Totally agree. Complete waste of time.

useless

You can adjust a traveler by centimeters, and be able to set it totally down in strong winds. Two sheets will allow you to adjust adequately from low to mid wind, but will fall short on fast depowering. You will also rely more on the vang upwind, so that's an additional concern to remember about, when the shit hit the fan. For cruising, that's fine as you will supposedly reduce your sail plan before the issue occurs.

Yes. Sail trim matters even more when racing....

I'd argue that it's basically only racing sailors that care enough about sailtrim to do these things :)

Fair questions, but probably too much to answer in a short video. For light wind ease all three to add fullness to the sail. Trim them as the wind gets stronger to flatten the sail. Trimming the cunningham moves the draft forward as wind gets stronger.

uh, centre of the boat?!! The middle in a line fore and aft.

blairrob does the main sheet and the traveller both move the boom

Yup, if you were holding the end of the boom with your hand and moving it left or right would simulate the movement of the traveler while pushing it up or down would simulate the easing or tightening the main sheet. That said, both do the job of the other to some degree.

Simple. Always as little as possible. Do you need much tightening, you need a new headsail.

Bending the mast flattens the mainsail. Assuming (as is usually the case) that tightening the backstay also tensions the jibstay/headstay, then the jib will flatten too.

As Marty says, tighter backstay will bend the mast (especially on a fractional rig with straight spreaders), which basically means that the masthead moves backwards a little which let's the head of the main twist out more, but it also bends the lower part of the mast forwards, curving the mast more and thus flattening the main. It also tensions the headstay which flattens the jib and makes the luff sag less, so it goes better to windward :) How much each of those effects actually happens depends on the rig and how stiff the mast itself is. A masthead rig doesn't really get much more effect than a tighter headstay/flatter jib, and perhaps just a little more bend in the mast if the rig was setup with some curve to start with. A fractional rig with the headstay a long way below the masthead, that also has runners, straight spreaders and a soft mast tube may not tighten the headstay at all and on some boats I've sailed, it almost felt like it was just the top of the mast bending aft and to leeward. It still trims the main a lot though, but probably more by twisting the top more than flattening the lower part of the sail.

His explanation is excellent, but only if you're already familiar with basic sailing terms.

To be fair, one shouldn't sail with genuas partly furled, even less so with them furled so much that moving the car forwards matter very much. Furled genuas doesn't make for very good jibs, especially not for going upwind. But sure, adjusting the car properly will oro8help to some degree, but it's a bit of a "lipstick on a pig" situation :/ Not even singlehanded racers sail with partly furled sails on bigger boats, they switch to smaller jib on an inner forestay or similar :)

@@Robinlarsson83 I'm not talking racing here. Just going out for a sail. Who wants to stop and change headsails when the wind is gusty. The great thing about a furling genoa is that you can react to the wind changes. Of course, if you know much of the trip will be upwind, load your jib. If you furl the genoa so it's all in front of the mast, it is relatively small and high up. A jib will certainly be more efficient. However, if you don't change the hauling position, the shape of the furled genoa will be awful.

Well, do you know basic sailing terminology? If not, start there :) if you do know them, well, perhaps start over with the basics of sailtrim? :) This wasn't very deep or technical tbh, and probably not really aimed at beginners. But, frankly, those of us who know the basics and could easily follow along, we didn't really learn anything new here either :/ a good refresher if you've been of the seas for a bit, or if you know the basics but want to get more into performance sailing, which I'd imagine is actually quite a few people. Considering how many sailboats you meet on the water that doesn't actually sail, or only sail very inefficiently, more people oro8dhould look at videos like this :P