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Old 01-11-2012, 19:01   #1
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Mast height, how to tell?

Hi there,

Can somebody tell me where I can find info on the mast height of some older designs?

I´m looking at boats between 22/27´but I cannot find any specs for them when regarding the mast height (bridge clearence is my concern).


Thanks,
Messias.
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Old 01-11-2012, 19:06   #2
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Re: Mast height, how to tell?

Depends on the boat I guess. But I think some of the bigger sail lofts tend to have sail dimensions on file for popular models.

Otherwise best to ask here but about a specific model. Somebody will know
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Old 01-11-2012, 19:11   #3
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check on sailboatdata.com
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Old 01-11-2012, 19:29   #4
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Re: Mast height, how to tell?

Quote:
Originally Posted by shamrock View Post
check on sailboatdata.com
+1

If you still aren't sure, you can still use the old Tan = opp/adj using a piece of line and protractor

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Old 01-11-2012, 20:01   #5
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Re: Mast height, how to tell?

Tape the very end of a measuring tape to the main halyard and hoist away. Then make a close guestimate as to how close it gets to the very top of the mast. You should get it within a few inches. Then measure the distance between the waterline and the point at which the base of the mast meets the deck. Your accuracy should be much less than a foot, which should be close enough. You want to give yourself a few feet of fudge factor when passing under bridges anyway. With power lines you never want to be anywhere close because they can arc many many feet.
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Old 01-11-2012, 21:28   #6
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Re: Mast height, how to tell?

Quote:
Originally Posted by messias View Post
Hi there,

Can somebody tell me where I can find info on the mast height of some older designs?

I´m looking at boats between 22/27´but I cannot find any specs for them when regarding the mast height (bridge clearence is my concern).


Thanks,
Messias.
This data is not generally listed. But you can scale it from photos or line drawings.

Go to SailboatData.com
If there is a line drawing for the boat in question, download a copy into MicroSoft Paint. A photo can work too if it is taken from directly abeam, slightly ahead or slightly behind and the result will over estimate the mastheight.

Paint shows the x,y coordinate for every pixel in a photo or bitmap.

Place the cursor directly on the bow and stern of the boat and record the values for each.
-Subtract Xbow from Xstern to get Xlength. Xb - Xs = Xl

Get the Y values for the masthead and waterline the same way.
-Subtract Ymasthead from Ywaterline to get Yheight. Ym -Yw =Yh

LOA is one of the values listed on SailboatData.com.

Yh * [LOA/Xl] = Mastheight.

This estimate will be good to better than 4", and probably better than 2".

Items atop the mast should be added to this height.

If you want to know about a 'Tall Mast' version but don't have a line drawing, scale the mastheight for the standard boat. Then check the P values for the standard and tall mast versions.

Pdifference = Ptall - Pstandard.

Add Pdifference to the scaled mastheight of the standard boat to get the mastheight of the tallmast version. This assumes that the boom height on the mast was not changed but that is a reasonable assumption to make.
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Old 02-11-2012, 05:08   #7
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Re: Mast height, how to tell?

Quote:
Originally Posted by Adelie View Post

Paint shows the x,y coordinate for every pixel in a photo or bitmap.

Place the cursor directly on the bow and stern of the boat and record the values for each.
-Subtract Xbow from Xstern to get Xlength. Xb - Xs = Xl

Get the Y values for the masthead and waterline the same way.
-Subtract Ymasthead from Ywaterline to get Yheight. Ym -Yw =Yh

LOA is one of the values listed on SailboatData.com.

Yh * [LOA/Xl] = Mastheight.

This estimate will be good to better than 4", and probably better than 2".

Wow... we have some really dedicated "rocket science" going here
This forum is of precious knowlegde indeed!

Thank you very much for your answers, because i´m not actually asking (yet) for a specific boat, just browsing through some old designs and don´t want to bother you (again, yet ) with too much newbee questions... but i´ll get to it soon!
As soon as I find one that I think it´s "the one", I´ll flood you with questions!
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Old 02-11-2012, 05:57   #8
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Re: Mast height, how to tell?

[QUOTE=messias;1074452]Wow... we have some really dedicated "rocket science" going here
This forum is of precious knowlegde indeed!

/QUOTE]

Not all of us Motor under some bridges, and when you hit one, you will know that you are taller than that clearance height. A few help.

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Old 02-11-2012, 06:35   #9
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Re: Mast height, how to tell?

Quote:
Originally Posted by Khagan1227 View Post
If you still aren't sure, you can still use the old Tan = opp/adj using a piece of line and protractor
That was going to be my suggestion--go find a sixth-grader who just finished geometry.
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Old 02-11-2012, 07:01   #10
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Re: Mast height, how to tell?

Pythagoras.

Angle of dangle = ..........
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Old 02-11-2012, 07:06   #11
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Re: Mast height, how to tell?

Quote:
Originally Posted by messias View Post
Wow... we have some really dedicated "rocket science" going here
This forum is of precious knowlegde indeed!

Thank you very much for your answers, because i´m not actually asking (yet) for a specific boat, just browsing through some old designs and don´t want to bother you (again, yet ) with too much newbee questions... but i´ll get to it soon!
As soon as I find one that I think it´s "the one", I´ll flood you with questions!
It's not rocket science, it's high school geometry and math plus a bit of experience. I know this because I tried to be a rocket scientist when I was in college and I couldn't hack the math.
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Old 02-11-2012, 07:09   #12
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Re: Mast height, how to tell?

Motivational video
http://www.topgear.com/uk/car-news/lorry-peeling-bridge-2012-10-26
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Old 02-11-2012, 07:36   #13
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Re: Mast height, how to tell?

I hope it won´t come to that, but hey... if my math is as near good as my present sailing proficiency...

In that matter of "clearance" and starting to appologise for the probable dumb question, but... is there any kind of "pivotting-mast" system in a 22´~28´ boat?
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Old 02-11-2012, 08:06   #14
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Re: Mast height, how to tell?

Quote:
Originally Posted by messias View Post
I hope it won´t come to that, but hey... if my math is as near good as my present sailing proficiency...

In that matter of "clearance" and starting to appologise for the probable dumb question, but... is there any kind of "pivotting-mast" system in a 22´~28´ boat?
Yes, the name you are after is tabernacle, popular with trailer sailer type of yachts.

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Old 02-11-2012, 08:22   #15
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Re: Mast height, how to tell?

THANKS Pete!

I´ll look into it right away, because when I was searching for "pivotting", I only had some kind of Race-setup...

And if it´s not too much to ask, is it possible to transform a non-tabernacle into a tabernacle keeping the same mast/sails, or it has to be a fully redesigned one? No races, no best-performances, no nothing... just fooling arround in the bay learning how to sail...


Thanks again!
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