How to measure mast height ?

[bbg]

If the tape measure hoisted on a halyard doesn't work, try this.

Hoist a barometer up on a masthead halyard - use binoculars to read the difference in air pressure between top and bottom of mast, and calculate the height based on the difference. If you want to know air draft, look at the pressure difference between top of mast and water level.

 

[StugeronSteve]

Or hoist the barometer to the masthead, drop it and time the fall of the barometric pressure reading.

Of course, if you are wanting to employ real science, use the doppler effect. Tie a very nervous person on to the end of a halyard and hoist them to the mast head, wait til they start to scream and drop them fast. Compare the wavelength of the scream at the top with that at the bottom, bung in a bit of simple maths and Bob's your auntie. Or he will be if you drop him astride the boom!

 

[Superstrath]

Ingrate

Harumph. A day later, and I see no "Thank you" from Mr. Dart for all our helpful advice.

 

[fireball]

And to get multiple readings - as a wimps scream can change pitch without movement ... tie them to a bungee and record each descent .... /forums/images/graemlins/smile.gif

Brendan - you should realise that it wouldn't be sensible to tie the pole every 3 foot - once you start getting near the top there would be far too much weight up the mast - what with the seagull, starling, squirrel, dog, nuts and small boy ... and all that whilst your on autopilot heading towards a bridge - asking for trouble!!

 

[AliM]

Re: Ingrate

no, no, no - you've all missed the obvious one. Ping the back stay, and compare it to the pitch of a guitar (or possibly a cello or double bass). Adjust for string tension, and string weight, and that gives you the length of the backstay. (Maybe ask that helpful maths A level student). Simple trig will then give the length of the mast. You can check it by doing the same sum with all the other stays. It's so easy and musical. It could start a trend in your marina.

 

[Lakesailor]

I may have missed it. Has anyone suggested the obvious method of careening the boat over and then simply pacing it out on the mud?

 

[oldharry]

Re: Ingrate

There is a MUCH simpler way than anything suggested so far: Trendy maths type teenagers have distinct drawbacks (I know - I had one!), measuring bits of string etc too fiddly, firing things over the mast will bring the H&S exec down on you - or the Compensation money grubbers. Shooting sh*itting Starlings, Shags etc is a bit environmentally unsound (so are the birds, but never mind!)

My method is accurate to within the inch, involves just sitting in the cockpit with a pair of binoculars, and is totally environmentally and legally safe.

Get one of those 'Inchworm' caterpillars. Hoist a bit of its favourite foliage to the top of the mast, sit back with G+T in hand to count the number of 'inches' it does do get to its dinner from the foot of the mast!

Simple really when you know how......

Oh and dont get a caterpillar thats about to Pupate -one bloke I know tried this, but his caterpillar never made it, and flew away as a butterfly somewhere about the spreaders a couple of weeks later.

 

[Lakesailor]

Re: Ingrate

But he may be one of the loonies who made such a thing about "polishing his mast" so the coefficient of adhesion make make this method suspect to say "It's suspect"

 

[Strathglass]

Use one of those laser distance measurers. Modify it to allow remote control of the reading button. Hoist it to the top of the mast on a haliard and measure the distance to the deck.
You can always use a pair of binos to read the dial if it doesn't hold the reading.

Iain

 

[MarkJohnson12345]

dismount the radome and point it upwards.

Should get a long thin signal, and when it ends that's your mast height.

Simple pimple.

 

[fireball]

This one is only possible if you have access to a powerful pump .....

Setup said pump and hose and create a plume of water that reaches the top of your mast.
Dismantle your depth sounder and hoist to the top of the mast (don't forget the cable, unless your on a tacktik wireless one) and place facing downwards at the top of the water column ... you can now read off the depth / height on your display ...
Whilst you've got the water pump going - it is recommended to knock off the seagulls and starlings from the top of your mast.

 

[StugeronSteve]

You're on to something there, young Fireball, me lad, but youve not quite got it. However, inspired by the cunning simplicity of your reasoning, I believe that I have come up with the ultimate solution.

Tie fish to main halyard and hoist to top of mast. Site fish finder on deck (pointing up), find fish and read off distance. Bring fish back down and grill, unless a lucky lightning strike saves you the trouble.

 

[fireball]

I bow to your superior logic!!! /forums/images/graemlins/laugh.gif

Although - there is one small flaw in your otherwise ultimately cunning plan ... and that is that you have forgotten the seagull ... you'd have to be mighty quick to get the reading off before the seagull makes off with your tea. ... /forums/images/graemlins/frown.gif

 

[Colvic Watson]

How many times have I heard the lunacy of tyeing a fish to the top of your mast, and how many people have to die before this insane practice ends? Dropping Jack Russell's from the top is the only safe and practical way of doing the job and any other suggestion displays a cavalier attitude to boat safety. If Lifeboat were still here he'd agree with me, mark my words.

 

[StugeronSteve]

The air rifle handy for those little annoyances.

 

[fireball]

Well - if your going to the bother of shooting the seagul you might as well time its descent as described previously ... saves going to the trouble of tieing the fish to the halyard to start with.

One method that hasn't been mentioned is creating a standing wave in a line ...

you know the one - you wave your arm up and down whilst holding a line and it creates the ripples in the length of the line - with one end at the top of the mast and you at the bottom you can count the number of waves and mutiply by the wave length....
If you want to get the total height of the mast then you'll have to do this from the water at the side of the boat.

 

[Colvic Watson]

[ QUOTE ]
If you want to get the total height of the mast then you'll have to do this from the water at the side of the boat.


[/ QUOTE ]
And if your boat is resting in the mud like ours? Or on sharp rocks? Would you recommend the method then?

 

[Lakesailor]

You\'ve been Had

I've just looked at Dart's profile. He hasn't got a mast!

 

[snowleopard]

Re: You\'ve been Had

[ QUOTE ]
I've just looked at Dart's profile. He hasn't got a mast!

[/ QUOTE ]
How do you figure that out??

 

[Colvic Watson]

Re: You\'ve been Had

Let's just hope it isn't because he followed the 'low bridge' method we advised earlier in the thread.