Freestanding

You haven't even asked me why?

Herreshoff was a smart dude.
He would use square spars for his smaller boats.

A problem Herreshoff was facing was how to go taller? They couldn't get any taller than the cables. They only had hoops... which could only go up until they hit the cables.
So, as you all know, he invented the sail track (or his brother did? just bear with me)
Awesome! Herreshoff has invented sailtrack! Now we can go higher.....past the cables.
And if you know your design (just kidding) you know that it had a dramatic effect on the racing rules....and in turn, the rules had to be changed.
And the new racing rules had a dramatic effect on yacht design. Almost overnight, every designer was seeing how high they could go.

 

Anyway, I am just experimenting with square spars, using his sailtrack, going a little higher. I suspected he might have left some gas in that tank.

 

I have built several, from 10' to 70' and designed several others. You are completely wrong about carbon fibre. It is cheaper, easier to use and stronger and stiffer than timber.
The carbon masts in the boat at ELEMENTARRY – Harryproa http://harryproa.com/?p=1753 are 8m/27' long, carry 11 sqm of sail/114 sq' of sail each and weigh 12 kgs/26 lbs, including the bonded on 2m/6.6' long boom.
The critical dimensions for mast design is the boat's righting moment and the bury, or distance between the bearings or deck and keel. The higher the rm, the stronger the mast needs to be. The harryproa has a righting moment of 800 kgm which I estimate is 6-8 times higher than your boat. The smaller the bury, the stronger the mast needs to be. On the proa, the bury is 700mm/2'3", about 60% of yours.
These masts don't have tracks, but they are easily added, or included in the lay up.
The materials in each mast and boom cost $AUS300/$US240. What would your timber, glue and coating cost if I was to buy it?
The carbon masts can be built by anyone who can use a string line and a jig saw and mix resin. Ideally they are vacuum bagged, but at this size it will not make much difference. How many dollars worth of machinery did you use on the timber mast?

At a guess, I would say a carbon mast for your boat would weigh about 6 kgs/14 lbs, cost $Aus180/$US140 in materials and take 4 days to build, much of which would be waiting for resin to cure.

A square section is stronger and stiffer than a circular section if the square side equals the circle diameter. Less strong/stiff if the square diagonal equals the diameter. The square section will be more draggy than the same size circular, which is detrimental in terms of flow onto the sail.

 

Wait. Wait!, don't go away angry. It is so great to hear from you......!
No, I do not have a closed mind about carbon.......I thought I said carbon would be lightest?
I made a carbon bow sprit......
My friend makes Acme tiller extensions (carbon).
I'm so excited to hear from you....I have a million questions but I have to go to work.
Quickly, some of the things that I had concerns.....but I'm not questioning you.........
How to make a tapered mandrel?
How to internal halyards?
How to boom attachment?
How to exit foresail halyard?
How to mask track?
How to make a big vacuum box?
How to post cure?
Do you wrap pre-preg?
I was concerned it might be fragile like my techy windsurf masts?
I'm sure you can do all of these things. Now I remember I said "carbon is good, I am not good at carbon"

I have to go to work but I will get back.
Yes, my boat has lots of bury.

The designer of this boat talked the talk about carbon.....but when I wanted to talk numbers...he got nervous. I mean, his diameter got bigger and bigger. It was never up to him to design a carbon mast for me, it's true.
So I got scared off of carbon fiber for the time being. I was envisioning an untapered fat masthead......maybe 4" diameter, all the way up...... (even less attractive than a box mast!) I got scared off
My estimate for carbon weight was a guess......but I also guessed 15lbs........but then I started adding things like mast step and exit blocks and other toys and I thought, "shoot, I'm at 20 lbs already before I srarted!
I absolutely believe YOU can do as you say.........I'm just explaining where my head was.

 

And I was able to get my mast as low as 22- 3/4 lbs. before I also started adding weight back on.

 

See, this is the problem, you're looking for a free ride, which is insulting.

A 22' long mast, carrying 120 sq. ft. of area, assuming a stayed masthead Bermudian rig, would have a mast diameter of about 2.5" at the base with a continuous taper to 2" at the head. Using a 15% wall thickness and building in white spruce, it would weigh about 8.5 pounds, before hardware. This would be a light racing stick, but serviceable. Increasing the scantlings to say a modest cruiser's sensibilities; the wall thickness would increase to 20%, the heel diameter would change to about 3" and the head to about 2 3/8" and this would weigh about 14.5 pounds. Of course, there's lots of assumptions and species, thicknesses variances that can be employed, but this is the range for a light to modest 22' stick with a heel and head cap and a single swallowtail at the gooseneck. It can be heavier, it can be lighter though I wouldn't risk it on anything but an all out racer, where you know you're going to lose a stick every so often.

Now, I haven't shown the math and I've had to make several assumptions (flexibility, RM, rig type, etc.), because of lack of information, but a 264" long stick carrying a stayed 120 square feet, isn't all that uncommon (I just did one a few months ago at 24' and it carried 200 sq. ft.) and this is about the threshold where the birdsmouth is overtaken in weight and flexibility by other materials. You can improve both of these issues with construction details, but costs and complexity shoot up dramatically.

As to your other "questions", well you might try Google, as there's lot of information available.

How to make a tapered mandrel?
How to internal halyards?
How to boom attachment?
How to exit foresail halyard?
How to mask track?
How to make a big vacuum box?
How to post cure?
Do you wrap pre-preg?

Asking these types of questions means you're no where near attempting this sort of thing, so get some research done, read a few thousand words and see if you're a little more versed with what needs to be done, what you can afford and what you might be able to accomplish.

 

This is in the old version of Kineey's book. They are for solid spars, but the calculation from solid to hollow for E can be done with any free online calculation
Sailmakers - Dabbler Sails - Sail Lofts - Sails for small boats - Sail Makers http://www.dabblersails.com/blog/blog.pl?type=show&id=43&pic_id=13

 

We all start with these Gonzo, but once you do the math and have a SOR to hit, these tend to be only averages and a tad on the heavy side. It's not hard work really, though an understanding of what's going on is necessary, if you want a light, stiff and strong set of spar scantlings. Anyone can design a pole that's way too much or too little of this or that and call it a success, at least up to when it breaks. It's another to use materials and engineering wisely, saving money, weight and insuring the stick will bend as predicted and stand in the strengths it was designed for.

 

Thanks Gonzo, that's helpful.
Wow! Have you guys seen Robs masts? (And proa) Really impressive! A couple of photos you can see the rigs play off each other or shadow each other at slightly different angles.

 

If anybody has built freestanding masts or owned them I would love to hear your experiences. Maybe weights, heights, just the basics.....thanks.
And pictures!

 

I've just given you the basics on your rudimentary and insufficient dimensions and provided information. I've built dozens of birdsmouth spars, about an equal amount being free standing masts.

 

I enjoy dealing with enthusiasts who are willing to have a go, so feel free to ask whatever you want, I will not be offended. If I am, I will stop responding.

With difficulty. I don't use mandrels (or moulds for masts) except for filament wound items. The mandrel is usually foam, either hot wire or cnc cut or turned in a lathe, but there are plenty of other ways.

I don't, as the bent mast is likely to be worn by them. I prefer halyard locks and halyard guides down the luff of the main. If you do, ensure the exits/enties are well reinforced.

Many ways. I use a wishbone tied to the mast with an adjustable line.

I don't like foresails on unstayed masts as the luffs are hard to keep tight. Better is a tall mast and good reefing or 2 masts. If you do use foresails, halyards are the same as on stayed rigs.

Include it in the build (bit tricky, but lightest), or bond on a piece of tube or glass over a dowel.

Bag, not box. Get a piece of clear plastic, seal it to the mould and off you go.

Build an oven from silver paper backed insulation and put a heater in it, or wrap the item in black plastic and leave it in the sun. Make sure the item is well supported.

Not willingly. When the laminate is consolidated, the off axis material contracts to a smaller diameter, so must kink, which is not good. Machine wrapping works, but is complicated to set up. Prepreg is not worth the cost and hassle for small one off items. Fun to play with though, but not until you have everything sorted.

Bash your windsurfer mast against a similar weight and length wooden mast and see which one survives. It won't be the wooden one.

Best bet is to get some carbon (Soller composites) and some resin and have a play, maybe build a short tube. Use Google, assess the best way for what you want to do, then ask me if there is anything you should know. OR I can sell you plans and instructions.
Don't use sarcasm on forums. a) it doesn't work and b) it pisses people off and you lose a potential source of information. Ignore is by far the best way to treat any anything that is not boat related.

 

Thanks Par, thanks Rob and Gonzo. I have plenty to yak about.....I have to go to work.

 

Thanks Rob. Very encouraging. (just seeing those masts makes me want to have one!)
And Par, I will definately be referring back to your work. I appreciate it thanks.
In fact I want to mention something about respecting your guys (all you guys) work.
I only designed my own mast because I had no choice. I wanted freestanding. I am not an engineer. I didn't think carbon was achievable for me at the time. I assumed I could never afford to have a mast properly designed so..... I made it up. Starting to feel embarrassed about my mast.
I have a new sail coming this week.

 

Don't be ridiculous! It takes bigger balls than most people on these forums have to design and build your own mast, from scratch. Be proud, of it and yourself. Neat video. Got any more?