Mooring Buoy Failure?

Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
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
Greg, thanks a lot for the tip. Do you have a picture of the "washer" installed on the ball and the "pendant holder that you describe? I'm having a hard time visualizing the arrangement you use.

Also, could you send me a PM with the contact info (phone number preferrably) for your yard?
 
Jun 14, 2010
2,081
Robertson & Caine 2017 Leopard 40 CT
I think @NYSail has the solution, but perhaps more scope is also needed.
BTW I’m of the opinion that the penant should be attached above the ball, and the lines should have floats to keep them from sinking when slack. This keeps hard growth off the lines and is less likely to result in chafe of the penant against chain. The ball should be sized so it’s more than half submerged when slack, so if the boat rides over the ball, the floated lines will pull over the top rather than get snagged beneath.
 
Jan 1, 2006
7,039
Slickcraft 26 Sailfish
... and the lines should have floats to keep them from sinking when slack. This keeps hard growth off the lines and is less likely to result in chafe of the penant against chain.
Interesting. It's local practice to let the loop drop to the bottom where it experiences LESS marine growth. I was skeptical about that it proved to be true even in the relatively shallow depths our moorings are in - 10-15 feet. The chafe part may be true but I'm not aware of it being a significant problem locally.
 
Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
Interesting. It's local practice to let the loop drop to the bottom where it experiences LESS marine growth. I was skeptical about that it proved to be true even in the relatively shallow depths our moorings are in - 10-15 feet. The chafe part may be true but I'm not aware of it being a significant problem locally.
You must have no appreciable tidal current there? I can't imagine it working here in Beaufort. We have a 8 foot todal swing here with pretty strong ebb and flood currents that tend to wrap the lines around the chain if the loops sink.
 
Jan 1, 2006
7,039
Slickcraft 26 Sailfish
We have about a 3' tide. But the mooring field doesn't see that much current. Maybe .5 kt. We do have a PM sea breeze 15 kts. or so which pushes the pennant buoy away from the mooring chain. I didn't mention that the pennant line is seized to the loop. But it is long enough for the loop to be at or near the bottom. There are many variables and that's why there are so many different configurations.
 
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
CWI (Carolina Water Works) buoys should have the galvanized washer, on top of the hole, then a sufficiently sized shackle... Your ball was simply installed incorrectly without the large galvanized washer. CWI ships these washers with the buoy's. You may want to ask him why it is not there.
 
Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
CWI (Carolina Water Works) buoys should have the galvanized washer, on top of the hole, then a sufficiently sized shackle... Your ball was simply installed incorrectly without the large galvanized washer. CWI ships these washers with the buoy's. You may want to ask him why it is not there.
Thanks Maine, Not sure what you mean by "a sufficiently sized shackle"? I don't know if the galvanized washer was there or not. It was on the first one that failed. If you look very closely at an enlarged picture of the second shot where you can see the black soft washer, there appears to be a very large threaded rod or something like that through the chain on the second or third link down. I think this was put there to bear on the buoy. Is that an acceptable way to do this. I tried to call Carolina Water Works to talk to them but only got a person who didn't really know their products. Thanks for the help though as I'll advise our club on this and make sure its not an installation issue the next time.

Did you have an opinion on the chain length thing. Is it expected or desired that the buoy completely submerge during a storm surge. That seems like a pretty good additional load on the buoy, even with the galvanized washer. Thanks in advance
 

NYSail

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Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
This is my current set-up. There is a steel threaded rod that goes through the ball. Mooring chain is shackled to an eye that is attached to the rod underneath. Then I have 3 foot peice of chain that is shackled to both the mooring chain and the eye on the rod on which my mooring lines are attached. I added the small chain so my lines do not run against the bottom of the ball.

Anyway if you zoom in you can see a smaller washer on top of two large washers. Those were the washers when I had my ball set up your way so that the shackle would not come in contact with the ball and prevents anything from going through.

Greg
 

Attachments

Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
Yes. Expected. It's got a buffering effect pretty similar to catenary, but in reverse direction.
This really should not be normal unless you are in a very shallow anchorage with scope regs that are really a bit too short. In otherwords your mooring should really never approach a 1:1 scope.

In our mooring field the code requires a 2:1 scope based on "max" high water which around here is about a +12' tide (average is closer to 10'). On a "max" high tide my own mooring is in 32' of water. This means we have 64' of chain to the ball. We would need a storm surge of 32' to attain 1:1 scope and submerge our ball.

"The mooring scope shall be approximately two (2) times the water depth at maximum high water."
 

NYSail

.
Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
I'm in 23 feet of water at high tide, 8 foot tide and have a mooring chain of 45 feet.
 
Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
This really should not be normal unless you are in a very shallow anchorage with scope regs that are really a bit too short. In otherwords your mooring should really never approach a 1:1 scope.

In our mooring field the code requires a 2:1 scope based on "max" high water which around here is about a +12' tide (average is closer to 10'). On a "max" high tide my own mooring is in 32' of water. This means we have 64' of chain to the ball. We would need a storm surge of 32' to attain 1:1 scope and submerge our ball.

"The mooring scope shall be approximately two (2) times the water depth at maximum high water."
Thanks Maine, That is what I expected. From what I've read the recommended scope is 2 to 2 1/2 times the max water depth. I also read somewhere that the pendant length should be 2 1/2 times the free board. I'll ask our diver who inspects the moorings periodically about what our mooring chain length is right now. I think they are planning on adding another 10 feet to the mooring chain.

I'm setting in about 21 feet of water at high tide so the recommended length of chain should be 42 feet to 52 feet. It would then take a 21 to 31 foot storm surge to get to 1:1 scope. If we have a 21 foot storm surge at high tide then all the piers will float off their pilings and there will be all kinds of debris going up and down the river knocking us off the mooring anyway.
 
Jun 14, 2010
2,081
Robertson & Caine 2017 Leopard 40 CT
In otherwords your mooring should really never approach a 1:1 scope.
In a strong blow I don't think it would take 1:1 for a boat to submerge a mooring. I think it would be expected even at 2:1 if the boat is pulling hard enough.
 
May 17, 2004
5,031
Beneteau Oceanis 37 Havre de Grace
Thinking through the geometry of this arrangement, it seems like if the pennant is too long the ball will get dragged underwater in any sufficiently strong wind. A longer chain will allow for a longer pennant, but only to a limit. If my trigonometry is right (admittedly I have only moderate confidence in that), the pennant must be shorter than the freeboard divided by the arcsin of (depth divided by chain length). So if your freeboard is 4 feet, depth is 21, and chain is 45, your pennant shouldn't exceed 8.2 feet. Is it possible that your pennant is a bit longer, and your neighbors' a bit shorter, leading only you too have the problem?
 
May 17, 2004
5,031
Beneteau Oceanis 37 Havre de Grace
Thinking through the geometry of this arrangement, it seems like if the pennant is too long the ball will get dragged underwater in any sufficiently strong wind. A longer chain will allow for a longer pennant, but only to a limit. If my trigonometry is right (admittedly I have only moderate confidence in that), the pennant must be shorter than the freeboard divided by the arcsin of (depth divided by chain length). So if your freeboard is 4 feet, depth is 21, and chain is 45, your pennant shouldn't exceed 8.2 feet. Is it possible that your pennant is a bit longer, and your neighbors' a bit shorter, leading only you too have the problem?
Checking my trig it appears the formula might be simpler. Looks like the pennant can't exceed freeboard times chain length divided by depth. So that would mean your pennant should be under 8.6 feet (with freeboard of 4, chain of 45, depth of 21).

For anyone else that wants to see/check my math:
IMG_20190918_173921.jpg
 
Oct 2, 2008
3,807
Pearson/ 530 Strafford, NH
First, we have had the same ball setup except we have two large shackles on top for two pennants. Secondly from time to time we would have the mooring chain twist enough so that during high tide the ball would submerge. The solution is to run reverse while still attached to the ball. At half throttle I watch the bow dip low just before the chain swivels straight. (Don’t do this after morning coffee, you might be cleaning out your shorts.). Then repeat if needed.

Having said that, some years we don’t get any strong winds so the chain would need stretching often. Same for many other boats nearby, it just happens. Every different setup has its quirks.
 
Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
Checking my trig it appears the formula might be simpler. Looks like the pennant can't exceed freeboard times chain length divided by depth. So that would mean your pennant should be under 8.6 feet (with freeboard of 4, chain of 45, depth of 21).

For anyone else that wants to see/check my math:
View attachment 169832
So, in the equation where c = xd where x is the muiltiplyer of depth required (ie scope c is 2 times depth or 2.5 times depth, which is the generally accepted scope)
substituting xd for c yields p (pendant length) = f (freeboard) times xd divided by d
the d's cancel and p (pendant length) = f (freeboard) times x (the multiplier of depth used for the scope)

SO the conclusion seems to bear out thae guidance that the pendant length should be 2 to 2 1/2 times the freeboard height (at the chocks) where the multiplier (2 or 2 1/2) is the same multiplier used to determine the scope of the chain.