Tacking or Gybing downhill??

[SloopJohnB 322]

Are they tacking or gybing down hill?

 

My take.

 

If they stay on the foils and don't slow down so the boat speed is always greater than the true wind speed the apparent wind angle will always be in front of the boat, passing around the bow and not the stern.

 

Flame away.

[Deep Purple 514]

Ha, I was just going to post this then thought better of it. The commentators made the statement that even though they are gybing, the sails pass through into the wind which is true at 30+ knots boatspeed in 18 knots of true wind.

 

I had to google it - Tacking or Gybing relates to the bow or stern passing through the wind but i couldn't find any reference to apparent wind or true wind. So I dunno...... hence thinking better of it.

[Guest]

They need to learn to shunt.

[SloopJohnB 322]

only if the boats get close enough together.

[Island Time 1,252]

When tacking or gybing was invented, they never had boats capable of making the apparent wind go so far fwd! My money is on the true wind - ie if the bow passes through the eye of the wind, its a tack. It would be interesting to note what the wind indicator does though -if they have such a basic device!

[RushMan 31]

It would be interesting to note what the wind indicator does though -if they have such a basic device!

I think I saw one on the end of the prod this morning. It was just a glimpse so I may be wrong

[SloopJohnB 322]

You beat me to it IT.

 

So tacking downwind is faster the than gybing.

 

Here's proof.

 

You are on sailing downhill on starboard (say 50deg twa) and you gybe, the wind has to move 260 degrees but if you tack it moves only 100 degrees.

[Island Time 1,252]

Come on SJB the wind does not move! Hmm that sounds kind of stupid - of course the wind moves or there would be calm! But I'm sure you get the point.

[SloopJohnB 322]

Apparently it moves.

[Island Time 1,252]

Haha very good!

[Guest]

Why do they not stay on the foils when they tack (going upwnd) then?

 

[Guest]

It is an important question - are they going up or downwind, because rule 18.1 says that rule 18 does not apply between boats on opposite tacks on a beat to windward, but approaching a downwind mark, rule 18 does apply.

 

Rule 13 says you must keep clear while tacking...

 

"After a boat passes head to wind, she shall keep clear of other boats until she is on a close-hauled course. During that time rules 10, 11 and 12 do not apply."

 

Even though the rules (including the definitions) do not define what 'head to wind' means, and do not define what 'a beat to windward' is in terms of is "the wind" concerned the true wind or the apparent wind, if this was ever challenged and taken to ISAF for a ruling I'd bet dollars to donuts that the outcome would have to be it is the true wind that must be used in both interpretations.

 

It has to be ruled that it is the TRUE wind, because otherwise you can end up with a paradox situations. For example, where two boats of different designs are on the same leg, and that leg is a "downwind" leg relative to the TRUE wind...

 

...IF the defintion of tacking, and head to wind and a beat to windward versus a downwind leg depends on the APPARENT wind, then one of those two boats of different designs might be going fast enough to bring their apparent wind forward of the beam, while the other boat is not. That would mean one of them was on a beat to windward and one of them was on a downwind leg.... so then does rule 18 apply when they get to the mark at the end of the leg on opposite tacks, or not?

 

Furthermore, a single boat that is alternating between going fast enough to bring the apprent wind forward of the beam, and then slower, so that it goes aft of the beam, and then back to forward of the beam would have to be ruled as one an upwind leg, then on a downwind leg, then on an upwind leg, all on the the same leg. And that's nonsense.

[Picklefork 0]

When a race officer sets a course the wind they set the course to is the true wind.

[Guest]

...unless it is an offshore race, for example...

[Picklefork 0]

When you attend a protest hearing one of the first things asked by the protest committee is - what was the wind direction, wind strength. This is normally the true wind at the point of the incident.

In my experience they are only ever interested in the course you sailed and the angle you are to that true breeze.

It matters not whether it is inshore, offshore, lake or river.