Dismasted at Sea! Amazing video!

[Tillikum]

Originally Posted by carstenb

This is why we have a cordless anglegrinder lying at the ready when we sail passages - there is no way I can cut through 12mm Dyform with a boltcutter

More important is what's on said cordless angle grinder. (you'll need spares)

And it's not a good time to learn how easy thin cutting disks are to break, or how just how lethal the pieces can be at 9,000 rpm. LEAVE THE GUARD ON and have a heavy pair of gloves and eye, if not face protection handy as well.

They'll cut through the Gordian Knot, or whatever part of you or anything else gets in the way!

And don't lose the wrenches or nuts or you may end up throwing that grinder in the bilges in disgust.

[donradcliffe]

Originally Posted by boatman61

Note to self...
Add cordless angle grinder to list of safety items owners must provide for delivery of their boat...

And you can steal bikes with it.

[houseofcharm]

A word to the wise-add a spare clamp on VHF antenna of some sort stowed below for such an unlikely event. Cut the cable and wire to the spare on a high point on the boat.

[houseofcharm]

So what, maybe a $35 repair? Do you fix it or just say phuket?


And would a deck stepped mast snap at the base?

[CaptJPMcGuire]

Good job guys. In your shoes you did what you could do. Hope there is no next time!! If there is --save the sail, dump the mast. You can rig the sail on the stub and make way. The radio antenna can be crudely spliced -enough to get out a signal.
Wise move NOT to panic-call a mayday or set off the EPIRB. You did have an EPIRB ?!! Crevice corrosion is a problem in any boat with concealed S Steel.
I planned on adding exterior plates on an Irwin --but went to dark side in a Grand Banks 42 instead.

[boatman61]

Originally Posted by donradcliffe

And you can steal bikes with it.

That's one for the 'Making a living while Cruising' thread..

[lestersails]

So was this crevice corrosion from intrusion and accumulation of salt water at the chain plate - deck junction? If so, what is the preventive maintenance here? Is one supposed to pull chain plates periodically? Never heard of that being done.

I dismasted a Snipe about 20 years ago for a related problem. I was given a very beat up Snipe by a colleague moving out of the area. I removed and reinstalled and carefully inspected just about everything on the boat, except for the stay attachments. Being green, I was over eager and over sheeted on my first outing and the forestay pulled right out of the deck. Re-established a functional mast using the jib halyard connected to the bow eye and limped back to shore with a reefed main (and a bruised ego).

That was not crevice corrosion but rather a weakened embedding of the forestay into the fiberglass of the bow. Not sure how I would have been able to diagnose that before it happened.

But back to the larger question - should one pull chain plates periodically to check for these types of problems?

[CaptJPMcGuire]

They can be industrially X-Rayed. Expensive but less that taking the chainplates out. I have suggested --adding external plates by drilling through hull-and existing plates and though bolting new plates on outside. I believe the 38 CaboRico had that set up --sort of

[requiem]

Originally Posted by Tillikum

More important is what's on said cordless angle grinder. (you'll need spares)

Why not a Hackzall? Would seem to avoid many of the issues you mentioned, just need to get the proper blades. Also useful for impromptu remodeling.

[john manning]

I think this crew did everything right. Despite the commentary, they were in calm conditions with light winds and close to port. Securing the mast and sails and motoring to port is the obvious thing to do. The only bit that surprised me was not releasing the sail from the top of the mast earlier.

I have experienced rigging failure and loosing the top of a mast (two separate incidents), fortunately in conditions not much worse than in the video. It wasn't worth doing anything more than this crew did, during those two events.

[Kaimana]

These people were lucky. The winds were relatively light (few whitecaps visible just before the demasting), and the mast came down sideways away from the crew, not down through the deck, or through the deck then through the hull. They didn't have to deal with a broken mast banging the side of the boat in 12-15 foot seas and a gale. Like I said, they were lucky.

The mast came down because of a single lost chainplate, and if I had to guess, it was to "crevice corrosion cracking" (CCC, sometimes referred to as "stress corrosion cracking"). Down a dirty and leaking hole in the deck (according to the video), which virtually defines the best conditions for creating CCC; the chain plate appears to have broken in half.

Unless you built the boat yourself, and you fabricated your chain plates yourself using 316L alloy stainless steel from a reputable supplier who could certify that it really WAS 316L, you have NO IDEA what kind of stainless steel(s) you have on your boat.

Sailboat manufacturers BUY the fittings that go on their boats, they don't MAKE THEM! So even though they exercise due diligence, they can't know for sure what type of stainless steel the various bits of hardware on your boat are. And 304 is cheaper than 316, and they need to make a profit to stay in business; you know: "it's just business".

And, that was 24 years ago when the boat was launched; all kinds of things can happen in between, and even 316L can experience crevice corrosion cracking in the right conditions: say a chain plate that's been beautifully bedded in Calk-Tex, Life-Calk, or Sikaflex.

That chain plate can experience corrosion BECAUSE it's been so beautifully bedded: it's completely sealed off on the backside so that little or no oxygen can get to the stainless steel there, and if you get a trickle of seawater coming in from a bolt hole, that can be enough to start CCC, yes, even in 316L.

(Below) What's happened to this stainless steel sailboat shackle is called "crevice corrosion cracking". I'm using this as an OBVIOUS case, but the cracks can be nearly invisible and weaken the structure the same amount as these have obviously done. This phenomenon occurs in the ABSENCE of oxygen, in other words, on the back side of your chainplates, mast tangs, and other critical boat metal hardware. Very often the corrosion is not visible until you've pulled the part off your boat and polished both sides to inspect it.


(Below) Same shackle; I pulled it apart with my bare hands. You know what's funny? I took this shackle off a mast I'd bought for one of my family's boats; the previous owner had been using it right up til he put the boat on the rocks and didn't need the mast anymore! FWIW, this is a Nicro-Fico screw pin shackle in 316 stainless that was manufactured around 1975; I had lots of them on my 37-foot cutter back then. This is what it looks like 46 years later.


I'd been a professional sailboat builder for 20 years when I took the 65-foot aluminum stick (750 pounds with rigging wires and tangs) off my 56-foot cutter to inspect and overhaul during a haulout. Ten years old, all the 1X19 wires (304 stainless steel) looked fine; there were no pull-outs, stranded wires, or other problems. All the chain plates and mast tangs looked fine, with almost no rust stains or other evidence of corrosion.

Then I took the boat on a 2,800-nautical mile ocean passage. Halfway through, I pulled in at Johnston Island for repairs; I'd shredded my mainsail and one of my jibs. While inspecting the mast again, I found that 13 of my total of 15 permanent rigging wires were stranded.

The one with the least stranding had 3, one wire had stranded in 19 separate locations.

I freaked out. And decided it was time to pull all the chainplates, AND mast tangs, AND through-mast pins, one at a time. Upon doing this, I found two chainplates and four mast tangs with noticeable cracks across the face from one side to the mast pin hole, two bent 3/4" solid stainless bar mast pins, and also two 3/4" Nylock nuts on my mast through-pins that had cracks. Needless to say, I replaced it all with new 316L stainless; tangs, chainplates, rigging wire, mast pins, and Nylocks. I also went up a size: where there had been 3/16" thick mast tangs before with 3/4" diameter pins, I replaced them with 1/4" thick tangs with 1" diameter pins.

The ONLY way to know if a mast tang, chain plate, or other stainless steel object is still good is to pull it, polish it with at least 600 grit wet-or-dry sandpaper, and inspect. Anything big is obvious, and tells you that you need to make a new whatever-it-is out of 316L stainless and replace the bad one.

You can still miss incipient cracks using straight visual inspection; these can be found by painting on some stuff that shows even teeny little cracks (this is called penetrant dye testing, and is used for non-destructive testing of metal welds, see here: https://www.weldingandndt.com/dye-pe...tructive-test/). You can find cracks that are invisible to the naked eye with this method.

So now I insist that everything on my boats be 316L. I pull all my 316L chainplates, mast tangs, and other hardware COMPLETELY OFF at 10-year intervals, polish it up, and inspect it.

How much is it worth to you not to have 400+ pounds of mast and rigging fall on you or your family?

With Warm Aloha, Tim

[MerMike]

The attached picture shows crevice corrosion on the chainplates after I pulled them at Brion Toss' recommendation during a rigging survey in 2019. I replaced all 4 of them with new, 316L (with mill test report) stainless. The old ones were vintage 1983.

[BelizeRumRunner]

I have dismasted twice. Luckily no one hurt in either case. Both times on a lake. The first time the sails went into the water and caused the boat to list seriously, but I managed to get the sails out of the water enough to prevent the boat from tipping too much. Now I carry a new set of bolt cutters, and I am not afraid to use them!

[Wotname]

Originally Posted by Kaimana

...........

Unless you built the boat yourself, and you fabricated your chain plates yourself using 316L alloy stainless steel from a reputable supplier who could certify that it really WAS 316L, you have NO IDEA what kind of stainless steel(s) you have on your boat.
...............

Ain't that the truth.

I made my own chainplates. Purchased a 6m length of 316L from a well known reputable supplier. They were out of stock and ordered in new stock from the distributor (also well known).

I took it home and noticed the manufacturing/distributor code sticker was still attached. The code number was many digits long but contained the numerals 304 in the middle of it. The invoice and delivery paperwork all showed the material to be 316L.

I was curious enough to ask the supplier to tell me what the manufacturing code meant - he didn't know but on checking with the distributor, it was revealed the material was actually 304.

They made all the usual excuses and replaced it. I could not determine if it was a honest mistake or not but I did ask for a signed certificate of conformance (CoC) to be supplied with the replacement. They told me the CoC would normally incur an extra charge but waived it in this instance.

Can one be too careful with chainplates, especially hidden ones? I don't think so.

In fact I strongly dislike hidden chainplates but I have to accept there are plenty out there.

[Iains boatyard]

“Who thinks its OK to "attach to a fishing buoy" overnight if the wind is too light to sail???? “

If you have spent time in theses waters you understand it is a viable option the fishing bouys are permanent ,the fishermen have many of them out on the current lines so they know where the fish run and tie off themselves. Try navigating at night thru a fishing fleet not knowing if they are pair trawling or stand alone boats.
I have have counted up to 60 on the horizon. Add to that flotsam and jetsam unlit fishing boats and FADs many miles out to sea. Been there done it can only say it is a tense experience plus going overboard to unfoul a prop in the middle of the night ….
As she noted windless nights calm seas, a god option you just light up (nav lights)and relax a little.