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Old 06-24-2020, 11:22 AM   #1
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Swing on the hook

Hi All,


We are just starting to anchor and I'm reading all I can about the subject. We've practiced and know our equipment (300' 5/16 chain) with a Bruce.
I found this big algebraic formula for calculating "swing". What do you do to calculate, guesstimate etc. for swing when you go into an anchorage that has other boats? We're going out this weekend for our first overnight on the hook... which will include 2 tides changes or more depending on how long we stay.


Thanks - Dave
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Old 06-24-2020, 11:51 AM   #2
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All boats swing differently, but the pattern is the same. Tide and wind will in general keep all boats down current/wind including the other ones in your anchorage.

My rule of thumb is to stay away from others. Few things are as irritating than being in a anchorage and looking out to find another boat 50’ away.
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Old 06-24-2020, 11:56 AM   #3
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Read the book by Earl Hinz; Complete Book of Anchoring and Mooring.

Definitive bible on the subject of anchoring.
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Old 06-24-2020, 01:07 PM   #4
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In steady winds with no current, boats will swing back and forth roughly 30 degrees side to side of the wind.

But with moderate winds and a tide change building to a fairly strong current, boats can go anywhere. I have gently bumped into boats several times over the years and it was always in that situation- most recently at the anchorage in front of Fernandina Beach and twice at the anchorage off of the CG station in Cape May.

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Old 06-24-2020, 01:15 PM   #5
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Read the book by Earl Hinz; Complete Book of Anchoring and Mooring.

Definitive bible on the subject of anchoring.


Sailboats with deep keels are pushed around by currents and powerboats more so by wind, so they can swing differently.

A large sailboat anchored near us after dark once, and woke us up later by knocking on our hull. They suggested we should move. I said no. It was a stalemate, so we both shortened our rodes (it was a calm night).

The Hinz book confirmed my suspicions: if there are any issues, the last boat in is the first one out.
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Old 06-24-2020, 01:23 PM   #6
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Check out handheld rangefinders...better at estimating distance over water than I'll ever be!
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Old 06-24-2020, 02:20 PM   #7
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Be aware of the currents where you will be anchoring. I eyeball everything which means I'm about right half the time. Try to get a sense of where your anchor is relative to your boat. That will tell you where you are likely to be when the tide changes.


Keep in mind that not everyone around you will have the same amount and type of rode out. This means you will swing differently. Try to account for that.


Where are you headed this weekend?
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Old 06-24-2020, 03:12 PM   #8
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You can always set your radar to .25 rings and keep other anchored boats outside if that if you can.
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Old 06-24-2020, 04:23 PM   #9
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Some people drop a stern anchor in crowded anchorages.

Also , depending on the boat, some people nudge up onto the shore. Run an anchor line up to a tree or a rock and you won't go anywhere. (watch for tides)

But the best solution is to find a less used anchorage.

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Old 06-24-2020, 04:31 PM   #10
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We are really lousy at estimating distances. I start out by assuming everyone is on 7-1 scope; on our boat, 5-1 was usually ample in non-storm conditions. If at all possible we try to anchor away from (outside of) the crowd that exists when we arrive. As Menzies suggests, we double checked using radar, and monitoring the motion of the group as current / wind shifted. Sometimes we might go around to the surrounding boats just to say hi and invite them to cocktail hour on our boat, and while we were at it ask how much scope they had out. We've made some very good friends over the years that way.
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Old 06-24-2020, 05:09 PM   #11
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Keep your distance from others until you learn how your boat behaves. Your boat may (probably) tack back and forth. It may not and stay arrow straight, but others may tack into you. In very light winds your boat may swing around the anchor in the opposite rotation than the other boats. Current can affect your boat different than the others.
Read your windlass manual to see if you must use a snubber, bridle, or chain locking device to unload the windlass.
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Old 06-24-2020, 06:38 PM   #12
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Some suggestions. Get a range finder. Inexpensive and they give accurate distances with no fuss or muss. You could use your radar, but the range finder will tell you quickly within a foot or so.
The worst time to anchor in a crowded anchorage is in "no wind or current". You can't tell where anyone's anchor is located or how they are lying to it. Give extra space under these conditions if possible.

So assuming a decent wind or current, the boats' anchors will be in front of them somewhere. Once you know what depth you will be anchoring in, you can figure out your swing room from your scope. So for example, in 10 feet of water with a scope of 5 to 1, you will swing approx. 50 feet in any direction from your anchor (50 foot radius plus your boat length). Ideally then, don't drop your anchor any closer than 50 feet (plus your boat length) (better 100 feet so in theory your circles don't overlap) to another boat. This is a starting point, but often people will come in after you and anchor in between you and another boat, taking up some of the "room" you left.

As Murray stated, the last boat in is the one that is supposed to move if a problem is expected or develops. When a boat comes in and anchors too close, I take photos, note the time and distance measurements and put it into my log, where I have already noted my time of arrival, depth, scope, etc. just in case of an insurance claim (never needed it yet) . In most cases, people coming in after you will move if asked, especially when told how far away they actually are (how close).
Lay your anchor down at the spot you have determined is good, and when the anchor is on the bottom, slowly back up while laying out your rode. Once your have reached the necessary scope, "set your anchor" by applying reverse throttle to ensure it will hold. Depending on your boat and HP, idle may be enough or part throttle. I am usually happy when my chain rode goes totally taunt and judging by our surroundings we are no longer moving. When the boat is put into neutral, it will move forward, which is another good indicator that you are adequately set.
Don't forget to use a bridle or "snubber" to take the load off the windlass even when "setting".
In a windy crowded anchorage, motor up behind a boat, keeping the correct distance side to side from other boats, and drop your anchor at least "half your scope" back. The boat you are behind should be at or near the end of their scope under those conditions. You will need a minimum of 2.5 times your scope between boats (fore and aft) of where you want to anchor when windy (more would be better).
Better yet, find an anchorage with lots of room.
Some good info from others already. We try for a 5 to 1 scope (unless big winds are expected) but sometimes have to settle for less (never less than 3 to1 for my comfort).
Edit: Always calculate scope for high tide and never anchor in a spot that has less than your boat's draft at low tide We can have some large tidal swings in our area.
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Old 06-24-2020, 07:02 PM   #13
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Originally Posted by Pete Meisinger View Post
Some people drop a stern anchor in crowded anchorages.
While this is true, some people also park across multiple parking spaces and in handicapped spots without tags.

Unless everyone else is also anchoring with a stern anchor, or you are against the shore, this becomes an issue. When you do this in the middle of an anchorage and nobody else is using a stern anchor, then when the wind and tide shifts, they stay in place and everyone else around them swings around their radius.

this causes a lot of issues and forces everyone else around them to toss out stern anchors. Now none of us get the breeze in our hatches.....THANKS!!!

The best thing to do is do what everyone else is doing. Ask the boat behind you how much line they have out, and make sure to drop behind the transom of the boat in front of you. This will ensure that when everyone swings, there is room.
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Old 06-24-2020, 09:58 PM   #14
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The below photo shows the ideal separation distance.
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Old 06-24-2020, 11:33 PM   #15
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You'll get a feel for it. One of the most difficult things is that local customs often dictate how this will play out. For example, it is rare here in the PNW for boaters to put out as much scope as many wish. My standard is 5:1 in normal weather and normal holding conditions, but that will get me into trouble swinging into the neighbors in many anchorages, where 3:1 or even 2:1 seem to be most common. We've learned that adjustments may be needed, up to and including weighing anchor and moving farther away from folks who don't seem to understand what's going on. I'd rather do that than be fending off other boats at 2 am. It does get uncomfortable at times when you're just distanced perfectly from the neighbors and some lunkhead plops down right in the middle, but I'd rather call their attention to the concern and risk prickly feelings than feel the big CLUNK in the middle of the night.

Having an anchor watch app on your phone or tablet is a wonderful way to really learn how your boat swings and what scope and tidal range do to influence the boat's excursions. Have a good spotlight or flashlight at the ready to help you sort out what's happening after dark when the tide turns.
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Old 06-25-2020, 05:38 AM   #16
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Read up on the Bahama Mooring method of anchoring , no real swing perfect for a crowded anchorage.
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Old 06-25-2020, 06:39 AM   #17
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I found it better to snub off one side only and a bit back from the bow. That way there was asymmetric loading from the wind and I didnít sail around as much. But my boat was an aft pilot house style so it tended to ride better anyway.
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Old 06-25-2020, 12:31 PM   #18
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Read up on the Bahama Mooring method of anchoring , no real swing perfect for a crowded anchorage.
This is a recipe for disaster if you are the only one who isn’t swinging with the current. Everyone else will swing and you won’t and they will swing into you.
Also having two widely separated anchors and rodes will almost guarantee that some one will lay their rode across yours. What happens if you want to leave before them?
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Old 06-25-2020, 01:07 PM   #19
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This is a recipe for disaster if you are the only one who isnít swinging with the current. Everyone else will swing and you wonít and they will swing into you.
Agreed!! This is just about as bad as using a stern anchor in the middle of an anchorage. The reason I'm vehemently pushing back is you guys are giving advise to a new boater, who will accept this as standard practice, as will anyone else who finds this post for years to come.

The golden rule is 'Do as Everyone Else is Doing'. If everyone is Bahama moored, then Bahama moor. If everyone is using stern anchors, then use a stern anchor. If everyone is on a single bower, then PLEASE do that!!

Ina tight anchorage, it is very likely that as you rotate around 180 degrees, you will be in the spot of the boat previously in front of you, and the boat behind you will not be in front of you. If you don't move, one of them will now be feet away if not hitting you.

Doing contrary to what everyone else is doing, or what is commonly practiced in that area is obnoxious. If you don't know gues (HINT: single bow anchor only is the most common unless swinging over a shoal, shallow, shore or channel will occur).
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Old 06-25-2020, 01:16 PM   #20
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Agreed!! This is just about as bad as using a stern anchor in the middle of an anchorage. The reason I'm vehemently pushing back is you guys are giving advise to a new boater, who will accept this as standard practice, as will anyone else who finds this post for years to come.
I couldn't agree more but don't limit that remark to just anchoring! There are numerous posts from time to time on various topics that are wrong in my opinion.
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