Measuring Angle of A "Tack" (pointing) - SailNet Community
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post #1 of 15 Old 06-03-2014 Thread Starter
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Measuring Angle of A "Tack" (pointing)

How do you measure the angle of a tack.... I hear people say there boats point at 40* or 35* (mine seems more like 90* between tacks)...

Lets say I want to go North (0*) and the wind is coming from the north...

Should I look at my compass on a starboard tack (say 40*) and then add the difference on a port tack (say 320*)...to come up with 80* and then divide by 2 for pointing angle...?

Or is there something else to the formula...?

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post #2 of 15 Old 06-03-2014
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Re: Measuring Angle of A "Tack" (pointing)

Nothing else to it. That's it. In your example, your boat is sailing 40 degrees off the wind and tacking through 80 degrees. Pretty simple.
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post #3 of 15 Old 06-03-2014 Thread Starter
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Re: Measuring Angle of A "Tack" (pointing)

Whats the desired (preferred) pointing angle then....I know depends on boat/conditions of sails etc..

But in general what is the range of "normal" compared to what is too wide and needs to be addressed..?

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post #4 of 15 Old 06-03-2014
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Re: Measuring Angle of A "Tack" (pointing)

When your boat is close hauled (approx 45 deg off the wind) and you are facing where the boat is pointing the tacking angle will be just behind your windward shoulder. (approx 100 deg from your heading).

It is usually easier to find a point on the land or a convenient cloud but 100 degrees added or subtracted from your heading will do for a compass course.

Phil
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post #5 of 15 Old 06-03-2014
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Re: Measuring Angle of A "Tack" (pointing)

One thing that is not immediately obvious is that the wind you feel is not true wind but a apparent wind which is a combination of the true wind and the wind you are making by your movement.

When you are sailing close hauled the wind may seem to be about 35 to 40 degrees off your bow so you may be tempted to pick a location 40 degrees off the opposite bow to head for when you tack.

In reality however with most smaller boat with tired sails the place you are likely to be able to aim to is going to be 90 degrees from your current course.

And of course if their is current your realistic new course can be wildly different.

But as to your calculation the 40 to 35 people are talking about is really off the wind angle so it is half of the full tack which is what you are talking about.

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post #6 of 15 Old 06-03-2014
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Re: Measuring Angle of A "Tack" (pointing)

Hey,

Here are some basic numbers:

For a 'racer' you better be able to tack within 90 degrees or you won't really be competitive (I am referring to 'high performance' boats racing one design, not PHRF).

For a moderate cruiser / racer with decent sails, you should be able to tack within 100 degrees.

If you have a older heavy cruiser with older sails, then greater than 100, but I have no idea of the actual numbers.

Barry

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Originally Posted by Squidd View Post
Whats the desired (preferred) pointing angle then....I know depends on boat/conditions of sails etc..

But in general what is the range of "normal" compared to what is too wide and needs to be addressed..?

Barry Lenoble
Deep Blue C, 2002 C&C 110
Mt. Sinai, NY

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post #7 of 15 Old 06-03-2014
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Re: Measuring Angle of A "Tack" (pointing)

Just turn the wheel, and stop turning when you have the sails how you want them on the other side.

Seems easier than trying to guesstimate angles and such.
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post #8 of 15 Old 06-03-2014
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Re: Measuring Angle of A "Tack" (pointing)

If you're turning approx 90 degrees through a tack that's 45 degrees off the apparent wind I'd say that's pretty typical goal.

But, As YorkSailor points out, you might typically need to turn 100 degrees since you will lose some boatspeed and thus apparent wind speed ( and angle) once you turn. Once you get back up to speed you should be able to " head up" a little more. If your turn is too tight at first, you'll end up pinching. I'd also try to use a steady fluid motion when you put the helm over to minimize the "braking" effect of the rudder.

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Last edited by Tempest; 06-03-2014 at 10:21 AM.
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post #9 of 15 Old 06-03-2014
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Re: Measuring Angle of A "Tack" (pointing)

Quote:
Originally Posted by Squidd View Post
Whats the desired (preferred) pointing angle then....I know depends on boat/conditions of sails etc..

But in general what is the range of "normal" compared to what is too wide and needs to be addressed..?

this is if your sailing in a pool in test conditions, in real life you need to factor in

waves
sea conditions
currents, eddies, drafts say from warm water to cold
physical objects like islands, jetties, piers, barges other boats
wind

angle is based on boat design FIRST...once you know what your boat should point to(using other owners experiences or the designers notes) then you need to play with the tune of your rig, sails, mast rake, bend...etc..etc...etc...

oh dont forget ballast, bottom paint...etc..

all will influence you tacking angles

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post #10 of 15 Old 06-03-2014
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Re: Measuring Angle of A "Tack" (pointing)

Quote:
Originally Posted by Tempest View Post
If you're turning approx 90 degrees through a tack that's 45 degrees off the apparent wind I'd say that's pretty typical goal.
.
Would this be more accurate?

If you're turning approx 90 degrees through a tack that's 45 degrees off the true wind.

The lesson from the Icarus story is not about human failing.
It is a lesson about the limitations of wax as an adhesive.
If you have an engineering problem solve it.
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