How Do You keep the Slack Out of Dyneema Shorelines?

[thinwater]

Nylon is good stuff for most anchoring and mooring purposes; if there is a shock load, it stretches. Too much stretch, however, and you can bounce around.

Dyneema is nice because it is chafe resistant, compact, and light. For practical matters it does not stretch at all, so shock loads can be rough.

Polyester has limited stretch, but if you have 100-200 feet out, there is some stretch.

I understand Dyneema and polyester shore lines are popular. Shock loads don't matter if there is no shock, which can only be guaranteed if there is no slack. This can be limited by cranking down on the bottom anchor and letting the nylon compensate. But if the nylon stretches or the catenary rises, then there is slack. If the tide falls there may be slack. The anchor can shift.

So how do you maintain zero slack?

 

[lpdsn]

So how do you maintain zero slack?

I just come back from the pub from time to time and tighten or ease them.

I don't use dyneema though. I tend to use old sheets to protect my warps from wear and tear on the top of the quay wall, with a three strand warp tied to it on the boat end with a sheet bend for a bit of stretch.

 

[Neeves]

There has to be more than one answer.

In the Med or Baltic tides are minimal and keeping lines tight, or tighter, is easier. In many parts of the world tides have a much greater range and 10m would not be unusual. I don't think there is a 'one size fits all' but there might certainly be a better way in some places than having to adjust at 2am, and again a 4am!

Jonathan

 

[thinwater]

I understand that chop will not come from the direction of the shore tie; there is no fetch. I understand tht some harbors are so well protected from waves the issue is perhaps moot.

I have tied up where there was fetch on the bow, however, and the boat surged fore/aft a few feet. How would non-stretch lines work? A combination of nylon and polyester has worked for me, but I have only done this a few times.

 

[DHV90]

Dyneema is nice because it is chafe resistant, compact, and light. For practical matters it does not stretch at all, so shock loads can be rough.

I understand Dyneema and polyester shore lines are popular.

is it? some ships use big dyneema where winches on each corner keep lines tight, but on small boats dyneema is wasted on, and poorly suited to, mooring applications. poor resistance to chafe, harsh transmittance of shock loads, expensive, and stiff. surely thats all the things you dont want in mooring lines? theres no need for it either, stretchy poly lines are adequately strong and chafe is going to be an issue whatever you use, certainly no less with dyneema.

 

[CCJ]

Nylon is good stuff for most anchoring and mooring purposes; if there is a shock load, it stretches. Too much stretch, however, and you can bounce around.

Dyneema is nice because it is chafe resistant, compact, and light. For practical matters it does not stretch at all, so shock loads can be rough.

Polyester has limited stretch, but if you have 100-200 feet out, there is some stretch.

I understand Dyneema and polyester shore lines are popular. Shock loads don't matter if there is no shock, which can only be guaranteed if there is no slack. This can be limited by cranking down on the bottom anchor and letting the nylon compensate. But if the nylon stretches or the catenary rises, then there is slack. If the tide falls there may be slack. The anchor can shift.

So how do you maintain zero slack?

Rubba snubba`s

 

[Greemble]

Weights & pulleys

 

[thinwater]

is it? some ships use big dyneema where winches on each corner keep lines tight, but on small boats dyneema is wasted on, and poorly suited to, mooring applications. poor resistance to chafe, harsh transmittance of shock loads, expensive, and stiff. surely thats all the things you dont want in mooring lines? theres no need for it either, stretchy poly lines are adequately strong and chafe is going to be an issue whatever you use, certainly no less with dyneema.

I'm not sure if I was clear. By shore lines I do NOT mean ordinary mooring lines to the quay. I mean shorelines when anchored in a cove too small to swing at anchor. This is common in many rocky areas.

 

[prv]

So how do you maintain zero slack?

I don't understand why you want to.

It sounds like you're trying to maintain plenty of tension in the shore lines because they are dyneema, and you need to nail the boat in place so that it doesn't move and then jerk to a stop when the dyneema line goes tight. But surely the answer to that is not to use dyneema in the first place!

Personally I would choose polyprop for long shore lines, probably the relatively loosely braided type in a fairly large size. It floats which means you can easily tow a long length of it ashore behind the dinghy or even by swimming, and it won't end up in your or anybody else's prop if a load of it ends up trailing around in the water for whatever reason. Big sizes will take a fair bit of chafe and UV before losing too much strength, and it's the cheapest fibre which means you don't need to feel too protective towards it when it comes to damage or cutting bits off. If you're really worried about chafe on rocks you could have a strop in something harder-wearing to tie onto - the boat we chartered in Greece a couple of years ago had a good rock-strop in some unidentified but surprisingly dense fibre which meant it sank easily into place around outcrops and boulders that were awash at the shoreline.

Pete

 

[Neeves]

I think Pete's comment valid - if you are using long shore lines then they must be such that they can be seen by someone who might be able to travel between your vessel and the shore (been there done that). So the lines should float, either because they have a low SG or because you add floats (and ideally lights - buy them in a fishing tackle shop).

We scavenge rope on beaches and splice for shore ties, they are free and sacrificial. Short lengths of chain are also useful (for rocks).

We would not use dyneema for a shore line but we might use it for a second (or third rode, but don't). its too expensive and for both rode and shore lines I'd prefer nylon with 'our' sacrificial strops to overcome chafe. We prefer nylon for both a second rode (+ some HT chain) and shore lines, because we have it for historic reasons. If we had to buy new we'ed go for polyprop or scavenge some more retired climbing rope (which we get for free).

But - we have an open mind and if it were shown that dyneema could be used, sensibly, the extra cost would not be a major factor as we would also use it as a third rode.

If you are well trussed up snatch loads should reduce, if not disappear, and the need for anything particularly strong recedes - unless you are using the same rope for something else in a different situation.

Jonathan

 

[thinwater]

a. I don't use Dyneema for this, but some very experienced people do. I was hoping such a person would chime in. But don't ask me to explain or defend beyond what I offered already--I'm asking the question and am mostly here to listen.

b. Certainly they need to be marked.

In fact, I'm quite certain there are probably good reasons, but I would like to hear them explained.

Remember that so long as there is no slack there is not much impact load, not unless there is a wake from the side, which in this cases is impossible. But how to control the slack?

 

[Neeves]

As a current example of using dyneema as a shore, or defined as a stern, line see here:

http://www.ybw.com/forums/showthread.php?492253-where-to-buy-long-length-dyneema

It would be interesting to learn the motivation.

Jonathan

 

[[70521]]

a. I don't use Dyneema for this, but some very experienced people do. I was hoping such a person would chime in. But don't ask me to explain or defend beyond what I offered already--I'm asking the question and am mostly here to listen.

What sort of tidal ranges do they work in?

I've not seen many boats moored up using lines to shore to keep a boat at anchor in the UK. Only done it once and that was to allow three people to climb a route and abseil back to the boat. We used old climbing ropes and I stayed on board to tend the lines.

 

[Neeves]

Shore lines are fairly common place in higher latitudes (think Labrador or Patagonia) also the Baltic, Med (think of Med moor) and we have used it in Bass Strait, 3m tides. The longer the shore lines and longer the rode - the more tide you can accept. In Patagonia shore lines can easily be 100m (and commonly 4 such will be carried).

Old climbing ropes are ideal. You need elasticity (or give) somewhere in the system.

Jonathan

 

[NormanS]

I've only ever used shore lines a couple of times, once knitted into a tiny wee pool in the rocks, and once 50 years ago in a chartered boat with a somewhat less than adequate anchor. (In a place where the SDs at that time said, "The surrounding trees kill any wind" Huh!)
My understanding is that the combination of anchor with shore lines, commonly used in Patagonia, is largely because of poor holding due to kelp. Lying to anchor(s) without other lines is so simple in my home waters, and I detest being moored broadside on to the wind.

 

[lpdsn]

What sort of tidal ranges do they work in?

I've not seen many boats moored up using lines to shore to keep a boat at anchor in the UK. Only done it once and that was to allow three people to climb a route and abseil back to the boat. We used old climbing ropes and I stayed on board to tend the lines.

Never seen it in the UK or Ireland. Hard to imagine it working well with a significant tidal range. Done it a lot in the Baltic though. Stern anchor then scramble ashore and find a tree, big boulder or even a ring set in the rock. But generally just using normal mooring warps - Sweden abounds with places where you can get a normal fin keel yacht within inches of a big rock or islet.

 

[prv]

Never seen it in the UK or Ireland. Hard to imagine it working well with a significant tidal range.

The shore lines we’re talking about will be several boat lengths long. A few metres up or down at one end won’t change the effective length all that much. Perhaps enough to be a problem if you’re trying to eliminate every last inch of stretch or movement, but as already discussed I think that concept is impractical.

Pete

 

[lpdsn]

The shore lines we’re talking about will be several boat lengths long. A few metres up or down at one end won’t change the effective length all that much. Perhaps enough to be a problem if you’re trying to eliminate every last inch of stretch or movement, but as already discussed I think that concept is impractical.

Pete

Against a quay, no problem. Not many places though where you can anchor close enough to tie off to something on land then have enough depth to just go up and down with the tide. And even fewer which are suitable when the wind changes direction, as it usually does. Whereas in the Baltic (E Sweden & Finland) there are numerous such places.

 

[Neeves]

Its horses for courses.

In many places the idea of anchoring means, as the word suggests, deploying an anchor - finish. For other people this is quite unusual, think of the description described above of the Baltic or a Med Moor. In higher latitudes long shore lines are very common.

Because we are focussed, on the common meaning and most commonly discussed form of anchoring, other options simply do not cross our consciousness - but other options do exist and can be quite appropriate. To arrive in Patagonia with only kit for the UK you would stand out as obvious neophytes where yachts commonly will have 2-4 big reels on the transom or centred round their mast and 2 anchors on twin bow rollers. They also tend to have multiple anchors (one yacht from Malta had 2 bow anchors and 3 other anchors immediately available festooned round the transom. In the Baltic it is quite common to see yachts with no anchor on the bow roller at all (looks naked!) - but an anchor with bow roller (if that is not a misnomer) on the stern.

I will not say we do it regularly but in very tight anchorages where bullets, of 50 knots or more, whip down the valleys and gullies at 180 degrees to each other the only way to enjoy any stability and security is to, get as close in to shore (where there is more shelter). We use more than one anchor, deployed in a 'V' of the bow, and shore lines off the transom. If the lines are long enough tidal influence is not a big issue. Being effectively stationary you can get close in, even with a 2m keel, as the yacht will not swing. In open anchorages I fully agree with Norman, securing broadside to the wind would be a nightmare and 1 or 2 anchors (the latter in a 'V') would be appropriate.

But how many carry 2 anchors that will cope as a primary, how many carry 2 complete rodes, how many carry sufficient to deploy decent shore lines and how many carry short strops or short chain lengths to put round trees or rocks? None of this might be meaningful in the UK - but it is commonplace elsewhere. We carry 2 rodes, have one long shore line, a long spare bridle, and could cobble together a second shore line (using 'normal' mooring warps). But the lines are generally all polyprop or nylon.

But returning to the OPs question - we find that as long as the rodes and warps are 'tightish' the yacht (and its a high windage cat) really does not move. The anchors are secure and the shore warps winched in, sheet/halyard winches - so we stretch the warps a bit. But how you might do this with non-stretch dyneema - I don't know. If push came to shove, I'd use the dyneema as part of a rode and add elasticity with a nylon snubber - I'd then use the nylon rode, that the dyneema replaced, as another shore line.

There are lots of right ways to anchor and the idea of one rode and one anchor is very restrictive (and alien to many).

Jonathan