Mooring Ball Under Water at High Tide.

[drewzn]

I am renting a mooring this season and when I was last on the boat, I noticed the chain must be too short for the mooring. The mooring ball is submerged at high tide. It got to where the entire ball was just under the surface of the water. I know this should be fixed, but is this something I should immediately be concerned about?

[Pete7]

How are you going to pick it up if you arrive back at high water?

Wonder if the riser has caught around the ground anchor with the change of tides?

Pete

[Hud3]

Seems strange that someone would set a mooring with the chain too short for the tide. Did you dive on it? The underwater tackle might be fouled somehow, shortening the chain. Inspecting it would be a good idea anyway, just to make sure it's sound.

[drewzn]

Pete7, I put a pick-up buoy on it and it has a good pennant, so picking it up is not an issue.

Hud3, I agree. I'm going to ask the ApprenticeShop (who I'm renting from) to investigate the mooring.

[rtbates]

Originally Posted by drewzn

Pete7, I put a pick-up buoy on it and it has a good pennant, so picking it up is not an issue.

Hud3, I agree. I'm going to ask the ApprenticeShop (who I'm renting from) to investigate the mooring.

Are you sure that they care about your boat as much as you do?

Just be 100% confident in what the diver tells you is down there..

[donradcliffe]

Was the boat on the mooring at the time, or was the mooring ball underwater without the boat there? I have occasionally had mooring balls go under in strong winds and/or currents. If the ball is going under without the boat pulling it under, its time to change moorings until they sort it out--there are some pretty big tides in Rockland.

[drewzn]

donradcliffe, The boat was on the mooring and it was at a time with some heavy tides and winds. Plus, my boat is 16K. And this was the first time I saw it submerged. I have been on the mooring for 2 weeks. I'll keep an eye on it and see what happens.

[Hydra]

Once, my mooring ball went underwater at high tide, with the weight of mussels on the chain. I couldn't find it, I had to ask a friend with scuba to dive and find it. After that, I hauled the chain out of the water at least once a year, to clean as much of it as I could.

Alain

[klem]

If the chain is actually so short that you have less than 1:1 scope at high tide, then you definitely need to deal with it asap but if there is sufficient scope and it was only the conditions that made it go under water, that is fine.

If you don't have sufficient scope, you will be putting very large loads on all of the your gear and risking dragging your mooring. Rockland's mooring requirements call for pretty short scope (less than 2:1 at high tide if I remember right). They also call for large granite blocks. If you boat is pitching up and down, you will be putting enormous loads on the mooring gear and your bow as it tries to lift the block off of the seabed. If the loads get high enough, the block will start to move. If your mooring is off of the Apprentice Shop, you are probably not in very deep water so you won't have very much chain to start with. Moorings that have short scope and are in shallow water are very susceptible to problems with high tides and storm surge.

If your pendants have more scope than the chain, in stronger conditions you can actually pull the mooring ball under water as the pendants and chain try to make a straight line. This is totally normal and not anything to be worried about. Usually in these conditions, the boat will surge backwards and forwards and the ball will go under, then pop up and repeat.

[Ortolan]

Yet another possibility is that the chain is wrapping itself around the shank of the mushroom anchor as your boat goes around & around with the tide & current - this is especially a possibility since it's a "new" problem within the last 2 weeks.

I almost rented a mooring in the CT River, but they made you sign a written agreement that you were in charge of "upwrapping the chain" around anchor shank periodically, especially prior to a tropical storm or hurricane warning. It seems they have a problem with chain wrap & if the chain gets too short, then a storm comes, it could pull the anchor right out.

[drewzn]

Thanks everyone for all the information. I went out to the boat yesterday and there was significant stress on the boat indicated by the chafe on the pennant from the fairlead and the samson posts. The Apprentice Shop is sending a diver out to check on it to see if the chain is wrapped or if it is too short for it's location.

The weather is forecast for nice days with light winds and the tide is getting lower for the next few weeks which will mean less load on the boat. If I don't hear from them about the diver before Friday, I'll tie up to their dock and see if I can use my dinghy to check if the chain is wrapped by dragging the mooring ball in a circle around the mooring location to see if it tightens up or loosens.

[Maine Sail]

Originally Posted by drewzn

I am renting a mooring this season and when I was last on the boat, I noticed the chain must be too short for the mooring. The mooring ball is submerged at high tide. It got to where the entire ball was just under the surface of the water. I know this should be fixed, but is this something I should immediately be concerned about?

Most likely suffering "chain twist" very common with our tides and swings especially on moorings without top swivels. It is town ordinance in Falmouth and top swivels are now required.. Chain twist results in short scope and in a worst case can result in the un-setting of a mooring. You should have a "swivel" below the ball that in most cases will prevent this but sometimes they don't. You'll need to disconnect and have your mooring guy "un-twist" it.

Also keep in mind this last week we have had very high tides. Here in Casco Bay about 3 feet above normal... I am assuming your ball is sized right for the chain...




The town of Falmouth mandates top swivels be used but some installers still disobey the law and do not use them.


"Each mooring must have one (1) top swivel; all swivels and shackles must be to the appropriate size diameter."

As the boat swings around the mooring, with wind and tide shifts, the chain twists & twists and as a result, it shortens. This chain can shorten so much that the ball gets sucked under water.

Short scope with minimal ability to retain caternary, especially in a storm, can literally lift the mushroom or granite block out of the bottom and the boat can begin to drag through the mooring field. It also makes shock loading of the hardware more likely with little to no caternary present. If the Apprentice Shop does not use swivels go to Hamilton, buy a LARGE one, I use 1" for a 36' boat, and hand it to them and pay them to install it...

While swivels are and can be a high wear item they can also easily be over-sized to compensate for wear. We use a 1" swivel on our own moorings and regularly get 4-5 years out of them. They have always out lasted our 3/4" top chain.

They are also available in 1 1/4" and 1 1/2" for larger vessels. Hamilton Marine sells them in these sizes. Are they expensive in that size, sure, but a LOT less than the hull deductible for my vessel. My 1" swivel costs about $100.00 far less than totaling my boat..

[zeehag]

i have seen chains wrap the block which is the anchor under water to shorten the chain. also weight of the growth on the ball underside and chain help, but isnt the main reason for the ball being underwater--check the chain for wrapping around the mooring anchor--is probably the cause of this phenomenon.