Mast measuring........would this work?

[dukes4monny]

Would this type of thing be any good for measuring the distance from the deck (e.g. chainplates) to masthead to check for perpendicularity of the mast?
I find that using tape measures or halyards for the job clumsy and not very accurate and am looking for a quick and easy (and accurate) way of achieving this.
Has anyone tried this?

 

[peter radclyffe]

laser or sextant

 

[peter radclyffe]

plumbbob

 

[William_H]

Mast verticality

My boat lives on a trailer in winter. I raised the mast. Using jacks got the hull level athwart ships using a spirit level then stood away using the level vertically to compare it to the mast. I used a similar system for checking rake. You could do similar on flat water if you can get the boat hull level in heel then check from a distancee the mast verticality.

I don't think the laser leveel would be easy to get a reflection off a suitable part of the mast. Perhaps the root of the spreaders would do. However I don't think verticality is nearly as critical as you might imagine.
good luck olewill

 

[willie4646]

Why dont you tie the end of a tape measure to your main haliard and pull it up the mast,thus giving you an accurate measurement.
Willie

 

[dukes4monny]

Some interesting idea's.......I ought to add that I am trying to do the measurements whilst the yacht is afloat so a plumbob would be out of the question.
I have tried it with a tape measure hauled aloft, but, unless it is a totally windless day, 10m of tape is a job to keep hold of and get an accurate length.
I would prefer to have a gadget that I can just point and shoot with

 

[Poignard]

Just get the end of the topping lift and take it to one gunwhale. Mark where it touches and then take it to the other side. If the mast is vertical the mark will coincide with the gunwhale on both sides. Unles you have a deformed hull!

 

[srm]

Have set up quite a few masts after they were stepped with the boat afloat.

Always used the main halyard to check it was vertical by taking end to one chainplate and making tail off on a cleat then end to opposite chain plate to estimate difference and adjust cap shrouds as neccessary. As a surveyor I know this method has errors, but they are within the tolerance of getting a mast to look right.

Tape measures on halyards up mast only work in zero wind as otherwise they blow out in arcs and need a lot of tension to get them straight.

As mentioned in an earlier post a laser measurer needs something to reflect the beam back, and its going to be very difficult to get the same target on each side of the mast when aiming at the top with the device held on a chain plate.

The simplest method is usually the best when working with boats. However, if you do try the laser measurer please let us know how you got on.

 

[dukes4monny]

Ok thanks. Not having used one of these laser gadgets I wasn't sure as to whether it would work with a surface which was not perpendicular to the device....a fact which both you and William_H have eluded too.
I know that these measurements are not that 'critical', but being an engineer by trade, I'm always looking for absolute precision

I do use a (rope) halyard to do the side to side comparison.....but then I do wonder whether I have the same tension when working from one side to the other...........

 

[Thistle]

Maybe ... but ...

Yes, it should do, if you can get a suitable target raised to the masthead and centred on the boat's centreline. A round fender up the sail track might do. Remember to have some way of bringing it down again

I'd have thought using a halyard or tape would be at least as easy and sufficiently accurate if the errors can be equalised on both sides (possibly by pointing straight into the wind.)

 

[Refueler]

Just get the end of the topping lift and take it to one gunwhale. Mark where it touches and then take it to the other side. If the mast is vertical the mark will coincide with the gunwhale on both sides. Unles you have a deformed hull!

May I suggest that you use spinnaker or main halyard in preference - as many boats the topping lift like mine is through a small block on one side of mast ... so not possible to use it for check. It has to be a line that goes to mast head centreline.

But principle I agree with totally ... it's what I do 4 - 6x a year as I have to lower and raise mast to get under bridges if I want to go to sea.

OP - I agree that a tape measure is difficult because it catches the wind so much being light and flat. A halyard on it's own is much better having more weight and rounded section.

 

[Poignard]

Obviously you are right but on my boat the topping lift is central.
[Which I suppose is some consolation for not having mast cleats with holes through them ]

 

[Refueler]

Obviously you are right but on my boat the topping lift is central.
[Which I suppose is some consolation for not having mast cleats with holes through them ]

 

[peter radclyffe]

Some interesting idea's.......I ought to add that I am trying to do the measurements whilst the yacht is afloat so a plumbob would be out of the question.
I have tried it with a tape measure hauled aloft, but, unless it is a totally windless day, 10m of tape is a job to keep hold of and get an accurate length.
I would prefer to have a gadget that I can just point and shoot with [/QUOTE
you are joking, a laser will not work afloat, unless your very lucky, like he said tie a tape to the halyard, buy a proper tape, with a ring in the end

 

[Tillernut]

I have got a cheap measuring device similar to this and it is not worth the money I paid for it. You have to pay £150+ for an accurate device.
Regards

 

[Ardenfour]

The type of laser level which is mounted on a gimbal inside the device will project a line all the way up the mast if you attach it to the mast base. Recently got a Black and Decker one at b & q for 6 quid. Sticks on with adhesive foam pads. Line is vertical as it is decoupled from the mounting surface, sounds ideal. My mast ain,t up yet or I'd try it myself.

 

[Refueler]

The type of laser level which is mounted on a gimbal inside the device will project a line all the way up the mast if you attach it to the mast base. Recently got a Black and Decker one at b & q for 6 quid. Sticks on with adhesive foam pads. Line is vertical as it is decoupled from the mounting surface, sounds ideal. My mast ain,t up yet or I'd try it myself.

You need boat absolutely level - so how do you make sure of that ? If not then mast may be vertical with respect to 'earth' but not your boat !

I have Laser measuring devices and levels - TBH - I wouldn't waste time trying to use for mast setting.

 

[Lakesailor]

Jaguar Yachts recommend using a halyard www.jaguaryachts.co.uk/JOA infosheet 1 masthead.doc
Just how accurate do you want it? Does 1" displacement on the tip of a 25/30ft mast really make such a difference?
The centre of effort for the sail is below half the height of the mast (depending how high your boom is) and there is a lot of movement in a rig and distortion in a hull when sailng to windward anyway ( see your lee cap-shrouds slackening).

 

[jason -and the arguenauts]

Can I suggest that you haul a length of electrical wire (the 12 v single strand type) tied to a halyard to the top of the mast - it will stretch very little and be far less affected by the wind. I always find that plumb bobs afloat are useless unless it is a totally windless day but thin wire helps a lot.

 

[dukes4monny]

Can I suggest that you haul a length of electrical wire (the 12 v single strand type) tied to a halyard to the top of the mast - it will stretch very little and be far less affected by the wind. I always find that plumb bobs afloat are useless unless it is a totally windless day but thin wire helps a lot.

What a simple but brilliant idea, thanks for that. I've ordered one of the laser doodaa's anyway (new toy)............so I'll be measuring everything for a couple of hours . Will also now have to get myself a spool of wire too.......