August 24, 2016

Sleeping well at anchor... [Updated Mar-2018]

One of the many joys of cruising is the feeling of liberation once you gain trust in your ability to anchor, in your ground tackle, and your method(s) of maintaining situational awareness. 

Denali Rose at anchor in Traitors Bay, Alaska [Near Ketchikan...] Great bear viewing area for only a 1/2 mile walk on shore... Hence the occasional float plane brings a load of cruise ship passengers for a quick tour.

Here we are anchored in 80 ft with rocks not necessarily close to shore bared at lower tides in several quadrants, and a large, very rapidly shoaling head of the bay which is aft of the boat in this photo.  [e.g., if the anchor dragged, the depth change is so abrupt, we would go aground before the anchor reached an uphill portion to reset upon...]

Just another typical anchorage in paradise...

Trustworthy anchoring is not unlike that feeling of accomplishment earned once you can quickly- and repeatedly- parallel park an automobile in a tight spot on a steep, icy road in heavy traffic. Not everyone gets there...

But this is not a discussion about how to anchor [nor parallel park...] This is about being able to relax afterward, while maintaining awareness... 

What do we do?

We begin by always recording a GPS track on one or more chart plotters when transiting, and especially when entering an anchorage area. [Many have tricky entrances and some require certain stages of tide as well for either optimied depth or current- or both...] 

That gives us a trail to follow should we have to bail-out of our anchorage in the middle of the inevitable tempest in the dark... [The author learned this the hard way... long, long story from long ago (pre-GPS) but with a happy, yet expensive, ending...]

While still tracking, we scout the area(s) where we would like to drop the hook by slowly driving in a circle repersenting the anchoring perimeter. This is how we evaluate the bottom and any obstacles within our chosen anchor zone... Our forward looking SONAR is also used during this stage. 

Before dropping the anchor, we will place the boat at the position we believe we want to drop the anchor [the center of the previously scouted perimeter] and perform a 360° turn-in-place [a back and fill maneuver...] to map the bottom with the forward facing SONAR from the anchor's view if you will. This is helpful later as we watch our swing at anchor. [Are we staying within the anchoring area we already scrutinized?] 

This also helps us to properly calculate the anchor scope required at high tide- especially on a bottom with uneven depth where the depth can often change by 100% or more depending where the boat is in the circle of swing... 
Side note: The 15-20 foot tidal variations in our present cruising area have negligible effect on the diameter of the circle of swing at anchor. [Use Pythagoras' Theorem to demonstrate this to yourself...] However, scope is affected- much more so in shallower anchorages [rare for us...] where tidal variation is a significant percentage of the depth anchored in.
We always continue GPS tracking once anchored. It is very informative to see where we have wandered while on our leash. It is also extremely enlightening if conditions worsen or we start getting hit with williwaws [katabatic wind gusts.]

Next, we always anchor as though we expect it to blow 60 knots. It only takes about 5 extra minutes to do this every time [and that includes deploying a bridle...] Because of this we rarely have to get up at oh-dark-thirty to deal with an anchor related issue. [Our own anchor anyway...]

OK. We're anchored. Now what?

Diligently maintain situational awareness while we enjoy doing other things...

This means staying cognizant of our boat's position with relation to land; other vessels and obstacles 
around us [above and below the waterline...]; the tide, weather, etc. 
When we anchor with the intension of leaving the boat [e.g., kayaking, a shore trip, visit another boat, or whatever...] we always wait at least an hour to confirm our swing [wind/tide] at anchor is as anticipated, and that the anchor location doesn't move without our knowing... This also give us time to recheck the weather, tide, anchor scope calculations, etc...
How do we maintain situational awareness full time while at anchor? [Hint: You can't if you ever plan to sleep...]

Since we spend a majority of our time in our pilothouse when on the the boat at anchor, we are always visually aware of what is going on around us [except when very dark or when sleeping...] If we are concerned about anything around us, we sleep in the pilothouse where, with just a sit-up, we can quickly glance outside. If an anchor watch is needed, the pilothouse is a welcome place in foul weather...

What about when we both sleep with no anchor watch? [i.e., normal circumstances...]

We typically set multiple anchor alarms, may set RADAR with guard zones set, always transmit and receive AIS, always depth alarms, and sometimes marine radio(s), etc. as needed.

On prior boats in the days before GPS [and then for a time, dithered GPS; hence no accurate anchor alarms] a tell-tale compass in one's berth area was somewhat handy to help with orientation when awakened at anchor and during a passage. But it didn't show one's position nor surroundings. One had to get up and look around.

Today we set 2+ separate GPS enabled anchor alarms.

We always use Drag Queen [which allows manual adjustment of actual anchor position].
Update Nov-2017: With Apple's update to iOS 11, Drag Queen no longer works on our devices. We will watch for new versions in the future, but haven't seen any in months...
We are now experimenting with Anchor! and so far find it to be a robust and detailed graphic anchor watch application...
To follow what other applications we are using/evaluating see our meticulously maintained page Computers, Devices, and Applications [we have and use...]

We always set anchor alarms on our Vesper Watchmate Vision AIS transponder and one of our Zeus2 MFDs. Depending upon circumstances, we might also set one or two tablet anchor alarms, a RADAR alarm and, if within cell phone range, our remote vessel monitoring system

All alarms are set with ever increasing- but safe- parameters. In this way they go off one at a time if things are happening slowly...

Setting several alarms takes very little time and provides the needed redundancy.
A note about the geometry of anchor alarms: 
Are you familiar with the GPS position error [up to 2x...] so common in most anchor alarms? If not, read this article from Boat US- which includes description of a fail-safe technique for setting two alarms on different apps.
Note that Vesper AIS transponders with anchor alarms updated in 2016 compensate for this error. 
Do you know of other products that compensate for this error? Please let us know by leaving a comment.
We also each have tablets with very accurate built-in GPS running navigation software as well as a mirror of the MFD showing the vessel's position and an overlay RADAR image, etc. These are always within reach- especially when sleeping.

If expecting weather or vessel traffic, or if either occur unexpectedly, we set zone alarm(s) on the RADAR [our 4G consumes very little power...] to warn of other vessels [or land...] encroaching on our comfort zone. 

The RADAR image is also viewable on our tablets- which is handy when awakened by a RADAR alarm while sleeping. We can quickly assess and mute the alarm from the tablet, and of course get up if necessary, or roll over and go back to sleep if not... [e.g., a dinghy passing through our RADAR watch zone is not worth getting up over unless they are coming to see us...]

Changing the depth alarm to suit is also important to us on those rare occasions we anchor in water shallower than 60ft at low tide... [This is another anchor watch function of the Vesper Watchmate Vision AIS.]

The Vesper AIS also allows us to set wind alarms [direction and or speed changes.]

If we only set one anchor alarm device, which one would we choose?
Without question it would be the Vesper Watchmate Vision AIS. [It is always set first regardless...]
Why? [Following is from the manufacturer's website:]

Safety at Anchor – Anchor Watch

Every sailor knows that being at anchor is no guarantee of total safety. In particular, anchors can drag without those on board being aware. Thanks to Anchor Watch, however, you can be safer and sleep well at night. That’s because Anchor Watch sounds the alarm if you drift outside a zone defined around your anchor position. Activate the anchor watch when you drop the anchor touching the Vision screen or using a mobile device to activate it remotely from the windlass or anywhere on-board.

Wind speed, wind direction change or minimum water depth alarms

Get added safety at anchor by setting wind speed, wind direction change and minimum water depth alarms and take quick precautionary action when these alarms are triggered.

Move Anchor Position

If your Anchor position needs fine-tuning after you have marked it, you can do that with the Move Anchor Position.


Vision plots your position in relation to the anchor and marks your positions over time for easy visual identification if you are dragging.

What about the flip-side: helping others become aware of us?

We have a large Blipper radar reflector mounted high on the main mast. [I imagine some may wonder why we stow a fender way up there...]

We also broadcast our position on AIS 24/7 when away from a dock. Additionally, our Vesper Watchmate Vision AIS transceiver allows us to tune alarm thresholds for different scenarios [including AIS Filters, depth, and wind direction and velocity.] Therefore, while at anchor we don't have any distant vessel alerts waking us up- only potential close encounters as established by values we set... [And the AIS is wired to an optional, very LOUD external alarm, and is viewable on our smartphones and tablets...]

To enhance our vessel's visibility to others when we are at anchor in the dark [remember it doesn't always get dark overnight in higher latitudes during summer...] in addition to the masthead anchor light, we also deploy 2 portable anchor lights about 7 feet above the deck near the bow and amidships. We have a 3rd anchor light [just like the portables] mounted on the stern davits- which also functions as a davit light when we are using the dinghy in the dark...

These deck level anchor lights are visible for 2+ miles and, since they hang upside down, do a nice job of illuminating the deck, too. This makes our boat very visible both from both water level and a distance. [Mast head anchor lights are difficult to spot/ triangulate from water level when close-to. Ours is 60 feet above the water...]

All [4] of our anchor lights have dusk-to-dawn photo sensors, so they are self managing.

What do we do when other vessels enter our self proclaimed 'safe zone'? [e.g., A 200 ft radius set on the RADAR.]

The first thing we do if there is vessel traffic encroaching on our safe zone in the dark is turn on our two LED deck lights [one on each mast of our ketch...] We have a switch next to our berth as well as in the pilothouse and cockpit. We can also turn them on remotely with our smartphones via the remote vessel monitoring system when we have cell signals. [This is handy when returning to the boat from the dinghy, kayak, or when on a dock.]

This adds more light to our deck, and perhaps indicates to the other vessel we know they are there...

We have a button in our sleeping cabin [as well as both helms] that allows us to sound the air horn [and a klaxon] if necessary should we decide a wake-up call is warranted for another vessel... [Or to alert uninvited guests on deck we are aware of their presence, which is a non-issue in our current cruising grounds... unless herons count...]

In dense fog, or if we have to anchor in a non-traditional area [e.g., an emergency requires we anchor where we are- possibly in the open location or fairway where other traffic might not expect it...] or other extenuating circumstances requiring appropriate sound signals, we broadcast the appropriate signal over the PA horn via our VHF radio. [The PA horn also acts as a microphone which is handy when transiting in low visibility situations. You can hear waves, other boats, people, fog horns, etc.- especially when motoring...]

Of course, it never hurts to keep the habit of flying the appropriate day shapes as well... [This is enforced in some areas/countries; for our sailboat a black sphere while at anchor, and a black cone pointing down while motoring...] Dayshapes signal our vessel's status to anyone near enough to care...


Using these techniques and approaches, we typically sleep very well at anchor- but always with a heightened level of situational awareness.

All of these modern electronics consume so little power that we don't hesitate to avail ourselves of their charms as needed.

Of course we don't rely solely upon electronics to keep watch- they are like any other aid to navigation; we don't count on any single one... Instead we post anchor watches during times of concern [regardless of reason] and I always check the physical world anytime I have a 'feeling' [What was that?] or am up for any other reason...

Always anchoring as if it will blow 60 kts with excellent, proven ground tackle and having a selection of trustworthy, dependable, proven electronic aids to back-up our physical monitoring enhances our levels of relaxation and comfort while at anchor. [And we are typically the only boat at anchor where we are exploring these days...]

Do you take any special measures to to help you relax while at anchor? [Favorite Sundowner recipes welcome!]  Please leave us a comment.

Related resources:

Denali Rose Ground Tackle Inventory
Computers, Devices and Applications we use


  1. We've had to use our GPS track to bail on dodgy anchorages in the middle of the nights. It's such a lifesaver to know you have a "safe" route already mapped out.

  2. So true, Ellen. It is to the point that if for some reason we didn't record a track on the way into an anchorage, I will go back out and do it again... I also like to track the circle of the estimated scope perimeter I navigate before dropping anchor.

    Tracking on an iPad after anchoring is very interesting too. You can quickly spot the deviations if conditions change.

    This personal requirement comes from an experience almost 3 decades ago [before GPS] when I was blown off the anchor [it broke, actually...] in continually reversing 70 knot williwaws and of course the RADAR and 12 volt spot light both failed... Talk about blind! It was a very bad night [week, as it ended up...] for me in that small bay, but a good one for Murphy...

    Here is to no one having such experiences again.


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