How Much Scope?

[sailorboy1]

I was at a new for me anchorage this past weekend. The bottom was rocky and I used a plow anchor and about 5:1 scope and was off to the side of the main pack of boats. Would have put out more scope, but it was deep and that was about all I had. I also drug the anchor while trying to set it. But I noticed the other boats probably only put out 2:1. Seemed for the most part others were just dropping the hook and hoping it set. Everyone seemed to be using a rope/chain rode so the "all chain" answer doesn't apply. I could tell if the wind direction shifted I was going to swing into the pack even though I was pretty far from it.

So is it normal for people to only use a 2:1 and drop thier hooks with their boats only maybe 40 feet apart? Or am I being a worry wart. If the wind had shifted it would have been me with the most line out and the furthest from the pack that probably would have been the problem (assuming everyone's anchor held).

[GordMay]

Originally Posted by Don Lucas

... So is it normal for people to only use a 2:1 and drop their hooks with their boats only maybe 40 feet apart? Or am I being a worry wart. If the wind had shifted it would have been me with the most line out and the furthest from the pack that probably would have been the problem (assuming everyone's anchor held).

No.

Often, many people reduce their scope ratio in “deeper” water (you don’t specify depth, but having used your entire rode @ 5:1, I assume it was a “deep” anchorage).

I don’t think, though, it’s usual to sit to a 2:1 scope, which is too little, even in “ideal” conditions; where (in a crowded anchorage) your 5:1 scope might seem, to others, a little “selfish” (tho’ prudent).

[Talbot]

IMHO, the scope used tends to be different for a lot of reasons:

inexperience/lack of knowledge
lightweight anchor/chain versus All chain and heavy anchor
length of time stopping (e.g. lunchbreak versus overnight)
knowledge of the weather

Personally I dont go by the 3 to 1 or 5 to 1 rule, I reckon that absolute minimum is 20m and then work at about 4 to 1 depending on circumstances using a mixed heavy chain and rope rode on a good sized anchor. But that has been anchoring in goood holding mud. I would definitely be lookig at the chart symbols for the bottom material, and adjusting in accordance with the holding.

[swagman]

I'm also with Gord and Talbot - circumstances dictate what is right or not.

I usually do adopt the depth x 4 ratio or even x 6 if holding is noted as poor, but in a crowded summer anchorage it is not good to quote the book when boats are banging together. You need to adjust and accomodate with what works for your neighbours.

Enjoy

JOHN

[Kefaa]

I have been taught that 7:1 is ideal in any condition and under some 5:1 is acceptable (rock being a good example). As the point is to give the anchor maximum holding power, 2:1 is unreasonably tight with other boats in the swing radius and any tide or current, is going to change the angle of pull enough that it may unseat the anchor.

Here is a discussion/article on length The Perfect Anchor Rode - SailNet Community

I will post the physics example someone sent me a while back if I find it.

[Southern Star]

John, I agree that you have to adjust to the circumstances including the local practice. That being said, 2:1 just doesn't cut it. If there is any chance of a blow I still try to go to 7:1 - particularly if I am one of the first boats to anchor. And if there is insufficient room in an anchorage for proper scope considering the bottom and the forecast, I move on.

Brad

[sailorboy1]

Thanks for replies. I admit I'm not all that experienced and tend to "go by the book". Some more info to maybe help my knowledge base on this one:
1 -depth was 50' when we dropped the hook at high tide with a tide change of about 9' expected, used a 35# CQR with 30' chain for my 39' boat
2 - bottom was rocky ledge and kelp per the guide
3 - was in the lee and wind that night was expected not to shift and to be about 10 knots (but all year the weather people have been telling lies)
4 - guide book stated the holding was poor, but an on-line search stated it was good in "settled conditions" and another article I saw the cruisers said they drug all the way across the anchorage, so I figured the holding was poor generally but Ok given the conditions
5 - I let out about a 4:1 before I set the hook, but I could tell I had drug and the next morning when I pulled it up figured I was about 50' from where I dropped. That amount of drag would have been a problem out in the pack
6 - I was out further off the side from the main mooring anchor field, but there was a 60 footer off my beam further out who also didn't seem to have all that much scope out (they may have been all chain)
7 - maybe possible that where I was the holding was different than out in the "pack" area and those there knew this

thanks for any more guidness, I look forward to the time that I sleep well at night at times like this

[George Wade]

The scope needed is whatever holds you securely. If it needs changing as wind and tide change, then change it; though two anchors may hold through changes in direction of wind and tide. So the book gets you started, then the real world dictates what is actually required.

thanks for any more guidness, I look forward to the time that I sleep well at night at times like this

Ships keep an anchor watch, sometimes we should, too. Even alarms of varied kinds.

[cchesley]

I think you're running into a common problem that we all face. Most of the above posters believe that 4:1 up t 7:1 are about the minimum they're comfy with. I share that. The reality 'out there' on our US waters in the summer is that there are far more of the weekend sailors who 'might' use 3:1 ("It just seems like so much rope, honey") The net result is that if we choose to anchor anywhere that is popular, we are at risk.

Frankly, I have shifted much of my cruising to the shoulder season because except in mild, settled conditions, I do not care to put myself at risk both by using short scope AND by being in too close proximity to others who use short scope. I also tend to go places that few others will go whenever possible for just these reasons. That's not all bad either.

[thinwater]

Originally Posted by Talbot

IMHO, the scope used tends to be different for a lot of reasons:

inexperience/lack of knowledge
lightweight anchor/chain versus All chain and heavy anchor
length of time stopping (e.g. lunchbreak versus overnight)
knowledge of the weather

Personally I dont go by the 3 to 1 or 5 to 1 rule, I reckon that absolute minimum is 20m and then work at about 4 to 1 depending on circumstances using a mixed heavy chain and rope rode on a good sized anchor. But that has been anchoring in goood holding mud. I would definitely be looking at the chart symbols for the bottom material, and adjusting in accordance with the holding.

I've anchored on too many bottoms that varied from spot to spot.

Better, go by feel on the set: quick and firm, probably sand or sticky mud; vibration, probably shells or small rocks; catch a bit and then drag with some resistance, perhaps weed. It depends on the anchor and I have worded it badly, but learn to read the feel coming up the line. You need to judge if it is well set, or just momentarily caught.


If you are going to anchor short, still set long.

[Kefaa]

You need to adjust and accommodate with what works for your neighbors.

To some extent - (e.g. not running 10:1), this may be true, but my neighbors may be those without experience or knowledge or concern for others. We all see them later saying "I always put my anchor down like this and never had the problem before..."

Like Brad suggests, if it is too uncomfortable, move on. If you are staying, then do what is safe and if you need to have the discussion with other boaters you can. But I doubt most will bother and those that do are either interested in learning what to do, or they are able to explain why this is an exception.

[Vasco]

I usually try to anchor in less than 10 feet of water if possible. If there's room I put out 100 feet of chain. This way there's no crazy fire drill at four in the morning when a squall comes through. Most of my cruising friends take this approach.

[cchesley]

Originally Posted by Vasco

I usually try to anchor in less than 10 feet of water if possible. If there's room I put out 100 feet of chain.

Oh, forsooth, would that that were possible, here in the PNW. 20-30' is a shallow anchorage and sheer heaven per this discussion!

[imagine2frolic]

I took a beating for this before, but I agree with Vasco, 10-1. I like to leave the boat, and sleep through the night. If I can't get out enough scope to do both I will move on. I too do my best to get in under 10' of water......i2f

[sailorboy1]

It occurrs to me that when I brought my boat north after buying it and I had a capitain on board due to insurance requirements; we anchored in a protected harbor that was empty. When I put out the hook and got to 4:1 he said that was enough (I put out more anyway). After we had floated back a while and the hook "seemed" set I throttled up in reverse to be sure it was set and he said that wasn't needed. Maybe some people, even lisicend capitians, just aren't as worried as I am! Or maybe I just prefer to be sure.