Imminent forestay pin failure?

[mastreb]

Here's an up-close picture of my forestay pin. It's a BWY large head pin.



You can see that it's jammed up against its ring-ding. What you might not be able to tell is that the ring-ding is rusted right there due to the water entrapment effect that causes stainless steel pitting.

You can see from the angle of the chainplate that the pin will always move to this position under pressure.

Has anyone ever seen a ringding fail? What's a simple solution here, to pin backwards (i.e., ringding up), or bend the chainplate down, to cause pressure to force the pin farther in?

This is the most important pin on the boat, so I'm a bit hesitant to make willy-nilly changes.

[fishheadbarandgrill]

Why not turn the pin around and have the ring-ding on the outside?

[NiceAft]

They are inexpensive enough. Why not just replace them every six months, or longer. How long has that one been there?

Ray

[Russ]

I would replace it with a cotter pin unless you need to lower it often, then as mentioned, replace it.

[Highlander]

all my ring dings r tie wrapped with plastic ties they help prevent the ring dings from moving & causing wear & catching on lines , if u tie wrap that pin from both sides with two ties should one ring ding fail the tie wrap on the other side will prevent it from coming out

J

[Catigale]

Has anyone ever seen a ringding fail? What's a simple solution here, to pin backwards (i.e., ringding up), or bend the chainplate down, to cause pressure to force the pin farther in?

Just like the man said. Put the tension on the clevis head, not on the ring-ding. If the ringding is corroded enough to rust in place, its ready to break under pressure too...

[Russ]

all my ring dings r tie wrapped with plastic ties they help prevent the ring dings from moving & causing wear & catching on lines , if u tie wrap that pin from both sides with two ties should one ring ding fail the tie wrap on the other side will prevent it from coming out

J

Photo?

I wrapped mine with rigging tape. Sticks to itself and keeps the rings from dinging.


--Russ

[mastreb]

Thanks Guys. It's been in place through the winter is all. I do trailer so I'm not going to do anything that requires cutting or unwrapping, but I will reverse the pin and replace the ringding any time I notice rust.

A pin with two holes for two ring-dings would be a good backup.

[BOAT]

Hey Matt - My fore-stay pin used to do that when I first got the boat. I have the big BWY pin too. But after I tightened the side shrouds the pin stopped dancing to the end of the plate.

I concluded that the reason the Pin was dancing was because the tension on the fore stay was too loose, but I really have no way to proove that and I could be totally wrong - but the pin has stopped migrating.

[DaveB]

Your Pin is to long, slips in the hole causeing fatigue. Get a shorter pin so it doesn't move side to side.
Like all standing rigging attachments, the pin has to be very close to the connection and pin it.
Pin to long causes fatige and will wear the pin and chain plate over time.
Dave

[mastreb]

Hey Matt - My fore-stay pin used to do that when I first got the boat. I have the big BWY pin too. But after I tightened the side shrouds the pin stopped dancing to the end of the plate.

I concluded that the reason the Pin was dancing was because the tension on the fore stay was too loose, but I really have no way to proove that and I could be totally wrong - but the pin has stopped migrating.

Yeah, I've been putting off buying a Loos gauge but clearly its time.

[yukonbob]

Shouldn't matter how long the pin is. If its an inch and a half or four inches long. If it's walking to the end then the ringding is the weak link. Longer pin just has farther to walk. I rig tape mine as well and keep the rigging tight. Haven't noticed if it's moved this year, but it did the first year and I'm pretty sure the rigging was too loose. I might try flipping the pin next year. It's in place this year (big bwy here as well).

[Divecoz]

I agree length of pin is insequential to the issue. Set pin tight against chain plate from the beginning.. IF it is traveling back and forth adjust rigging / tune rigging.. That said.. a short pin with not travel ...it just has no room to move.

[BOAT]

Mathew, I have a Loose Gauge, you can use mine. I can drive to Cardiff if you want.

[Judy B]

I'm in agreement with folks who have said the length of the pin isn't critical. IMO, rigging tape is all the original poster needs.

(I put rigging tape on the forestay pin every time I raise the mast on one of my trailerable boats. I cut it off at the end of the day and throw it away. It costs me $10 per season.)

Ring-dings don't break from overloads in my experience. In my experience, rope catches and pulls out ring-dings. Pins don't break from wear and tear in my experience. (and the experience of the life-long sailors who have taught me over the years) Getting the length right is of relatively minor importance. Getting the diameter right is of critical importance. Protecting the ring-ding from being pulled out accidentally is of critical importance.

I don't see a potential structural engineering problem caused by a clevis pin that's too long per say. It should be okay, as long as the pin is sized properly to the diameter of the hole in the chain plate (or bow stem fitting if we're discussing forestays).

Clevis Pin Diameter: This is important!!! The pin diameter and chainplate/stemplate hole diameter must match closely, so that the loads are spread over the largest bearing area on the hole edge. If the pin is a smaller diameter than the hole, the pin will bear on just a small area of the hole, and the metal around the hole will deform. The pin is massively strong for the application -- in the real world, people never break the pin, and ring- dings (circ-clips) don't fail due to lateral loads. The real engineering skill goes into making sure the bearing surface of the chainplate is strong enough

Clevis pin Length: The pin is going to slip longitudinally no matter how tight you tune the rig when the boat isn't moving. When you tune the rig, you are setting the tension when the boat is at rest and the loads are static and constant. When you sail, the loads are dynamic, and change according to how the boat is moving. The tension on each individual shroud or stay changes as the boat rolls, yaws and pitches. It goes from tighter than you tuned it to way looser than you tuned it as the boat moves through waves or as you tack. You shouldn't tighten the rigging enough to prevent the pin from sliding slide back and forth along the axis (and I doubt you can even tighten it enough to keep the clevis pin trapped).

The take-home message here is this: Put rig tape on all ring-dings so they are protected from being pulled out by lines that are flogging or catching on your clothing. And make sure the pin is the right diameter.


Fair winds,
Judy B
Sailmaker