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Fore and Aft Anchors

Brian D

Moderator
Feb 17, 2006
4,531
Lancer 27PS MCB Camp Pendleton KF6BL
I know that when setting an anchor one should use a scope of 7:1 ~ 10:1 based on conditions of the seabed and surface. But if one wants to set a stern anchor, should one use the same scope as the bow anchor? Or, can one get away with lesser scope? The purpose of the aft anchor is to reduce the swing of the boat while at anchor.

Thoughts?
 

dLj

Mar 23, 2017
530
Hunter 30 Snug Harbor, Lake Champlain
Under the umbrella of using the stern anchor to limit swing, I use a 3:1 to 5:1 scope.

dj
 
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Brian D

Moderator
Feb 17, 2006
4,531
Lancer 27PS MCB Camp Pendleton KF6BL
Under the umbrella of using the stern anchor to limit swing, I use a 3:1 to 5:1 scope.

dj
Same anchor size, dj? Or are you carrying different size anchors?
 
Oct 19, 2017
5,058
O'Day 19 Littleton, NH
Great question Brian.
My take on this is all about the purpose of the stern anchor and circumstances.
As you said, the purpose of a stern anchor for maintaining steady position on your bow anchor shouldn't require the same holding power as the bow anchor. However, under a changing tide where swinging at anchor is to be expected, you may want to consider the consequences of finding yourself with the stern anchor becoming your primary anchor when the tidal current reverses. When I think about any long term (more than a couple of hours) anchoring, I would also expect there to be a period with a cross wind that works against your anchor set. Not being able to swing at anchor would result in a perpendicular vector of force working to bring both anchors together on the windward side. Having more scope out would help to keep both anchors set. In a crowded anchorage with limited scope availible to set the second anchor (backing down to twice the score, then warping back after dropping your stern anchor) means you work with what you got.

-Will (Dragonfly)
 

dLj

Mar 23, 2017
530
Hunter 30 Snug Harbor, Lake Champlain
Different size and type. I've also just used a weight with chain and rode attached to stop swinging. But the aft anchor will usually be smaller that the main anchor. Used to use a CQR up front and a Danforth in the back. Right now I have a modified Danforth up front and a small Bruce for the back. But I don't usually anchor where I have to worry too much, at least here on Champlain...

dj
 

dLj

Mar 23, 2017
530
Hunter 30 Snug Harbor, Lake Champlain
With movement from tidal changes I would not like to set a fore and aft anchor. I might set two fore anchors, only if needed, into a swivel so they don't get twisted up. Tidal shifts typically don't create the swinging that I had interpreted Brian had asked about. Tidal shifts tend to keep a boat pointing in one direction, and then the other. Swinging happens perhaps at slack tides. But in those cases I'd prefer to put up a small aft sail to stabilize the boat, or hang a weight off the stern essentially straight down to help minimize the movement. That weight might not even always be touching the bottom. I used to have a mesh bag I could put stone cobblestones in. It's pretty cool what all you can do with stones cut into large rectangles for cobblestones...

In the few times I've been in ocean tidal shift areas where I can't allow the boat to swing, it has been where I'm in a small cove. Then I would typically run long lines to shore - not to an anchor. Then you have all the scoping problems of tidal shifts that you have to figure out. A very different situation.

dj
 

Brian D

Moderator
Feb 17, 2006
4,531
Lancer 27PS MCB Camp Pendleton KF6BL
Since I don't anchor much, except to practice, I haven't taken into consideration changes in wind and current. So that kind of makes my question above moot. One would have to be on constant watch for changes in wind and water. And I guess in a crowded anchorage one must do as the others or else bad things could happen.
 

dLj

Mar 23, 2017
530
Hunter 30 Snug Harbor, Lake Champlain
Since I don't anchor much, except to practice, I haven't taken into consideration changes in wind and current. So that kind of makes my question above moot. One would have to be on constant watch for changes in wind and water. And I guess in a crowded anchorage one must do as the others or else bad things could happen.
Perhaps and perhaps not. If your boat tends to oscillate at anchor and makes you uncomfortable, then hanging weight off the stern will slow that down quite a bit (in all boats I've used it anyway) and you will still swing around on the bow anchor as wind and tides/currents push. It really just adds a dampening system into the swing...

FWIW....

dj
 

Brian D

Moderator
Feb 17, 2006
4,531
Lancer 27PS MCB Camp Pendleton KF6BL
Interesting. I have a 2.2# claw anchor that I never use. Might try dropping it off the stern next time I practice anchoring. See if it drags and when it does, will it dampen my swing enough to not worry. Might not, but one never knows until one tries.
 
Feb 5, 2004
3,934
Tartan 3800 Westport, MA
will it dampen my swing enough to not worry.
The more important question is, why would you want to dampen your swing? I'm puzzled.

I always anchor when I'm out. I have NEVER seen anyone with fore and aft anchors, and I don't think it's a very good idea in an event.
 

Brian D

Moderator
Feb 17, 2006
4,531
Lancer 27PS MCB Camp Pendleton KF6BL
As you cheer on your anchor...

Swing to the left, swing to the right, stand up sit down, bite, bite, bite. ( or is that a golfer whose ball just rolled by the hole?)

More for comfort I guess. Granted swinging on the hook does give different views. LOL
 
Jul 27, 2011
3,364
Bavaria 38E Alamitos Bay
The more important question is, why would you want to dampen your swing? I'm puzzled.

I always anchor when I'm out. I have NEVER seen anyone with fore and aft anchors, and I don't think it's a very good idea in an event.
Come to California sometime and you'll see a lot of it.
 
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Oct 19, 2017
5,058
O'Day 19 Littleton, NH
The more important question is, why would you want to dampen your swing? I'm puzzled.

I always anchor when I'm out. I have NEVER seen anyone with fore and aft anchors, and I don't think it's a very good idea in an event.
Granted, I don't have a lot of experience anchoring in different environments. Most of my experience is overnight oceanside bay anchoring where the anchorage is open and either we were alone or the anchorage was well established as a good anchorage. We did set a stern anchor once, in a river, I think, where the winds were affected by the shore. The problem with such an anchorage is that there may be periods of slack water, say when the incoming tide meets the out following river, and eddying currents and inconsistent micro fingers of wind can cause nearby boats to swing out of synch. In our case, we didn't want to swing into a shoal nearby. Weather, local water conditions and geography, as well as traffic all play a part in what you decide to do. I've not been on a boat that swung a lot at anchor, but I've seen them. You never know who your anchor neighbor might be until the weather comes up. Then, you don't want to have to move.

-Will (Dragonfly)
 
Jul 27, 2011
3,364
Bavaria 38E Alamitos Bay
Brian,
The answers to your questions depend on what you wish the stern anchor ultimately to do, as some of the respondents have noted. The critical situation would be if anchored relatively close to shore for say, shelter. So the shore is windward of you. You wish to put out a stern anchor to hold the boat offshore (i.e., does not allow it to swing around and drift toward shore) if there is a change of wind direction or other conditions. So, the stern anchor, if that occurred, might be holding the boat against the wind and sea. It should have the same holding power as the bow anchor. In my opinion, if anchoring overnight in that kind of setting, bow and stern should have the same holding capacities. That is, of anchor sizes rated for the vessel, with the same strength of rode, & SET to similar scopes, etc.

It's a different situation if the boat is anchored bow toward sea and a stern anchor is wished to keep the vessel aligned bow-on to the in coming surge or swells; or to prevent the boat from yawing extensively, as you noted. In that case, the stern anchor would not need the same holding power. So, it might be a smaller anchor set on reduced scope, etc., under the expectation of no significant change in conditions.
 
Last edited:
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Mar 1, 2012
1,820
1961 Rhodes Meridian 25 Texas coast
I have sometimes used a small anchor off the stern, but to one side, just to stop, or limit the swing. I would NEVER anchor bow and stern- when that is required i use a Bahama moor- both off the bow, which allows the boat to swing with tidal shifts, or wind change. In this picture there are actually two anchors attached at the bow, but the one led aft is just dropped inside the stern cleat. Bedtime comes, it gets picked up and dropped to the side so the boat can swing. The beach is just out of sight behind the dinghy
anchored at Cavallo.jpg
 
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Feb 5, 2004
3,934
Tartan 3800 Westport, MA
I've not been on a boat that swung a lot at anchor, but I've seen them.
By swinging I don't mean oscillating, or sailing around on the anchor or mooring, I mean the big, general condition caused by wind or tide, where everyone in the anchorage swings together. I want my nose into the wind at anchor, and I pick a spot where I won't be up against a lee shore. If there's any sea at all, a stern anchor can be dangerous, swamping you. A life was lost along with the boat out this way a few years ago, when a motor boat anchored by the stern to fish and a big wave swamped and eventually sunk it.
 
Jun 14, 2008
6,747
Hunter Legend 40.5 Long Beach, Shoreline Marina, CA
Whenever we did an overnight raft in Mariners Cove or other, we always set a couple of smaller stern anchors on a short scope to keep the raft from swinging around and twisting the rides. When close in while in Catalina, we, as the other boats, set stern anchors.
 

Brian D

Moderator
Feb 17, 2006
4,531
Lancer 27PS MCB Camp Pendleton KF6BL
@Rick D funny you should mentioned Mariner's Cove. I did a raft up there several years ago. I was surprised at how much we swung around. I don't recall anyone putting down a stern anchor.
 
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Jul 27, 2011
3,364
Bavaria 38E Alamitos Bay
I have NEVER seen anyone with fore and aft anchors, and I don't think it's a very good idea in any event.
So, I would agree that it's usually not a "good" idea. But I believe there can be times when it not only is a "good" idea, but maybe even an imperative one. Sailing a variety of venues, one sees things not done at home. A vessel that wishes to lay at anchor under shelter of a high rock or cliff face might want to be CLOSE. With gale winds blowing over, the best shelter would be close along side the rock/cliff. Bow and stern anchoring would be necessary to "moor" the boat in the best (i.e., correct) attitude awaiting passing of that weather. You sometimes see boats doing this at the islands here off CA.
 
Feb 14, 2014
4,027
Hunter 430 Saba Waveland, MS
I have a bagged anchor left by the PO and brand spanking new, never used it.

I thought about using it as a stern anchor to always face a 4th July fireworks show from off shore, with a lot of small boats nearby. I hesitate using a stern cleat for tie off in heavy seas, since it was not designed for a anchor.
_____
I do have two bow anchors with tie off anchor cleats for a snubber.

You got me thinking about two bow anchors dropped to form a...

Y

Wouldn't that work also?
Jim...
 
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