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Old 3rd January 2009, 11:03 PM   #51
Ken
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Unregistered,

"The speed of a yacht relative to the waypoint it wants to reach".

It it seems to me that if you have a 1500 m upwind leg and it takes a slalom board 10 minutes to reach it and a formula board 8 minutes to reach it, then the formula board has a faster VMG.

On the other hand, it the mark is a beam reach, then the slalom board would have a faster VMG than Formula, but my comments related to upwind and downwind, not beam reaching. Everyone agrees on who's fastest on a beam reach.

A slalom board will not be faster upwind or downwind than a formula board.
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Old 3rd January 2009, 11:29 PM   #52
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Two things Ken

1) Question never said anything about "upwind" legs.Poster hinted he was finding "formula" difficult in 20knots +. ;hence advice 'Try Slalom kit ???

2) Your interpretation of VMG (saying without doubt Formula has better VMG .period) is utter nonesense.
Velocity Made Good is about where you want to go !
In all races (and even speed,apart from perhaps GPS timed events;where it wouldnt matter where you attained "Velocity") the board with best VMG always wins. Formula does not always win everything; therefore your statement is WRONG.

Formula has best VMG to upwid buoy in "most" conditions.
Formula has best VMG to downwind buoy in "most" conditions.

How on earth can a board with slower VMG win any race ????
Slalom always wis races such as Defi. But not according to some Formula sailors ????
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Old 4th January 2009, 02:54 AM   #53
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Unregistered, you are arguing for the sake of it. Clearly, VMG is inapplicable to the discussion of sailing on a beam reach because there is almost no measurable leeway angle when sailing a board specifically designed for beam reaching performance. Everyone who knows racing understands that "VMG sailing" means sailing to a mark (high or low) at a speed and angle combination that delivers the board to the mark in the least amount of time. In other words, VMG is "actual boat speed after adjusting for such factors as current and leeway." VMG is the upwind or downwind vector of boat speed.

Again, beam reaching to a mark is included in the literal definition of VMG sailing, but is understood not to be part of the context. You can't simply redefine a term of art in an attempt to make your point that FW boards are slower on a beach reach than a slalom race board in 20 knots. A point which, by the way, nobody cares to dispute.

Moreover, the first poster did seek advice about sailing formula in 20 knots. I assure you that whatever advice may be given that pertains to racing FW gear in 20 knots pertains to sailing FW gear in 20 knots sans racecourse. Additional advice that does not apply to FW racing may be helpful to the non-racing sailor sailing FW gear.

Either offer help that pertains to the question or offer nothing. Your position is akin to suggesting that a driver try a family estate wagon with auto transmission after the driver seeks help with driving a 1991 Porsche 911. Your observations are interesting but not germane.
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Old 4th January 2009, 08:18 AM   #54
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Speed boards are the fastest, yeah so cool
but
slalom boards are fastest on a slalom course
and formula boards are the fastest on a windward leeward race course.
wave boards are best at wave sailing!!
bet you didn't know that.
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Old 4th January 2009, 05:23 PM   #55
Floyd
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Cool Vmg

Actually Unregisterd (both of you) VMG has nothing top do with windward marks.
Its purely and simply the velocity made good taking into account leeway;tide; water flow (or whatever)in the DESIRED direction.

Slalom boards have fantastic VMG; even upwind when everything is taken into account.
It is relative; even a humble low volume waveboard in rough/big wave conditions can easily have the best VMG.ie its only one sailing !!!

Yes Formula in some conditions has best VMG in SOME directions. (never all )
Slalom in 20 knots may well have better OVERALLL VMG even to a winward mark.(Isonic 144 versus Formula in 25 mph ???)I wouldn`t like to decide.Suspect it would be down to sailor.

Speedboards on their day have best VMG to end of speed course.the DESIRED direction. There is a tendency in sailig for disciplines to hijack phrases thinking they are there own.This is one of them. VMG is a generic sailing (and flying;canoeing;walkingetc ) term.

Think we need some wind !!!
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Old 5th January 2009, 03:20 AM   #56
Ken
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Floyd,

I think we are all still learning what VMG means.

After reading what I copied from a Wakipedia article which I pasted below, it looks like in this author's definition, VMG is only relative to an individual craft trying to get to the windward or leward mark as fast as possible. Comparing VMG between different boards is of no value since each craft has one and only one VMG in a particular situation. Two boards could have very different angles of approach to a windward mark (one higher and slower and one lower and faster), with both reaching the mark at the same time. Which as the best VMG? Neither, but board speeds would have been quite different. One sailed a longer course with greater speed and one a shorter course with slower speed. In other words, VMG does not apply to beam reaching since the angle of approach is a straight course, unless there is a strong current running then VMG would apply.

VMG is not just speed, but a combination of both speed and angle of attack to get to mark that can't be reached on a straight course.

From Wikipedia:

"Velocity made good, or "vmg," is a term in sailing, and specifically yacht racing, that refers to the component of a sailboat's velocity that is in the direction of the next mark. The concept is useful in sailing, because a sailboat often cannot, or should not, sail directly to a mark to reach the mark as quickly as possible. Sailboats cannot sail directly upwind, and it is usually less than optimal, and sometimes dangerous, to sail directly downwind. Instead of sailing toward the mark, the captain wants to choose a point of sail that optimizes velocity made good.

Consider the scenario of a boat trying to sail directly north, with the wind coming also directly from the north. Because the boat cannot sail directly into the wind, the sailor must alternate between northeast and northwest headings, which are commonly called "tacks." On a northeast tack, the sailor will generally point the sailboat as far north as it can go while still keeping the winds blowing through the sails in a manner that provides aerodynamic lift that propels the boat quickly through the water, then they will fall off to a certain degree to create more forward wind pressure on the sails and better balance of the boat, which allows it to move with greater speed through the water, but with a less advantageous angle toward the mark.

A good sailor can intuitively strike the balance between speed and advantageous angle within a certain range of degrees, because the boat will either obviously slow down too much or get too far off course. To find the optimum angle with more precision, though, the sailor will want to determine the velocity made good, which usually requires computation and instrumentation.

Suppose you are on a setting of 60 degrees NE, and the speed of the boat is 5 knots. By falling off to 65 degrees NE, you can speed up the boat to 5.2 knots. Is the extra speed worth the less direct progress toward the mark?

The answer requires basic trigonometry. In both cases you want to know the northward component of the velocity vector, which requires taking the cosine of the angle between north and the sailboat's heading.

cos(60) * 5 = 2.50 knots made north (vmg)
cos(65) * 5.2 = 2.20 knots made north (vmg)
In this case, the more upwind setting clearly makes more velocity made good toward the mark, despite the lesser speed."

For what it's worth.............

Actually I had some wind on Jan. 1 and again yesterday. Sailed both days on an iSonic 111 and a Maui Sails 6.6 TR4. It was 84 degrees in Dallas, TX yesterday.
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Old 5th January 2009, 06:33 AM   #57
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Yep; Wikipedia says
"VMG is velocity of board in desired direction" but then goes on and on and on.....
Nice one Ken
For what its worth I went out on mountain bike today.Hot and sunny.
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Old 5th January 2009, 03:14 PM   #58
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most of freeriders have an oppinion that their TOW has more value and quality comparing to Formula. often they fail at first attempt to lift formula sail off the water because of weak back. but they are majority and they enjoy feeling themselves members of majority tribe. they don't enjoy sailing they enjoy being not worse than others in their tribe
I sail formula or wave depending on water conditions.
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Old 7th January 2009, 02:20 AM   #59
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Quote:
Originally Posted by Floyd View Post
Actually Unregisterd (both of you) VMG has nothing top do with windward marks.
Its purely and simply the velocity made good taking into account leeway;tide; water flow (or whatever)in the DESIRED direction.

Slalom boards have fantastic VMG; even upwind when everything is taken into account.
It is relative; even a humble low volume waveboard in rough/big wave conditions can easily have the best VMG.ie its only one sailing !!!

Yes Formula in some conditions has best VMG in SOME directions. (never all )
Slalom in 20 knots may well have better OVERALLL VMG even to a winward mark.(Isonic 144 versus Formula in 25 mph ???)I wouldn`t like to decide.Suspect it would be down to sailor.

Speedboards on their day have best VMG to end of speed course.the DESIRED direction. There is a tendency in sailig for disciplines to hijack phrases thinking they are there own.This is one of them. VMG is a generic sailing (and flying;canoeing;walkingetc ) term.

Think we need some wind !!!
Floyd: Respectfully, umm, no. At least not when people are talking about VMG in a racing situation. For example, when two boats are racing in proximity to each other each may not be sailing in a way that takes them to the mark in the shortest time. Covering a competitor is one example of this, but the time must come when the boat ahead breaks cover. In sailboat racing vernacular, this decision is communicated to the crew with the command "Go VMG."

It's certainly true (as you point out) that VMG by definition applies to every boat/board individually at any time, in any direction. But the point of debate is not whether two types of boards have different VMGs when sailing at divergent angles, but whether one board type has a better VMG when each are sailing at the SAME angle. So the question about whether a slalom board has a better VMG than a FW board can only be answered in a common-sense way. That is, since the slalom board cannot sail as high as a FW board, does the FW board have a better VMG at the angle limits of the slalom board. The answer is a resounding "YES" because the basic speed edge of the slalom board dissolves at the the limits of its tacking angles. FW kit will go faster over time and be able to maintain its sailing angle whereas the slalom board will need to foot in the lulls. Thus, the FW board has better VMG.

-Dan
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Old 7th January 2009, 03:14 AM   #60
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Cool

Except at 90 degrees to wind or in really rough conditions or ... or...
Amazing how racers put their own spin on things to make point.

Point was (and is) VMG is relative to type of sailing.
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