Stewart,
I think I used 1.5mm hoop pine ply.
I made it by having a cedar backbone 33x19 tapers into provide the leading edge. A spacer of 1.5mm ply and cedar inside and a cedar trailing edge. Just form the shape around the spacer and made a carbon tube which I routed into the back end to take the sail bolt rope. Just cut a slot with diamond saw. I even had a tricky little sealed grove in the trailing edge of cedar so the halyard come down the inside of the mast and still keeping it sealed.

The mast I made was only 6m long, Carbon inside and out, cost $300AUD. I weighed it and did deflection tests on it and compared it to a 6m long superwing. about the same. But never sailed with it as I made it for a friend.

I'd have used 1mm if I had it.

Yes, please.

Again, I really want to find out what happened here as I may well have access to adressing the cause of this issue if indeed it is related to the production of the mast section. It is a serious possibility that a new F16 alu mast design and new die will be made then.

Wouter

Gato

http://www.formula16.org/content/view/13/36/lang,en/

1.4.5 The weight that is measured at the mainsail hoist height of a mast lying perfectly horizontal with its base supported at the bottom edge of the mast section is referred to as the "mast tip weight". The minimum mast tip weight of a fully fitted mast, excluding standing rigging, is set at 6.00 kg for reasons of seaworthiness and to guarantee fair racing.


Standing rigging is defined as sides stays and forestay. All the rest remains on the mast, that includes for example shackles used to secure the stays to the hound fitting.


7.17 Standing rigging

All the stays connected to the mast, excluding the diamond wires.


Just as additional data; ISAF certified measurer has measured 7.8 - 8.2 kg tipweights on alu superwing F16 masts. Carbon masts typically are down to what is minimally allowed 6.0 kg although exceptions to this rule of thumb have been measured.


Taper won't help you much in the weight department, it can help in the way of sail shape control in thetop of hte mainsail however.

Wouter

Not so much in weight no, but if we speek of heelingmoment ther is some multiplication to do

sounds interesting..

I now believe Nicole's mast was western red cedar backbone and balsa aero-front.. Finally found some old pictures of her 76 world championship winning boat..
The bolt rope was routed if I recall into the flat back of the cedar.. But to be honest that could be incorrect and the picture doesn't suggest..

I spoke recently to the last Aussie C wing designer and he suggested he would do a ply wing mast if there is ever a next time.. So maybe your onto the next big trend.. *smiles*

I also can't recall where I last saw the ultrathin aero-grade ply.. Think it was at the local hobby shop.. Used for model gliders and planes..But the issue will be scarfing 1 mm thick ply!! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Wing designer, as in wingmast or as in C-cat full size wings? If the latter, put him to work on documenting everything he knows on the subject! Better put him to work on documenting anyway. What would it take to get him to do it?

That sounds like an ungodly amount of work to do right. When you are all done the you have 1 mast that in all likely hood is not quite what you really want.

Why not build a gypsum/screed mold and lay up a traditional full carbon stick? The process for the mold is very simple to do at home and could be used for several attemps to dial things in. The actual mast build process is fairly straight forward as well. The biggest A class mast builders do not use autoclaves, even though ideally they should produce a slightly better finished product.

Well there are a lot of ways to approach the problem. I guess that if you were rely looking for a super spar in wood/carbon the best thing would be to opt for a technique that in French are called “bois moule” (sorry for my spelling). You take rely thin strips of wood, almost like shavings and cross laminate them at 45 deg to the length axe of the spar (on a male mold) like when you use BX 45 deg carbon. Like that you have the wood fibres orientated in the most favourable way. On both sides of that some carbon UD and eventually some 0/90 deg cabon (This is only guesswork).
But for my purpose this is too much work.

barlow built some awsome ply / epoxy / glass / carbon masts about 20 years ago; they were truly things of utter joy.

Could one of the people who know, Phill, Wouter etc. Please post the moments of inertia for the "superwing" so I don't have to start from scratch if I develop a laminate spec for Gato.

http://www.composites.com.au/

there are some wing mast section properties in their products section...the AC145W is the A-class one (60 x 145 mm, 167 x 37.5 cm^4 (although they have an equivalent aluminium second moment of area value too?)). Weight of 1.29kg/m.

Although not of the same scale, during my model multihull building phase a few years ago, I built some very simple carbon wing masts of up to 1.8m (about an inch of chord length). They were great! Extremely stiff and easy to build, not to mention more durable than the equivalent aluminium ones. They were a similar weight.

It's good to see ppl willing to try building their own carbon masts. I may be convinced to give it a go sometime (just sketching up some ideas now).

A thought just came to mind while designing Gato's mast. When the "tip weight" criteria was added to the mast rule what calculations were done in determining a suitable number? The reason I ask is concentrated point loads can have a big effect on the mast's dynamic behavior.

Don't know, although I think the starting point was a standard taipan mast configuration.