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Go Back   SailNet Community > General Interest > General Discussion (sailing related)
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  #1  
Old 06-27-2007
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navigation question

When we are cruising, the winds are always on the nose.
I don't care when or where we are planning our trips; Murphy always puts the wind squarely in our face.

My question;
For the purpose of this discussion, I sail at 45 degrees to the true wind
and my destination is 50 nautical miles straight upwind.

How many extra miles will I have to sail?

Will my total be 75 Miles?( X 1.5) 100 Miles?( X2) Or something in between?

Sorry, but I have never been able to figure that out.

Part 2 of my question.

When beating up wind to your destination, what do you do; make extremely long legs with few tacks? Make frequent tacks and keep the legs shorter? Start with long legs and shorten them as you reach the destination?

I'm more interested in Part 1. I have never been able to come up with a definite answer.

I know, its simple Geometry. Please help me, its been a lomg time since High School.

Murphy, could you please let me sail a beam to broad reach just once?
That's not a lot to ask for, is it?
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Last edited by sailortjk1; 06-27-2007 at 10:00 PM.
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Old 06-27-2007
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I go with longer tacks, maximizing my speed to cover as much ground as possible. It has also been my observation that no matter what way the wind is blowing, one tack will take you backwards. The other day, even after turning almost 40 degrees off the wind, it was still on my nose. I've determined that the only time you have good wind for sailing is when you are anchoring or docking.
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Old 06-27-2007
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The distance is to be covered is 70.7 miles. High school trig.
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Old 06-27-2007
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1. The formula is dist sailed = dist made good / cos angle. In this case the cos is 1/sqrt 2 and the divisions cancel so it becomes dist made good * sqrt 2= 1.414 x 50 =70.71.
2. The wind is actually rarely dead ahead so one tack is shorter than the other. It also may swing.
So you sail the shorter side first in preference. You sail towards the direction you expect the wind in turning will become a header ie more against you. When it changes you tack and can then sail higher ie more directly.
Because of possible wind changes it doesn't pay to make a single long tack to the point where just one more will get you there (the layline) nor do frequent short tacks as they slow you. Depending on the distance , keep in the middle between the two laylines with moderate tacks on the shorter line if one tack is favoured. If you imagine two lines converging in a triangle, the closer you get the more the lines converge so the tacks become shorter.
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Old 06-27-2007
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Thanks guys.
My wife helped me as well, and she came up with the same.

All I have to remember is x1.414
You have made it easy for me.
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Old 06-28-2007
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Watch the America's cup and see it in practice complete with laylines and distances between boats as computerised add ons.
PS use 1.5 as it easier and the bit extra is allows for leeway.
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Old 06-28-2007
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In the real world, in your cruising boat, you will not be able to make 90 degree tacks, and the wind which is in your face will generate a current which adds to your misery. Most cruisers will end up motoring the 50 miles.
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Old 06-28-2007
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Quote:
Originally Posted by donradclife
In the real world, in your cruising boat, you will not be able to make 90 degree tacks, and the wind which is in your face will generate a current which adds to your misery. Most cruisers will end up motoring the 50 miles.
Sail the Great Lakes, no currents here.
We end up sailing about half the distance than start the motor.
Its not a problem when you don't have a schedule or destination planned.
No destination or schedule, thats easy, sail to the next reachable port.
But like our next weekend trip. We want to be in Chicago for the 4th of July activites. Its 85 nautical miles, I'm sure the wind will be on the nose.
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