Mooring to a swinging Buoy

[tckearney]

Hi Guys, I am looking for advice on using a swinging mooring.   I have a B42.   I have been offered a new swinging mooring rated at ten tons.  The ground tackle consists of  two 60kg Samson Anchors holding a ground chain 26mtrs long and 32mm stud link.  With a riser of 20 mtrs of 22mm chain.   It can get quite rough in a northerly at this area and I have seen at least two boats break the moorings.  However in both cases it was due to poor mooring maintenance.   My Bavaria has just a single forward roller as per picture.   What would be the best way to tie up to the mooring bouy?  I have considered having a Y shaped strop that would go on both fwd cleats and run fwd of the bow under the anchor,  to the riser chain and on a swivel fixing.  Or should I go for just a very short strop over the fwd anchor roller, so that the riser chain is always taking the weight.   However  this would mean  removing the anchor into the anchor locker each time I moored up.  I must admit I very seldom anchor.   Another suggested using a car tyre between the boat and the Bouy to reduce any snatching, but that does not sound very professional.    I have checked with the insurance company and they say as long as the complete mooring  is manufactured,  approved and  annually inspected  (at £175) by the Mooring/Towing company then that is fine.   There are several other boats in the area, the biggest being a Fisher 38 at 11tons, but all others are less than 30ft and under 3 ton.  Any help making my decision would help.   My marina fees are over £5500 pa and rising, this mooring is £40pa and mine for life and is also almost at the bottom of my garden and clearly visible from my window.   

[Bav32]

So you just use one buoy for mooring? Do you row ashore?

If yes, then I would use a snap hook, or whatever they are called, and tie two ropes to that. That would be an easy way to hook up to the buoy.

Then again, if you are connected to a buoy in front, and have the aft into a pier, then I would just use one rope and not trough the roller. Just tie it to the cleat normally. This is the way I have been mooring my boat for at least 10 years.

Hope my thoughts make sense

[Craig]

I'm confused by your set up and a number of other factors need to be taken into account for this mooring.

If you are looking at the strain induced by 70kn winds on a 42 ft boat in flat conditions, have a look at a book called "Harbour Manoeuvres" by Lars Bols. I don't have my copy here but there is a good calculation in the first chapter on how much force per m2 the wind induces at different velocities. It has little to do with the weight of the boat, just the cross section facing the wind. From memory it is probably in the tonnes of force in 70kn, a speed you may get in a decent storm. These forces don't take into account wave action or increased loadings as the boat "sails" on an anchor.

I don't know what a Samson anchor is but 60kg rating for each of the 2 anchors ( or anchor points)  sounds too low. Is the Samson anchor an attachment device, not a ground anchor as such? 

Most moorings I have come across have a concrete block on the bottom attached to a riser, either chain or rope. Sometimes the block on the bottom is designed to drag through the mud in extreme conditions, such as flood flows in a river. If your riser is attached to a larger chain line, then I would check how this line is attached at the ends and if other risers are attached to this line.

If you have wave action, then the length of the riser must be compared to the expected maximum wave height, average depth of water and tidal rise and fall. A near vertical mooring line attached to the bow is going to put a large downward force on the bow when a wave hits. The riser should be long enough so that angle of the riser to the bottom is less than about 30 degrees at maximum wave height. Again, the actual measurement is a bit of black magic as the longer the riser, the more "sailing" the boat does the more it increases the pull on the riser when the boat "tacks" back. The "tacking action" is not a shock loading as such but it will probably double the force on the riser.

I suspect your weak point won't be the mooring but the load on your bow. All you can really do is have the riser long enough so that the downwards force is reduced and have the riser attached to the capstan post, both bow cleats or preferably the whole 3. If you expect a storm you may wish to run lines from the bow cleats back to the winches to reduce the forces on the cleats.

We comfortably ( didn't think so at the time) sat for 3 days in the Bora in Croatia with winds gusting up to 75kn with 60m of 8mm chain attached to a 20kg Kobra anchor in 4m of water. We put down a second anchor, a 15kg CQR on about 15-20m of chain to decrease the "sailing" effect. There was no wave action and the chain did not touch the water for a few boat lengths in front of the boat. No catenary. This was in a 38ft Bavaria.

If you are tied ashore with stern lines you will need large snubbers that can take a lot of movement beteen the aft cleats and the quay attachment. You may be better attaching the aft lines to the winches and definitely not through the fairleads, particularly if the lines are angled a lot as they pass the fairleads. After a relatively minor storm in Greece, but with waves up to 1m, we watched a diver recover 3 fairleads that were ripped from 2 boats. Basically, stern tie ups in wave conditions is to be avoided at all cost.

Craig
"Shirley Valentine"
Gold Coast
Australia

[geoff]

My b40cc  has been on a swinging mooring every summer for 20 years. My club uses concrete blocks . I added a second roller to the left of your existing and use 2 strops up through the second roller then one to each bow cleat . the strops have had big rubber snubbers in  , but having been on the boat in some rough wx I found that they made no differance so not now. The only reason that we only use the mooring in summer is the availability of very cheap marina deals  in winter. If the mooring laying people know the local conditions then go with their advise. A cold beer on a warm evening on a quiet mooring is beyond price [well £5500 anyway]  Geoff

[Rampage]

The mooring layout given by the OP is common in rivers and straits where there’s a significant tidal flow.  The two anchors are laid out so the bottom chain is parallel to the flow: at the centre of the bottom chain is a riser with a swivel coming up to a buoy.  There’s usually a second swivel under the buoy to which the bridle is attached leading to the boat.  Given 2 x 60kg anchors (most of us only carry a 20kg or so anchor) the setup is well capable of dealing with the likely conditions provided it’s maintained on an annual basis.
As to the bridle between the mooring and the boat, the usual setup is to use 20mm rope in a two legged bridle, eye spliced at the ends.  The bridle comes up through the bow fairleads and onto the bow cleats using the eyesplices.  If your fairleads and cleats can cope, then you could use 25mm rope instead.  The rope needs protection from chafing where it goes through the fairleads: old fire hose is often used as it’s cheap and is good at resisting chafe.  The rope must be inspected frequently through the year and replaced if it shows any significant signs of wear.
The alternative is a chain bridle (one legged as Geoff suggests) brought back to one of the cleats.  That removes the chafing concern but means you’d either need to fit a second roller or move the anchor into the locker.  That’s what I currently do with my Hurley 18 with the anchor secured to the foredeck.
I used to keep my 38 on a mooring like this in the Menai Straits and has no trouble with it but my insurers wouldn’t cover me year round.  I had to move the boat ashore or to a marina from November to March.

[Symphony]

Agree to seek advice from the local mooring contractor. Either the single strop or double as suggested work. However suggest you use the saving in marina fees to invest in a second bow roller on the port side dedicated to the strop. Our club moorings use 22mm rope strops, but other swinging moorings I have used in the past had chain strops. with a good bow roller with flared cheeks there is less chafe than using the fairleads. My preference would be not to use the cleat but to install a substantial bollard on the foredeck on the centreline behind the anchor locker, probably above the forward bulkhead so that it can be braced to that. Centreline cleats, bollards, sampson posts etc were almost universal on boats built before the advent of marinas.

[tckearney]

Has anybody got a picture of the second roller attached to my type of bow roller.  That was my first choice but looking at the set up it is hard to imagine how it would all fit together without scapping the complete roller and buying a different type.   "Craig",  I do have the book you mention so will look it up.   "Rampage", thanks that makes me feel more assured.   All moorings in the area up to 5tons are just 2 x 400kg weights, train wagon  wheels infact, with  10mtrs of 32mm ground chain and a 22mm riser chain.   I think the option for the first season (next year) would be using a chain over the anchore bow rollers  and move the anchor to the fwd locker.  I'll try that later today.  I would also use a 25mm secondary rope with chaffing hose to the fwd cleat.   I do not have fairleads.     Any other observations welcome, it all reassures me.   
PS the mooring fee saved is to go towards new teak deck.  Anybody used Flexiteak or Decking, they now are the same company

[Symphony]

Looking more closely at your photo, the bow fitting is different from many other Bavarias where the roller is offset from the centre and the forestay central so adding another bow roller is possible. You would need a complete new fitting, wider than the current one with the forestay central and a roller either side. Not a quick or cheap job! Using your current roller with the anchor in the locker seems the best way, but would still require a cetral cleat as I assume your cleats are on the toe rail - not a good lead for a heavy strop.

For your deck suggest you look at www.teak-decking.co.uk who do prefabriacated panels in teak or www.moodydecking.co.uk who do panels in either teak or synthetic. Both work from templates of your deck and the panels are bonded on. Very similar to the method used on current production Bavarias.

[geoff]

My bow roller set up was as yours is  I think. I used a bow roller from a local chandlery , stainless U section with flared ends and a keep pin   This was then bolted onto the existing using 2 of the original bolts and one aditional, snug up against the forestay mounting. Works well and has room for 2 strops . I will try to take a photo on Tuesday. Geoff

[diverphil]

if it helps this is our roller set up on a 33c