Hurricane wind effect on rigging on the hard

[zippy]

I was curious about the effect hurricane force wind would have on the rigging of a boat on the hard. My numbers showed that 200 mph winds would exert the same force on bare poles as 49 mph wind would exert on 1000 square ft of sails. The numbers may be off but there are clearly severe stresses on the rig from 200 mph wind, especially when the boat is rigid in the stands and the load is cycling over hours.

Should rigging be replaced after being subjected to these loads. Even if no damage is obvious, the life of the rigging must be appreciably shortened. I am sure that many sailers are discussing this issue with insurance companies.

[billknny]

Originally Posted by zippy

I was curious about the effect hurricane force wind would have on the rigging of a boat on the hard. My numbers showed that 200 mph winds would exert the same force on bare poles as 49 mph wind would exert on 1000 square ft of sails. The numbers may be off but there are clearly severe stresses on the rig from 200 mph wind, especially when the boat is rigid in the stands and the load is cycling over hours.

Should rigging be replaced after being subjected to these loads. Even if no damage is obvious, the life of the rigging must be appreciably shortened. I am sure that many sailers are discussing this issue with insurance companies.

It would be interesting to walk the yards where so many boats lost rigs to the storm to see what the most common point of failure was. Swages? Chainplates? Spreaders? Mast fittings?

My understanding is that if there was no permanent elongation of the wire, the stress did no permanent damage. The bits other than the wire are much more amenable to visual inspection for damage.

[Quadrille in JB]

The post-hurricane in-yard damage I saw wasn't limited to the rigging. Many boats were simply "knocked down" on the hard due to the heavy side loads from the wind. I haven't noticed any rigging only damage. Most of the damage was done to the adjacent boats as they were struck by the masts.

[travellerw]

Originally Posted by Quadrille in JB

The post-hurricane in-yard damage I saw wasn't limited to the rigging. Many boats were simply "knocked down" on the hard due to the heavy side loads from the wind. I haven't noticed any rigging only damage. Most of the damage was done to the adjacent boats as they were struck by the masts.

I second this.. In Antigua the boats were subject to 100 knot sustained wind (125 gusts). ZERO boats sustained rigging damage from the winds.

[demacsea]

I'm not sure that you can calculate the load on the rigging on the basis of its diameter. Due to its circular shape the wind might flow around it, minimizing the load exerted upon it. Just a thought, but I might be entirely wrong...

[Emerald Sea]

I would suggest that you have a full visual inspection and non-destructive testing performed on all the welded and non-welded connections on your rig followed up with a detailed report. Hire an experienced and qualified NDE inspector familiar with sailing rigs do this. If the results are good you will have both piece of mind and a report to show your insurance company.

[NevisDog]

Originally Posted by demacsea

I'm not sure that you can calculate the load on the rigging on the basis of its diameter. Due to its circular shape the wind might flow around it, minimizing the load exerted upon it. ...

Yes, interesting thought - things are never simple - but wind can raise much greater cyclic loads flowing around a near-circular mast or wires due to vortice shedding, so whatever static load is calculated, you can likely double it for dynamic load/vibration. (That's why fins are added to tall chimneys - to prevent vortices forming and shedding.)

Just watch a circular mooring line and float react in a strong tidal flow; if the line is anywhere near vertical, it can perform a merry dance in reaction to the flow.

But wouldn't an insurance company claim that such 'gradual' damage due to high winds stretching the rigging, if not catastrophic, is just normal fair wear and tear? No different to surviving a hurricane at sea, with similar dynamic loadings?

[sailon46]

In Nanny Cay, most boats on the hard lost their masts, while the ones in the water sank for other reasons with their masts intact. According to a naval architect I know the reason been that boats on the hard especially tied down in cradles don't yield to the wind while the ones in the water do. Especially with the deck stepped masts all the new boats are required to have, so they can break away without sinking the boat.
FYI
Ernie on the Mary Jane

[Cadence]

I would think sailing loads would be far higher even though the heel is somewhat of a relief. The only thing I could see causing higher stress on the hill would be loose shrouds vibrating to the point of harmonics.

[NevisDog]

Originally Posted by Cadence

I would think sailing loads would be far higher even though the heel is somewhat of a relief. ...

If that were true, then why did every yacht in Nanny Cay lose its mast on the hard? Few yachts at sea in hurricanes lose masts. In that amount of wind, lashed down to a cradle, everything will vibrate like well-tuned piano wires, not just loose items.

[Cadence]

Originally Posted by NevisDog

If that were true, then why did every yacht in Nanny Cay lose its mast on the hard? Few yachts at sea in hurricanes lose masts. In that amount of wind, lashed down to a cradle, everything will vibrate like well-tuned piano wires, not just loose items.

JMHO. Maybe they were all tuned the same and playing a concerto. Vibrating is different than a harmonic not in a musical sense. Although some shrouds do sing dockside.

[hellosailor]

"then why did every yacht in Nanny Cay lose its mast on the hard? "
That's easy, Dog. Poseidon takes care of his daughters. Stick 'em out of his reach on the hard, and they become Gaea's problem, and she could care less about them, they don't belong on land.
Who needs physics when the old ways can explain it all?

[NevisDog]

So, maybe there's much to commend the 'old ways' of putting to sea when a storm is forecast. Or maybe not - there's likely quite a difference at sea between 'storm force' and '200 kts'!

[jmschmidt]

I've been told that on my boat, a Newport 41, the mast and rigging will generate 4,000lbs of force from the lowest wind classified as hurricane force, Cat 1 starting at 74mph, not knots. The info didn't specify with sails on and furled or off and stowed below. I assume that it meant on and furled because the info was on heavy weather sailing.

[Seas the Day]

I'm moving from Sydney to Vanuatu over the next year where they get a cyclone (NH Hurricane) every year or so. My preparation choices are 1) to leave the boat on a 'cyclone rated mooring' in my deep harbour or hard stand in town. If I go the hard stand way then I would remove the mast and standing rigging and strap everything down hopefully away from other boats that leave their masts on.