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Okay.  Please correct me if i'm wrong on any of this.  

I'm looking for masts for my Tiki 46. I would prefer aluminium but i cannot find 7-8 inch diameter with a 3/16 wall anywhere in north america. (except from a couple of flagpole companies that will not even return my call when i mention i'm looking for a mast.  They wouldn't even sell me two lower, untapered, sections that were the exact right dimensions. I even had a friend who worked for a tent company try to buy the lower sections and they refused!!!)

The closest i could get is 1/4 inch wall but that weighs 345 lbs for 48 feet (need extra for 2 splices to make 42 feet, as they usually come in 20 foot sections)

So i resigned myself to build the two masts out of douglas fir using the birdsmouth method.   I figured i needed about 150 bd ft of douglas fir per mast and THAT weighs anywhere from 2.2-2.5 lbs a bd ft, making the total weight anywhere from 330 - 375 lbs?!   

That seemed like a really heavy mast and was the reason i didn't go with the 1/4 inch aluminium tube in the first place, so is that a reasonable weight for a mast? and if it is i might as well go with the aluminium tube at 1/4 inch.

Any suggestions?  It's been keeping me up at night and i've even bought a used regular monohull type mast but i can't bring myself to use it. (the gaff and sleeve wouldn't work anyway)

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The 1/4 inch is in the range recommended by the Wharram site, so  i guess i'm asking if this seems heavy?

Some companies will make a die and you can have your tube extruded to your specs. Worth exploring. It will cost you extra to get your die made but you own the die and could charge other T46 uses a charge to get back your costs or go in with others building the t 46///??? I wouldn't go for wood just yet. Keep digging and you will find what your need. Don't talk masts to some of these flag pole suppliers, just talk tube...have fun

Have you thought about carbon fibre?  It's more expensive but will save weight compared to aluminium or wood.  I'd recommend C-Tech in New Zealand.  They're very helpful and I found their prices good.  They'll make any size you want, although like aluminium, lengths will have to be joined, but that's no problem.  They build all kinds of spars, including huge ones for racing dhows in the Middle East.  I got them to build tubes for new crossbeams for my Tiki 26.

Yes. if money were no object i would spend $6000+ per mast in carbon fiber, but with that budget, i'd probably own a gunboat, lol.

i'm not actually concerned that much about weight except if a 1/4 " wall mast in aluminium at 345 lbs is too heavy for the tiki 46.

 Dont really know what masts weigh and researching shows ranges from 100 lbs to 3000 lbs.

The problem with flagpoles is they are tapered in the upper half, so useless for the design, so unless someone wants two tapered sections,they won't sell me just the lowers.

Hi Mike,

The range of wall thickness which Wharram specifies for Alu masts for a Tiki 46 is 3/16" - 1/4" which is 1/16 of an inch variance.  For a 13m long 6061 mast the weight will be about 193kg for 3/16" and 253kg for 1/4".

the boat was designed for wooden masts which as you say weigh about the same as the 1/4" wall alu mast, so it should not too much difference so long as the rest of boat is not too heavy already - at least in my opinion.

I will have to cross this bridge myself at some stage as I am also building a Tiki 46, but I sort of like the wood idea...

R

ps - calculator at:

http://www.aalco.co.uk/online-tools/weight-calculator/

My masts have the following specs and were extruded in south africa: 

Total length    fore and aft mast   12,800 m
Diameter of the mast section           170mm
Wall thickness                         4.5mm
Grade of aluminium   6061 T6

Now i can tell you that these masts bend quite a bit in a good blow and if i was in the market for new masts i would make them thicker / stiffer. Remember that wharram don't have any spreaders and the compression loads get quite high. I'm actually in talks with a composite specialist who is doing the calculations to see if filling them with epoxy foam will stiffen them up.

In the meantime i sail very conservatively and last season in the caribbean i never sailed with less than 2 reefs.

For my tuppence worth of advice is go as thick as you can and sod the weight.. or if you are going to have them extruded then have some internal webs ( internal X) that run the length of the mast..

Marty

Hi Robert. thanks for the numbers but i think you mean pounds, no? 253 kg is like 600 lbs. Good luck with the build, i'ts a huge project.

And Marty, thank you , i will go with the 1/4 wall much less reluctantly

Tiki 30 in Freijó wood, have 50kg. 9m, 140mm dia, 2,5cm wall, wharram construction. To compare.

As a matter of interest could you post the suppliers and costs as i know that this topic is always coming up and i'm sure other members would be interested in where to source materials.

I don't know how heavy my masts are but i expect that they would weigh around 100kg or more. Two people can just about lift and carry them around.

https://www.metalsdepot.com as recommended by budget boatbuilder and the total for 4 sections of 24 feet was $3464 us.

Now on to splicing suggestions........epoxy/rivet, 3m5200/rivet, just epoxy after acid wash, just rivet,, just 3m5200?

If going for Aluminium, sand nice and smooth and make sure you get them anodised. Remember some alloys not suitable to anodising.  Not good for your sail sleeve to have that white powder abraiding away your sail.

Just Rivet



Mike Haromy said:

https://www.metalsdepot.com as recommended by budget boatbuilder and the total for 4 sections of 24 feet was $3464 us.

Now on to splicing suggestions........epoxy/rivet, 3m5200/rivet, just epoxy after acid wash, just rivet,, just 3m5200?

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