Many mariners do not realize that basic navigation is impossible without accurate time keeping. This is ironic since so many hours at sea are spent lamenting how slowly time, and forward progress, seems to be going. Curiously it wasn’t until the 1760’s that a self-taught English clockmaker by the name of John Harrison perfected a clock that could remain accurate despite wild fluctuations in temperate, humidity, atmospheric pressure, not to mention the corrosiveness of salt air and the constant movement of sea travel.
Precise time keeping allowed scientist to make accurate measurements of heavenly bodies and therefore solve the mystery of longitude. And with correct calculations of longitude cartographers like Captain James Cook could make meticulous charts, many of which are still in use today.
Although it works on the same principles, navigating today is nothing like what Captain Cook had to do. In fact, it isn’t much like what sailors of the 1980’s had to contend with either. Advancements in electronics produced clocks that are accurate to the millisecond. The exploration of space gave us the satellite-based Global Positioning System (GPS). Paper charts were superseded by the electronic chartplotter, and the parallel rule and dividers have been replaced with touch screens.
So, where do you start your modern-day navigation journey?
Learn The Lingo
Most activities that involve a specialized skill set also come with a specific vocabulary. It is important to learn the proper terms and phrases so that you can accurately communicate with other boaters, understand reference material and stay safe.
Common Navigation Terms
Latitude – the vessels position north or south of the equator.
Longitude – the vessels position east or west of the prime meridian (the designated starting point located in Greenwich, England).
Position – the exact latitude and longitude coordinates of the vessel.
Heading – the compass direction the vessel is pointing towards.
Course Over Ground (COG) – the actual direction the vessel is travelling, which is not necessarily the same as the vessels heading.
Speed Over Ground (SOG) – the actual speed the vessel is travelling over the surface of the globe, which is not necessarily the same as the speed of the vessel through the water.
Velocity Made Good (VMG) – the speed the vessel is travelling toward, or away from, a location.
Cross Track Error (XTE) – the distance the vessel is off the intended track or route.
Rhum Line – a theoretical line representing the shortest and most direct route to a destination.
Waypoint – a chosen point along a route, expressed as latitude and longitude coordinates, usually denoting a course change or stopping point.
Understand The Basics
As of November 2019 NOAA (National Oceanic and Atmospheric Administration) stopped producing traditional paper charts. This shift reflects the fact that most sailors now rely solely on electronic navigation tools. However, understanding the basic theories of navigation and being able to apply them in the real world is still important.
I don’t mean that you need to master a sextant, but you should strive to learn how to plan a route and plot a position on a chart. As well as, understanding the measurements and calculations involved in dead reckoning and running fixes. Not only will knowing these skills better help you comprehend the information that the equipment is displaying but it will provide a backup system in case of a catastrophic emergency.
These days paper charts are rarely used for daily navigating, but I think it does pay to sit down with one. Paper charts give you a static, big picture overview. No zooming or scrolling required. Orienting your position on paper makes it easier to piece together the small tidbits that you see on a digital screen.
As always there is plenty of books, videos and information online. Just as learning the theory of sailing is much different than being out on the water, so too is reading about navigation and actually putting those skills to the test. Taking a basic navigation class provides hands-on, interactive training, and for many this is still the most effective way to learn.
Chartplotters vs. Apps
As technology continues to evolve so does navigation. More sailors are using navigation apps and inexpensive handheld devices in the cockpit. Can you navigate solely with a handheld device and apps? Yes. Is it the best choice? That is debatable.
A chartplotter is an LCD screen that combines digital renderings of charts, satellite GPS data and information from other shipboard instruments such as the depth sounder, wind instruments, speed log and radar. These vital pieces of information can be displayed in one comprehensive overview, giving the person navigating an easy to understand picture of where the vessel is located, in real time, in relation to the surrounding environment. New generation chartplotters also integrate weather forecasting and passage routing services.
Chartplotters are specifically designed to function in a marine environment. This means that they can be splashed with salt water, touched with dirty fingers, are easily viewed in bright conditions, have night modes that will not destroy your night vision, are able to withstand high heat and deep cold, are hard wired into the vessels power bank and are power efficient. It also means that they come with a hefty price tag. On top of the price of the equipment it is necessary to purchase the correct format of digital charts for the areas in which you are sailing.
These costly outlays are the main reason more people are picking up other digital devices to navigate. Afterall, why shell out thousands for a piece of equipment when you can just download an app onto a smartphone or tablet that you already own? Although there are many good navigation apps available today and interactive platforms allow people to share real time information about local hazards, there are drawbacks to these devices.
Many users complain that screens are difficult to see in bright sunlight. Not to mention that a cover is needed as tablets and phones are not waterproof. These devices are also not designed to be left in the hot sun, which is all but unavoidable while sailing. Overheating can cause the device to malfunction or even lead to irreparable damage. Handheld devices are also power hungry, so it is necessary to have a 12V USB outlet available nearby to recharge. As well, operating systems in digital devices are notorious for crashing as they are usually running several programs at once, and these days often require constant internet connectivity to function properly. None of these characteristics are handy in a device that the safety of your vessel and crew depend on.
Most navigation apps have a basic free download but for access to more detailed features a subscription is required. Platforms such as OpenCPN are totally free but can demand more user knowledge to download and format charts and imagery. If you are sailing in remote areas or have poor or limited internet access using an app-based navigation system can also require some preplanning as you need to ensure that you have all the charts, updates and information required to run offline.
Although some navigation apps that run on handheld devices can interface with depth sounders and wind instruments, it requires that your onboard instruments are Bluetooth enabled. A feature that only the latest versions of those instruments are equipped with. Which means you could be in for a pricey refit if you are choosing this style of navigation.
All that said, the navigation programs and apps that are available for handheld devices are well reviewed and often accurate. In the right hands a tablet can get you where you want to go safely. Used as a compliment to an onboard chartplotter means that you have double the amount of information available and can make safe, informed decisions about navigation. Carrying one as a backup in case you experience equipment failure and you can’t go wrong.
Aides And Hazards
Whichever system you choose to use to navigate it is important to realize that it is almost always human error that causes accidents. And don’t be fooled into thinking that only rookies make mistakes, even the most experienced sailor can overlook a crucial detail and cause havoc.
Tips To Avoid Mishaps
Cross Reference Information – The more sources of information you look at the more detailed a picture you will have. Look at different versions of charts, different programs and both digital and physical charts when available. Also check out cruising guides and sailing forums for first-hand info, this is especially handy when sailing somewhere new.
Zoom in When Close to Land, Reefs & Shoals –Be aware that some details are not included on all scale layers of electronic charts. It is precisely this that caused Team Vestas Wind to hit a reef doing +20kts during the 2014/2015 Volvo Ocean Race. The shallow reef did not appear on their charts until the user zoomed in tightly. Unfortunately, this was only realized after the multimillion-dollar boat was all but totalled. Simply zooming in and out through all the layers of the chart where you are sailing is an easy way to avoid catastrophe.
Understand the Margin of Error – No chart is 100% accurate, neither are GPS coordinates or depth sounders. I’ve seen depth sounders give false readings because of a thermocline or a dense school of fish, watched our little boat icon traveling over land while we were safely in 50 meters of water, and have witnessed a sailboat high and dry on a reef in Tonga because they were navigating at night with charts that were known to be off by as much as one quarter of a mile. It is impossible to know the exact margin of error in every situation but being conscious that it is always there will help you navigate safer.
When in Doubt Slow Down – It is difficult to make safe decisions when the action feels like it is playing out in hyper speed. There is no need to enter an unfamiliar anchorage at full throttle or push the boundaries of your abilities if it means putting your crew and vessel in harms way. Take a breath, slow down and be safe, not sorry.
Look Away From the Screen – Chartplotters and nav apps can feel a bit like a video game, one where the helmsman steers and maneuvers the little boat icon on the screen. In reality that little icon is only a representation of what is happening in real life. Paying attention to your vessel and surroundings and trusting what your senses are telling you should be your focus, not the screen.
Whether you are a weekend sailor who stays close to home or someone who is planning a blue water voyage, good navigation is imperative. Keeping up with the latest trends in technology is important, but so too is understanding the fundamentals skills. Expanding your data base will give you the most diverse and detailed information but using your real-world experience is also essential. Like any specialized skill set it can take time to become proficient, and it never hurts to brush up on what you have already learned. Remember it doesn’t matter how fast you get there, if you don’t arrive safely.