Strength of anchor rope?

[Doodlebug]

When traveling up the thames, I understand I need 5 times the depth of the water. But I cant find anywhere a mention of the strength of the rope that is needed?

 

Does anyone have any experience in this.

 

I also cant decide between 3 strand or 16 plait rope. I would assume the 16 plait is stronger but I have only ever seen the 3 strand stuff on boats before.

 

Can anyone help with this?

 

Thanks

 

Doodlebug

[The Bagdad Boatman (waits)]

I lost an anchor and chain under the Humber bridge when using an old 15 mm polypropylene rope as an extension. After that I used 22mm kernmantle ropes. It depends in the weight and width of your boat, a wide beam has more current pushing against the bow than a well crafted narrowboat. There is a good place at Nottingham army surplus. The 16 strand if thick enough is strong and springy so it absorbs shock loading better, lovely to handle.

Edited February 20, 2013 by The Bagdad Boatman (waits)

[carlt]

Three strand twist Nylon is the usual choice but braided is better.

[Doodlebug]

Ok, so, what I would call climbing rope, is the better alternative?

 

We are on a narrowboat so I wouldn't have thought the current would have much effect but its the initial tug that the boat will give on the rope I worry about.

 

I found some rope which is rated at 1.5 tons but I have no idea how much our boat weighs and how much effect the river will have on the boat.

 

I assume the place I am planning to tie the rope to will hold!

[by'eck]

Try Anchorbraid (8 strand) - its called that for a reason.

 

16mm has a breaking strain of 6500 Kg!

[nicknorman]

Not massively experienced in these matters, but the rope needs to have strength for 2 main reasons - one to stop the boat moving away downstream / downwind. And secondly to allow the anchor to be retrieved when wanting to move off.

 

I would have thought that for the former, the rope doesn't need to be particularly strong since, with the chain (hopefully) mostly lying on the bottom, there is plenty of "give" to limit the peaks of pull. Assuming not anchored in the sea, the amount of pitching (and hence tugging on the rope) due to wave motion is likely to be pretty low. The amount of force needed to keep a boat stationary in a moderate current is pretty low.

 

Retrieving the anchor can be another thing altogether! You need to be able to lift the dead weight of chain and anchor, and free the anchor from mud / rocks / entanglement with objects on the bed of the waterway. That can require a lot more force!

 

So in summary I would have thought, especially for non-tidal thames, that the 3 strand would be quite adequate. If you want to anchor in the Humber, tidal Severn etc, maybe something stronger!

[BEngo]

Not massively experienced in these matters, but the rope needs to have strength for 2 main reasons - one to stop the boat moving away downstream / downwind. And secondly to allow the anchor to be retrieved when wanting to move off.

 

I would have thought that for the former, the rope doesn't need to be particularly strong since, with the chain (hopefully) mostly lying on the bottom, there is plenty of "give" to limit the peaks of pull. Assuming not anchored in the sea, the amount of pitching (and hence tugging on the rope) due to wave motion is likely to be pretty low. The amount of force needed to keep a boat stationary in a moderate current is pretty low.

 

Snip

 

 

The major requirement of a narrowboat anchor warp is that, in emergency, it is able to absorb the shock of stopping the moving boat. If you are 16+ tons stonking down Thames at the permitted 8mph (?) overground that is a lot of energy. Maybe even more on the tidal bits. The loads when stopped are minor in comparison. I know the anchor should drag a bit, but Sod's Law continues to apply and a broken anchor warp is not going to stop you going over the weir.

 

Buy the biggest and longest rope you can afford/store. Nylon or other stretchy material is better than Kevlar or other exotic no-stretch stuff. Conventional rope is easier to splice than braided.

 

N

[Detling]

The breaking strain of the rope is not usually the major issue with modern synthetic rope. You need to be able to pull on the rope without cutting your hands, pulling several tons of boat against a 2-3 knot current, in order to recover your anchor requires a lot of heaving on the rope. If the anchor refuses to come up and you need to use engine power to try to break it out, again you need a good grip, although you will have taken a turn around a bollard/T post you should never tie the rope off when doing this. Anything under 16mm diameter will hurt/cut your hands, 18mm is better.

[carlt]

The breaking strain of the rope is not usually the major issue with modern synthetic rope. You need to be able to pull on the rope without cutting your hands, pulling several tons of boat against a 2-3 knot current, in order to recover your anchor requires a lot of heaving on the rope.

Possibly when an anchor is a regularly used bit of kit but, as is usually the case with inland boating, it is used only in emergencies, I want it to stop my boat heading for a weir in flood conditions without breaking.

 

Recovering the anchor is way down my list of priorities.

[magnetman]

.

 

anchors are consumables when used inland because the potential cost of the alternative for example whacking a bridge or a weir makes the price of the anchor, chain and warp irrelevant.

 

I have chain not rope but if wanting rope I'd use minimum 16mm multiplait

you do need a bit of chain as well or the anchor won't bed in.

[RichardN]

The IWA published some guidance a few years ago, summary of it at the bottom of this page: http://www.thamescruising.co.uk/wordpress/?page_id=296

 

Bagdad Boatman's story of snapping 15 dia rope is a bit scary.

[bizzard]

If your drifting in a strong current and deploy the anchor to stop you and tied off its rope, chain, securely to a bollard or whatever its possible that the anchor flukes could snag on something really solid and immovable like old buried masonry, old heavy chain ground tackle, sunken wreck, anything, so with a heavy vessel something will ''give'', perhaps bust the anchor, bust a chain link, snap the rope, bust your bollard, cleat or Hawspipe lock, tear your foredeck off, yank the bows off.

It might be best to attach say a great big old cannon ball to a rope to stop you as this would ride over most debris on the river bed without snagging, but of course in an emergency and desperation the anchor is the first thing to come to mind.

So for that reason its wise to deploy as much anchor cable as possible to provide as much droop and springyness to make any sudden snag less sudden.

 

''What lies on the seabed and twitches?''--------------------A nervous wreck.

Edited February 20, 2013 by bizzard

[carlt]

Bagdad Boatman's story of snapping 15 dia rope is a bit scary.

I wouldn't use polypropylene to hang my washing out.

 

Degrades in sunlight, little elasticity, fraysand is uncomfortable to handle.

 

It's only uses are mooring up BW pans and, because it floats, rescue lines tied to liferings.

[luctor et emergo]

Should you not have the anchor line round a suitable bollard/tstud, twice, to play it out untill the anchor bites, when you gradualy slow the boat down, before tying off?

 

Relying on a generic length of line, and bringing the boat to a sudden stop, seems to be verging on the hopefull to me.

[bizzard]

Should you not have the anchor line round a suitable bollard/tstud, twice, to play it out untill the anchor bites, when you gradualy slow the boat down, before tying off?

 

Relying on a generic length of line, and bringing the boat to a sudden stop, seems to be verging on the hopefull to me.

Normal anchoring when stationary or nearly so, just let it go, wind, tide, current will automatically position the boat to ride naturally to it then just pay out or haul in as required. Big ships just drop it ''plop'' then play it out according to wind strength, tide, swinging space available ect. If your using the anchor in an emergency to stop you yes start playing it by hand around a bollard but if you've come to the end of the rope in deep water and still find there's not enough out you'd have to cleat it off or let it go.

[BEngo]

Normal anchoring when stationary or nearly so, just let it go, wind, tide, current will automatically position the boat to ride naturally to it then just pay out or haul in as required. Big ships just drop it ''plop'' then play it out according to wind strength, tide, swinging space available ect. If your using the anchor in an emergency to stop you yes start playing it by hand around a bollard but if you've come to the end of the rope in deep water and still find there's not enough out you'd have to cleat it off or let it go.

 

 

That's how to do it, if you are in a position to do so, but most narrowboats aren't built that way. Downstream for example you'd want the anchor at the stern. OK on a cruiser but watch the rope as it runs out, tighter on a semi trad and the rope is even more dangerous, but where do you put it on a trad, let alone stow the rope? Lobbing it off the roof is not much good as then you are nowhere near a bollard to surge the rope round and use as a brake. If you secure the rope on the roof be prepared for a really big leany moment as the strain comes on.

 

If the anchor is up the bow is there room to swing the whole boat plus the anchor cable? Then you 9or some crew) have to get to ot to lob it off.

 

It's all a compromise and I think the best one is a lot of big stretchy rope (Nylon for me) with the anchor secured at the appropriate end for the way you are travelling. In extremis, lob it off and hope. You cannot be worse off than you were before. Worry about getting it back later- the insurance might even pay!

 

N

[Greedyheron]

Just wondering, as I come from the sea and have yet to get used to being inland.

Current boat has anchor with chain and then rope. End of rope is secured to a bolt in the chain locker. This is not designed to take weight, just to prevent the whole lot being chucked over the side and disappearing, I keep a knife on hand in case I need to cut it free. If anchoring, I check depth log, wind rope/chain around cleat so I have the right amount and then chuck the anchor over. I can then pay out more if I need to.

Inland, boats don't seem to have a depth sensor- how do I know where to cleat the rope off? Do I attach it to anything? Taking blizzards point I would be concerned that whatever I tied it to might be pulled off. I'm not sure about being able to hold onto an anchor line with 20 tons of boat pulling the other way.

[Chris Pink]

Drop it first with all the rope and chain you've got. Hopefully this will result in a handful of slack rope. Then pull it in and tie off.

 

A drifting narrowboat won't exert much pull. Maths experts will tell you the inertia of 30 tons drifting at 3 mph but it's not huge.

[nicknorman]

Just wondering, as I come from the sea and have yet to get used to being inland.

Current boat has anchor with chain and then rope. End of rope is secured to a bolt in the chain locker. This is not designed to take weight, just to prevent the whole lot being chucked over the side and disappearing, I keep a knife on hand in case I need to cut it free. If anchoring, I check depth log, wind rope/chain around cleat so I have the right amount and then chuck the anchor over. I can then pay out more if I need to.

Inland, boats don't seem to have a depth sensor- how do I know where to cleat the rope off? Do I attach it to anything? Taking blizzards point I would be concerned that whatever I tied it to might be pulled off. I'm not sure about being able to hold onto an anchor line with 20 tons of boat pulling the other way.

If going downstream on say the tidal Trent, consider what would happen if you drop anchor following engine failure etc. The boat will have to swing through 180 deg (assuming rope doesn't tangle on the rudder/skeg etc) and in doing so it might hit something or ground. Therefore I think its perceived wisdom to keep the anchor at the upstream end of the boat. Unlike seagoing boats, narrowboats are less badly affected by being anchored from the stern (eg no keel!).

 

On the subject of peak pull, the chain will pull straight as opposed to it lying on the bottom, helping to remove peak load. And narrowboats tend to lose much of their speed through the water fairly quickly once the drive is lost. It would probably be sensible to wait as long as reasonably practicable before dropping anchor so that the boat is at minimum speed (depending on what is looming ahead!). Of course at sea, you would point into wind / tide and drop anchor only once speed over the sea bed was zero or slightly negative. So its a bit of a different thing inland.

Edited February 21, 2013 by nicknorman

[Keeping Up]

My thoughts, as I have both a mudweight and an anchor, would be to keep the mudweight at the stern when travelling downstream. The big advantgae is that the mudweight is small enough to accommodate within easy reach yet without it being a trip hazard, and can easily be moved from bow to stern or vice-versa

 

It may or may not hold securely, but in the event of engine failure it would certainly slow the boat and bring about a measure of control, allowing me consider the various options which may or may not include dropping the anchor off the bow where it normally lies, or possibly even bringing the anchor to the stern.

 

The mudweight is an old 56lb weight that I bought from eBay

[Doodlebug]

In terms of where to attach the anchor everyone has said to tie it upstream so the boat doesn't swing round, but bear in mind if on the thames or another tidal river you would want it downstream if the tide was coming in since the speed of the tide would outweigh the speed of the river.

 

I do worry about the rope being either too thick or thin, but I would much rather have it too thick so i'll go with what is suggested.

 

The anchors only real purpose is for an emergency so I agree that its more of a consumable. If the engine packs up and we are gaining speed towards a weir or the sea, the price of the anchor would be the last of my worries!

[magnetman]

what bothers me is that on the Thames there are signs saying 'The anchor is your lifeline'

 

if I fall in I do NOT want someone throwing me an anchor

 

maybe I am taking it too literally

[David Mack]

My thoughts, as I have both a mudweight and an anchor, would be to keep the mudweight at the stern when travelling downstream. The big advantgae is that the mudweight is small enough to accommodate within easy reach yet without it being a trip hazard, and can easily be moved from bow to stern or vice-versa

 

It may or may not hold securely, but in the event of engine failure it would certainly slow the boat and bring about a measure of control, allowing me consider the various options which may or may not include dropping the anchor off the bow where it normally lies, or possibly even bringing the anchor to the stern.

 

The mudweight is an old 56lb weight that I bought from eBay

 

Have you tried it to see if it works?

 

A couple of years ago the engine on Fulbourne stopped unexpectedly as we were going upstream on the Thames above Henley. As it wouldn't immediately restart I went up to the front and tied our mudweight - a builders bucket full of concrete with a length of chain cast in it - to the bow line and lowered it over the side. It slowed us down, but didn't stop us and was clearly dragging along the bottom. Fortunately the current pushed us towards shallower water out of the main channel and I could then pole the boat to the bank.

 

Would a 56lb weight do any better?

[Keeping Up]

Have you tried it to see if it works?

 

A couple of years ago the engine on Fulbourne stopped unexpectedly as we were going upstream on the Thames above Henley. As it wouldn't immediately restart I went up to the front and tied our mudweight - a builders bucket full of concrete with a length of chain cast in it - to the bow line and lowered it over the side. It slowed us down, but didn't stop us and was clearly dragging along the bottom. Fortunately the current pushed us towards shallower water out of the main channel and I could then pole the boat to the bank.

 

Would a 56lb weight do any better?

 

No I haven't tried it yet (it's on my "to do" list for this summer, if the Thames will let us on without flooding) - but my feeling is that a significant slowdown and possibly heading into shallower water, is a pretty good solution while I work out what to do next.

[NMEA]

No I haven't tried it yet (it's on my "to do" list for this summer, if the Thames will let us on without flooding) - but my feeling is that a significant slowdown and possibly heading into shallower water, is a pretty good solution while I work out what to do next.

 

If you are in clear water then using something of that nature to "kite" to the shallower areas or even to help get a line ashore does work, however if you are just upstream of a bridge or the the like it will simply mean you crash into a parapet stern first, there is no substitute for a proper handbrake and that is the correct anchor and rode for the cruising area and for the rig to be ready to deploy at seconds notice. There is currently a vessel that was towed into a Thames marina that had an engine failure without the right emergency gear and it is a complete mess, but less of a mess than the nerves of the crew, if you are leaving the safety of the puddles then you need to be prepared. I do sympathise as anchor deployment in the correct manner to slow a vessel without putting so much strain on the rode that it snaps in a "panic" situation is not simple and most people on here will have little opportunity to practise it, and that's what makes boating less stressful inasmuch as the practice gives confidence as one has experienced the results and knows what to expect rather than being told what to expect.