Mooring compensators

OutOut

OutOut

New Member
Joined
21 Sep 2021
Messages
10
Visit site
Good evening,

Looking for a bit of advice, we had a very bumpy night at the weekend in Cowes.

The ropes were quite loud, and we had a very bad jolt on the lines every 5 to 10 min.

I believe that we should get some shock absorbers to use while moored in rough weather.

while looking online there is a huge array of different ones, Metal springs to rubber tubes, there is far too much choice and we don’t know what to go for.

to give a little context the boat is 34 foot motor cruiser flybridge weighing about 6 to 7 tones.

thanks in advance
 
Had good opportunity to review these by walking along the pontoon after a storm where several boats broke off the pontoon (breakwater got smashed in and waves came into the marina, fun times).

Those black rubber dongs (Forsheda, Unimer, etc.): Snapped in half, ends torn off or rope tore through the ends.
Plain metal springs: Broken spring or permanently compressed. Also, they screech when they're intact and have seen a little use.
Two-stage metal springs: Held, still working. Various models performed better than others, but they all survived intact. Take note, the fancier ones have brass sleeves around the moving rods that make them silent, the ones without can be noisy. They also provide the best absorption: The red things inside are hard rubber and provide the second stage after the spring is compressed.

As our rubber dongs were broken, we replaced them with the fancy two-stage springs. They were pricey, but nothing like nearly losing the boat to motivate a bit of spending. Few years later they're still doing great and we love them. Worth the money.
 
Most of my mooring lines are nice stretchy ones such as nylon. Keeping them as long as possible but also tight normally means that there is no real jolting unless the weather is really bad. I did have one of those rubber bone things but found it a waste of time and wrecked one.
Ropes making a noise from the cleat or fairlead is something I have found just about impossible to stop.
 
OutOut said:
Good evening,

Looking for a bit of advice, we had a very bumpy night at the weekend in Cowes.

The ropes were quite loud, and we had a very bad jolt on the lines every 5 to 10 min.

I believe that we should get some shock absorbers to use while moored in rough weather.

while looking online there is a huge array of different ones, Metal springs to rubber tubes, there is far too much choice and we don’t know what to go for.

to give a little context the boat is 34 foot motor cruiser flybridge weighing about 6 to 7 tones.

thanks in advance
Click to expand...

With winds out of the N in Cowes because of swell it is better to avoid the west Cowes marina and moorings and use East Cowes Marina's visitor berths or better stil go upriver to Island Harbour marina or the visitor pontoons off the Folly Inn .

W have used the rubber dog bone shock absorbers very successfully over many years and if fitted properly in the line as in being wound multiple times around 'bone central' which allows maximums stretch plus a fail safe IF it breaks ours have lasted well. Not on all lines, but selected ones to suit location and wind/swell movements, ,Mostly it is one or more lines that 'jerk'. When we had a 41ft sail boat berthed with ass exposed to prevailing westerly blows across Poole Harbour we had snubbers on both bow lines whilst both fore and aft springs were as taut as we could get them and were snubber free., We also had one general mooring warp with rubber bone that was called on away from home if need ed and used to double up over say a bow or stern line jerker and take the sting out of the jerks. Easier to do than describe, sorry. Priority is to allow boat movement only in a safe direction whilst preventing it going towards say the main pontoon/dock .
 
OutOut said:
while looking online there is a huge array of different ones
Click to expand...
Indeed, but it's a clear cut case of you get what you pay for.
I tried first hand, and also heard several experiences on, quite a few of them.
Eventually, I decided to byte the bullet and I forked out an outrageous amount of money for these things.
And after some years of experience with them, I can confirm that they are the real deal - nothing else comes close.
If you need badly some mooring compensators, you'd never regret the money spent on them.
But if not, you could as well keep lines tight and rely on their stretch, rather than spend less but waste your money.
 
My experience is that you must go oversized...well oversized...otherwise they just break in a storm.
Also because you rely on the rope to stop the spring or rubber from over stretching (and in the springs case compressing), you must make sure you haven’t put too much slack in the system (especially if your ropes are also elastic)
 
OutOut said:
Good evening,

Looking for a bit of advice, we had a very bumpy night at the weekend in Cowes.

The ropes were quite loud, and we had a very bad jolt on the lines every 5 to 10 min.

I believe that we should get some shock absorbers to use while moored in rough weather.

while looking online there is a huge array of different ones, Metal springs to rubber tubes, there is far too much choice and we don’t know what to go for.

to give a little context the boat is 34 foot motor cruiser flybridge weighing about 6 to 7 tones.

thanks in advance
Click to expand...

Unless you define what mooring lines you were using we have no idea what might be best for you.

If you were using dyneema as mooring lines - I'm not surprised at your bad experience.

Tell us how you were moored, how many lines, how long, what diameter, what was the mooring line constructed from etc etc, and you will get more knowledgable answers.

I would agree, choosing the location for your overnight stay based on the weather forecast is a key issue - see Robins post earlier.


Historically many people moored comfortably simply using carefully chosen mooring lines, correctly located, of a sensible diameter and judicially placed without the needs for rubber dog bone things and heavy (on wallet and kgs) stainless springs.

Jonathan
 
Last edited:
Neeves said:
Tell us how you were moored, how many lines, how long, what diameter, what was the mooring line constructed from etc etc, and you will get more knowledgable answers.
Click to expand...
Do you mean that all previous answers were unknowledgeable because everyone assumed the OP is already using proper mooring lines, and nobody asked their colour? Talk about analysis paralysis... :rolleyes:
 
Neeves said:
Unless you define what mooring lines you were using we have no idea what might be best for you.

If you were using dyneema as mooring lines - I'm not surprised at your bad experience.

Tell us how you were moored, how many lines, how long, what diameter, what was the mooring line constructed from etc etc, and you will get more knowledgable answers.

I would agree, choosing the location for your overnight stay based on the weather forecast is a key issue - see Robins post earlier.


Historically many people moored comfortably simply using carefully chosen mooring lines, correctly located, of a sensible diameter and judicially placed without the needs for rubber dog bone things and heavy (on wallet and kgs) stainless springs.

Jonathan
Click to expand...

I generally find it's the bow line that squeaks, related to short finger pontoon on home berth and poor angle for the line. I'm 40foot and by far not the biggest boat.
Following thread as this has been on my to do list for a while
 
MapisM said:
Do you mean that all previous answers were unknowledgeable because everyone assumed the OP is already using proper mooring lines, and nobody asked their colour? Talk about analysis paralysis... :rolleyes:
Click to expand...

If the OP was using all the correct mooring lines he would not need to ask the question - he needs compensators. But we don't know and I have learnt - never assume.

Far from unknowledgeable but adding stainless springs or rubber compensators if the OP was using one dyneema line fore and another aft (which I acknowledge is unlikely) seems to me to be daft if all that was needed was a couple of springs and a couple of other lines. The answers were very knowledgable - but I'm not sure we know what the problem is, or was. Throwing money at an unknown and ill defined problem is surely not the answer.

But if you have devined the correct answer - good for you. We need more people like you around. Most of the time we have to guess and half the time the replies are a waste of time because insufficent information was provided at the outset.

Jonathan
 
Thinking a bit more deeply of your description of your uncomfortable night. And trying to guess the environment and your mooring practice.... :)

Most, in fact all I can think of, rope will stretch linearly (not quite true but as close to linear as makes no difference in your situation) - until they fail. Ropes do not stretch a bit and then stop stretching.

For you to suffer snatch loads, the jolt you mention (feels like running into a brick wall?) was when one or more lines were suddenly tensioned and there was no elasticity available. Your description did not have sufficient detail but this might occur when there was a sudden gust in a slightly different direction to the average and you might have had one (or more) inelastic lines the took that gust. Equally the jolt might have been a big wave (but I think you would have mentioned if it were a wave or chop. Your lines might also have allowed your boat to hit the wharf every 10 minutes or so - because you were too near that part of the wharf - again I think you would have worked that out.

I suspect you have a mix of mooring lines, most are adequate but maybe one or two are not offering you any elasticity. The absence of elasticity might be because the textile fibre is inelastic ( for example dyneema), because the lines were too short or far too beefy. Having said all that you will not feel a jolt if the boat does not move - as to have a snatch the boat has to a accelerate and then come to a complete stop when one or two lines went taut (and did not stretch).

If my analysis has any merit you need to find which of the lines you were using lacks elasticity, is too beefy or too short - and change it (for a line that offers stretch - longer, thinner or made from a more elastic fibre (nylon).

You can add compensators but if you add them to lines that already offer elasticity - you are wasting your time (and money) and if you tie alongside again and moor in the same pattern that gave snatch loads and have the same conditions then you will still have snatch loads - unless you add the compensator to the guilty line (or lines).

I'd invest in a new, or some new, nylon mooring lines and try them first - before you invest in compensators. I'd make sure that when you use the lines you ensure they are long, short lines do not offer stretch.

Take care, stay safe

Jonathan
 
Most probably the snatch movement would be swell related rather than wind gust induced in the location the op mentioned, a well known phenomenon there .that doesn't arise farther up river , but of course not near the town hotspots.
 
And continuing my analysis ensuring paralysis.

The fact you boat moved sufficient to give you a snatch strongly suggests your ,mooring lines are slack, too slack. Your lines should not be bar tight but sufficiently tight that the boat cannot move much at all. Any movement is then accepted by your mooring lines and they stretch to accomodate the gust.

If you stop the boat moving you will not be able to generate snatch loads.

I'd save your money, at least short term, polish up your mooring arrangement, ensure your mooring lines offer elasticity, check for abrasion - and you are good to go, or stay.

I can assure you most people moor their boats without using compensators relying on their mooring lines. If you don't believe this - simply walk round a marina and note how many use compensators. Even in exposed locations it is perfectly safe to simply use, correct, mooring lines.

And continuing my analysis - decent mooring lines are needed, whether you have compensators or not, and mooring lines are factorially cheaper than stainless springs.

If as Robin suggests the movement is as a result of swell or chop - I would have thought you would have identified this as the cause - but you make no mention.

Jonathan
 
You must log in or register to reply here.

Share this page

Top