Pultruded Carbon Spars

[David L Alston]

I have most recently put a new boat on the water and therefore needed to build some new rigs. I was a little dismayed to find that all if not most of mast tubing available seemed to come from the same manufacturer.
I did consider making a laminated wooden mast but the dimensional specification one would need to achieve made it near impractical and I dislike driving nails into my hands.

But that is not the point…

These fully imported aluminium masts were/are not exactly inexpensive compared to a 2000mm length of 10mm or 12mm pultruded carbon tube.

One believes that the motivation for specifying Aluminium spars was originally based upon the cost and the wide availability of Aluminium Tubing.

Clearly however this situation has changed over the years and aluminium masts spars have near become a SINGLE SOURCE supply item:-

A situation which clearly is most unhealthy

I dread to think what it must be like in some countries.

Pultruded Carbon tubing is now manufactured in great quantities worldwide by literally hundreds of manufacturers.

Could we seriously consider removing or opening the Class Rules to included Pultruded and Wrapped Carbon tubing using the same dimensional limitations:-
• Round and constant section
• Constant wall thickness.

Before you pounce upon me could I ask you constrain yourselves to the subject of ALLOWABLE MATERIALS rather that Technical Advantage for this is a totally different subject.

[David L Alston]

I will confess to be disappointed at the lack of comment particulalry from the souther hemiphere RSA in particular. No parcels containing biological waste have been thrust through my letter box and no E-mails.

So what is one to conclude:-
a) It is summer and nobody actually cares and is griped with sailing fever
b) Everybody is content using masts from the usual chandlers when a carbon one is cheaper and posibly better.

Dave

[Stevew23]

I'm not sure why you think anyone here in RSA has issues with this in particular - every now and again someone imports a batch of masts, still much cheaper than local carbon fibre last time I looked , although that was a while ago now.
Someone here used carefully chosen dowel for masts awhile back , but maybe he enjoys driving nails into his hands - if you dislike it so much , I'm sure we can find someone who'll oblige you....

[CHATIN Achille]

Most of other sailing RC Classes are much more open on mast material, and they have definitely gone for Carbon.

Formerly, Carbon masts were definitely more expensive than Aluminium or Wood. Times have changed. Perhaps a new discussion could seriously be opened on that subject, as availability/cost of these materials are different worldwide.

But hang on a minute! Opening for Carbon concerning masts & booms can/may also lead to improve boat performance!
Not an easy task

[David L Alston]

I will confess not to have even looked at this forums for a while and it seems that no one else has either.

To respond to Stevew23 a RSA NCA officer

Steve I have spent the past 6 months working in RSA and lived there for some 20 year before returning to the UK. So I do know your part of the world

I do not understand your comment :-

‘if you dislike it so much , I'm sure we can find someone who'll oblige you’

And do not quite know if it was intended to as derogatory as I interpreted it to be. We WILL discuss this at Rietvlei when next I come. Also why someone did not tell me that the Nationals were being sailed at Midmar Day on the very week I was in Durban ….sailing alone on the Blue Lagoon Pond

But back to the point at hand:-

The rate of exchange is horrific - R25 to the pound so If a mast cost me £30, which it does near enough, then it is costing you R750 ish. I do not know your supply chain and perhaps you fellows have got it sorted but it is still costly no matter how you put it. However it is not health to become beholden upon someone slipping in a bundle of mast into the country. This situation is the death of the sport/class

To respond to Chatin Achille

I keep being told that – an Aluminium mast is cheaper than Carbon. This has not been my experience thus far. As I said earlier the last price I paid was around £30.00 for a 1800 length but I paid £14.99 for 2m of 10mm OD carbon tube.

And you are indeed correct we should be discussing this seriously.

Performance Improvement - this is subjective

You cannot have pre-bend so you have to cut a sail with enough allowance to get the forestay tension
The carbon mast I have is not stiffer to be honest than the aluminium mast

The mast holds the sail up and does not contribute directly to performance. But who cares even if it does - providing we are working in the dimensional framework of the class rules i.e. round and not tapered.



Getting Side Tracked

But let us not get side tracked from the point. The point being that the class rules were intended to restrict the cost of construction and using commonly available materials.

The 11mm aluminium mast is NOT commonly available. The mast mostly used one believes to be near single source, a situation that is not healthy.
Wood is not a viable alternative not for any other reason than the dimensional tolerances are too tight to reliable meet.

The choice of material should be open to the builder / skipper and not needlessly constrained.
++

[Olivier Cohen]

Hello David, Achille,

You are right, it's now possible to find carbon tubes at a lower (or similar) price than the alloy ones which are used by majority of IOMs today.
But you compare the best alloys with poor quality carbon tubes.

Just have a look at Sails etc website on this page http://www.sailsetc2.com/index.php/prod ... spars.html

On 10 mm diameter, you have 10 mm low stiffness (Carbon fibre round tube, 10 mm diameter x 1 mm wall thickness, 44 grams/metre. This is ordinary kite tube quality carbon tube with about 40% of the stiffness of our standard quality spar material) at 10 GBP/meter

But you have also high module 10 mm tube (Carbon round - 10 mm diam. High modulus carbon fibre round tube, 1 mm wall thickness, 44 grams/metre.) and the cost is 37.75 GBP / meter.

If carbon is allowed for IOMs, which tube do you believe will be used for racing ?

So clearly it will lead to cost increase compared with ~10 GBP/meter alloy tubes used today.

[David L Alston]

Olivier

The point of this discussion was not if a GBP 20 Carbon Mast was better than a GBP 30 Aluminium mast or if the quality of Product A is superior to Produce B.

At the moment the builder has NO choice at all, or indeed very little, and this is not a health state to be in. We have only the Class Rules to blame for this since wood is no alternative at all.

The decision should be the Builder’s or at the very least provide the Builder with some choice.

IOM was never intended to be a ONE Design Class – and certainly NOT a Single Source Class

One is reluctant to get into a debate over who is selling what or who is using what since it is totally irrelevant.

However that I would be very surprised if Sailsetc actually make the Carbon Tube they sell but I do know of countless manufactures of Carbon Tube that produce extremely stiff tube with 0.5mm wall. - But again this is not the point.

Dave

[Olivier Cohen]

Sorry if I misunderstood, but your title can be confusing. I will try to answer.

Dave, current preferred source for aluminium masts in IOMS is absolutely not a single source.

Even if PG modelisme masts are recommended for current benchmark IOM, there are other suppliers, such as sailsetc for example.
PG modelisme is single source for PG modelisme's masts, but you can uses Sailsetc or others masts on your IOM.

I don't understand your point.
10 years ago sailsetc's masts were used by almost everyone. Were you complaining about single source ?

[David Turton]

There is an enormous variance in the quality of carbon fibre and the resins available to build masts and with that comes price variance. Inevitably opening up to carbon will lead to someone building a mast using ultra high modulus prepreg carbon, autoclaved baked at 200c to achieve the stiffest mast possible developing another arms race obsoleting the current fleet of ioms. Even using low modulus variance in the curing and post cure process will alter final tube characteristics.

[David Alston]

It is amusing to see this go around in the usual circle.


From defence of the current situation regarding the near single sourcing of aluminium tube to the customary prophecy of obsolescent of the fleet interspersed with technical reasons why aluminium masts are superior to pultruded carbon tubes.

I would suggest that none of this is actually relevant because:-

The current permitted alloy was introduced some 5 or so years ago without any consideration of any obsolescence of the majority of the fleet i.e. boats owned by the majority of the club sailors.

The Class Rules regarding the dimension of the mast restrict the mast section to:-
a) Minimum diameter 10.6mm
b) Maximum deviation on outside diameter 0.3 mm
c) Maximum deviation of tube wall thickness 0.1 mm

Minimum Diameter
Why 10.6 mm. well this is not the debate. However carbon tube sizes are generally 12mm OD or 7/16” [ 11.1 mm] so there is little or no opportunity to make the mast smaller in diameter.

Maximum deviation on Outside Diameter
Why 0.3mm. again this is not the debate. However pultruded carbon tubes are of constant diameter and there is no opportunity to make the mast oval

Maximum deviation of tube wall thickness
Why 0.1 mm. again this is not the debate. However the pultruded carbon tubes are of constant wall thickness and there is no opportunity to make the mast taper internally
A distinct disadvantage might be that pultruded carbon tubes are straight and cannot be easily bent in order to provide jib tension and so the main sail will need to be cut adoringly.

The key to the proposal is the word ‘Pultruded’ i.e. not wrapped or all fibres running parallel to the axis of the mast.

So without the customary dooms day prophecies of obsolesce and technical inferiority may we consider providing a the builder / owner the option of using a Pultruded Carbon mast and spars

Or is there some thing I am not seeing?
I suggest that this will make no difference to anyone other that to give a reasonable choice other than the unreasonable choice of wood.


Also - I am NOT COMPLAINING as has been stated by Mr Cohen simply making a proposal AND inviting DISCUSSION.


And if Aluminium mast are superior why worry at all. Just as the allowing of coloured resin in the hull layup??


..

[RoyL]

What you are missing is that stiffer carbon masts require new, differently cut sails. Which would likely mean replacement of all current rigs. And it is a certainty that once you allow carbon spars in, as others have said, you will find someone selling high modulus tubes that cost in excess of 100 pounds. Aluminum tubes remain widely available and are still reasonably priced. And again, as others have pointed out, the French masts are the current flavor of the month in the IOM class, but will likely be superseded in the future.

[Richard Moroney]

I have re rigged my "Image" with an unstayed carbon mast. I used the guide on the Sails etc page for the US One Metre rig as a starting point. The joins for the 3 short lengths of tube were placed to match the luff of my main, when bent. This solves the "problem" of having to have new sails. I deliberately sourced medium spec Carbon uni pultruded tubes. Very inexpensive and no horrendous postage due to the short lengths required. Cheaper than the PG tubes I bought for strain gauge experiments of the various floppy alloy tubes available.
Now I have a boat that takes seconds to rig. No shrouds, No spreaders etc. A real doddle to assemble too. The forestay tension is now significantly greater. No extensive shoreside fiddling to obtain a good sail shape either. No "black art" pre bend needed.
I have built many rigs and always found it a pain when My boats were requested complete with rigs. No such trepidation with the carbon rig and I would consequently charge far less were I still building boats.
I deliberately sourced middle range tubes and would not want to go any stiffer than what I have because that would severely restrict light weather set up.
The only reason to go for the ultimate CF tubes would be for ultra skinny masts, which are not allowed anyway.
Sailmakers could easily suggest the best mast joint placings to suit their sails.
Try it out, just for fun.

Richard