Tacking 101

[barnakiel]

Originally Posted by Jman

This not accurate, VMG to the mark combined with weather forecast is exactly how routing software works. (...)

You are assuming the wx routing being done over a large stretch of water and over 'many' forecasts (= over a sequence of time series grib data, e.g.). Akka may mean the actual best tactics to get thru the existing weather to a relatively closer target. This could be, e.g. a day end WPT as generated by wx routening software for a longer open water passage.

You are both right, and Akka pointed his finger in the right direction.

Without polar diagrams and assuming the WPT is far off, we can approximate the solution by sailing VMG to the WPT. When polars and wind data are available, our daily choice will be governed by 'wind VMG' with an eye on long term wx forecast and then also on historical wx data (pilot charts).

In fact, not all wx routing software applies the same logic / algorithm to the problem of long range (WPT hundreds of miles off - beyond the reach of immediate / wx data). Fire up Deckman, MaxSea and Adrena, feed them with the same data, see what you get.

Akka is 100% right if we think of a smaller playfield - WPTs spaced within one time series data set.

Cheers,
b.

[Stu Jackson]

Originally Posted by OldFrog75

That sounds good in theory but what is the practical application? My handheld Garmin does not compute VMG to the wind. Does yours?

Sure it will. But YOU have to make it do that. Find the wind direction and swet a waypoint out about 1,000 nm in that direction. You now have a VMG to the wind based on that waypoint.

Then you compare it to the waypoint to the next mark and work from there.

[OldFrog75]

Originally Posted by Stu Jackson

Sure it will. But YOU have to make it do that. Find the wind direction and swet a waypoint out about 1,000 nm in that direction. You now have a VMG to the wind based on that waypoint.

Then you compare it to the waypoint to the next mark and work from there.

Ok. Good suggestion but I don't think it's practical on an amateur race course, which is where I do the majority of my sailing. Winds shift too frequently to make that a viable alternative. Besides, toggling back and forth between Wind waypoint and the mark waypoints would drive me crazy.

[Jman]

Originally Posted by barnakiel

You are assuming the wx routing being done over a large stretch of water and over 'many' forecasts (= over a sequence of time series grib data, e.g.). Akka may mean the actual best tactics to get thru the existing weather to a relatively closer target. This could be, e.g. a day end WPT as generated by wx routening software for a longer open water passage.

You are both right, and Akka pointed his finger in the right direction.

Without polar diagrams and assuming the WPT is far off, we can approximate the solution by sailing VMG to the WPT. When polars and wind data are available, our daily choice will be governed by 'wind VMG' with an eye on long term wx forecast and then also on historical wx data (pilot charts).

In fact, not all wx routing software applies the same logic / algorithm to the problem of long range (WPT hundreds of miles off - beyond the reach of immediate / wx data). Fire up Deckman, MaxSea and Adrena, feed them with the same data, see what you get.

Akka is 100% right if we think of a smaller playfield - WPTs spaced within one time series data set.

Cheers,
b.

Wind VMG should be identical on both tacks, unless you are talking VMG to an average wind direction. Or your boat is totally out of tune.

Wind VMG is just a tool, and a poor one at that, to monitor if you are pinching or too far off the breeze, upwind, and the opposite downwind. It does not in any way factor in a destination.

Most wind instruments will calculate a VMG Wind number for you, but maximizing that will not necessarily get you to the destination faster, in fact it could be a broad reach to the destination, and VMG wind means nothing, everyone of course knows this, so they don't need an instrument to tell them.

If you start with the destination directly up wind from you on a short course, as soon as you move a few feet on one tack or another the mark stops being directly up wind of. You are immediately on the short tack to the mark.

Short course racing is way different tactically than passage making. Weather forecast that are in hourly gribs mean nothing. But you generally have a wealth of information that can get you started on the right tack. You probably have a daily forecast, or local thermal elements that will let you know which way the wind might trend. While tuning up pre-race you can make notes about oscillations, duration, degree. Are the puffs generally lefties or righties? Are there other classes of boats ahead of you that you can look up the course and see if there is new wind coming down.

The general rule is that if you think the wind is going right, go right, if left then go left. If you predict accurately, tack when the header arrives. If it is oscillating you can tack back and forth on each header, and you may be on your way to earning a pickle dish.

This all only accounts for wind direction, but velocity can be even more import, fortunately you can see that on the water, and get over to it.

Obviously a full dialog on all aspects of racing to a mark can't be covered here. The are many books on the subject, but you will still be beaten by the people who have more experience, and ability to read the wind. That is what separates professional tacticians, from the rest of us.


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[Paul J. Nolan]

Originally Posted by Winf

Ok, so having just clocked up our first 5000 miles I thought it was high time I learned to sail.

That isn't funny or cute. It's pathetic. Your 5,000 miles isn't an accomplishment. It's an embarrassment.

Tacking. When to do it? Most efficient way to get where I want to go?
For some reason I just can't seem to get my head around when I should be tacking. What is the best overall strategy(s) to use?

What you're doing is like asking the other guys on the football team how to wipe your backside. This is something very basic you should have picked up a long time ago. Asking about it is going to raise eyebrows; people will talk about you after you leave the room, and not in admiring tones.

You cannot learn to swim by asking swimmers much. You can't really learn it by reading. Even a degree in fluid mechanics will not make you swimmer. Swimming lessons will not make you a swimmer. There is no way around it: to become a swimmer you have to get in the water and swim!

It is the same with sailing. The way to do that is to get a small boat. (Here we go again). I think the best choice is a Laser. But it's not the only choice. It's also important to get a boat that is sailed and raced locally--at your own club. If you live in Scow Country, perhaps an M16. Or a Snipe, or a Y Flyer or a Windmill. It doesn't matter as long as it's small, fun to sail, and self-rescuing. Get a copy of The Sports Illustrated Book of Small Boat Sailing. Read it. Then go sailing. Every spare hour, all season long. At the end of the season you'll know something about sailing, which puts you far ahead of where you are now. Next season, race. Every weekend, every Wednesday night. At the end of that season, you'll know how to sail upwind and down in heavy air and light, how to tack and jibe, what headers and lifts are and how to best use them to your advatage upwind and down, what laylines are and why to avoid them, what the Death Roll is and how to avoid it, and much, much more. You'll know how to sail. That alone will not make you a sailor, but you'll be well on your way. And you will have answered all the questions in your original post and many more besides.

Now I look forward to returning to your original post and reading the rest of the thread.

Paul

[Paul J. Nolan]

Originally Posted by SteveInMD

The best way to learn is to spend some time on a racing boat.

Here's some good advice from a guy that gets it!

I am always amused.when someone asks a question that reveals his problem is in fact his utter and woeful ignorance (Owner's Bed With Access From Both Sides) and not at all the subject of his inquiry, yet so many people respond with earnest and lengthy explanations focused on the question while remaining blind to the questioner's real need. The original poster's problem is not tacking, it is that he doesn't know how to sail. He learns to sail, he won't need to ask about tacking. He'll already know!

Paul

[barnakiel]

Yes.

I think we agree on the differences between tacking 101 for the sake of making it first to the next mark (be it on the race course or towards a day-end target WPT gotten from a routening software) vs. tacking 101 for the sake of a long passage. These two modalities use similar notions, they may somewhat overlap and complement each other, but can be seen as 'not quite the same thing'.

My attitude is perhaps less orthodox, due partly to my present angle (being a wx router and, to a lesser extent, wx tactician) while my racing days are long past. When I raced, we did not have plotters, digitized polar diagrams, nor electronic wind instruments. This much said, I am shocked (mildly, but repetitively) by how few cruisers use how little of how much is available. I put it on my racing past bias and I say let people sail as they please as long as they make it to their destination happy and in one piece.

Also in our own boat, knowing some of the general points of how it should be properly done, I must admit I will more and more often trim for comfort rather than for speed or efficiency. So that we can laugh and say barnakiel tacks ... so that ALL crew members can get comfortable sleep (him, at the helm). He may tack back too - back onto the 'wrong tack' - when he finds the right tack happens to be the more rolly one. Or else when woken up by a slap from a wave ;-) "B's tacking 101 ;-)

Well. The good news is the thread is about tacking, not about anchors ;-)

b.

[Jim Cate]

Interesting POV, Barnie. We too come from a racing background, but it was a really long time ago, when we sailed seat of the pants, with a compass and a knotmeter. We have most of the required gear to do all the mod cons, but prefer to do it more in the old ways, not because of Ludditism, but because we enjoy it. (This refers to routing at sea, not accessing wx info or using modern charting methods.) And Ann and I, being old farts, don't drive the boat hard at sea, and tend to trim for comfort, just as you do (unless, of course, there is another boat going the same way and Ann is at the helm!).

Cheers,

Jim

[Paul J. Nolan]

Originally Posted by jrbogie

while on starboard tack and the wind goes left? you just got headed. tack onto port to get back on the new lifted tack. if the wind goes right? smile, you just got lifted closer to your mark. think opposite when on port tack.

The thread has drifted into a general discussion of windshifts and tacking. Of course the general rule sailing upwind is tack on headers. But I don't greet every lift with a smile. If you cross the center of the course and are headed toward the outside of the course the last thing in the world you want is a lift. A lift will hurt you and the farther out in the corner you are the more it will hurt. You are (desperately) looking for a header to send you back to the center on a lift. The farther away from the center of the course the more a shift will help or hurt you. It's like leverage. Leverage made Lehman Bros. and Bear Stearns look good for a long time. Then when the "wind" shifted, it destroyed them.

A starting line square to the wind is not necessarily a good line. If, when the blue flag is dropped at 30 seconds, the fleet is spread out uniformly along the line, the committee has done its job, and well. But if the fleet is bunched up at one end of the line or the other, then the only thing for the committee to do is signal a postponement and reset the line until the fleet votes its approval by spreading out uniformly.

And the weather mark's "being off to one side" or the other has no bearing on where along the line to start as long as the mark cannot be laid from the line on a single tack.

As is so often the case, Jim Cates is right. Cruising is different from course racing. But I am still of the opinion that a couple of years sailing and racing his own boat (not riding the rail on a forty footer) will stand the cruising man--and the OP--in good stead.

Paul

[Jim Cate]

Cruising is different from course racing. But I am still of the opinion that a couple of years sailing and racing his own boat (not riding the rail on a forty footer) will stand the cruising man--and the OP--in good stead.

I quite agree with this! I reckon that it is kinda important to start at a pretty low level of competition... local club racing comes to mind. Jumping into a more sophisticated racing crowd will, IMO, be less educational, 'cause they will all be gone before the beginner gets to the start line, and this is pretty un-fun and it's hard to learn from that position. As skill levels increase, moving up the racing ladder is possible, but may not be necessary to learn the lessons that are needed to improve skills as a cruiser. And it is not necessary to equip one's boat with all the mod cons of racing. I'm kinda astonished to see carbon or vectran sails in beer-can races these days!

But in general, a couple of dozen races will improve one's boat handling and windward trim skills, even if the podium is never seriously in sight. And it is often a bit of fun as well, and you meet some neat people as a rule!

Jim