mast weight difference

[Joakim]

John Mast is known for its rather light aluminium masts. E.g. X-Yachts use it often. You could also try Nordic Mast.

Note that not all carbon masts are light. Quite often the difference in weight is small compared to a light aluminium one.

 

[rob denney]

John Mast is known for its rather light aluminium masts. E.g. X-Yachts use it often. You could also try Nordic Mast.

Note that not all carbon masts are light. Quite often the difference in weight is small compared to a light aluminium one.

Only if the carbon mast has been poorly built or over specced compared to the alloy one. Built properly, a carbonmast will be 50-70% lighter.

We are not accepting any orders until March/April next year, but if you can wait until then, plus 6 weeks for shipping, experience has shown that we are cheaper than the EU manufacturers. If you can wait, i will get you a price once work resumes in mid January.

rob
www.etamax.com.au

 

[SeriolaDumerili]

thank you Rob. Do you have info from your EU customers about shipping and custom costs?

 

[Joakim]

Only if the carbon mast has been poorly built or over specced compared to the alloy one. Built properly, a carbonmast will be 50-70% lighter.

True, but most production boat optional carbon masts seem to be only 10-30% lighter (the total weight including standing rigging, but not boom, as measured in ORC). Only the high end racing boat carbon masts seem to be truly light.

E.g. First 34.7 is quite close to the OP boat and mast. The alu mast total weight is a bit under 130 kg and carbon about 110 kg. X-332 has a bit taller alu mast at 110-120 kg (I think it is made by John Mast).

Farr/Mumm 30 has about as tall carbon rig at 64 kg, but it is a much lighter boat with half the RM thus it is not a fair comparison.

Melges 32 has a taller rig at 70 kg, but it also is a much lighter boat with much less RM.

GP33 about the same height, alu rig 98 kg, carbon 94 kg.

 

[fastwave]

Mast listing all manufacturesr

http://www.rimast.com/db/dbIndex.php?page=Profils&l=En

 

[SeriolaDumerili]

thank you fastwave! my boat is fastwave 30. is this coincidence or...

 

[rob denney]

thank you Rob. Do you have info from your EU customers about shipping and custom costs?

No. Best bet is to contact a shipping agent and find out what is involved. We would build it in 2 pieces, with a sleeve, so that it could travel in a container. So get total (the actual freight cost is probably less than all the BS extra charges) freight costs for a package 12m long x ~400mm x ~200mm. I don't think there is any duty into the EU. Local taxes/VAT will apply.

Joakim,
Rig weights are always going to have smaller percentage gains than mast weights. A correctly designed and built carbon mast will still be 50-70% lighter than an alloy one, if both are designed for the same loads.

 

[Joakim]

Rig weights are always going to have smaller percentage gains than mast weights. A correctly designed and built carbon mast will still be 50-70% lighter than an alloy one, if both are designed for the same loads.

I have just compared quite many masts in ORCi certificates for 34-38' C/R-boats with P about 14 m and RM 120-170 kgm/deg. All are 9/10 - 19/20 fractional two spreader rigs without runners. Boats like Salona 37/38, First 35, X-37 etc.

The aluminium mast rig weights are 150-180 kg and carbon 92-180 kg. Most carbon rigs are 120-160 kg with a very few under 120 kg and some over 160 kg.

Can you explain where does the huge span in carbon rigs come from? Interestingly one of the heaviest carbon and lightest mast is found from boats that have done very well in ORC Worlds:
http://data.orc.org/public/WPub.dll/CC/32035.pdf
http://data.orc.org/public/WPub.dll/CC/32032.pdf

It's hard to imagine that this purpose built boat would have chosen a bad quality carbon mast. Maybe they wanted a very stiff one?

Are all carbon masts about 100% carbon or are some using a mix of glass and carbon? What about HM carbon and laminating methods?

I have a boat in that range with a quite typical Selden C211 profile. The rig weight is 172 kg including Furlex 207 profile. The profile should be 5.34 kg/m and the mast is 17 m thus it should be about 91 kg. The rods should be about 20 kg + turnbuckles and fittings. I couldn't find weight for the Furlex profile nor for the spreaders.

So changing to carbon should give much lower section weight and also lower spreader weight. Also changing the aluminium forestay profile would save something.

 

[powerabout]

you can get very light carbon rig if you use very expensive high modulus carbon then laminate drops and maybe profile as well
they are all made from prepreg in female mold with bladder and autoclaved

 

[bjn]

Sorry for my ignorance, but could you explain "laminate drops and maybe profile as well"?

What is the price, modulus and strength of a normal carbon laminate compared this expensive pre-preg high modulus?

Even when using normal carbon composite, it seems strange to me that it's not lighter. Could it be that wear/fatigue will make carbon weaker with time, until it eventually breaks? And to prevent that, it has to be built extra strong/heavy? which makes it as heavy as aluminum?

If i recall right, aluminum is more affected by fatigue than steel. And the modulus to density ratio is the same as steel. So a custom steel mast could in theory be made lighter to the same strength. But then it would probably have buckling problems, as a result of the thin skins. Which could prevented by laminating the skins to a core. But then carbon composite seems like a better choice again...

 

[SukiSolo]

Be careful if you just use the 'e' value. Just as important or maybe more so are the compression values of the different materials, otherwise we would still be using wooden masts... at least until the high modulus, high compression loaded carbon(s) came along!.

 

[Joakim]

If i recall right, aluminum is more affected by fatigue than steel. And the modulus to density ratio is the same as steel. So a custom steel mast could in theory be made lighter to the same strength. But then it would probably have buckling problems, as a result of the thin skins.

Modulus defines stiffness and yield strength defines strength. Aluminium has the same modulus to weight ratio as steel. Strenght to weight ratio depends on the quality of steel and aluminium used. High strength steels need to be cold molded like rods while quite high strength aluminium can easily and cheaply be extruded as a profile. You couldn't make the same profiles from steel, since it would be too prone to dents. Just like you can't make steel bicycle frames with the bigger size tubes used in aluminium frames. The bigger profile makes the mast both stiffer and stronger.

Here are some mechanical properties of several different carbon laminates compared to aluminium and steel: http://www.performance-composites.com/carbonfibre/mechanicalproperties_2.asp

 

[bjn]

Modulus defines stiffness and yield strength defines strength. Aluminium has the same modulus to weight ratio as steel. Strenght to weight ratio depends on the quality of steel and aluminium used. High strength steels need to be cold molded like rods while quite high strength aluminium can easily and cheaply be extruded as a profile. You couldn't make the same profiles from steel, since it would be too prone to dents. Just like you can't make steel bicycle frames with the bigger size tubes used in aluminium frames. The bigger profile makes the mast both stiffer and stronger.

Here are some mechanical properties of several different carbon laminates compared to aluminium and steel: http://www.performance-composites.com/carbonfibre/mechanicalproperties_2.asp

Thanks, some of that UD carbon is just extraordinary compared to metals. I haven't worked in material science, but I've had the education. I didn't remember the specifics about alloys and heat treatment, but I knew the yield strength of the best alloys were pretty proportional to density, like the modulus. Some other metals, and some wood, was in the same ballpark of specific strength as well, I think. But UD CF exceptional.

Thanks for the data on carbon masts, very interesting. What do you think is the reason the carbon masts you've mentioned aren't as light as they could be, compared to aluminum?
Did you have numbers on a Marstrom mast? those are supposed to be top of the line, right? but are they significantly lighter than an aluminum mast?

 

[powerabout]

I wouldnt touch Marstrom since it changed hands...

 

[bjn]

I don't know much about the change, but I don't see it like you do. I think their masts might get better from the change. Göran himself retired, and the other changes was only in management, if I'm right. No change in manufacturing staff. The tools and skills should be intact. And not distracted by crazy carbon boat projects.

Maybe my question to you came out wrong before, but it was genuine. Drops? were you talking about the shape of a drop. Like a wing mast?