Building a mast

I am in much the same situation with the beams, hence my interest. A new thread sounds like a good idea.

Phills suggestion for the profile for the Blade mast is 130 x 64 and if I am using the same profile as for the Mini it would give 135 x 63,5, other ideas?
I have that one in my computer so it's easy to scale.
If everybody is happy with that I start cutting.

Humm, lets see if anyone can spot the differences ?

F18 masts use 1.6mm wall

F18, total crew weight 140-170 kg, double trapeze, total righting moment 774 kgm, spinnaker, forestay with jib, total 21.15 sq. mtr upwind sailarea and typically 9:1 or 10:1 mainsheet with crew using both arms to work it. 12:1 and 16:1 cascaded downhaul. Mast survives severe impacts with watersurface

Tornado use 2mm...

(I repeat that this is the ALUMINIUM Tornado mast)

Tornado, total crew weight 140-170 kg, double trapeze, total righting moment 900 kgm, forestay with jib, spinnaker, total 22.82 sq. mtr. upwind sailarea, typically 9:1 or 10:1 mainsheet with crew using both arms to work it. 12:1 and 16:1 cascaded downhaul. Mast survives severe impacts with watersurface

A class... 1.2-2mm

(I repeat that is dependent on where you measure; sides are 2 mm, front/web are 1.2 mm)

A-class, total crew weight 60-90 kg, total righting moment 334 kgm, single trapeze, double forestay and no need to have a tight forestay, total sail area 13.94 sq. mtr. , typically 6:1 mainsheet with skipper using only 1 arm to work it. 8:1 downhaul. Mast breaks during severe impacts with the watersurface.

So yes, the wallthickness are similar where the masts in the way of strength, loading and durability are not.

Wouter

Well Wouter, I was asking about the profile, and as those spars dosent’t have the same profile it is not so straight forward to compare the wall thickness. You of all should know that it makes a difference just if one puts the carbon on the inside or the outside on a 4 mm thick wall of a wooden spar with the same profile. Let’s keep this kind of discussion on the F16 forum in the future, it seems to belong there. That was my reason not to shift it over there, even if somebody did the mistake to do it.

Gato, you've probably seen thats I've just asked for some data on the existing ali masts assuming someone comes fwd with it I'll try and put a laminate spec together for you. When are you hoping to start?

I would also be very interested in the laminate schedule. We are not doing anything about it this year, but there are other projects looming on the horizon. Suitable masts costs an arm and a leg up here, so doing a wood/carbon/glass sections would be perfect.

No worries, I don't have time at present to do it from scratch but if someone gives me a leg up with the ali data then I'm happy to put something together (all care no responsibilty)

Gato,

Actually the cross section of the carbon mast I quoted in my post is as good as identical to the superwing F16 mast crossection. Of course all comments about higher loadings, smaller wall thickness and such also hold for the F16 superwing.

I'm amazed at the shear stupidity of some people here. Did you guys honestly think that I hadn't checked for that ?

And Gato your comments on putting carbon on inside or outside of the mast is just misplaced. Failure of the mast is not because of the crossection failing but because the wall is buckling locally under compression loads and thus initiating a larger failure mode. Increasing local buckling resistance (double sandwhich construction) is therefor more important then the downsides of placing some carbon on the inside of the mast. If you are using 4 mm thick ply then you can just as well forget about the whole project altogether as the ply will already weight 8.5 kg on its own and won't do much in the way of strength and stiffness.

But I get the hint. I will scram off now and leave you guys to discovering these things yourself.

Who needs a qualified engineer anyway right ? I only went to

school

and learned nothing !

Bloody ignorants !

Wouter

Scarecrow, Yes I have seen and it would be rely nice if you could do that, it’s a little bit beyond my abilities; I would have to use the crystal ball. But there is no real hurry for my part to start with the laminate; I think we will go into April before that. Btw. I will try to get my hands on BX carbon you managed in a very soft way to convince me!! Seeing myself winding UD at 45 deg. clockwise and anticlockwise on a 8,5 m spar using my favourite epoxy whit the best hardener to gain low viscosity but with a pot life of max 45 min... Prefer to destroy the material on the water.
If we could decide on the profile I could start to cut stations and line everything up and do the timberwork.

If somebody is interested in “guessing” the final weight the wood weight glue included will be something around 6,5 kg. The mast I already made had a wood weight of just under 5 kg, and I used spruce instead of WRC on that one.The calculations are adjusted by a sharp plane.
There is another thing that is troubling me a little. If we shift to all carbon my method of joining the strips by glassing them together will result in some completely useless extra weight in glass, but I don’t see myself doing it with carbon. In that case I would portably have to put all the carbon going on the inside and bag it.

Gato, lets assume you're going to use your existing profile. Can you please email it to me and I'll use its geometry when defining laminates. Do you have access to a tube for the track? do you definately want to strip plank or is ply an option? Whats the minimum practical thickness for your stripping system?

I will get you the profile, and I can put you in contact with the French arcitect who has the original alu spar or profile. (comming from a Mattia cat 20 feet+)
I deffenetly want to try one in stip. For the ply there is no option 4mm the thinnest you can find in a wood producing country like Finland (this one made in France...)

Scarecrow,

(all care no responsibilty)

, I dont think anybody expects more than that from advice/work given freely. I for sure sure dont. <img src=

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Gato,

I looked at getting some WRC, and it was very expensive. I dont know what prices you get, but for me it is either spruce (we can select our planks ourself) or all carbon. Would be interesting to know what you pay for carbon and WRC in Finland. Spruce is cheap here, and we have tracked down a local source for carbon fibers at EUR29 a Kg.

WRC 2500 Euros/m3 Carbon BX 310g 35 Euros/m2 Custom made epoxy around 7 euros/kg.

So Rolf, Shall I take some epoxy and come over to Norway to buy my carbon, I think it will pay the trip.

I will make the strips from 4mm ply, and the tube for the track (sail) I will make myself in glass or carbon

It is a very special deal we have got with a manufacturer who thinks our project is cool. Basically we get to buy leftovers from their production of uni, bi and triaxial cloth for our own use in this spesific project. Cloth weight and length is limited. From 4 to 20 meters and heavy weaves, but as we pay for the kilo we can live with that.

Sh...t, I was alredy trying to find a big lorry <img src=

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Just wondering if somebody did supply the data.

Of course not. I'll do it from scratch it will just take a bit longer.

Rolf, you could always strip plank a female mould and then make a straight carbon mast.

Scarecrow,

I'll try checking with some of the other guys to see if they know the numbers on the current masts. As the superwings are extruded by AHPC, it is possible that they have not run the numbers on it but gone by experience when doing the die.

Female mould and laying up a 'classic' carbon mast is a possibility. Doing it in wood would be a more fun project on the other hand. <img src=

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My bad I thought the superwing was the default mast extrusion that wouter refers too any generally successful F16 mast will do.

Feamale or male, think you end up with the same amount of sanding, it's just a question if you want to do it on the mould or on the spar.
The thing with this metod of using stip planking is that it's easy, cheep and a fast way to get a staight or even a tapered mast.
when I started my first one I had been expecting a lot more work.
I would be more than happy if enyone takes the advise and use it to make a mould

Folks,
I do not want to interrupt the flow here so I will make this short.
The fact is I keep all my emails both sent and rxd. I went looking back through them to find some mast deflection data and stumbled across emails about work I was doing on a composite mast.
Back in 2003 I made a carbon composite section 6m long and did some deflection tests without and then with cardon on the outside of the section. It's kind of nostalgic reading through the old emails. From the emails it seems this was just before building the Blade prototype.

How time flies.

I also did comparative deflection tests with a superwing and Aussie wing of the same length so I could see how this project compared. (The Aussie wing 50x125mm extruded in Australia in the 80s to combt the importation of Sori sections for the A cat fleet. But in reality it was too heavy.)
I have rough sketches that include all components and layups I used.
Anyone interested in doing a bit of experimenting I'd be happy to send these emails to you so you can either improve on what I had tried or just say oh well it is better done some other way.

It seems from the emails I had worked out a way of modifying the technique to produce an F16 mast that would weigh around 9.91kg without fittings. How is not detailed in the emails. But If pushed I could probably work it out again.
I never actually sailed with this mast just did static deflection tests. So no guarantees.

Anyhow just thought I'd mention it.

Regards,
Phill

I now have all the data I need (thanks Phill). I should have a mast for you by next weekend.

Gato, what sort of timber will you be using?

F16 mast design is done. Will let Gato work out the bugs before giving it to anyone else though.

Theoretical tube weight with 4mm gaboon ply (stripped) core approx 11.5kg. Real world this will go up due to bog etc. Timber makes up about 45% of the weight.

So friends, what do you think, I started to build the F12 cat that Scarecrow designed. Personally I think it would be fare to him to build the mast for the F12 first using the same method. My intention is to have this one in the water before end of may, and to be able to present it to the clubs at the opening of the season.

Gato,
do you ever get out of the shop ? <img src=

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Just joking but you seem to have a lot going on. Good luck with the new project and please post pics.

What do I think? I wonder how you are getting all this stuff done! Otherwise, I think it is great to get some F12s in the water. It is also really inspirational to see what is done, the results, and the spirit of cooperation. Fantastic.
We are busy stripping hull halves and building bulkheads. But next year, I have a hunch a strip/ply mast will be a project.

There are no secrets, I sold my television about ten years ago <img src=

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