

My son looked at the huge black and blue knot distorting on my shin and asked, "Did you break your leg?"
"No, it's just bruised, but now do you see how fast we were going?"

It sounds like you took the shot to demonstrate the physics lesson to your son. Speed can kill you if you are not careful.

 

[dLj]

Just yesterday Sue and I were sailing in light/variable wind, say 5 to 11 knots with main and 135% genoa. On a broad reach, boat speed was 2 to 4 knots. On a close reach, boat speed was 5 to 6 knots. The point of sail absolutely affects boat speed, particularly in light wind. There is no arguing over perception when you are measuring boat speed.

BTW, when on a broad reach, there was no heeling. When on a close reach, we were heeling even in the lighter wind. In gusts approaching 14 knots, we were easing sheets as apparent wind moved back to increase sail efficiency and to prevent excessive heeling and the resultant helm pressure. It's not an illusion that heeling is associated with speed. In this case, it's a fact. Speed increased with associated heeling. Of course, keeping the boat as flat as possible with an increase in wind speed improves speed, but let's not perpetuate a myth that heeling is slow.

It gets a bit more complicated. It depends upon hull design. Some boats are meant to be healed to gain waterline and hence more speed. Most boats have a "preferred" amount of heal - that depends upon hull design. My boat likes to run fairly flat, if I get her healed beyond her comfort zone, she slows down - measured data. I've had other boats that behave differently.

dj

 

[dLj]

"Wing on wing" is truly an acquired taste! In light wind, it is difficult to keep the head sail filled without the aid of a whisker pole. In a strong, wind, keeping the head sail is not so problematic but it also becomes less and less for the faint of heart without a boom preventer!

Hahaha - for sure! I happen to love running wing on wing. But it does take a lot of practice. I pretty much ran the entire milk run wing on wing. I do have a whisker pole, and I ALWAYS use a preventer unless I'm close hauled - even sometimes then also. I use my preventer even when anchored. It keeps my boom totally stationary.

dj