Mooring Buoy Failure?

Oct 26, 2010
1,881
Hunter 40.5 Beaufort, SC
When Dorian passed by here I had a mooring buoy failure where the ground tackle attachment to the buoy "pulled through" the buoy. We had the same failure when Hurricane Michael swept through. In both cases only my buoy failed and all the others at the club were fine. I did not separate fromt he buoy but in both cases, the boat was now direcly connected from the mooring lines to the chain and then to the mooring anchor at the bottom. I am the furthest boat out and in the deepest water.

They are responsible for the ground tackle, buoy and swivel. I attach to the swivel with a heavy duty shackle and then my mooring lines. My lines are about the same length as other boats of my size. They will be replacing the buoy soon.

Does anyone have any speculation as to why the buoy is failing this way. This buoy was less than 2 years old? I am thinking that since I am in deeper water that the chain is a little too short and when the storm tide comes in at high water (we have an 8+ foot normal tide here) the short chain causes the buoy to try to submerge and thus it over stresses the connection at the buoy? Any other ideas.

Mainsail - do you have any perspectives?
 

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Jan 1, 2006
7,039
Slickcraft 26 Sailfish
I think your theory sounds pausable. Do the other mooring buoys that survived have the same arrangement with the chain going through the buoy? I thought that arrangement is out of favor. As I recall I think the better way is to have your mooring line attach directly to the chain, under the buoy, to the light mooring chain and not be attached to the buoy itself. We would attach the pennant to the end of the mooring line on the loop and let it hang near the bottom where, the lower O2 content of the water helped keep the line and loop less funkified. Every harbor we visited had a different way to do it. So I don't think there is one right way. I have limited experience with moorings but that's my 2 cents and worth about that much.
 
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Oct 26, 2010
1,881
Hunter 40.5 Beaufort, SC
I think your theory sounds pausable. Do the other mooring buoys that survived have the same arrangement with the chain going through the buoy? I thought that arrangement is out of favor. As I recall I think the better way is to have your mooring line attach directly to the chain, under the buoy, to the light mooring chain and not be attached to the buoy itself. We would attach the pennant to the end of the mooring line on the loop and let it hang near the bottom where, the lower O2 content of the water helped keep the line and loop less funkified. Every harbor we visited had a different way to do it. So I don't think there is one right way. I have limited experience with moorings but that's my 2 cents and worth about that much.
All the mooring buoys are the same. The mooring line does attach directly to the chain that goes through a tube in the bouy so we are attached to the chain, not the buoy itself. With this failure, if I keep my mooring line attached to the cleats on my boat then I am firmly attached to the bottom. However, if I take the mooring lines off my cleats, the chain will drop through the buoy and go straight to the bottom.
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
Take a look at Wayne Hamilton's video. The mooring buoy supports the chain, the pennant connects to the chain.
 
Jun 29, 2010
1,287
Beneteau First 235 Lake Minnetonka, MN
Attach your lines on the chain under the buoy always.
 
Oct 26, 2010
1,881
Hunter 40.5 Beaufort, SC
Attach your lines on the chain under the buoy always.
I don't think that will work with the type of buoy they provide at our yacht club mooring field. The chain from the bottom is 7/8 inch and feeds all the way from the bottom through a tube in the buoy and then out through the top of the buoy where it is supported by a kind of ring on the top. My shackle to my mooring pendent is attached directly to the chain that goes to the bottom. Thus, when the ball fails, (chain pulls throught the tube) I am still directly fastened to the actual chain that goes all the way to the bottom. I am not in danger of breaking free since the buoy just supports the chain when it hasn't failed but if it fails in this mode noted, it no longer supports the chain and just "guides" it. I am not in fear of breaking free. The difficulty is just that when it fails this way I can't get underway until we secure the chain so it won't drop when I disconnect from my cleats. Otherwise it would just fall through the tube to the bottom. The club is resonsible for the ground tackle and mooring ball and swivel at the top. They just have had to replace this ball twice now and I'd like to avoid it.
 
Oct 26, 2010
1,881
Hunter 40.5 Beaufort, SC
When you're looking at the thumbnail pictures in the original post you're looking at the top of the mooring buoy, not the bottom. The chain to the bottom goes through a tube in the center of the buoy and I attach to where the chain protrudes up through that tube. Hope that clears things up.
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
Attaching underneath isn’t always possible or practical.
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
If the mooring is designed properly, the connection is always below the mooring ball directly to the chain. Here's a page with a couple of good images of a proper mooring.

 
May 17, 2004
5,025
Beneteau Oceanis 37 Havre de Grace
BoatUS shows the pennant off the top of the ball, so there might be more than one right answer on how that should be done. Picking Up A Mooring - BoatUS Magazine. In any case it sounds like the ball and tackle aren't the OP's property, so making the connection on the bottom isn't really an option anyway. And even if you did somehow tie off the bottom in the OP's setup, if the ball breaks free of the chain it'll just float away and you have the same problem.
 
Sep 22, 2018
1,869
Hunter 216 Kingston
I understand how your mooring is setup as one of my neighbours experienced the same problem once. A temporary fix to keep the chain from dropping to the bottom is to connect sufficient alternate flotation to the anchor chain, think old boat fender(s) etc. Or connect a chain directly below the ball and again as it exits the top.

This will let you cast off, sail and return until they get it fixed.
 
Oct 26, 2010
1,881
Hunter 40.5 Beaufort, SC
BoatUS shows the pennant off the top of the ball, so there might be more than one right answer on how that should be done. Picking Up A Mooring - BoatUS Magazine. In any case it sounds like the ball and tackle aren't the OP's property, so making the connection on the bottom isn't really an option anyway. And even if you did somehow tie off the bottom in the OP's setup, if the ball breaks free of the chain it'll just float away and you have the same problem.
Correct on all counts. The style of this mooring ball the chain goes up a tube inside the ball. I am not tied off to the mooring ball. I am tied directly to the chain that goes all the way to the bottom.
 
Oct 26, 2010
1,881
Hunter 40.5 Beaufort, SC
I understand how your mooring is setup as one of my neighbours experienced the same problem once. A temporary fix to keep the chain from dropping to the bottom is to connect sufficient alternate flotation to the anchor chain, think old boat fender(s) etc. Or connect a chain below directly below the ball and again as it exits the top.

This will let you cast off, sail and return until they get it fixed.
I understand all that - I know how to solve the getting underway problem too. What I'm really looking for is some idea of "failure mode". I'm not looking to change the type of mooring ball (its not mine and I can't dictate what they use) nor to somehow tie off my pendant below the ball since this type of ball is not designed for that. If I somehow tied below then if it fails again you are correct, the ball will just float off. I am attached directly to the chain that goes to the bottom so I'll stay moored, just without a ball. So lets not discuss those things.

What I was hoping is that someone would have some idea for THIS TYPE OF MOORING BALL what is going on that is causing it to fail so we don't have to keep replacing it. Mine is the only one that does this in our entire mooring field and I'm not the only 40 to 45 foot boat in the field so its not the boat size. My pendant length is about the same as the other big boats. The only explanation that I can come up with is that the chain to the bottom is too short to allow for the storm surge and it is completely submerging the ball and that stress from the bottom onto the attachment place in the tube is causing it to fail. I don't think this style ball nor any mooring ball is designed to be pulled down by a short chain and fully submerged. That is the only failure mode that makes sense to me. I'm trying to get them to put in an extra 10 foot of chain to give some more room for a storm surge in addition to just replacing the buoy.
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
We don’t have chain, we have a 3/8 solid shank. The ball takes none of the load. There is more than one way to do this. Local knowledge and/or conditions should prevail. What has worked here should not be assumed to work anywhere else.
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
The only explanation that I can come up with is that the chain to the bottom is too short to allow for the storm surge and it is completely submerging the ball and that stress from the bottom onto the attachment place in the tube is causing it to fail.
Probably answering your own question here. Anchor scope calculations with consideration to extreme fetch might be a good place to start.
 
Oct 26, 2010
1,881
Hunter 40.5 Beaufort, SC
Probably answering your own question here. Anchor scope calculations with consideration to extreme fetch might be a good place to start.
Your right, probably coming to the conclusion that that is the only reasonable failure mode. Was hoping someone else had seen this and could say "Oh yea been there done that." as confirmation. I think I have them convinced to add some chain to the scope.
 
Sep 22, 2018
1,869
Hunter 216 Kingston
I assume this is what your mooring ball looks like new.
A94651B6-CBAD-4E9D-AC28-2993A02FE3E3.jpeg


The reason my neighbours failed just like yours is during a storm the waves were causing the ball to submerge. We lengthened his anchor chain and it didn’t happen again so that sort of confirms your theory. The “tube” the chain passes through just isn’t designed to handle the forces of the ball trying to surface as the pitching of the boat jerks the ball around under the water..
 
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Oct 26, 2010
1,881
Hunter 40.5 Beaufort, SC
I assume this is what your mooring ball looks like new.

The reason my neighbours failed just like yours is during a storm the waves were causing the ball to submerge. We lengthened his anchor chain and it didn’t happen again so that sort of confirms your theory. The “tube” the chain passes through just isn’t designed to handle the forces of the ball trying to surface as the pitching of the boat jerks the ball around under the water..
Yep - that is exactly what my ball looks like. Sounds like I might be on the right track and I'll let them know that adding chain "might" reduce the propensity to tear out the tube attachment. Thanks and thanks to all the other people that responded since it helps us all know more about the way to attach to a mooring and maybe learn a little more about our equipment. Sorry if I sounded a little short when the topic moved away from my particular situation.
 

NYSail

.
Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
Over the past 3 years I now attach under the ball with a pendant holder on top which I personally love. However what I do notice that on top of your ball where the chain comes through there does not appear to be a BIG washer to hold everything on top. My yard rigs the balls and I know mine had 2 large washers that had an overall width that was much bigger than the hole in the ball. The chain comes through the hole and then washers then the heavy duty shackle is put on to prevent it from going through. When storms would come through it is common to see the ball under the water as the boat stretches the chain out. From your picture it does not appear to be set up that way. It appears they are relying on the size of the shackle to hold the chain which may in fact just be ripping the hole apart when there is a lot of action. The large washer will not let the shackle beat the ball up.

Good luck.

Greg