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Author Topic: 2 piece masts.  (Read 4265 times)

tigertiger

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2 piece masts.
« on: January 11, 2008, 08:50:29 am »

On my little Victoria I have a 2 piece mast.

Is this feasible for larger masts?
Has anyone done it?

I am thinking of a 3 meter mast for a scale sail vessel.
It would ideally be in wood if this is possible, but could be in fibreglass or alloy.

Any comments or suggestions welcomed.
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JayDee

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Re: 2 piece masts.
« Reply #1 on: January 11, 2008, 11:46:47 am »

Hello Tiger,

Yes, I have seen two piece mast on large boats.
On a J Class boat, I joined two fibreglass poles, one fitted inside  the other, with a metal band around the top one, to limit how far it entered the lower one.

Most of the stress on a mast is in compression, it is being crushed, so a tapered mast, bigger at the bottom, is best,
A wooden one, with a metal tube joining piece, should work ok!.

What are you planning to build with such a large mast ??.

John. ;)
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tigertiger

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Re: 2 piece masts.
« Reply #2 on: January 11, 2008, 12:56:23 pm »

Hi Jaydee.

Not sure yet, I am thinking out of the box. But a solution for 3m will work for 2m.

I want to build some ovrsized boats. Maybe a Britannia or an Altair at 1/16th.

But what I will be looking for as a prime consideration with all models is portability. This winter I will strip down my Mary J Ward and start cahnging the fittings to make her collapsible. My only bugbear is that I glued in the bowsprit, but because she is only about 1.2 m overall I can live with that.

With all these changes there will be compromises on the 'scale' appearance of the rigging. but I want to be able to sail easily. I don't have a van, or even a car in Shanghai, so I need to used taxis or be able to wheel things about. I think I can get a way with a 2m long skilly box on the bus, and put wheels on one end for the big stuff. And if I do make a 3m hull it will probably be in two parts, bolted together, with consideration for the drop keel.

When I do move up to the big lake (480 km2)in several years time, I have a dream of building a 3m model and sailing it across the lake, followed by me on another boat. ::) :)
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JayDee

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Re: 2 piece masts.
« Reply #3 on: January 11, 2008, 03:56:48 pm »

Hello Tiger,

I found a big problem was the Mainsail, it was 7 feet long where it attached to the mast.
OK, you have a mast that comes apart for travelling, but the sails have to be rolled up !!.

Sails don't like to be rolled up !, if they are pressed flat while rolled, you have a sail that looks like a staircase- - - not good, not pretty, but it happens !!.
My sails were made of Mylar, which, when creased is almost impossible to get flat again, I solved the problem by hanging them up in the roof of my Estate car, which was dead awkward to do, up against the roof lining.

So, I had made a mast that was nice and short, but putting the sails in the car was more trouble than taking the boat fully rigged in the same car !!!!.
It travelled fully rigged, it was easier to do.

Taxi travel would mean another box for the rolled sails, the sails would have to be made and fitted, taken off and rolled, then a box made to suit them.

I think you will need some very sweet Taxi drivers !!.
Think about it   ;)

John,
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tigertiger

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Re: 2 piece masts.
« Reply #4 on: January 12, 2008, 02:17:51 am »

Hi Jaydee

What are the sails on the bluenose made of? I thought cotton, which (I think) should roll or soft fold around a piece of foam rubber sheet (1cm thick).

I would think about rolling from the bottom to top, so only the length of the foot of the sail will be the issue.

What do you think?

TT
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Welsh_Druid

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Re: 2 piece masts.
« Reply #5 on: January 12, 2008, 10:02:12 am »

TT

If you buy sails (or masts) from the Sailmakers, they will be posted to you in a cardboard or plastic tube (plastic downspout for example). Sails rolled and packed in these tubes will not crease - even Mylar - (with a internal tube diameter of 6cm they do not need to be tightly rolled) and, provided there are no spreaders sticking out, you can slide the mast down the centre of the rolled sails.

I just measured a couple of these tubes stuck in the corner of my workshop - 1.4 and 1.3 metres.  Wouldn't that answer your transport problem ?

Don

Ps - Mid January now - when will we expect you at Llanberis ?
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tigertiger

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Re: 2 piece masts.
« Reply #6 on: January 12, 2008, 02:33:16 pm »

Hi Don

I will land at Gunchester on the 22nd. If you can PM me your Phone number I will give you a bell when I get to my brothers in Colwyn bay and we can sort something out.

Regards
Mark
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tobyker

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Re: 2 piece masts.
« Reply #7 on: June 22, 2008, 05:35:51 pm »

Some simple dinghies had two part alloy pole masts with an 18 inch (or so) smaller section telescoped and riveted into one piece - the top mast just fitted over this with no locking devices.
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Jimmy James

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Re: 2 piece masts.
« Reply #8 on: August 03, 2008, 07:21:40 pm »

You can try the fishing tackle shops and buy a cheap telescopic fishing rod for from £4 to £20 (UK) they are from approx 8 to 15 feet long made from fiberglass very light weight and very strong each section is approx. 1 to 1.5 metres long and approx. 1.5 inches in Dia. at the but end all you have to do is drill a small hole to put a locking pin between the sections you use to keep them from collapsing into each other. I've often used 2 or 3 sections as masts & other remaning  sections as booms, gaffs, yards, & bow sprits
Jimmy (Freebooter)
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MikeK

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Re: 2 piece masts.
« Reply #9 on: August 04, 2008, 04:59:42 pm »

Sails etc (and others) used to do alloy groovy of interlocking diameters for the Marblehead swing rig masts so it must be still available

Mike
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andywright

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Re: 2 piece masts.
« Reply #10 on: September 10, 2008, 08:44:13 pm »

You can buy carbon tube from PJ Sails, or Sails etc in i metre lenghts, or more if you want to pay for the postage, any way if you start with 14mm at the bottom, 12mm fits insideit, and 10mm inside that the tube has to be inserted 4 x the dia. The ends of the tube can be wrapped in carbon tow to stop the tube splitting. For easy removal of sails use luff pocket sails (not exactly scale on a model of britania), or spend more money and buy groovy masts. Instead of full length luff pockets you could use inch strips of white ripstop every 150mm, which would not be vey visible. I will have luff pocket sails on my web site shortly when I build my mini 40 catamaran.
www.windpowersails.8m.com


Andy
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tigertiger

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Re: 2 piece masts.
« Reply #11 on: September 11, 2008, 02:12:07 am »

Hi Andy

... The ends of the tube can be wrapped in carbon tow to stop the tube splitting...
What is 'tow'?

I cannot access your website, probabley something at my end.
I think I know what you mean by luff pockets, but I have never seen them so I don't know how thye would be rigged.

Can you do a figure please?


REgards
Mark
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ooby

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Re: 2 piece masts.
« Reply #12 on: September 11, 2008, 02:27:18 am »

Tiger,

Here's a two piece mast on a large J-Class Shamrock V.  http://www.deltamyc.com/J-Rig.htm.  Their first mast failed at the splice.  The "fix" survived to win the AMYA National Championship, J-Class.  This website is also a great build log for anyone considering construction of a larger sailing yacht.

Ooby
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tigertiger

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Re: 2 piece masts.
« Reply #13 on: September 11, 2008, 02:51:29 am »

Hi Ooby thanks for the link.

However I would like to try to avoid a 'groovy' mast if I can, as I am working with historical scale sail.
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