Mooring Lines for Alongside with Swell

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Gypsy

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A few days ago we entered a small port on the Nth coast of Crete and were allocated a berth alongside a solid concrete jetty. We are in a Ben 473, later a Bav 47 was berthed behind us, 20m back towards the entrance of the marina. Similar sized boats but we are probably heavier as we are loaded for cruising whereas the Bav was a charter boat..

The first night was fine, then the weather changed and Nth winds developed waves of 1m+ outside and a swell came into the marina of around 30-40cms during the following night.

I had a bow line and stern line and 2 springs with plenty of fenders against the wall which also had car tires, however the incoming swell caused the boat to range along the jetty to the extent of the slackness of the lines and their elasticity and therefore there was a huge shock onto the cleats and ropes when the boat reached the extent of its 'harness'. I tried different combinations of tension and ensured all ropes were taking the strain as equally as I could but kept having visions of the cleats ripping out, or if I tensioned the lines to much the hull being forced against the fenders and eventually popping them.

Meanwhile the Bav behind me had only a stern line, fairly short to the shore bollard and a bow line, both quite tight holding the boat to the jetty with virtually no ranging but it 'cork-screwed' terribly as the swell swept past.

As soon as I could, I moved into the marina about 50m and took a stern to the wall mooring which meant the swell came to us side-on. The boat rolled a lot but there was no threat to the cleats. We changed our sleep style by 90deg and slept well.

So, forum experts, what can you advise about the best way to tie up in the circumstances I have described?

We didn't sustain any damage and I don't think the Bav did either, but it a good testament to the Bav cleats that they held on for another night after we moved.
 
Ray

Not much you can do except, move! We have learned to watch the locals, for when you suddenly find you are the only boat on the quay. Sometimes we just sit the "storm" out anchoring in the harbour, if it is affected by swell. You get the swell but save your guard rails etc.

You would need a lot of buckets to damp the surge down!

Cheers
 
There are a number of strategies to use in these sort of circumstances. Firstly, remember that fenders are there to be sacrificed to protect the hull! When we've been caught in a heavy swell whilst alongside, we use two large spherical fenders as our first line of defence, with all the other fender hung between the hull and the wall. If you have a plank, then if you hang that between the wall and the fenders it will also provide a measure of protection from abrasion from the wall. We use springs to limit fore and aft movement and bow and stern lines to keep the hull close in to the wall. The springs will have shock absorbing metal springs fitted if we expect things to get really rough to minimise snatching. The ropes used are all mooring lines with a good bit of stretch in them as well to further dampen snatching.

If the harbour layout permits, I'd also put the kedge out midship to pull the boat off the quay. Use the dinghy to deploy it and then a genoa winch to tension it. Doesn't stop the boat surging but does help to minimise grinding against the quay. Also, if you have to leave in a hurry, you can use it to pull yourself off the quay before heading out. Not always possible as the rode may block part of the harbour or there may not be enough room.

Finally, if you're in a small place, look at running a line across to another quay to hold yourself off the wall.

Not always possible to do anything other than sit it out, which can be uncomfortable but if you've got mooring lines with a bit of stretch in them and a set of shock absorbers for the springs, then I don't think there's much danger of pulling the cleats out of the deck. Oh and watch out for chafe: I've had 18mm lines wear through in a few hours of this sort of treatment.
 
have you tried hanging an anchor on a short strop from the middle of the springs
It may dampen the shock load a bit.
You probably have a kedge as well so that could go on the aft spring

Possibly your boat is too big for it to have much effect but it does help on smaller boats
 
We had a similar experience a few years ago and found the only solution (apart from moving which was impossible) was very long nylon fore and after lines, that was in a heavy (6 ton) 26 footer and our warps were at least 50` long and led aft from the stern cleat and similar bow line from forward cleat, that on top of traditionla but very long nylon springs tended to make the breast lines take minimal load., which took out all the shock load over the 2 days we were stormbound alongside a wall. We also took great care to prevent chafing.

Just occasionaly you are thankful for that locker full of rope :)
 
Gypsy said:
......... Any takers for the "tie tight to the wall" to avoid any ranging even though the boat will buck and squirm?
Click to expand...

Certainly not me !!! Lines should be slack to allow ranging. In any swell the boat will have a natural frequency and amplitude of surge. The more you can allow this to happen the less impact on ropes and fixings. More damage occurs trying to prevent surging than allowing it if room permits.
 
Try adjusting the length of the springs. You can get unlucky and end up with a length which corresponds to the wave frequency and then you surge back and forth. If you adjust the length you can avoid the syncrhonized oscillation to some extent.

I have had this before when tied along side in Port Vendres. Relatively little swell, but I woke up in the middle of the night as we were surging back and forth a good 7m or so. I changed the length of the springs by tieing to different bollards (and move the boat a bit to be able to do it and that calmed things down a fair bit.

Of course it was pissing down with rain when I did this.
 
The answer is heavy weights on the warps, which is not a luxury you will have available, except you could bundle up your anchor chain for one, at least. Leaving plenty of slack means you may get to the end less often, but will range away from the quay. Also, if you can run the warp round a bollard or through a ring and then make fast somewhere much further away it gives you more length to stretch, but may need chafe protection.
 
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