Tired of hearing how stiff brand so & so is.

No cut & paste or link to an advertisement here

Here's the challenge:

Manufacturers, retailers or punters.

Grab your so called stiff boom (carbon, fibreglass or alloy) & measure the flex at a max extension across the widest point.
Just stand on one arm & pull up on the other, not high tech but should give enough for a comparison.

Name the brand, diameter, model, size and amount of flex in mm.

If you are really brave add the price for comparison to stiffness

I'm guessing the silence will be deafening

Paul,
Great idea although to make it a little more scientific why not nominate a certain weight (say 30kgs) hung at widest point and measure the amount of flex.

sounds like a good way to break a boom.

That's exactly how I used to do it but figured I would be struggling to a response without making it complicated

I beleive it should be marked on a boom similar to IMCS on a mast.

Imagine that, a manufacturing standard

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boardboy said...
sounds like a good way to break a boom.

30kgs dead load wouldn't even come close to touching the sides of the actual live load a boom is put under... well not mine anyway

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boardboy said...
sounds like a good way to break a boom.

What, no faith in your chosen brand?

If it breaks that easy you wouldn't want to use in the ocean

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Paul Kelf said...

boardboy said...
sounds like a good way to break a boom.

What, no faith in your chosen brand?

If it breaks that easy you wouldn't want to use in the ocean

i have faith in my boom - but i wouldnt want to put it under signifigant stresses which differ from what it would experience sailing.

The original test method here sounded like a deadlift - i can deadlift over 180 kgs.....maybe i can try on your boom?

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sausage said...

boardboy said...
sounds like a good way to break a boom.

30kgs dead load wouldn't even come close to touching the sides of the actual live load a boom is put under... well not mine anyway

i wasnt refering to your method - 30kgs dead load no problem - ill do that test.

Easy to find the stiffest with this test. It'll probably be the heaviest and have the fastest grip..

A downwards pull on a clamped boom would test the flex in the arms and the flex in the head too.

Of course you'd have to specify lengths. No point measuring a wave on zero extension against a formula on full extension.

I'd sacrifice a little stiffness for durability!

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ejmack said...
I'd sacrifice a little stiffness for durability!

I'd sacrifice a little stiffness for durability stamina

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Paul Kelf said...

Tired of hearing how stiff brand so & so is.

No cut & paste or link to an advertisement here

Here's the challenge:

Manufacturers, retailers or punters.

Grab your so called stiff boom (carbon, fibreglass or alloy) & measure the flex at a max extension across the widest point.
Just stand on one arm & pull up on the other, not high tech but should give enough for a comparison.

Name the brand, diameter, model, size and amount of flex in mm.

If you are really brave add the price for comparison to stiffness

I'm guessing the silence will be deafening

In fact lets also add weight into the challenge, some are stiff but weigh about 10 kg

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barn said...
Easy to find the stiffest with this test. It'll probably be the heaviest and have the fastest grip..

A downwards pull on a clamped boom would test the flex in the arms and the flex in the head too.

Of course you'd have to specify lengths. No point measuring a wave on zero extension against a formula on full extension.

I can't see that working with an articulated head but the rest is pretty simple to do.

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ejmack said...
I'd sacrifice a little stiffness for durability!

You can get that with an alloy boom

Tested (very unscientifically) an older Chinook 195-255? non monocoque carbon (not at full extension cause I couldn't be bothered pfaffing around with the adjustable outhaul). Flex at widest point was about 2.5cm.
Never felt that this boom was incredibly stiff.

German magazine SURF tested the mayority of booms currently available on the market. The results below come directly from this test.

Stifness in N/mm measured at 10 and 44 cm extension. The higher the values, the stiffer the oom is. All booms tested are in the 180-240 cm range.

Brand, model, price / stifness + 10 cm / stifness + 44

ALU
Aeron OS Slalom € 229/ 32 / 25
Aeron V-Grip € 249/ 31 / 19
AL360 Ergal € 299/ 26 / 22
Gun Expert € 239/ 24 / 19
NP X3 € 230/ 27 / 22
NP X6 hybrid € 449/ 28 / 23
North Sails Gold € 479/ 26 / 21
North Sails Silver € 289/ 22 / 21
Prolimit Assault V-grip € 249/ 31 / 25
Severne Race € 189/ 30 / 24
Unifiber Universal € 109/ 19 / 17
Unifiber RDG € 159/ 18 / 15

CARBON
Gun Select € 489/ 35 / 29
Prolimit RDG Team € 779/ 39 / 27
Gaastra Blue € 749/ 44 / 34
NP X9 € 999/ 46 / 39
AL 360 € 790/ 60 / 49
North Sails Platinum € 1239/ 65 / 60
Severne Enigma € 799/ 71 / 56

As you can see a proper alu boom is nearly as stiff as a cheap carbon boom. The magazine also noted that a hybrid boom with carbon back end doesn't add any stiffness or added value to the boom except the higher price.

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Paul Kelf said...

ejmack said...
I'd sacrifice a little stiffness for durability!

You can get that with an alloy boom

That's exactly I switched to carbon - alu was corroding and turning to mush. I broke three in one year.

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TheTank said...

ALU
Aeron OS Slalom € 229/ 32 / 25
Prolimit Assault V-grip € 249/ 31 / 25

CARBON
Gun Select € 489/ 35 / 29

As you can see a proper alu boom is nearly as stiff as a cheap carbon boom. The magazine also noted that a hybrid boom with carbon back end doesn't add any stiffness or added value to the boom except the higher price.

This doesn't include weight so it's still hard to value the alloy against the carbon. You might assume that while the Gun is only marginally stiffer than the Alloy booms listed it is probably a great deal lighter.

Far more difficult to measure but the guys above are right, durability is a major factor for most. If a carbon outlasts the alloy alternative by a decent margin the price may be negligible over time... doing a 5 year boom Total Cost of Ownership would be interesting, even if it was just a general alloy to carbon comparison.

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shear tip said...

Paul Kelf said...

ejmack said...
I'd sacrifice a little stiffness for durability!

You can get that with an alloy boom

That's exactly I switched to carbon - alu was corroding and turning to mush. I broke three in one year.

My Alu boom average was very similar ShearTip and also my reason for switching to Carbon. Saying that, I'm on my third carbon (and not the cheap ones) in about 2 years. It seems as though the boom is the weak link in the chain so to speak as I've yet to break anything else (apart from the occasional nose ding & harness lines). I guess my point was stiffness isnt everything and I'd happily sacrifice a little for a well designed and made boom which actually lasts. A stiff boom feels awesome, but if it breaks after six months because it's not made well then I'd rather the less stiff one which lasts 2 years. I'm only 82kg btw, don't jump all that high & look after my gear (gentle off the water and wash down afterwards)

But I suppose this thread is about boom stiffness, which is great. Keen to test my carbons now.

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ejmack said...

shear tip said...

Paul Kelf said...

ejmack said...
I'd sacrifice a little stiffness for durability!

You can get that with an alloy boom

That's exactly I switched to carbon - alu was corroding and turning to mush. I broke three in one year.

My Alu boom average was very similar ShearTip and also my reason for switching to Carbon. Saying that, I'm on my third carbon (and not the cheap ones) in about 2 years. It seems as though the boom is the weak link in the chain so to speak as I've yet to break anything else (apart from the occasional nose ding & harness lines). I guess my point was stiffness isnt everything and I'd happily sacrifice a little for a well designed and made boom which actually lasts. A stiff boom feels awesome, but if it breaks after six months because it's not made well then I'd rather the less stiff one which lasts 2 years. I'm only 82kg btw, don't jump all that high & look after my gear (gentle off the water and wash down afterwards)

But I suppose this thread is about boom stiffness, which is great. Keen to test my carbons now.

The problem with booms is they can break & bend fairly easily if you are prone to catapulting because the load is huge & instant.

Carbon booms generally only break with crashes from what I've seen.
Good alloy booms tend to fatigue over time & cheapies just snap or bend.

I have a couple of alloy booms that I use & they are as stiff or stiffer than a cheap carbon & they are years old now, admittedly they are custom made & a bit heavier. One has had replacement front fittings and the other is slightly bent after hitting someone recently at ~ 28 knts

A soft carbon boom might last, masts flex a lot & can last for long periods but using a soft carbon would be horrible & to me pointless.

I will measure some of my booms on the weekend, carbon & alloy.

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Paul Kelf said...

Carbon booms generally only break with crashes from what I've seen.

Recently cracked the first time a carbon boom (160 - 220cm MK Carbon) just hooking back-in from a gybe right at the point load of the harness lines (I used to have lines very close together but now space them about 20cm apart to spread the load) . This boom was purchased 2nd hand but unused and had never had a catapult on the tack (side) that it broke. I was surprised at just how thin the wall thickness was as compared to a really old Autima carbon (used up until the above mentioned one replaced it) and that has been through the wringer and yet still going strong.

I have replaced it with hopefully a more reputable brand although having ever only used larger dia booms, the 29mm diameter doesn't yet give me (albeit perceived) any great sense of security.

Previously I used ali's (for my larger sails that the Autima didn't fit) up until about 3 years ago but had a bad experience 2.5km out to sea with a new one snapping at the head where the double ali reinforcing tube transitions into single tube after only 6 sessions .

The MS carbon 190 - 240 that superseded the ali is now 3 years old and still going strong so cost versus durability here has been about $320 / year - not too bad at all.

C'mon snags, get the weights out and do the test on the MS Carbon.... Should do it myself but relying on your pursuit of a decent stiffy could save me the effort!

Steve,
I'll try and take some definitive measurements this w/e. Maybe at min, max and mid extension - this should hopefully provide some useful feedback.

I know before even doing it the MS carbon will be quite heavy but for peace of mind where I sail I'm more than happy to give up weight for durability.

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TheTank said...
German magazine SURF tested the mayority of booms currently available on the market. The results below come directly from this test.

Stifness in N/mm measured at 10 and 44 cm extension. The higher the values, the stiffer the oom is. All booms tested are in the 180-240 cm range.

Brand, model, price / stifness + 10 cm / stifness + 44

ALU
Aeron OS Slalom € 229/ 32 / 25
Aeron V-Grip € 249/ 31 / 19
AL360 Ergal € 299/ 26 / 22
Gun Expert € 239/ 24 / 19
NP X3 € 230/ 27 / 22
NP X6 hybrid € 449/ 28 / 23
North Sails Gold € 479/ 26 / 21
North Sails Silver € 289/ 22 / 21
Prolimit Assault V-grip € 249/ 31 / 25
Severne Race € 189/ 30 / 24
Unifiber Universal € 109/ 19 / 17
Unifiber RDG € 159/ 18 / 15

CARBON
Gun Select € 489/ 35 / 29
Prolimit RDG Team € 779/ 39 / 27
Gaastra Blue € 749/ 44 / 34
NP X9 € 999/ 46 / 39
AL 360 € 790/ 60 / 49
North Sails Platinum € 1239/ 65 / 60
Severne Enigma € 799/ 71 / 56

As you can see a proper alu boom is nearly as stiff as a cheap carbon boom. The magazine also noted that a hybrid boom with carbon back end doesn't add any stiffness or added value to the boom except the higher price.

Some impressive numbers there from a couple of brands, both alloy & carbon.
I wonder how they actually did the test & measured it in N/mm?

The boom was clamped at both ends and they measured:
- the deflection in (mm)
- under a constant load 40kg at a fixed position from boom head

You get that magic number, stiffness N/mm!

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The Windsurfing Shed said...
The boom was clamped at both ends and they measured:
- the deflection in (mm)
- under a constant load 40kg at a fixed position from boom head

You get that magic number, stiffness N/mm!

How exactly do you get that magic number?
As Tank said "the higher the number the stiffer the boom"
So it is not the measurement of flex under load.

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Paul Kelf said...
How exactly do you get that magic number?
As Tank said "the higher the number the stiffer the boom"
So it is not the measurement of flex under load.

N/mm is a measure of how much force is required for every mm of deflection.

Use F=ma
F, force
m, mass is 40kg
a, acceleration is 9.81m/s (acceleration due to gravity)
therefore force applied with the 40kg weight, F=392.4N

So taking say the severne enigma @+10, the boom would have deflected with the 40kg load attached, 5.5mm (392.4N applied, deflection was 71N/mm, 392.4/71 = approx 5.5mm).

So basically, they would have put the weight on, measured the deflection, reversed the maths that I did. And arrived at the N/mm figure.

The NP x3 would have deflected 14.5mm.
The North Silver, which is well known for being spaghetti would have deflected 17.8mm

Also of interest looks like the typical north marketting speak has some substance to it. The North Platinum is less stiff than the Severne Enigma at +10cm extension, but overtakes it once extended out to +44cm. That oversized tail must work!

Windless day here today so results are in. Just need to calculate figures based on Swoosh's and Remi's parameters. Watch this space................

Hi paul,

I'm not sure what your point is. Are you selling booms? Your avatar is flying the flag for Hydrodynamix, but you're not a site sponsor. Have you measured a hydrodynamix boom? How does it compare to the other booms listed by German Surf Magazine? Why not post some numbers - you seem pretty confident that other's "so called stiff" booms aren't...

nice yard !!