Hurricane Dismastings when moored

[home_maarten]

As far as I know, most of these catamarans have rotating masts.. This limits the ways in which they can be stayed and that might impact the failure mode, together with their inherent stability...

[admiralslater]

Last year there where a couple of cats in Greneda that had lost their rigs without damage to the mast insomuch as there where now big impacts . The feeling amongst riggers was that it was harmonics that caused the vibration and bending of the rigs . Some snapped some flew away but the standing rigging failure was not deemed responsible

[HopCar]

Originally Posted by DefinitelyMe

Here in Bermuda we actually don't get that much flying debris during hurricanes but boats still often lose their masts. Very interesting to hear that stuff about vortexes (or is it vortices?).

One of the leading causes is failing to remove a roller-furling headsail. Even a tightly-rolled headsail can be pried free by the wind. Then either the mast comes down from the violent shaking or the boat breaks free from the mooring from the increased load.

I have seen the aftermath of many hurricanes. I’ve never seen a mast survive if the head sail wasn’t removed. It’s a lot of work, but you have to remove all exposed fabric, including furled sails, if you want to avoid damage.

[tbodine88]

Generally Dismasting is only part of your problem. My friend Nick Maley got his boat out of a tree after Wrong way Lenny in Antigua. In this video from the Bahamas

https://www.youtube.com/watch?v=_tr0NMRSCt8

,

there a a few boats shown ashore, which will require some effort getting afloat again, the equipment for which is difficult to find in the islands. The boats shown apparently didn't have masts. I remember seeing a fine ketch in Great Inagua that had blown onto the beach when the winds had changed and the crew was inattentive. It was ship shape and ready to sail about 100 yards from the water.

[Talbot]

Originally Posted by CassidyNZ

Except that mast on cats offer a lot more resistance to wind than monohulls simply through their inability to heel. Most cruising cats are (relatively speaking) quite heavy and will stay reasonably flat even with severe pressure on the mast.

And whilst I’m not a cat expert, my perception is that on big cats, the mast sections are quite large (?) offering more resistance.
.

It is for this reason that cat masts are of heavier construction than monos, and standing rigging is much thicker. The sail cloth is also heavier. Thus capable of standing comparable shocks to monos despite not being able to shed load by heeling.

[smj]

Originally Posted by home_maarten

As far as I know, most of these catamarans have rotating masts.. This limits the ways in which they can be stayed and that might impact the failure mode, together with their inherent stability...

I would guess that way less than 1% of the cats that lost their rigs in a hurricane had rotating masts, they just aren’t that common.

[tweekes]

Thinking that cats don't heel with the wind or squirrel around as much, the mast is always presented perpendicular to the wind so you have max resistance to it as opposed to a mono that will heel and present a smaller cross section for wind resistance.

[a64pilot]

Originally Posted by hobsonlea

Having seen this painful video of a Production Cat, a Fountaine Pajot Lucia 40, from earlier this Nth Hemisphere season, I was surprised how strong the rig was.



https://youtu.be/dqAt18kcljc

When I first saw that video, I sure hoped it was at low tide, then was amazed the tow boat was so full of people.
However I bet it wasn’t at low tide, how did they get trapped with is much mast higher than the bridge if the tide isn’t rising?

[hobsonlea]

Originally Posted by a64pilot

When I first saw that video, I sure hoped it was at low tide, then was amazed the tow boat was so full of people.
However I bet it wasn’t at low tide, how did they get trapped with is much mast higher than the bridge if the tide isn’t rising?

I think it was here 44° 0.872' N 15° 15.077' E
Zdrelec Passage. Lists bridge clearance as 16.6m.
Lucia is more than 19mtrs..
0.29mtr tide about 1ft

[drivn2ironman]

As the point was well made. Cat's do not sway/lean like mono hulls do, so the wind pressure built against the mast places a much higher stress level on all the standing rigging.
I remember when I was younger my dad had replaced his standing rigging in New Zealand, and during a sailing event he was dismasted. The rigging was less than three years old. After inspection and x-rays of the fitting, it was noted that it has corroded from within the compression sleeve. (Not even three years old, but it was in the tropics). I am not surprised as to how many are dismasted, as I'm sure the standing rigging is aged on most of them.

[caymancat]

Many of the pictures of dismasted boats that I have seen, show the mast buckling somewhere near where the boom attaches. The boom of course has a great deal of windage and swings on the mast, generating a great deal of stress.
Removing the boom before a storm would reduce windage on the rig considerably and increase the chance of mast survival.

[sailorboy1]

I recently adjusted my rig and used a tension gage and in the end it is tighter than it had been in the past. I've noticed that the rig vibrates and oscillates a lots less than it used to now.

[DefinitelyMe]

Originally Posted by caymancat

Many of the pictures of dismasted boats that I have seen, show the mast buckling somewhere near where the boom attaches. The boom of course has a great deal of windage and swings on the mast, generating a great deal of stress.
Removing the boom before a storm would reduce windage on the rig considerably and increase the chance of mast survival.

Possibly. But there is also an argument to be made for actually increasing windage aft in order to reduce yawing. A boat with a high bow might benefit from this, and the loads on gear can actually be reduced overall in this way. Depends on the boat.

[DefinitelyMe]

Originally Posted by drivn2ironman

As the point was well made. Cat's do not sway/lean like mono hulls do, so the wind pressure built against the mast places a much higher stress level on all the standing rigging.
I remember when I was younger my dad had replaced his standing rigging in New Zealand, and during a sailing event he was dismasted. The rigging was less than three years old. After inspection and x-rays of the fitting, it was noted that it has corroded from within the compression sleeve. (Not even three years old, but it was in the tropics). I am not surprised as to how many are dismasted, as I'm sure the standing rigging is aged on most of them.

Yup, we lost a shroud on a rig that had been brand new 2 1/2 years previously. In Niue...... Not exactly the best place to find parts! Crevice crack corrosion and/or fatigue. Now we have synthetic rigging and bronze turnbuckles and i will never go back.