Weak Stainless Steel or Strong winds in SOF

[BartW]

this broke in October, even before the storms in November,
luckyly there were 3 other sternropes to keep Blue Angel in position until the harbor staff fixed it.

 

[AndieMac]

Nasty break Bart.
What are you going to replace it with, a larger gauge SS shackle or change to galvanised steel?

 

[shaxi]

if for me ,i am used to using the galvanised steel ! but maybe hard to choose !

 

[Poignard]

Here's one I broke earlier! It was made with a crack almost all the way through one limb.

In future I will not trust any s/s shackle in a critical application unless it is from a reputable manufacturer.

http://www.ybw.com/forums/attachment.php?attachmentid=14387&d=1320146015

 

[sailorman]

i would choose a galvanized shackle & add a strop around the compensator for the occasion when the shackle breaks. then you still have a warp intact but slack.
well thats how mine are set-up

 

[Nick_H]

looks like a classic case of stress corrosion cracking. As others have said it may be worth using galv steel shackles which are less prone to such fractures, and add a strop in case it fails.

 

[MapisM]

As others already said, galvanised steel may be a better choice for any given size, but I'd use a bigger one too.
Anyway, in my experience, the real reason why it broke is probably another, i.e. the lines were too slack.
See, it's never the static load which can break these things, it's always the dynamic load generated by the boat's own weight, when she's free to move either longitudinally or laterally.
It doesn't take a lot, just half a meter movement can already generate an inertia which on a heavy boat like yours translates in huge peak loads on the lines.

For longitudinal movements, this is what I normally do - in sequence:
1) secure the bow lines at the preset length;
2) tighten strongly a couple of stern lines with the cockpit winches;
3) secure a second couple of stern lines (the main ones) to the cleats;
4) release the first couple of stern lines (secondary) from the winches and secure them to the cleats.
Notes: being doubled, the secondary lines serve also the purpose of leaving the berth without the need of a dock hand. Also, leaving the winches free gives you the option of tightening other lines, just in case.

For trasversal movements, another couple of stern lines crossed astern imho is a must in Med mooring.
In some boats, it can be tricky (or even impossible) to use them, but that becomes a serious problem with strong crosswind, particularly with gusts, because no matter how tight the other lines are secured, the boat can swing sideways, and also these lateral movements can generate the peak loads I was talking about.
If it's really impossible to cross lines astern (due to the passerelle, or any other reason), try at least to tie them as laterally as possible. The problem with this solution is that you're often restricted by the other boats moored near yours.

 

[jfm]

Yup, off the cuff it looks a classic case of stress corrosion cracking, or possibly intergranular attack if the s/s wasn't great quality. The shackle looks way to small for the job imho. I would want a mild steel shackle whose pin kinda just fits in the thimble loop on the blue rope, top left of 1st picture. I mean a shackle double/triple the size of your proken one. The loops on the spring are too small of course for a big shackle, but that's because the spring device is too small as well for a 70t boat.

 

[jfm]

AsFor trasversal movements, another couple of stern lines crossed astern imho is a must in Med mooring.

I agree the concept 100% Mapis, becuase of trigonometry and the forces on your aft cleats if you don't. But you have to be careful about neighbours. If you have transverse lines and they don't, they "lean" on you in a cross wind

 

[Deleted User YDKXO]

I agree the concept 100% Mapis, becuase of trigonometry and the forces on your aft cleats if you don't. But you have to be careful about neighbours. If you have transverse lines and they don't, they "lean" on you in a cross wind

Agreed. I always use crossed stern lines in addition to my main stern lines but my neighbour (yottie of course) doesn't with the result that, in a NE bora, he leans on me. My new fender socks, bought this year at great expense and effort, are already torn on that side and winter hasn't even come. Also agree with your comments on Bart's shackle. Looks way too small for his boat. I've got larger (galvanised) ones for my poxy little boat

 

[DAKA]

take note of the experienced med forum members.

I chip in only as Stainless steel is of interest to me, I have been going on about its unsuitability for mooring for years.

316 Stainless steel is brittle compared with galvanised steel.

I deduce it is the snatching which has broken the shackle.
(possibly enhanced as others have said , with slack lines)

We all know in a straight pull the shackle would outperform the blue mooring line however if you shoot a bullet at them both the rope will survive as it flexes out the way, the stainless will sheer.

You can easily find out if it is fatigue failure or a single snatch...........
If you take a photo of the end and magnify it there will be evidence of beaching marks (assuming its fatigue failure).

Fatigue fractures beach, looks like a cross section of a tree as the cracks open a little more with each tug, easy to see with a magnifying glass .

It is my guess however that it has failed with one single snatch and there will not be any beaching marks.

This is important as upgrading to a bigger 316 stainless steel may not afford much extra protection.

Where upgrading to galvanised steel will afford you the flexibility that is required in this situation.

Look for the macro setting on your camera for a nice close up of the end section.

 

[MapisM]

Agreed. I always use crossed stern lines in addition to my main stern lines but my neighbour (yottie of course) doesn't with the result that, in a NE bora, he leans on me. My new fender socks, bought this year at great expense and effort, are already torn on that side and winter hasn't even come.

I agree with your and jfm comments on neighbours, of course.
But at least in the "home berth", where also the neighbours do not change so frequently, I've always found that talking with them of the mooring lines arrangement can help a lot. After all, they're also not interested to damage the boat, fenders, etc. - hopefully!
Re. fender covers, in my experience it's best to use the ball shaped ones rather than the cylindrical. The vertical friction (which is common with strong crosswind, because the boats tend also to roll a little, not just to move laterally) is in fact the worst for the covers, and with the ball shaped fenders such friction is much lower, because they can roll also vertically to some extent.

 

[vas]

...

Re. fender covers, in my experience it's best to use the ball shaped ones rather than the cylindrical. The vertical friction (which is common with strong crosswind, because the boats tend also to roll a little, not just to move laterally) is in fact the worst for the covers, and with the ball shaped fenders such friction is much lower, because they can roll also vertically to some extent.

Fully agree MM, but tell us where can one store the ball fenders? I can nicely store 3 decent size barrel ones on each side on dedicated "pockets" at the bow, but spherical ones???

 

[Deleted User YDKXO]

I agree with your and jfm comments on neighbours, of course.
But at least in the "home berth", where also the neighbours do not change so frequently, I've always found that talking with them of the mooring lines arrangement can help a lot. After all, they're also not interested to damage the boat, fenders, etc. - hopefully!
Re. fender covers, in my experience it's best to use the ball shaped ones rather than the cylindrical. The vertical friction (which is common with strong crosswind, because the boats tend also to roll a little, not just to move laterally) is in fact the worst for the covers, and with the ball shaped fenders such friction is much lower, because they can roll also vertically to some extent.

I would speak to my neighbours if I ever saw them. One thing that amazes me about Med boats is how little they are used!

 

[BartW]

didn’ expect so much useful info when I posted this thread, thanks !
next Monday I will take two now very big galvanized shackles with me to Cassis,
and will investigate the options for bigger springs.

For longitudinal movements, this is what I normally do - in sequence:

I do a similar but not exactly the same sequence,
when Arrival On the home berth,
-Secure bowlines in preset position,
- fix both main stern lines to a cleath (they are hanging on a neighbor boat when possible)
-Unfold passerelle
-bring a 3th sternline to the winch (I have only one stern winch on port side) and tighten strong
-tighten both main stern lines.
-untighten the line on the winch and use that line + one extra for the crossed lines
The disadvantage of one winch is that i loose too much strength by the elasticity and play on the main stern ropes. I am considering to place a winch on SB as well.

One cross line obstructs the folding of the passerelle, but that’s only a problem when I leave the boat alone for going home. Then one person stay’s on the boat to push that rope to a side while another is folding the passerelle. Then coming ashore via a neighbor boat.

When I’m not on my home berth, I use looped stern lines for easy departure without a dock hand.
Like here:

 

[MapisM]

Fully agree MM, but tell us where can one store the ball fenders? I can nicely store 3 decent size barrel ones on each side on dedicated "pockets" at the bow, but spherical ones???

Good point. I must admit that I also have nowhere to store them decently, and normally I just pull them inboard and keep them inside the walkarounds. Not the most elegant solution, arguably, but it's fast and easy. And I like that, when boating!

 

[MapisM]

I do a similar but not exactly the same sequence,
when Arrival On the home berth,
-Secure bowlines in preset position,
-fix both main stern lines to a cleath (they are hanging on a neighbor boat when possible)
-Unfold passerelle
-bring a 3th sternline to the winch (I have only one stern winch on port side) and tighten strong
-tighten both main stern lines.
-untighten the line on the winch and use that line + one extra for the crossed lines
The disadvantage of one winch is that i loose too much strength by the elasticity and play on the main stern ropes. I am considering to place a winch on SB as well.

Yup, our sequences are very similar.
The only difference is that I skip your second step, because I start with the "secondary" lines, tightening them with the winches, so that the "main" lines are directly secured in their final position.
But I understand that having only one winch complicates things.
Shame really, I can't see the rationale behind that choice form Canados, and I fully agree with your idea of installing one also on the other side, if feasible.

For the transverse lines, you might also consider to install cleats on the corners of the swim platform. With them, you could forget the passerelle interference. And if you fear the risk that anyone on the swim platform could hit them with bare feet, maybe you could use retractable cleats. The platform looks thick and substantial enough to fit them, but it's difficult to judge the structural strength just looking at the pic.

Re. looped lines, yep, I also use them, and also in my home berth.
Those which I called "secondary" are looped, and I leave them tied in parallel to the "main" lines.
Before leaving, I can pull the main lines ashore from the dock first, recovering the secondary ones afterwards from the cockpit.
This requires two cleats on each side, though.

 

[vas]

Good point. I must admit that I also have nowhere to store them decently, and normally I just pull them inboard and keep them inside the walkarounds. Not the most elegant solution, arguably, but it's fast and easy. And I like that, when boating!

That's what I also do with mine...
Nicely was refering more to issues of safety rather than elegancy of presence. To clarify and being new to largish boat with 8-11yro kids, whilst motoring to destination they easily get bored and start figuring ways of playing on board. On Sunday they spend half the time playing hide and seek (four of them ) hiding in the fb, cabins, under the helm seat!, in the crew cabin on the bow, was really amazed. However doing all that meant running like crazy on the walkarounds, which none of the us liked much with fenders around (need to renew mine and get quick release cleats to be able to store them all in place)

cheers

V

 

[AndieMac]

For the transverse lines, you might also consider to install cleats on the corners of the swim platform. With them, you could forget the passerelle interference. And if you fear the risk that anyone on the swim platform could hit them with bare feet, maybe you could use retractable cleats. The platform looks thick and substantial enough to fit them, but it's difficult to judge the structural strength just looking at the pic.

I doubt if you will get enough structual strength to secure a cleat into the swim platform to hold a boat that weight and windage, swinging in anger M, that is without major surgery.

 

[MapisM]

I see what you mean AM, in fact I did mention the caveat on structural strength.
But I've seen platforms on boats of the vintage of BA which were indeed built as solid as pavements.
In fact, I've even seen some of them supporting large extensions built afterwards, with no need for major strenghtening.
That's the reason why I said that it looks thick enough, though of course it's just an impression, subject to some careful checks before fitting any cleats.