Anyone familiar with the different types of carbon fiber tubing?

[BCRider]

I watched the videos to get some ideas of my own. It's an interesting rig for sure. If I didn't already have two of the smaller sails and short mast on hand already.....

I'm wondering if your original breakage might have come from the mast folding down and striking one of the leeboard ends? I've got lots of my own history of water crashing to support the idea that it's hard to break stuff unless it hits something with hard edges or the luckless sailor actually falls hard onto part of the rig. Not something you're likely to do on a kayak but which as a windsurfer I was all too vulnerable to doing....

I still think that stainless tubing is a good option. But I would have similar confidence in a length of the 20mm x 14mm carbon tubing given how it looks to be done. Best of luck with whichever way you go and happy sailing.

[A.K. Boomer]

Did you aluminum post snap as the base? can you just cut it and then build a heavy duty collar for it to slip into?

[gellfex]

BCRider The tube needs to fit the existing sliding blocks unless I'm going to dive deeper and remake those too, which I'd like to avoid, I need 19mm OD. But they do list 19x15. I'm in communication (sort of) with the Chinese mfr to see what they can provide. As is they can only do 1000mm, so I'd need to fabricate a new 150mm extension plug for the masthead anyway.

Did you aluminum post snap as the base? can you just cut it and then build a heavy duty collar for it to slip into?

If you look at the rig, it's a tube that slides up another tube on 2 brackets. It snapped were it emerges from the top bracket, at precisely the spot of most ft/lbs force from a overhung load.

[mattthemuppet]

make a new upper clamp that is designed to breakaway/ release above a certain load? ie. above what the mast would normally experience but below what capsizing would cause.

[Joel]

I was going to make a joke about spring loading the mast, but... maybe a semi-flexible connection with a lower yield isn't such a bad idea?

[elf]

I'd make one out of wood. A laminated wood mast would not only look better, but would perform better in a dunking.

[gellfex]

elf you missed the part that it needs to be tubular because there's bungee inside.

mattthemuppet & Joel I thought of that kind of safety rig, but given the design it's not easy to pull off, I'd have to have the upper bracket release under pressure, and the lower pivot.

[elf]

Laminated wood masts can be hollow and usually are

[BCRider]

Laminated wood masts can be hollow and usually are

I think you also missed the part where it's only 3/4" in diameter. A wood mast of that size simply wouldn't stand up and would be far more flexible in the wind.

Gelfix, from the sounds of the communiques on the carbon option it sounds like stainless tubing will end up the winner. And that would not be the end of the world. Probably a couple of pounds heavier than the aluminium option? And maybe a bit under that?

[gellfex]

I think you also missed the part where it's only 3/4" in diameter. A wood mast of that size simply wouldn't stand up and would be far more flexible in the wind.

Gelfix, from the sounds of the communiques on the carbon option it sounds like stainless tubing will end up the winner. And that would not be the end of the world. Probably a couple of pounds heavier than the aluminium option? And maybe a bit under that?

Well, considering the 6061 spar is 2/3 of a lb, a few lbs would be a lot! Actually, relative density is 2.8 to 8 g/cm3, so a SS spar would be 1.88 lb. No, not the end of the world, but not optimum. The tensile strength of the steel is not quite 2x that of AL, so losing wall thickness seems counterproductive, unless the way SS reacts to this sort of stress is different from AL. Would the extra lb up top be dramatic to the performance? I guess it's hard to see how directly, but the whole rig is so light it's still worrisome.

[elf]

I think you also missed the part where it's only 3/4" in diameter. A wood mast of that size simply wouldn't stand up and would be far more flexible in the wind.

Gelfix, from the sounds of the communiques on the carbon option it sounds like stainless tubing will end up the winner. And that would not be the end of the world. Probably a couple of pounds heavier than the aluminium option? And maybe a bit under that?

But it floats

[garyhlucas]

Being a sailor myself I’d go carbon fiber in a heartbeat. Even a few extra lbs at the top of a mast on an unballasted hull will likely have a big effect and losing weight up there is very desireable.

[gellfex]

Being a sailor myself I’d go carbon fiber in a heartbeat. Even a few extra lbs at the top of a mast on an unballasted hull will likely have a big effect and losing weight up there is very desireable.

I agree. I found this table of comparison, it makes a strong case for carbon.

Carbon Fiber vs Aluminum Measured
Measurement Carbon Fiber Aluminum
Modulus of elasticity (E) GPa 70 68.9
Tensile strength (σ) MPa 1035 450
Density (ρ) g/cm3 1.6 2.7
Specific stiffness (E/ρ) 43.8 25.6

EDIT: crap! why won't they let me even hand format a table to be readable!

[mattthemuppet]

from what I know about carbon fiber the numbers above are meaningless. CFs properties is exactly what the designer wants them to be, based on layup, short vs. long weave, direction, percent resin, chopped fibers vs weaved mat, how the piece is cooked and on and on. All of which affect elasticity (and in which direction and under what conditions), density, strength, stiffness and so on. I'm not saying that a piece of off the shelf CF pipe won't work for you, but unless you have the specs modeled for that particular layup and mix, then there's no real way of knowing what you're getting. It's like saying you're going to build your house out of stone - ok, what stone? How? How thick? etc etc.

[gellfex]

from what I know about carbon fiber the numbers above are meaningless. CFs properties is exactly what the designer wants them to be, based on layup, short vs. long weave, direction, percent resin, chopped fibers vs weaved mat, how the piece is cooked and on and on. All of which affect elasticity (and in which direction and under what conditions), density, strength, stiffness and so on. I'm not saying that a piece of off the shelf CF pipe won't work for you, but unless you have the specs modeled for that particular layup and mix, then there's no real way of knowing what you're getting. It's like saying you're going to build your house out of stone - ok, what stone? How? How thick? etc etc.

That all sounds perfectly reasonable. But still, compared to the aluminum which failed at its first test, do you really think I can go wrong?