Dismasted

[Uricanejack]

Not inertia. While Inertia may have an effect. The main reason the boat rolls faster is the change in the centre of gravity.

The weight of the Mast is relatively high, it acts at the masts centre of gravity so a small g. Probable close to half way up the mast. Under normal conditions this weights position raises the boats centre of gravity a G.
The boats stability is a combination of the effects of its centre of G acting down and it’s centre of buoyancy acting up.
They want to be in line. incline the vessel and it will create a righting lever to bring the vessel back upright provided they are both in line.
The lost of the mast. Will do two things. If lost overboard, the weight is gone, the weight of the boat will be less it will float higher the center of buoyancy change to a position slightly lower.
The loss of the weight high up will cause the overall boats center of gravity to be quite a bit lower.
This lower centre of gravity will creat a larger righting leaver when the boat is inclined or heeled resulting in a faster more sudden return to upright.

The boat will be more stiff.

The change in stability is often expressed by comparing a theoretical position Metacentric height with the center of gravity.
Or GM
The GM will get quite a bit larger with the loss of the mast and rig.

M is a theoretical position on the centre line through which a vertical line up through the centre of buoyancy acts when the vessel is slightly inclined.
The centre of buoyancy moves to the low side when the vessel is inclined.

Sail boats are generally kind of stiff. Take the mast of they get a lot more stiff. So without the mast a sailboat will tend to roll faster and more violently than with the mast.

 

[Daydream believer]

Everyone mentions the actual wire rigging. But on my boat there are lots of ropes leading to the cockpit. Plus all the in mast electrics. Just releasing that lot must take a while. Getting sails clear of the boat must be awkward as they may well be laying across the rigging.
I broke the mast on a silhouette when I was in my teens, but we drifted to the bank so just hopped ashore (in the mud :ambivalence & waited for the tide to go out. The mess was incredible.
What it must be like on a full blown cruiser, especially with, say, the kite up, must be one hell of a tangle.

 

[vyv_cox]

Read about Hammond Innes motoring his new steel boat to UK from Holland. No rig , and it had a nasty short roll. Very unpleasant.
The inertia of the mast matters.

Strange coincidence, I am reading that book right now.

 

[KellysEye]

A list of the best bolt cutters: https://www.gearhungry.com/best-bolt-cutters/ What concerns me is the handles are much shorter that the one we carried.

 

[JumbleDuck]

JD
You do speak English as well, don't you?

I'm an academic and have been fluent in pedantic gibberish so long that my English are rusty.

 

[capnsensible]

I'm an academic and have been fluent in pedantic gibberish so long that my English are rusty.

Its good to have the talent to work it out with a pencil.

 

[mjcoon]

I'm an academic and have been fluent in pedantic gibberish so long that my English are rusty.

In contrast with the tool kit thread that claims that cheap tools rust sooner, whereas the posh ones resist for longer?

Mike.

 

[vyv_cox]

A list of the best bolt cutters: https://www.gearhungry.com/best-bolt-cutters/ What concerns me is the handles are much shorter that the one we carried.

I agree. I initially bought a pair with handles about 18 inches long. I tested them on a length of 8 mm 1x19 wire and they came nowhere near cutting through. I replaced them with a pair almost twice as long that cope very well.

 

[rogerthebodger]

I'm an academic and have been fluent in pedantic gibberish so long that my English are rusty.

JD

I simperise with you I have the same issues but I am not in an academic environment so most of the people I get involved with tend to ignore me as I think they don't understand my pedantic English. The additional factor is a lot of the people where I live don't have English as their first language and don;t understand Engineering. Computer systems design and the local Laws.

 

[Vicarage]

We've got a set of hydraulic croppers. When we replaced the backstay I played around trying to chop it up with various bits of kit onboard. Manual croppers were as good as useless, even with the wire flat on the ground. Hydraulic ones went through the wire like a knife through butter. Horrendously expensive through.
A handheld angle grinder might be equally good and cheaper, though obviously then you've got sparks and heat to contend with.

 

[Seven Spades]

The angle grinder is the way to go.

 

[JumbleDuck]

Not inertia. While Inertia may have an effect. The main reason the boat rolls faster is the change in the centre of gravity.

Raising a 50kg mast 8m long on a boat displacing a ton from horizontal to vertical has a minute effect on the position of the centre of gravity but a very large effect on the second moment of inertia in roll. Remember that we are discussion dynamic response to transient loads, not stability in general.

 

[Kukri]

A friend just sent me a snap of herself sitting, in a becomingly decorative pose, in the pulpit of a carbon fibre maxi, anchored in a tropical bay, wearing her professional yottie rig of white T shirt and navy blue shorts, holding a cold beer, surrounded by an awful lot of taut Dyneema and no wire or rollers. They had done a big race and were delivering to the next regatta when the stick lost interest, 100 miles into the South China Sea, so they gathered up the bits, sorted a jury rig, reversed course and are on their way, gently downwind, to a port where they can be hauled out.

How to get dismasted in style?

 

[pyrojames]

I think that just suggests that you have stylish friends,

 

[Gwylan]

Share the reservations about how good the bolt croppers will be.

Wondering about a battery powered angle grinder. The 18 volt versions are pretty serious. But then there will be the charging issue.

 

[westhinder]

A friend just sent me a snap of herself sitting, in a becomingly decorative pose, in the pulpit of a carbon fibre maxi, anchored in a tropical bay, wearing her professional yottie rig of white T shirt and navy blue shorts, holding a cold beer, surrounded by an awful lot of taut Dyneema and no wire or rollers. They had done a big race and were delivering to the next regatta when the stick lost interest, 100 miles into the South China Sea, so they gathered up the bits, sorted a jury rig, reversed course and are on their way, gently downwind, to a port where they can be hauled out.

How to get dismasted in style?

I won’t even try to imitate her. I could manage the white T-shirt and navy shorts, but the result would be nowhere near as decorative. The only carbon on the boat might well be in my pencil.

 

[weustace]

I seem to recall a remark in the 79 Fastnet report that some skippers found the use of bolt cutters difficult in heavy weather due to the need for one hand to cling onto the boat. I've always considered a junior hacksaw to be my preference, and carry one (+ a number of spare blades) instead of bolt cutters. I tried it on some old rigging when I changed my rigging a few years ago, and it went through my 5mm backstay (small boat!) like a knife through butter, even with minimal tension.

 

[Seajet]

My boat has a lot of form and ballast stability, but is very twitchy when the rig is down - and I do call the effect of the upright mast on rate of roll inertia.

We can never carry everything ideal or we'd be towing another boat of at least equal size full of tools, spares and first aid kit etc - so re dismasting, having read the excellent Crash Test report I go for the cordless angle grinder - it's such a useful tool onboard for other stuff too.

 

[Stemar]

Share the reservations about how good the bolt croppers will be.

Me too. I've often thought that it would probably be easier to cut the turnbuckle or the thread that goes into it than the wire, but have never had a spare to test. Has anyone tried this?