Race instruments offshore: Is it more than just a numbers game?
Sometimes there is simply too much data. Especially when you are trying to helm faster, which you always are.
In brief
For readers short of time. The full argument, and the method, follows below.
Most boats are not slow because of poor training or skills. They are slow because nobody has checked whether the instruments are telling the truth.
Start with the fundamentals: a clean log, batteries at 12.8 to 13.5 volts, charged pilot remotes, and red light at night.
Delete the plotter’s history. Old routes and waypoints are noise, and noise costs decisions.
The mast carries three numbers: heading, boat speed, true wind angle. If you need to read it twice, it belongs below.
True wind is not measured. It is calculated from four inputs, and if any of them is wrong, your polars are worthless.
Calibrate in order: boat speed, heading, apparent wind angle, upwash. Correct a tack offset by half the difference, never all of it.
Consistently hitting 100 per cent of target is not a fast boat. It is a calibration problem. Expect 90 to 98.
Downwind, put the pilot in true wind mode, provided the true wind is right. An uncalibrated system is not safer, just confidently wrong.
Variation in the Solent went through zero in late 2021 and is heading east. The chart to compass arithmetic every British sailor learned now runs the other way.
Integrated electronics fail together. Carry paper charts and a swung compass: Team Vestas Wind hit a reef its screen did not show at the zoom in use.
The highest return habit of all: a twenty minute tack symmetry test on the way to the start. It is free, and almost nobody does it.
And in a picture:
The full article:
There is a moment, early in any coaching engagement, when I know whether I am in for a quick conversation or a long afternoon.
It happens when I step onto the boat for the first time. I am not even looking at the instruments, not yet. I am watching how the crew relate to them. Are their eyes pulled to the displays the way some people compulsively check a phone? Or are they scanning the boat, the horizon, the trim, using the instruments as one input among several?
That tells me a great deal about how information is being used on board. After many years coaching offshore boats, from club campaigns to serious programmes, I have come to believe that most boats are not slow just because of poor training or skills. They are slow because they are looking at the wrong numbers, or at too many numbers, or worst of all at numbers nobody has ever verified are correct.
What follows is not a complete instruments manual. It is one part of what I do when I first step aboard as a coach. But it is a foundational part, because if the information on board is not clear, consistent and trustworthy, then every tactical decision, every trim change and every steering input is compromised from the start.
1. Before I look at an instrument
When I first step onto a race boat I run a quick mental check that begins not with technology but with fundamentals.
Is the log clean and properly aligned? Is it actually reading water passing beneath the hull, or is it fouled, offset, or partially obstructed? Are the seacocks where they should be? What are the batteries doing? Are we comfortably above 12 volts, ideally in the 12.6 to 13.5 range that indicates a healthy charge state? How many phones are plugged into USB sockets, quietly draining the system while the crew are below?
The domestic and engine start batteries, are they properly isolated? I have seen races compromised, and one delivery turn frightening, because someone had discharged everything into a shared bank and the engine refused to start when conditions demanded it.
Then visibility. Are the instruments set to maximum brightness for daylight? Does every crew member know how to switch to night mode, and not just a dimmed version but proper red screen mode that protects night vision? Do the autopilot remotes work? Are they charged?
I have seen entire instrument systems rendered useless by a flat battery in a wireless remote. It sounds almost embarrassing to write down. It happens, consistently, on boats that would describe themselves as serious racing campaigns.
Then the crew. Do they all have torches? Do those torches have both red and white modes, and does everyone understand when to use each? Red light preserves the rhodopsin in the eye, the photopigment responsible for night vision, and a crew that has protected theirs will be faster, calmer and safer than one that has been blasted with white light every time someone checks the chart table.
All of this happens quickly and in parallel. I am also clocking the engine, the sails, the safety gear, the food and water, the general organisation of the boat. Offshore preparation is holistic. You cannot compartmentalise one system while ignoring the rest. Once I am satisfied the boat is fundamentally sound, I turn to the part most crews think they have already got right.
The instruments. That is where the real work usually begins.
2. The plotter: clarity over history
The first place I look is the plotter. More often than not, it is full of old data.
Old routes. Old tracks. Waypoints from deliveries, from races years ago, from half formed plans that never became anything. It is not navigation. It is accumulation.
The problem is not untidiness, though there is a decent psychological argument for a clean workspace. The real problem is cognitive load. When a display is cluttered with irrelevant information the brain must work harder to find the signal in the noise. Research from aviation, an environment that shares much of offshore sailing’s mix of fatigue, time pressure and high stakes decision making, has consistently found that increasing the volume of available information does not improve decision quality. Often it degrades it, because the mental effort of filtering irrelevant data consumes capacity that should be available for action. Offshore, especially at night or in deteriorating conditions, that bandwidth is not a renewable resource.
So the first job with the plotter is simple: delete.
Not refine. Not archive. Not tidy up and come back to it. Delete. Keep the trusted waypoints, the essential marks, the current race information. Everything else is noise, and offshore, clarity beats history every single time.
3. Three numbers on the mast
The mast display is where the key information is communicated to the helm in real time. It is the interface between the boat and the people sailing it, the data visible to the helm and the trimmers in all conditions, often in spray, in failing light, in the middle of a cold watch at 0200.
What I am looking for on a mast display is three numbers. Heading. Boat speed through the water. True wind angle. Those three govern direction, efficiency, and the boat’s relationship to the wind. Everything else is at best secondary and often actively irrelevant. You can have more displays, and modern screens will show anything the system can generate, but in my experience the big three need to stand proud.
If those three numbers are not immediately legible, large enough to read at a glance from the wheel, in a font that does not require squinting in spray, we fix that before anything else. Here is the part that consistently surprises people: if there is more data on the mast than those three numbers, I do not automatically add to it. Usually I remove it, or make it smaller than the big three.
Because if you need to read it twice, it should not be on the mast.
This is not a rejection of modern instrumentation. Systems from B&G, Raymarine and Garmin are remarkable, and the information available through a fully integrated setup is extraordinary. But the mast is not the place for a dashboard. It is the place for the three numbers that need to live in the helm’s peripheral vision at all times. Everything else belongs on the cockpit screens or at the nav station, where it can be consulted deliberately rather than absorbed passively or, worse, ignored passively.
A note on helming
The word helm comes from the Old English helma, meaning tiller: the physical lever slotted onto the rudder post, the point where human intention meets the mechanism that moves the boat. To be at the helm is not a figure of speech. It is a precise description of where you are and what you are doing.
Which is why the word “driving” still annoys me! You drive a car because you are managing an engine and a mechanical linkage to a road surface. You supply the power and the direction, and the machine obeys. On a boat the helmsman is doing something fundamentally different: reading the wind, the sea state, the sails, the heel, the feel transmitted through the helm, and constantly negotiating between all of them. The rudder is not primarily a direction device. It is a drag device, and overusing it costs speed. A good helmsman steers as little as possible, not as much as possible.
Driving implies dominance over a machine. Helming implies a conversation with the sea. That distinction is not pedantry. It reflects a completely different understanding of what is happening beneath your hands.
It also reflects the concentration the job demands. When you are on the helm, that is your job. You cannot helm effectively and simultaneously manage the deck, call tactics, navigate and make crew decisions. The best sailors understand this instinctively. They delegate everything else while they are steering. Single and double handed sailing operates differently, and that deserves its own discussion.
Which brings me to a training idea I return to constantly, the Three S’s: Sea, Sails, Speed.
The idea is deliberately simple, and that is precisely its value. The best helmsmen I have worked with do not scatter their attention across a cockpit full of instruments and competing demands. They cycle through three focal points, in order, and repeat.
Sea first. Look at where the boat is going. Judge the movement of the bow relative to the water ahead, or to the clouds, the land, the horizon. This is where you feel how much helm you are actually applying, whether the boat is working with the sea or fighting it, and where the next wave or gust is coming from. The sea is always the primary reference.
Sails second. Look at the luff of the headsail or the spinnaker. Is the flow correct? Does it correspond with the heel angle and the current trim? The sails tell you whether the boat is properly powered, overpowered or starved, and that information should be read in the context of what you just saw from the sea.
Speed third. If you know your target speed, and you should, because you have learned it from your polars, the number on the mast tells you immediately whether the boat is where it needs to be. Because boat speed sits alongside true wind angle on the mast display, your eye takes in both in a single glance. If the speed is right, the angle will be right. The numbers make sense together, or they tell you something is wrong.
If a course is being sailed rather than a pure wind angle, the VMC will be set by the tactician or navigator, and a brief glance at the mast confirms alignment. Then back to sea, sails, speed. That is the cycle.
It sounds too simple. Simplicity is exactly what the helm demands. The boat will sail better for it. It nearly always does.
4. The true wind question
This is where many boats quietly lose miles, race after race, without ever working out why.
Apparent wind is what your sails actually feel: the combination of the true environmental wind and the artificial headwind created by the boat’s own forward motion. It is what your masthead sensor measures. It is real, in the sense that it is the wind your rig is responding to at any given moment. But it is reactive. As the boat accelerates, apparent wind clocks forward. As the boat slows, it opens. In a seaway, particularly downwind, with waves pushing the stern and the boat surging and checking, apparent wind can oscillate in ways that are deeply unhelpful as a primary steering reference.
True wind is the actual wind blowing across the water, independent of the boat’s speed and direction. Critically, it is the reference system your polars are written in. The performance targets that define what your boat should be doing at any wind angle and wind speed, the numbers that tell you whether you are performing or just moving, are built around true wind angle and true wind speed.
My preference offshore is to steer to true wind angle. It is a more stable reference, particularly downwind and in confused sea states. It aligns directly with the performance benchmarks we are working towards. And when a boat is surfing down a wave and accelerating, precisely the moment when apparent wind is at its most misleading, true wind angle holds steady and keeps the helm on course rather than triggering an overcorrection.
Miles Seddon, who worked for B&G from 2005 to 2013 and built the electronic package for the Volvo Ocean 65, put the stakes plainly in Sailing World in July 2014: “The holy grail of any instrument system is to be able to provide an accurate true-wind direction.” He went on to say that reliably spotting a small shift can be worth significant mileage. He is not talking about comfort. He is talking about miles.
There is a caveat, and it matters more than anything else in this article. True wind is not measured. It is calculated. The system takes apparent wind angle, apparent wind speed, boat speed and heading, then derives true wind from those inputs using vector mathematics. If any of those source values are wrong, and they frequently are, the true wind angle on your display is wrong. And if your true wind angle is wrong, your polars are worthless.
The rule, then. A well calibrated, verified system justifies steering to true wind angle. A system with unknown or doubtful calibration means trusting feel, trusting boat speed, and keeping apparent wind available as a cross check. Never navigate blind on a derived number you cannot validate.
Which raises the obvious question, and it is the one the original version of this article never properly answered. How do you validate it?
5. Calibration: the work almost nobody does
Most crews treat calibration as something that happened once, at commissioning, probably by the company who install the electronics onboard, and is therefore done. It is not done. Sensors drift, hulls foul, paddlewheels wear, masthead units get knocked during rig work, and the numbers quietly go out of true while everybody carries on trusting them.
The order below matters. Each step depends on the one above it being right, because true wind is derived from all of them. Calibrate out of order and you will chase an error around the system for an afternoon and finish where you started.
5.1 Boat speed first, because everything else rests on it
Boat speed is the foundation. It feeds the true wind calculation, it is the number the helm steers to, and it is the number your polar targets are measured against. Get it wrong and every other reading inherits the error.
The method is a comparison against speed over ground, in flat water with as little tidal stream as you can find. Seddon’s own framing, in the same article: “Boatspeed calibration is relatively straightforward and is easiest in non-tidal flat water, where a direct comparison between speed over ground and boatspeed can easily be made.”
Run a reciprocal pair. Steady speed on one heading, record log and SOG over a minute or two, then turn through 180 degrees and repeat at the same throttle or the same sail trim. Averaging the two directions cancels whatever residual stream you could not avoid. Do it at two or three speeds across your working range, because paddlewheel error is rarely linear: many logs read close at six knots and badly high at nine.
Expect the log to read high. It usually does.
Not reading correctly? I wonder why?
Two refinements that separate a real calibration from a quick check. The first is heel. Seddon again: “as the heel angle increases, the boatspeed reading usually increases. Again, this is due to the change in water flow over the hull surface and applies to all sensors.” A boat calibrated upright and sailed at 20 degrees of heel is not calibrated. If your system supports a heel correction table, populate it. If it does not, know the offset and carry it in your head.
The second is tack. Most hulls read differently on port and starboard because the sensor sits off the centreline and the flow over it changes with heel direction. Check both. If they differ, that is a real asymmetry, not noise.
5.2 Heading, because true wind is built on it
A heading error puts a constant offset into every true wind number the system produces, and it is invisible unless you look for it.
Swing the compass, or run the automated calibration the system offers, and then check it against something external: a transit ashore whose bearing you can take off the chart, or a long steady run compared against GPS course over ground in slack water. A fluxgate sitting near a speaker magnet, a laptop, a phone charger or a newly fitted piece of gear will be wrong in a way no amount of software calibration fixes. Look at what is physically near the sensor before you blame the sensor.
5.3 Apparent wind angle, the offset almost every boat carries
Now the masthead unit. Almost every rig has a small alignment offset, either because the vane was not fitted perfectly fore and aft or because the mast itself is not perfectly aligned.
The test is tack symmetry, and it is the one every crew can do without any equipment at all. In steady conditions, sail upwind on port, settle, record the true wind angle. Tack, settle, record it on starboard. The two should be close to symmetrical about the wind. If you are showing 42 degrees on port and 52 on starboard, you have a five degree offset which makes a huge difference to your target speeds and target angles.
Seddon gives the correction rule, which is the part the April version of this piece was missing: “If the true-wind direction is lifting tack-to-tack (when you exit a tack, the true-wind direction indicates you’ve been lifted), then the true-wind angle is reading too wide and half the error should be subtracted.”
Half the error. Not all of it. Applying the full difference is the most common mistake and it simply moves the error to the other tack.
5.4 Upwash, which is not an error but a distortion
The final layer, and the one that distinguishes a well set up boat from a merely calibrated one. The rig and the sails bend the air before it reaches the masthead unit. The sensor is reading wind that has already been disturbed by the thing it is mounted on. Seddon’s term for the combination of these effects is upwash, and he notes it is most visible in the true wind direction.
Upwash varies with wind speed and with wind angle, which is why a single fixed offset never quite fixes it. Serious systems handle it with a correction table indexed by apparent wind speed and angle. Most club boats do not have one, and do not need one, provided the crew know the distortion exists and do not treat the last two degrees of true wind direction as gospel.
5.5 What good looks like
You are not chasing perfection. You are chasing consistency and a known offset.
Tack symmetry within two or three degrees. Log and SOG agreeing within one to two per cent across the working range in slack water. True wind direction that does not swing wildly through a tack. Polar performance landing in the 90 to 98 per cent band that experienced offshore navigators expect in typical racing conditions.
That last number is the honest test, and it is worth stating plainly. If you are consistently hitting 100 per cent of target, or better, you do not have a fast boat. You have a calibration problem.
Do this properly once, before the season, and check it with the tack symmetry test before every race. It takes twenty minutes on the way to the start and it is the highest return twenty minutes available to an offshore crew.
6. True or magnetic? The consistency rule
This is not, at heart, a theoretical debate. It is a communication question.
My preference is magnetic heading displayed at the mast as the helm’s primary reference, with true heading used within the navigation systems. Magnetic bearings are what we navigate by in practice, what we communicate by on the VHF, and what most crew have worked with since their first sailing course. True heading has its place in passage planning, in integrating with chart plotters and in interpreting synoptic weather. But it is a conversion step away from immediate practical use.
What matters more than the choice is consistency. Everyone on board must be working within the same reference framework, and must know they are.
Small discrepancies between a compass bearing and a chart plotter, one reading true, one reading magnetic, the difference unrecognised, become navigational errors offshore. In a marina this is ignorable. On a long offshore leg, approaching a tidal gate or entering a harbour in the dark, it is not. At a race mark, rounding on the wrong side of it, it is expensive in a different way entirely.
Why variation is about to start mattering again
Magnetic north is not fixed. It wanders continuously, driven by the slow movement of the Earth’s magnetic core, and the rate and direction of that drift changes over time.
When I began sailing, variation in the English Channel was somewhere between seven and eight degrees west. On a paper chart, with parallel rules and a pencil, that difference had to be applied correctly every single time you laid off a course. Get it wrong and you were not navigating. You were guessing with false precision. The mnemonic we used was compass to true, add east, meaning you added easterly variation, or subtracted westerly. It was a discipline, and it was taught carefully, because the consequences of reversing it were not theoretical.
Consider a Channel crossing. If your course is seven degrees in error, one full compass rose graduation, and you sail for ten hours at six knots, you will cover sixty nautical miles. The cross track error, distance multiplied by the sine of the angle, is 60 x sin(7 degrees), or 7.3 nautical miles. The 1 in 60 rule gives you the same answer faster: one degree of error produces one mile of lateral displacement for every 60 miles sailed. Seven degrees, sixty miles, seven miles. Either way you are more than seven miles from where you believe yourself to be.
Seven miles is the difference between winning and losing a race. In the wrong conditions, off a coast like Selsey Bill, it is the difference between a safe passage and putting the boat aground.
Here is what has changed, and it is not a historical footnote. In September 2019 the agonic line, the line of zero magnetic declination, crossed Greenwich for the first time since around 1660. The British Geological Survey records it moving west at about 20 km per year, and says it “will continue to pass across the UK over the next 15 to 20 years”. Dr Ciaran Beggan of the BGS: “By 2040, all compasses will probably point eastwards of true north.”
Read that carefully, because it is the opposite of what most British sailors have assumed their whole lives. Variation in our waters is not a small westerly number quietly shrinking to nothing. It has gone through zero and it is heading the other way. Every skipper who learned to subtract when laying off from chart to compass is going to have to learn to add, and the generation currently being taught navigation in near zero variation has no instinct for either.
For now the number is small enough to ignore in the Solent. That is exactly why it is worth understanding. The habits that come from taking variation seriously, checking it, applying it, never assuming it is negligible, are the habits of a navigator rather than someone following a line on a screen and hoping.
7. Testing before the start
As we head out towards the start area, we test. Not passively observe. Actively test.
Port tack. Starboard tack. In reasonably consistent conditions the true wind angle on each tack should balance, not identically, but within a few degrees of symmetry about the wind direction. This is section 5.3 applied as a pre race check rather than a calibration exercise, and it takes two minutes. If it fails, we note the offset, we work around it, and we do not pretend it is not there. Pretending is the most common response and the most damaging one.
Then boat speed against GPS. In negligible tidal stream and calm conditions the two should correspond closely. They almost never do.
This matters for one precise reason. Polar targets are the benchmarks against which you measure performance. If boat speed reads two or three per cent above reality you will appear to be hitting your targets when you are not. You will look fast when you are average. The feedback loop that drives improvement, notice underperformance, identify cause, correct it, is broken before the race has started.
8. The autopilot problem
I check the autopilot next, and this is where I often find the most significant and least acknowledged source of lost miles in offshore racing.
Upwind, most pilots behave adequately. The course is relatively stable, the steering inputs modest, and a degree or two of wander is manageable. Downwind is where it matters, and where the physics of pilot behaviour can work actively against you.
Here is the mechanism. A pilot steering to apparent wind angle will, in any meaningful seaway, misinterpret wave induced acceleration as a wind shift. The boat surfs down a wave and accelerates. As speed increases the apparent wind clocks forward, towards the bow. The system reads a windward shift and bears the boat away to compensate. That is precisely the wrong input at precisely the wrong moment. It induces oscillation. In worse cases it leads to accidental gybes, broaches, torn sails, and a situation in the middle of a black night that nobody needs.
Switch the pilot to true wind angle mode downwind and it steers to a reference that does not react to wave induced speed variation. The boat accelerates down the wave naturally. The pilot holds course. Over a 24 hour offshore passage the difference in miles sailed can be substantial.
Beyond mode selection there is tuning. Gain, response time and damping settings that produce smooth steering in calm water may be entirely wrong in a seaway. A pilot wandering 15 or 20 degrees either side of its target heading on a downwind leg in two metres of swell is not helping the boat, it is actively costing it distance. The honest conclusion in those conditions, not the comfortable one, is that a rested human helm will be faster. The crew should know how to make that call, and make it without hesitation.
Note the dependency. Everything in this section assumes the true wind angle the pilot is steering to is correct. An uncalibrated system in true wind mode is not safer than one in apparent wind mode. It is confidently wrong instead of visibly wrong.
9. The plotter through the race
The plotter’s role changes as a race develops, and the mistake most boats make is treating it as a static tool: the same setup, the same brightness, the same information density from the start gun to the finish.
Before the start it is a tactical instrument: line bias, approach timing, laylines to the first mark. At this stage I want it purposeful and uncluttered, with nothing on screen that is not relevant to the next twenty minutes.
During the passage it becomes a navigational and strategic tool: route context, approaching weather systems if we are actively routing, AIS for traffic management. It earns its complexity here, and the navigator should be comfortable working it at depth.
At night it should be simplified again. Minimum brightness consistent with visibility. Minimal information on screen. The temptation to run the same bright, information rich display through the dark hours is real, because it feels more in control and more professional. But the intrusion into night adapted eyes is a genuine performance cost, and the cognitive demand of a cluttered screen on a tired crew at 0300 is every bit as damaging to boat speed as poor upwind trim or a badly set spinnaker.
10. Data as interpretation, not truth
Every instrument system, however sophisticated, follows the same chain: sensor, calibration, computation, display. Wind is distorted by the rigging and sails before it reaches the transducer. True wind is derived by vector arithmetic from inputs that are themselves estimates. Targets are modelled on polar data representing an idealised version of your boat in standardised conditions.
None of this is reality. It is a model of reality, and error accumulates at every link in the chain.
The America’s Cup programmes, the IMOCA ocean racers and the offshore grand prix boats carry extraordinary sensor arrays. For example: Oracle Team USA’s AC72, which raced in San Francisco in 2013, carried hundreds of sensors through the hulls, the underwater fins and the length of the mast. The teams using that data most effectively were not the ones with the most of it. They were the ones with the clearest frameworks for interpreting it, the fastest processes for acting on it, and the discipline to know when to trust the number and when to trust the sailor’s hands instead.
In 2013, even then, hundreds of sensors and today’s America’s Cup plus AI just 4 people on one hull and two foils!
At club offshore level the principle is identical. The sailor who understands that their true wind angle is a calculated estimate, dependent on calibration quality at every step, will use it better than the sailor who treats it as ground truth. Scepticism and active calibration are not signs of distrust in the equipment. They are signs of understanding it properly.
11. What the fastest boats actually have
After many offshore races, crewed and short handed, in benign conditions and in weather I would prefer not to repeat, I have arrived at a conclusion simpler than most people expect.
The fastest boats are not the ones with the most data. They are the ones where the right data is visible, the system is internally consistent, the crew trusts it, and decisions get made quickly and confidently as a result.
That last element matters more than is generally acknowledged. Speed offshore is not purely a function of trim, angle and polar targets. It is a function of decision quality, and decision quality degrades when information is uncertain, overloaded or contradictory. A crew that trusts its instruments makes calls. A crew that does not either hesitates, spending seconds on a doubt that should have been designed out beforehand, or stops looking at the instruments altogether and sails on feel alone, which is a different kind of failure and an expensive one.
In most cases, within twenty minutes of stepping onto a boat, I can tell whether it is set up to perform or merely set up to look as though it should. The instruments are a large part of that judgment, not because data is everything, but because clarity, consistency and crew confidence are the invisible infrastructure on which every other element of offshore performance is built.
Get the information right and everything else becomes possible. Get it wrong, or leave it unverified as most boats do, and you are racing with one hand tied behind your back. You may still finish. You will never quite know how much faster you could have been.
Postscript, September 2026
This piece first went out in April, to a fraction of the people now reading. Five months and a full season later, three things look different.
The calibration section above did not exist in the original, and it should have. The April version told you true wind was a derived number you should not trust blindly, then left you there. That is half an article. The method in section 5 is the missing half, and the order of operations within it is the part that saves an afternoon: speed, then heading, then apparent wind angle, then upwash. Chase them in any other order and the errors move around the system faster than you can pin them down.
The variation story turned out to be more interesting than I wrote it. I described near zero variation in European waters as a quiet historical curiosity. It is not. The agonic line crossed Greenwich in 2019 and is still moving west across the UK. Within the working lifetime of anyone currently racing, British variation goes easterly and the arithmetic every RYA course has taught for decades reverses. That belongs in section 6, and now does.
The season also sharpened one conviction. Of everything in this article, the twenty minute tack symmetry test on the way to the start is the single highest return habit an offshore crew can adopt. It is free, it needs no equipment, and almost nobody does it.
Note: system failure, human failure
I was trained as a navigator at Dartmouth, and the Royal Navy’s approach was unambiguous. You learn the fundamentals before you touch the equipment. Dead reckoning, working your position from a known point using course, speed, leeway and elapsed time, was the foundation. Depth, tidal streams, weather and a working knowledge of the coastline were the tools you layered onto it. A log and an echo sounder made the job easier and more precise, but they confirmed a picture you had already built in your head.
I mention it because the fragility of modern integrated systems is something every offshore crew needs to understand before it becomes an emergency.
The masthead unit carries the wind transducer that feeds apparent wind angle and speed to every display, every calculation and every performance target on board. If it fails, the cascade through the system is immediate and wide. Most offshore racing boats run an NMEA 2000 network, a digital backbone designed in principle to let individual devices fail without taking down the others. In practice the network is only as reliable as its power supply. NMEA 2000 devices are specified to run on 9 to 16 volts, with 9 volts the stated floor, and voltage drops along a long backbone before it ever reaches the far end. If your batteries are not delivering clean voltage, and offshore after a long night with pilot, instruments and navigation lights all drawing from the same bank that is not guaranteed, devices do not degrade gracefully. They shut down, power cycle and output invalid data. The whole information picture can disappear at once. In reality the NMEA 2000 network and the devices on it are even more voltage aware and it is normal for warnings at just 11.9volts with errors occuring immediately nothing is done.
At that point a handheld GPS gives you latitude and longitude. A phone with charts downloaded before departure gives you a usable position. But without a physical chart you may have coordinates and no way of contextualising them. You know where you are in numbers. You do not know where you are in relation to the reef two miles ahead.
There is a case study that illustrates this with uncomfortable precision. On the night of 29 November 2014, on the second leg of the Volvo Ocean Race from Cape Town to Abu Dhabi, Team Vestas Wind, one of the most technically advanced racing yachts afloat, crewed by some of the most experienced offshore sailors in the sport, ran hard aground on the Cargados Carajos Shoals in the west Indian Ocean. The navigator had gone off watch and was asleep. The crew on deck had the chart displayed. The problem was the zoom level. At the scale in use the shoals appeared as a blue shaded area with spot depths between twenty and eighty metres. Only at sufficient magnification did the chart reveal low lying islands surrounded by drying reef.
Team Vestas Wind on the Cargados Carajos Shoals, November 2014. The reef was on the chart. It was not on the screen at the zoom in use.
The independent report, chaired by Rear Admiral (Rtd) Chris Oxenbould with Stan Honey and Chuck Hawley, concluded that “the electronic navigation charts in use on the boat failed to correctly show the Cargados Carajos Shoals at several common zoom levels”. The Volvo Ocean Race subsequently required all teams to carry paper charts. Not as a gesture to tradition. As a recognition that a physical chart, properly studied, does not depend on a zoom level to show you what is there.
If your VHF is still working when everything else has failed, there is a final recourse worth knowing. The Coastguard receiving stations on the south coast sit on elevated ground and their range is considerable. It is entirely possible to raise Solent Coastguard from mid Channel, and in the right conditions from further south. But any course they give you is only useful if you have a compass you can trust, one that has been swung and corrected, with its deviation card to hand. Which brings us back, as everything eventually does, to the fundamentals.
My own backup is a ruggedised tablet loaded with charts and routing software, with enough battery capacity to run it for the duration of a race plus a reserve. On most modern racing yachts it connects to the boat’s own network and gives me independent access to all the data.
The backup. Independent of every piece of the yacht’s electronics.
It is not a complicated setup. It represents a philosophy every offshore crew should share. Understand the technology deeply enough to know exactly how it can fail, and make sure that when it does, you are not starting from nothing.
Preparation. Decisions. Execution. From first shift to first place.
Stuart Greenfield FirstShift — Yacht Racing Intelligence From first shift to first place.
Offshore racing is never just about the boat, the forecast, or the routing software.
It is about decisions made under pressure, in changing conditions, by tired people trying to keep the boat moving fast and safely in the right direction.
That is where races are won and lost.
At FirstShift, my aim is simple: to help owners, skippers and crews race offshore with more clarity, more confidence, and better preparation whether that is a RORC Channel race, a Fastnet campaign, or your first serious step into offshore racing.
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