Swinging mooring advice

[Lightwave395]

I have just put my boat on a new to me swinging mooring and having not done much of that would appreciate any advice...

The mooring is 'substantial' with a 10mm chain riser and pickup buoy, could do with advice on an anchor snubber to stop any snatch. It's an ex-racer rather than a substantial cruiser so the bow roller is not ideal, I'm looking at a heavier duty replacement but is a chain hook secure enough to take the tension out of the riser. The couple of boats around me my size ( 12.2M) have tugboat rope bridles from their mooring buoy rings but that seems a lot of rope in the water when you're not there plus I'd struggle to get anything bigger than maybe 18mm with a cover or 20 / 22mm without through my bow fairleads

Any input gratefully received

 

[doug748]

If you are inside the Vilaine I would not worry too much at all. The buoy and riser help a great deal with snatch and you have no worries about swell and frequent fast moving large traffic. No cyclical tidal flow also helps but I would still use a swivel above the buoy, at least at first.

I would go with the 18mm with some protection, on a single strop but the connections and mousing arrangement must be impeccable. In my experience it is lost pins that often cause the problems.

.

 

[vyv_cox]

Perhaps times have changed but 10 mm chain for a boat your size seems only just enough for an anchor, definitely not 'substantial' for a mooring.

My first boat on Menai Strait was a lightweight 27 footer. The ground chain and riser were 3/4 inch and the pickup between buoy and boat was 1/2 inch. These dimensions were recommended by the contractor. There is probably a good deal of difference between conditions there and where you are but 10 mm seems barely adequate.

 

[tjbrace]

I learned a few years ago not to use the front fairleads for our mooring strops (2). The angle to the buoy is quite sharp causing the strops to wear through very quickly on the lower edge of the fair lead which also acts as toerail. Instead, I bring the strops to the forward cleats directly which gives a good angle. I will try to post a photo which might help.
I’ve not had much joy using strop covers, but this way I see no wear on the bare strops.

 

[Rappey]

10mm galvanised only lasts a few years until it rusts through. Usually there is a very large chain on the sea bed to act as a snubber then ¾ or ⅞ as the riser, with a10mm chain from mooring buoy to boat. The 10mm is often changed each year as it rusts badly

 

[Lightwave395]

Perhaps times have changed but 10 mm chain for a boat your size seems only just enough for an anchor, definitely not 'substantial' for a mooring.

My first boat on Menai Strait was a lightweight 27 footer. The ground chain and riser were 3/4 inch and the pickup between buoy and boat was 1/2 inch. These dimensions were recommended by the contractor. There is probably a good deal of difference between conditions there and where you are but 10 mm seems barely adequate.

Interesting, I'd even thought that perhaps the riser should be 8mm ! The boat weighs around 7.5 tons loaded so is quite light, I think beefing up / replacing the bow roller is needed but it's the snatch from the riser on the cleat I'm concerned about too

 

[Stemar]

10mm chain is light for a mooring riser, but still likely to be stronger than whatever it's attached to on the boat. Just keep an eye on it. Wear will happen between the links, where it isn't obvious. As for a pickup, in Portsmouth harbour, I use a polysteel bridle. With a monohull, a fairly short bridle, one arm through each bow fairlead would be ideal.

Polysteel is a UV-resistant polyprop laid rope, so it's easy to splice, and it floats, which makes picking up easier, plus it's unlikely to go looking for your prop. A Brummel splice aorund a hard eye shackled to the riser, and eye splices at each bridle end works for me and, in salt water, lasts longer than chain.

 

[Lightwave395]

10mm galvanised only lasts a few years until it rusts through. Usually there is a very large chain on the sea bed to act as a snubber then ¾ or ⅞ as the riser, with a10mm chain from mooring buoy to boat. The 10mm is often changed each year as it rusts badly

The riser is 10mm stainless steel (which may not be a good thing ?

 

[vyv_cox]

Interesting, I'd even thought that perhaps the riser should be 8mm ! The boat weighs around 7.5 tons loaded so is quite light, I think beefing up / replacing the bow roller is needed but it's the snatch from the riser on the cleat I'm concerned about too

My first boat on that mooring only displaced about 3 tons. We kept the same mooring for all three boats that we owned, finishing up with a Sadler 34 weighing nearly 7 tons loaded.

Snatch never really seemed to be a big problem. The depth was a minimum of about 6 metres, rising to around 12 metres at HW springs. The weight of riser and the large buoy that supported it seemed to have a strong damping effect. It was a condition of the contract that a chain pickup was used but we never found the need for an additional snubber.

All three boats had substantial bow rollers.

 

[Daydream believer]

I learned a few years ago not to use the front fairleads for our mooring strops (2). The angle to the buoy is quite sharp causing the strops to wear through very quickly on the lower edge of the fair lead which also acts as toerail. Instead, I bring the strops to the forward cleats directly which gives a good angle. I will try to post a photo which might help.
I’ve not had much joy using strop covers, but this way I see no wear on the bare strops.

That is the best way if the cleats allow it. 2 equal length strops, to individual shackles, one each side. The buoy should have a swivelling eye on top to prevent tangle. One can then use the chain laid lightly over the bow roller with no tension , being over length, as a backup in case something did fail. A 6mm chain would be perfectly OK for most small yachts in a short term emergency.

 

[Stemar]

To prevent wear on mooring strops, a length of old fire hose is a good thing. Have a chat with your local fire station

 

[B27]

Do I read it correctly, there is just a pickup buoy and a riser, no 'mooring buoy' as such?

The dynamics of boats moored like that are different from when a buoy is in the system.
If it's snatching, you probably want more weight on the riser, i.e. lift a bit more of the heavy chain off the seabed.
And/or you want more damping from the riser moving around in the water, i.e. if the riser was thicker, then dragging it sidewise through the water as the boat moves would take more energy from the motion.
I think it's a dark art because every case can be different, and the wind varies too!
Copy what works locally is usually a fair strategy.

 

[Lightwave395]

Do I read it correctly, there is just a pickup buoy and a riser, no 'mooring buoy' as such?

The dynamics of boats moored like that are different from when a buoy is in the system.
If it's snatching, you probably want more weight on the riser, i.e. lift a bit more of the heavy chain off the seabed.
And/or you want more damping from the riser moving around in the water, i.e. if the riser was thicker, then dragging it sidewise through the water as the boat moves would take more energy from the motion.
I think it's a dark art because every case can be different, and the wind varies too!
Copy what works locally is usually a fair strategy.

No, sorry, there's a bloody great chain anchoring a large mooring buoy with a ring on top, the 10mm s/s chain riser is attached to that. I do wonder too if the riser is a bit short but it was fitted by the yard. I meant to take a pic before we left the boat but we were very keen to get off...

 

[B27]

We used to find a short tether from the buoy to the bow worked better.
It means the boat can't move much before the pennant goes tight.
Some people take some of the weight off the buoy onto the bow of the boat, then relative motion of the buoy and the boat is less of an issue.
Some people find a nylon pennant with some give in it works well.

It all depends on what your mooring is exposed to.

 

[Graham376]

No, sorry, there's a bloody great chain anchoring a large mooring buoy with a ring on top, the 10mm s/s chain riser is attached to that. I do wonder too if the riser is a bit short but it was fitted by the yard. I meant to take a pic before we left the boat but we were very keen to get off...

I think there's confusion over terms here. The riser is the chain or rope which attaches the buoy to the mooring block or ground chain. I think what you are calling riser, is the strop or pennant.

 

[Lightwave395]

I think there's confusion over terms here. The riser is the chain or rope which attaches the buoy to the mooring block or ground chain. I think what you are calling riser, is the strop or pennant.

Yes, sorry, that's my mistake, I mean the chain from the mooring buoy onto the boat (with the pickup buoy attached ) !

 

[B27]

Yes, sorry, that's my mistake, I mean the chain from the mooring buoy onto the boat (with the pickup buoy attached ) !

I'm calling that a 'mooring pennant', it might also be called a mooring strop?

 

[Rappey]

We used to find a short tether from the buoy to the bow worked better.
It means the boat can't move much before the pennant goes tight.

Thats not great as the mooring buoy itself gets shaken around much more violently with small waves leading the the eye of the mooring buoy tearing off prematurely. The line from the buoy to boat around this area is usually 3 metres long which gives the buoy an easier life. If you have a hippo type then there is no eye to get torn out.
Hauling the mooring buoy up is even worse as when the boat rides over the mooring the large shackle underneath starts grinding into the hull.
Twin strops on a narrow hull can often end up wrapping around each other to the point where the whole mooring gets wound up, dragging the boat down.

 

[Stemar]

Ah, in that case, 10mm is plenty. Still keep an eye on it for wear, though.

 

[Rappey]

The riser is 10mm stainless steel (which may not be a good thing ?

When you add a stainless component to a mooring the mild steel its connected to diminishes rather quick when submerged. Keep an eye on it.