Cruising Anchor Chain Length

[daletournier]

I'll just add one more thing, you mention that inevitably when cruising the world you will anchor in 30-40m at some stage, I disagree.

Most boats are just not equipped for that depth therefore they dont and they still manage to circumnavigate. You do, because you can.

The other problem with anchoring in that depth is it's almost impossible to know if your dug in well, backing down on your anchor takes on a new meaning when trying to stretch that amount of chain out and feel see that its holding well.

In the few occasions where I've only had those depths as a option without practically being on shore (think sides of volcanoes) I move on, even if it means staying out to sea heaved to to rest.

Am I as qualified as you? probably not BUT after living at anchor for 3000+ nights around the world and only dragging once I'd say I do have some runs on the board.

[a64pilot]

Originally Posted by noelex 77

Read some of the material from Steve Dashew it may make you change your perspective in what you consider is short scope. He is much more game than I am when accepting small amounts of chain. He uses a very large 110kg Rocna, which helps especially on a narrow beamed and relatively low windage 64 foot power boat, but does not give the anchor an easy time:



SetSail FPB » Blog Archive » More on Anchors and Sizing:



“We are surrounded by a lot of 40- to 50-foot (12- to 15-meter) yachts. The water is 55 feet (17m) deep at half tide. We set our big ROCNA anchor on 2.5-1 scope, and then, with a firm bite established, shortened the chain rode to 100 feet (30m). A scope of 1.6-1. If you calculate the angle off the bottom, combine the chain length with Wind Horse’s length, we need about 150 feet (45m) of swinging room.

Compare this to a 40-foot (12m) yacht anchored with a normal sized anchor. They will need at least 4-1 and probably 5-1 scope. Take their length and add it to 240 feet (74m) of chain, allow for angles, and you have a swinging radius of 220 feet (67m) at a minimum. The smaller boat with its normal (undersized by our standards) anchor takes a lot more room than the bigger boat with an oversized anchor. Is there a lesson here?

Not only does this work in crowded anchorages, but it benefits you in secluded spots which might otherwise be too tight with a normal anchor.

The anchor, regardless of design, will set faster, being bigger. This means it drags less before it digs in. That reduces the risk of it fouling debris. And since you take less swinging room, the chain sweeps a much smaller area of the bottom as the boat changes position, again reducing the risk of fouling.”

I’d bet my 88 lb Rocna on a 12 Ton 38’ boat likely is sized about what he has.
I’ve anchored at 3 to 1 maybe less, a lot has to do with the bottom, and the weather forecast, good clean sand where the anchor can bury forever, OK
I still feel better at 4 or 5 to 1, and if Wx is going to be bad or suspect bottom, I want 7 to 1.

You can only not have enough scope, you can’t have too much. What’s the point in pushing your luck?

[daletournier]

Originally Posted by a64pilot

I’d bet my 88 lb Rocna on a 12 Ton 38’ boat likely is sized about what he has.
I’ve anchored at 3 to 1 maybe less, a lot has to do with the bottom, and the weather forecast, good clean sand where the anchor can bury forever, OK
I still feel better at 4 or 5 to 1, and if Wx is going to be bad or suspect bottom, I want 7 to 1.

You can only not have enough scope, you can’t have too much. What’s the point in pushing your luck?

The old saying "no one dragged by having to much chain out" is valid.

The only time I ever have 3:1 out is in deep Anchorages , I believe the sheer quantity of chain out compensates for the lesser scope.

If unsure I'll add another 20m of nylon line making sure it's not on the bottom, only had to do this twice and probably didnt need to.

[sck5]

"You cant have too much rode" Absolutely true when at anchor.

However, you CAN have too much weight in the bow. Whoever it was above who had an 88lb. anchor plus chain on a 38 ft. boat might well benefit from getting rid of some of that weight up forward.

FWIW I lived on my 33ft and then 40ft Calibers for years in the Caribe, Bahamas and East coast. 125 ft. of chain and 100 ft. of rope (used once) did the trick. Never once dragged. But I would want more if I went to the Pacific.

[daletournier]

Originally Posted by sck5

"You cant have too much rode" Absolutely true when at anchor.

However, you CAN have too much weight in the bow. Whoever it was above who had an 88lb. anchor plus chain on a 38 ft. boat might well benefit from getting rid of some of that weight up forward.

Everything's a balance. I've cut the amount of chain back.

I'm not sure how A64 fits everything on his boat..lol, he's got a talent

[sck5]

sure, you are right but 88lbs? That seems like overkill to me. And I am a devout believer in overkill.

[Adelie]

Consensus and anchoring don’t go together.

My opinion:
30-40m G43 chain plus 100m nylon on main bower.
Another 30-40m G43 stored in bilge for Pacific where anchorages run deeper and in case the main bower is lost.

[noelex 77]

Originally Posted by a64pilot

I’d bet my 88 lb Rocna on a 12 Ton 38’ boat likely is sized about what he has.
I’ve anchored at 3 to 1 maybe less, a lot has to do with the bottom, and the weather forecast, good clean sand where the anchor can bury forever, OK
I still feel better at 4 or 5 to 1, and if Wx is going to be bad or suspect bottom, I want 7 to 1.

You can only not have enough scope, you can’t have too much. What’s the point in pushing your luck?

I absolutely sympathise. There is no point keeping chain in the anchor locker when you can deploy more scope safely and without inconveniencing others. I have been awoken too many times by a strong un-forecast wind at 2am wondering why I didn’t deploy more chain not to learn my lesson.

However, what about that spectacular/convenient/crowded anchorage that can only be successfully used with a short scope. There are times when anchoring at a short scope makes sense, or perhaps is the only option. Do we bypass these anchorages or take advantage of them? What about if only moderate scope is feasible, but a strong wind is forecast. Do we move even when this may be inconvenient or even unsafe? What about the very deep anchorage, or the anchorage with poorer holding?

Modern high performance anchors together with powerful electric anchor windlasses are recent developments. These improvements enable even a small crew to easy handle large new generation anchors. These inovations have revolutionised anchor performance. We can now use anchorages with poorer holding and smaller swinging room that would have been very unwise when I started sailing.

Like having a shallow draft boat this opens up numerous anchoring possibilities.

My advice would be to fit the best and and largest anchor you can comfortably manage. This will give much higher anchor performance than our forefathers enjoyed. This increased performance will allow some leeway when anchoring at shorter scopes, poorer holding, stronger wind etc. These advantages are real, take advantage of them when appropriate.

[s/v Jedi]

Originally Posted by daletournier

Hi Jedi, your approach is very solid, yet it is just your opinion. You aren't the only one that has cruised a long time or anchored deep.

Shock horror, I've gone from 120m down to 80m. My experience in places like raja ampat Indonesia (amongst others) etc where you often have to anchor deep is that less scope is actually required. 3:1 is generally fine when anchoring in 20-25m.

In regards to anchoring in 30m+, I wont, I will move on, 30m+ is crazy deep, it's a problem if you are fouled ,its a problem for many windlasses etc, yes I know your windless can handle it .

Yes, bigger, stronger and more is better BUT where does that stop?,do I buy a ship?

Many successfully go around the world with 100m of chain or less.

Dale, yes mine is an opinion, yet it’s shared by a very large share of experienced cruisers, naval architects etc. and, like mentioned before, the cruising design legend himself, Steve Dashew. He is the reason we have what goes even beyond my recommendations.

Is 1:3 scope enough for deeper depths? Yes, sure, I fully agree.
Is 80m rode enough in Indonesia? Never been there but I believe you.
Move on from any 30m+ anchorage? No, there are places that don’t afford you that luxury.

That is the thing: the OP asked for any place incl. the Med where I already identified an anchorage that is that deep and authorities will under no circumstance allow anchoring elsewhere.

If you newly set off for world cruising, you should take a primary all chain rode of 400’ plus a secondary nylon with chain leader of 300’. Sure you can take off with less, like you write, many have proven it is possible, and people crossed the Atlantic rowing, but if you set off with less then know it is a compromise

[Cayuse51]

There are different ways to approach it. We sailed around the world on a light catamaran with 50 meters of 10 mm chain, 30 meters of rope, and an oversized Spade anchor (35 kg). Like with many things, I am sure more is better, but we had no problems.

[Sandydog]

All that chain is crazy. 1/2 inch chain would weigh 1000 pounds. I don't want that in my bow. With the proper type and size anchor and periodic checking for abrasion, it should be fine.

[Cheechako]

I like 200 ft. I have used 150 ft though also. Either was backed up by 100-150 feet of nylon which never really saw the light of day except in unusual circumstances.
With room and no "weight in the bow" issues, I would go with 200 ft. But 150 ft works great in the Caribe etc. it gets you ~8-10:1 scope in 15 feet or so of water.

[kev_rm]

Your scope is below what anyone would recommend. Got a 7:1 picture?

Originally Posted by noelex 77

A picture beats 1000 words. I have lots of photos . I have already posted a photo of the chain leading to a Rocna (see post #12). This was with an all chain rode (not chain and rope combination) in 25 knots. 5m @ 4:1.

Here is another example:
This was also an all chain rode, rather than chain and rope.
This was an Ultra anchor in 6m of water @3.5:1. The wind was 25 knots with gusts to 30.





Another example. This was also in 25 knots of wind. In this case there is not only the chain, but a Rocna anchor that is acting as a kellet and adding to the chain weight. Nevertheless the total weight of chain and anchor is lifted off the bottom.



Or this Delta in 25 knots 8m 4:1.



These examples show boats with an all chain rode rather than a chain rope combination, but the latter will only make things worse. The exact windspeed where all the chain will be lifted depends upon many factors such as the scope, the thickness of chain relative to the size of the boat, the windage and displacement of the boat etc etc, but with only 30m of chain available my estimate is that the chain will be lifted and that the catenary will be essentially lost at around 20-25 knots of wind. I think this is a reasonable ball park figure.

The only caveat I would add is that some sailors, especially those less experienced at anchoring, sometimes overestimate the force when judging wind-speeds they are experiencing. I am talking about a genuine 20-25 knots not 10 knots with occasional gust into the low 20s that is sometimes loosely referred to as “it was blowing 20-25 knots last night”.

[noelex 77]

Originally Posted by kev_rm

Your scope is below what anyone would recommend. Got a 7:1 picture?

These are scopes cruising boats have selected. I have no control of the scope other boats select. I can only photograph the result.

A scope as high as 7:1 in 25 knots in 6-8m of water is not very common so I don’t think I have any photos of that type of combination.

The question was related to deployment of 30m of chain. All the photographs I have posted show boats that have deployed between 25 -40m of chain. Additional rope rode to extend the scope to your preferred 7:1 would not change the weight of the rode. The angle at 7:1 would be lower but the lifting of the rode would stay substantial the same as the total weight in the rode would be unchanged.

You can choose to dismiss the photographs if you wish. I can never capture the exact parameters you request, but I think the general concept is clear. It does not take much wind to substantially lift and straighten 30m of chain.

[HeinSdL]

Originally Posted by noelex 77

Another example. This was also in 25 knots of wind. In this case there is not only the chain, but a Rocna anchor that is acting as a kellet and adding to the chain weight. Nevertheless the total weight of chain and anchor is lifted off the bottom.

I am struggling to understand what's going on here. The Rocna is clear off the seabed (indicating a lot of tension), yet the Danforth is not dug in AT ALL! Just kind of relaxed there with an inch or so of each spade gently scratching the seabed. I give up! (but that fish there to the left of the Danforth is in agreement with me, it is also wondering, judging by its expression, how that anchor can do so well without bothering to dig in)