Navigation Tips for Day and Night – Don’t Become a Statistic

Coast Guard Auxiliary boat crews receive excellent training and must pass their initial and requalification checkrides to demonstrate competency.  While the vast majority of patrols are executed safely, there are those where mishaps occur and it’s no surprise that the worst of them occur at night.  Many factors are at play – the skillsets of the coxswain and crewmembers, weather, fatigue, and more.  But the combination of your skills and the diligence to apply them are the most critical to keeping safe.

Night ops can be very rewarding and I personally enjoy them due to the additional challenges needed to both be safe and to accomplish the mission.  There is no point to pushing out into the darkness if you can’t do the job – you definitely need to be “on your game”.  You might even be forced into the night as a result of a mechanical issue or other factor that unintentionally stretches out your patrol duration. 

To qualify as a crewmember or coxswain, you must complete a night patrol per the Boat Crew Qualification Guides.  But there is currently no requirement to conduct any night patrols to maintain your currency so it’s entirely possible that you only do one night patrol (two for coxswains) in your entire Aux career.  It’s pretty easy to see the potential risk when folks are not on their game at night.


What are some of the causes of night mishaps?  Here’s a list which is by no means complete:

  • Incomplete risk assessment
  • Excessive speed
  • Poor lookout
  • Low situational awareness
  • Physical (vision) color blindness
  • Lack of proper navigation
  • Electronics unfamiliarity
  • Helm unfamiliarity
  • Fatigue from long day
  • Get-home-itis
  • Unfamiliarity with the Navrules (lights, stand on/give way)
  • Unfamiliarity with the region
  • Flotsam

Some of these items require a high degree of diligence in order to be safe.  They require you to “follow the rules” and be squared away.  Sometimes boat crews relax and get casual on things like line handling commands or proper radio prowords, but all of these things are important to be safe and effective.  At night they are critical.  When I talk to boat crews I regularly hear comments like “that’s not how we do it”.  

There are two opposing ways to look at how folks consider key knowledge and skills:

Opinion 1 – “All that policy stuff is not really necessary”

Opinion 2 – “That’s the policy but also the lore of the craft so excel in it”

Do experienced operators really do these things?  YES!  Cutting corners does not make you more “cool”.


This is a bell curve I came up with that illustrates the population and their focus on being squared away (or not…):

We’ve all seen this in all areas of our lives.  Novices in any endeavor tend to follow the rules and be very careful.  As they get more experience they begin to “know it all” and relax on important practices.  Then there are the true experts, who know the importance of following the rules (perhaps as a result of bad experiences) and are again very attentive.  A similar concept exists with airplane pilots – the most dangerous pilot in the sky is the one with 200 flight hours. 

I used to give a lot of sailboat instruction and I saw the same sort of bell curve related to the volume of the skipper.  Low time students were pretty quiet, the intermediate skippers were the screaming Capt. Bligh’s, and the highly experienced sailors were quiet and effective.  Not surprisingly, the male skippers were a lot louder than the female drivers, who also tended to learn more quickly because they listened and “followed the rules”.


What are some of the things to pay special attention to at night?

  • THOROUGH briefing (discuss night vision)
  • Full facility check (including compass light, spotlight, wipers)
  • Weather (visibility, wind, tide, current, waves)
  • PPE check (don’t forget the strobe light battery)
  • Personal flashlight (I prefer a headlamp with a red mode)
  • Which pocket is which PPE?
  • Anti-exposure coveralls – make sure head flotation inflator is in place, zippers secured, straps/belt properly latched
  • Electronics review (chartplotter, depth sounder, radar)

Don’t forget that it can take as long as 30 minutes for full acclimation of your night vision, and just an instant of white light kills it and starts that clock all over again.  Turn down the brightness on all instrumentation and electronics, and make sure the lookouts are protected from bright light sources.

Before getting underway, use your checklist and don’t forget to:

  • Check your gearbox(es) and throttle(s) while still moored to assure proper operation. 
  • Check your steering from lock to lock. 
  • Check your navigation lights and consider adding additional shielding that might reduce reflections back to you (but maintain compliance with Rule 21 of the Navrules).  Black tape around the bow pulpit rail helps for glare from the masthead light.
  • Post proper lookouts who are up to the task and squared away
  • Make sure communications are clear between members and make it understood that there will be a briefing before any evolution.

Create a navigation plan.  Don’t just look at the little boat symbol on your chartplotter like it’s a video game.  Lay down a route, check distances, confirm fuel aboard.  Also – turn off the “tracks” or “trails” function on your chartplotter.  It ends up cluttering your screen into a big mess and obscures important information.  If you don’t have a chartplotter, use a paper chart and create a table of landmarks and navaids with bearings.

Are you up to speed on your Navrules?

After getting underway:

  • Regular engine compartment checks every 30 minutes – check for leaks, smells, sounds
  • Rotate duties – fatigue happens faster at night especially when wearing anti-exposure coveralls (which I insist on at night regardless of temperature).
  • “Slow is smooth, smooth is fast”
  • What’s the most important safety device on the boat?  Answer here


Keeping track of your position and knowing how to get to your destination at night is both more difficult and more important and that’s a recipe for disaster.  So it’s critical to do a good job of it.  Many small boats don’t have a chartplotter, and even those that do need to be prepared to use manual methods in case it fails.  There is also little or no room to stretch out a chart and maintain a proper navigation plot.  Fortunately, there are skills and methods you can use to maintain a safe navigational situation at all times, on any boat no matter how small.

Don’t rely on floating aids to navigation, especially a single one.  It might not be on station.  And a displaced buoy is more dangerous than one that is “not watching properly” (unlit) or missing – if you see it you might rely on it and proceed into a hazard.  

When you see a desired light you should measure the light’s period with a stopwatch – don’t use “One Mississippi…” – at night, every light tends to be the one that you are looking for when you’re tired and you want to get home.


When in an area of currents and high wind, the combination will set you off your intended track and your heading might be significantly different than your Course Over Ground (COG).  In other words, your bow might be pointed in one direction and your boat is actually moving over ground in a very different direction.  During the day it is easier to intuitively compensate but at night the difference might not be obvious at all.

In this example, the boat’s heading is 231 degrees (heading out of the channel on the boat’s port side) while the COG of 241 degrees is still in the channel.  In which direction is the current setting?  This boat will need to carry a 10 degree angle to port with respect to the channel in order to stay in it.


A similar concept (and hazard) exists with a phenomenon called “homing”.  Consider the image below:

You might be approaching the first pair of buoys at a harbor entrance and you aim your bow towards them and all looks good.  Several minutes go by and you are still steering towards them.  You probably haven’t looked at your compass and you don’t even realize you are unknowingly adjusting your steering as the result of a current.

In other words, it’s not good enough to be heading towards the entrance – you need to be aware of what COG is needed to clear any hazards.  Just sight over the main compass or use a hand bearing compass and note the bearing to your destination, regardless of which way the bow is pointing.  You might be carrying a significant wind and current correction angle but as long as you monitor your COG you know that you are tracking the desired path over the bottom.


You can also use “danger bearings” to ensure you are staying in safe water.  This might be the single most powerful navigational technique you can use to avoid hazards. 

Assume you are heading northward near Half Moon Bay in California and want to make sure you are well clear of Southeast Reef.  There is a red “2” buoy marking the northwestern end of that reef.  Using a chart (before you even leave the dock) you can measure the bearing needed to ensure you are always west of the reef and then you can make the proper chart notation as shown.

While convention is to always plot in degrees True, this example shows the bearing in degrees Magnetic to make it easier and less prone to error when correcting for variation and using a hand bearing compass.  You can also momentarily steer the boat towards the buoy and note the heading on the main compass.  As long as that bearing is no less than 316 degrees Magnetic, you know that you are west of that line.  

As mentioned before, you should not rely on a single aid to navigation (especially a floating one) – this example shows a way to compare navigation data and confirm your location.

This example also assumes zero deviation – you should check your deviation card and apply the correct value to derive the proper compass bearing.  And you should get your compass adjusted to minimize your deviation as well.

Here’s another example of danger bearings in San Francisco Bay, just north of the San Mateo Bridge.

Once you pass the lighted daybeacons at San Bruno Shoal, it is 4.7 NM to the San Mateo Bridge along a poorly marked route with very shallow waters on each side of the channel.  By setting up NMT and NLT danger bearings you can just glance at your compass with the bow pointed directly at the center span of the bridge and know you are not running into shallow waters.  You can note these and other bearings on a reference card so that when operating in your regular AOR you have them handy at all times.


You can use bearings to objects to determine when you should make a turn along an intended trackline.  In the example below, the boat is traveling southeastward along the Half Moon Bay coast and is intending to turn eastward between the reef hazards.  This is a particularly hazardous area and you do NOT want to get it wrong.

The boat is on its intended course and takes buoy G “1” down the port side as expected.  Ahead the red “2” buoy is also visible, as well as the light on the end of the breakwater off to port.  As the boat progresses, the bearing of the breakwater light should be monitored until it bears 008 degrees Magnetic and then the turn can be made between the reefs with the green buoy to port and red to starboard.  

Note that we are NOT relying on the green “3” buoy as the turn reference.  The light on the breakwater is in a fixed position and much preferred.  After the turn, we expect to pass between the two buoys as a secondary reference check.

Once again, we are departing from standard practice of working in degrees True for the sake of easier small boat navigation.  Also, it is assumed that the hand bearing compass experiences zero deviation – this should be checked, and make sure to take sightings away from metal objects or electronics.  Or, you can momentarily slow and turn the boat towards the desired navaid or landmark to read off of the main compass.


Ranges create the most reliable lines of position and are the easiest to use.  They don’t rely on a compass reading and if you use landmarks then their positions are totally reliable.  

It takes a bit of practice to pick out good ranges in your AOR.  You don’t need to use navigation aids – any landmarks will work, and you can use them for both approaches and for danger bearings.  They can be used at night as well, by choosing lights or prominently lit structures on shore that are well distanced from each other to provide a properly sensitive range bearing.

But they only work if you document them and not rely on memory.  I have notebooks with sketches of hundreds of ranges that I used when pinpointing good diving spots in my competition spearfishing days.


What’s this?  Just a fancy way of saying using depth to navigate.  There are some sophisticated techniques which can be used in this method of navigation, but the easiest is just being aware of which depths are safe in your area and which might be useful for navigation.

Once again, imagine approaching Half Moon Bay from the south and you are suddenly completely enveloped in fog and have no visual references.  You are proceeding roughly northbound and are inside the hazardous reefs.

You look at the chart and see that the 30 foot contour line (also called an isobath by scientists) ends right at the end of the breakwater.  After correcting for the height of the tide, you know that you can continue on course until reaching that depth, and then follow that depth to the harbor.  It doesn’t need to be a plotted contour line – you can examine the depths and determine a depth that will work for the situation at hand.  

Also make sure you know if your depth sounder is calibrated to the surface (preferred for nav purposes) or to the deepest draft of the boat.

You need to be VERY careful that the depth changes are such that a consistent line can be followed.  It is also very important to use dead reckoning with this method so that expected changes in heading occur as predicted.  If something doesn’t seem right – STOP.  Anchor (if safe to do so) and reassess the situation.


Not all boats have radar, and those that do have it often don’t use it.  After all, the magnetron only lasts about 3000 hours and many owners don’t want to use up that clock.  Or they frankly don’t know how to use it properly.  But the Navrules (Rule 7) states that it shall be used if fitted and operational.

I highly recommend that folks take the time to learn how to properly use their radar and understand its benefits and limitations.  A great way to learn is to use it during the day and learn how to correlate what the screen says to the physical world you are seeing.

Newer radar units have automatic tuning which sometimes works well and other times is totally worthless.  But one way or the other, a radar system needs to be constantly tuned to the conditions of the weather, and of the selected range.  There are three main tuning controls – gain, sea clutter, and rain clutter. 

As a rule, the sea clutter and rain clutter should always be completely off unless you need them.  Then the gain can be adjusted as desired.  It takes practice to use radar properly and take advantage of the navigational features like the VRM and EBL.  Go out with someone who knows how to use it properly.  Learn how to use danger ranges (similar to danger bearings) and other methods to stay in safe water.

On Auxiliary Facility SEARCH ENGINE shown above, I prefer to have discrete components for the various purposes of GPS, depth, radar etc.  In this way a single failure does not wipe out all of my navigation information.  From left to right – Furuno radar, Furuno sounder, Furuno charplotter (in North Up mode), Lowrance chartplotter (in Head Up mode), and Robertson (Simrad) autopilot.  Why two chartplotters?  I’m lucky that a friend upgraded his electronics and his hand-me-down is still perfectly suited to my use.

*  *  * 

When I operate at night as coxswain I rarely stand a helm watch while transiting underway.  It’s much more effective to have a qualified and properly briefed crewmember at the helm so that I can focus on the radar, chartplotter, depth, and the mission at hand to maintain overall situational awareness.

Operating at night increases risk significantly. Make the effort to develop the skills needed to be confident and safe while completing the mission. 

Be at the right end of the “bell curve”!