Lug Sail Good Tack vs Bad Tack

This time I'll have a look to see if my skiff's Lug sail has a good tack and bad tack! Does it?
I compare a few occasions when I sailed side by side with Pedro on his Goat Island Skiff, Bruno on his Topper and me on my GIS too.
Pedro's boat and mine have the sail rigged on opposite sides of the mast so when I sailed on the so called Good side he is sailing on the Bad tack.
Bruno's Topper is not affected by this and it's really useful has as some degree of standard.

You'll be able to see both sails on both tacks and in different wind conditions too.
Have fun!!

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[MikStorer]

That's totally the opposite of what we get with the Oz Geese where we are racing fleets of boats and swapping boats.

Before we started to really get used to racing the boats there seemed to be a difference. But with regular fleet sailing we have a much better idea of what is happening. Both tacks are the same for equal ability sailors sailing nearby but not blocking each others wind.

But now the equally good sailors can stay close together with their sails on opposite sides of the mast. Not just once, but race after race.

With the sail to windward it is the good tack. Everyone can sail the boat fast. With the sail on the leeward side the speed is more tricky to find. But if the speed is found before pointing and then the boat is pointed ... the speed is equal ... just have to remember the feeling of speed on the easy side and make sure that speed it equalled on the more difficult side.

I would say that the light wind sections are inconclusive in your video. In each case the boat pulling away is in clear wind and the other isn't.

The medium/strong footage is more compelling.

One of the things we have found with the geese is using the sheet with more aggressive easing in gusts to make sure heeling is not too much also prevents leeway. Don't ever pinch the boat upwind in gusts. Just ease the sheet and hike. Pull the sheet in again when the power drops so we don't heel to windward. Boats that pinch go sideways. Boats that ease stay on the same line and go much faster.

[brucekjesbo]

I think you have something there…..I never thought of “good tack/bad tack” before, but what you showed makes sense!

[billdykes]

What a fantastic video! Best presentation on the subject I have ever seen. I have sailed a type of sailing canoe in Japan called a Sabai from Okinawa for about 12 years. It's a very strange boat. A shark fishing boat, coated in shark liver oil to preserve and water-proff with sails often dipped in pig's blood also for preservation. Used to be a pure dug-out canoe but now uses three planks as the big trees are all gone. Traditional sabani sailors have no outrigger for support. They are the most unstable boats in the world but after about 4 years of regular practice you can get the balance of it even in strong winds and on the open sea. The rig is a Chinese style (adapted by the Okinawans) junk rig with bamboo stretchers mounted outside the sail. You canot dip the rig and must plan ahead for which side you want to rig on. Without a doubt, and with several hundred years of practice, I can tell you the Okinawans totally agree with you. It is common sense to them that they lose the effort from any sail area before the mast. Furthermore there is more air disturbance in such a situation. To see and learn about the crazy Sabani boats you can Google "Sabani Okinawa". Now I have moved to the south of France and am about to buy an old lug-sailed mackerel boat from Brittany and so I need to learn the lug sail. Your video is great, please keep them coming. Kind regards, English Bill, port of Marseillan

[phyconautwaterworld]

Thanks for this useful test of a long standing hypothesis. It gives substantial support for the utility of symmetrical rigging and/or use of a dipping lug sail.

[marB]

Thanks for very good explanation and examples! 👍

[fosterprice]

Great video. Thanks for the analysis and especially the advice at the end. Cheers

[gregaldworth]

Buuut, you have an engineer's analytical mind and your analysis makes complete sense.

[zvonimir]

I like your videos. Greetings from Croatia

[TheCrioGod]

Nice introspective on this matter, very educational 😁

[jasonstork]

I am revisiting this video because I have exactly the same issue as you do. My bad tack is the one where the sail is pressed against the mast. Despite what Mik says is possible I have not yet achieved it. I lose angle and about 2 knots of speed on the bad tack in around 10 knots of wind.

I need to do some more work on my sheeting arrangement and I can see that I have some sail twist issues when I look at some of the videos I took, so a big part of this is my inexperience, but I am learning heaps thanks to you and Mik Storer and Ross Lillistone.

[captaincolumbus]

You get more sailing from a bad tack. My friend has a very fast power boat he gets his afternoon on the water done in 30 minutes and then he watches the street. Peace and love everyone 💕 Peace and love. 🇹🇹🚣‍♂️🇯🇴 Rick

[earlhall]

The tension differences in the downhaul can make a very significant difference in how the leading edge of the sail splits the airflow. I think Mike Storer has found that also. Also if the outhaul downhaul and outhaul are both tensioned more so the sail is flatter, the portion of the sail ahead of the mast will not have such a different angle of attack, and may start to contribute some lift. Perhaps that is why in stronger winds when the sail is tensioned flatter that the good/bad tacks show less of a speed difference. Not an expert - just guessing .

[RulgertGhostalker]

the axle would just have to be perpendicular to the sail spar at the angle you want the spar. ( see previous comment )
then every tack is a good tack, and you could also go past center, stop in the middle, and rig to sail downwind.
each sail spar end would have it's own side to swing...one end swings on the port side, and one swings on the starboard swings up, while the other swings down.

[jetta]

My experience indicates better boat speed (in rough conditions) when on the 'Good Tack' and better pointing ability on the 'Bad Tack'. I've been sailing dinghies competitively for 64 years.

[jwboatdesigns]

When teaching marine design at University, we ran some wind tunnel tests on various rigs, and I was interested in how the lug rig and the junk rigs performed on each tack. We found that in both cases, all else being equal, the boats were faster and pointed better on the tack with the mast on the leeward side. I'd suggest that you might look for other differences.

[rockykoast]

I'm intrigued by lugsails, so studying up a bit. I've seen 2 of your videos so far & already learned much!
My boat is an old gunter-rigged Mirror. My goal is to try dinghy cruising. I'm kicking around the idea of a single balanced, boomless lug sail instead of the main & jib, impressed with the apparent ease of handling on Roger Barnes' ilur. No boom to hit you on the head, easy to drop in a squall.. perhaps dispense with the standing rigging....

[mikefule]

Good video, and the first I've seen attempting to make a direct comparison. However, I don't think your results are conclusive. There are other differences, including the weight, position, and ability of the two sailors, and I doubt that the boats are absolutely identical. If you had swapped boats and done the same comparison and got the same results it would have been more conclusive. As others have pointed out, you are sailing with an unusually big draught (belly) in your sail in the light winds. It seems to work for you. My own boat is also balanced lug. I find she has a good tack and a bad tack, but it depends on the wind, the surface conditions, and most of all, what mood she's in. On a windy day, the so-called "bad tack" helps to keep the sail flat and it becomes the "good tack". On a windy day in a non-planing boat, you are limited to hull speed, and once you can achieve that, any theoretical "inefficiency" in the sail is irrelevant. On a day of low winds, I find the biggest single factor is putting my weight in the right place and sitting still so as not to disturb the airflow over the sail. Thanks for posting the video. Genuinely interesting.

[johannpcurry]

On Scamp I can not find a difference in speed on either tack. I wonder if it is because it has a round mast....a square mast must have decrease laminar flow comparably. Also scamp appears to has more sail forward of the mast. have you experimented with moving the yard and boom more forward? when I"m sailing on your "bad tack" I see two foils. One forward of the mast and one aft. like a jib and a main. the shape of the sail looks pleasant. with how your rig is set up right now to my eye your bad tack doesn't have clean foil lines. hope this can help you. Thanks for posting your videos.

[RagtimeBillyPeaches]

I don't believe that the loss of sail area is as detrimental on the 'bad' tack, as the fact that the luff shape destroys the air flow over the sail. I wonder if flattening the sail draft while on the 'bad' tack might help some.

[kenwebster]

There is more going on here than simply good an bad tack. That doesn't mean your wrong about that though. Most of the time when your showing the bad tack your also in a disadvantage wind from the other boats and when you are showing the good tack, your in an advantaged position. You see, a sailboat is deflecting the the wind. Changing the local wind direction around it in the direction a a knock on that tack and a lift on the opposite tack. It also slows the wind speed slightly. So, if you are level, overlapped or aft & whether you are anywhere from their windward to lee side you will experience a knock and be unable to point as high as them & you will have less wind speed than they do. So, you will be disadvantaged in both wind pressure and pointing ability.

If you are in front on the same tack anywhere from their lee bow to windward bow, you will have the advantage of wind pressure and pointing ability over the other boat. So this makes it difficult to make valid comparisons between boats that are close to each other.

However, just thinking abut airflow over sails, I think you are correct, because the mast is a big disrupter of airflow. The layer of air that is affected by the skin friction of the sail is called the boundary layer. When a sail is attached to a mast, the boundary layer typically separates form the sail, but reattaches further downstream, forming a "separation bubble". This tends to happen on both sides but reattaches more easily on the windward side than the lee side. If it does not attach on the lee side, this is a stall. Racers place tell tails on their sails to indicate whether flow is attached or not and that helps adjust the sail shape to maximum efficiency. Anyway, the point is that on the bad tack, I would expect a large area of boundary layer separation to occur around the mast area, particularly on the lee side which will spoil both pointing and power. However, on the good tack, the mast is mostly in free air away from the sail, so it will not generate a separation bubble on the sail. So I expect you will have more efficiency on that tack.

There are, or at least have been double ended lateen rigged boats designed to reverse direction so that the sail is always on the lee side of the mast. They change tacks by simply reversing rather than going about. They use 2 steering boards, no rudder. Have you ever seen anything like that, I have only read about it? Maybe its historic.

Regards,
Ken