You’re approaching a notorious current station where predictions call for 1.8 knots of ebb at your arrival time. Your route takes you directly through the channel, and at your vessel’s 8-knot cruising speed, you’ve calculated a comfortable transit. But when you arrive, the GPS shows you’re making barely 5 knots over ground. The current isn’t 1.8 knots—it’s pushing 3.

What happened? The predictions were based on astronomical forces and historical patterns. The observations would have told a different story—one influenced by rainfall, wind, and upstream conditions that the prediction models couldn’t anticipate.

Understanding the critical difference between current predictions and real-time observations transforms how professional mariners approach tidal current planning. Predictions provide your baseline plan, but observations reveal what’s actually happening in the water right now. The gap between these two data sources often contains the information that prevents delays, saves fuel, or identifies hazardous conditions before you reach them.

In this comprehensive guide, you’ll learn what current predictions actually predict (and what they don’t), how real-time observations differ from forecasts, when the gap between prediction and reality becomes significant, how to access both data types efficiently, and the decision-making framework professionals use to synthesize prediction and observation data. Whether you’re transiting narrow channels, planning fuel-critical passages, or navigating unfamiliar waters, mastering this dual-data approach ensures your current planning reflects actual conditions.

Understanding current predictions: what they tell you

Current predictions are mathematical models based on decades of observational data and astronomical calculations. NOAA develops these predictions by analyzing the gravitational effects of the moon and sun, historical current measurements, and the physical characteristics of each waterway. The result is a prediction of current speed and direction at specific times throughout the tidal cycle.

These predictions work remarkably well for astronomical tides—the regular, predictable component driven by celestial mechanics. In locations where astronomical forces dominate, predictions typically match reality within 10-15%. That’s good enough for most planning purposes.

But predictions have limitations. They assume normal weather conditions, average river flow, typical atmospheric pressure, and standard water temperatures. When any of these factors deviate significantly from historical averages, predictions become less accurate.

What goes into a current prediction

Current predictions are built from tidal constituents—individual components representing different astronomical cycles. The primary lunar semidiurnal constituent (M2) accounts for the moon’s twice-daily influence. The solar semidiurnal constituent (S2) represents the sun’s twice-daily effect. Dozens of other constituents capture variations in the moon’s orbit, the earth’s tilt, and the interaction between lunar and solar forces.

Prediction algorithms combine these constituents with local waterway characteristics—channel depth, width, bottom roughness, and hydraulic characteristics. The model knows that certain channels amplify specific constituents while dampening others. It understands how constrictions accelerate flow and how shallow areas create more bottom friction.

The final prediction represents the sum of all these components. At a specific time on a specific date, the model calculates which constituents are in phase, which are opposing, and what the net result means for current speed and direction. This astronomical approach works beautifully for the predictable component of currents.

The prediction accuracy spectrum

Not all current predictions are created equal. Some stations produce highly accurate forecasts; others frequently miss the mark. Several factors influence prediction reliability across different locations.

Locations with simple tidal patterns and minimal non-tidal influences generate the most accurate predictions. A deep channel with regular geometry, far from river mouths, with consistent weather patterns produces predictions that rarely deviate more than 10% from reality. The East River in New York or Deception Pass in Washington demonstrate this pattern—their currents follow astronomical predictions closely.

Locations influenced by river discharge, wind, or atmospheric pressure show larger deviations. The Chesapeake Bay Bridge Tunnel experience significant wind effects. The Cape Fear River near Wilmington responds to rainfall hundreds of miles upstream. These stations may show prediction errors of 30-50% during unusual conditions.

Some waterways exhibit even more complex behavior. Shallow estuaries with multiple inlets, bays with irregular geometry, or channels affected by offshore storm surge can produce conditions that differ dramatically from predictions. In these locations, real-time observations become essential.

Real-time current observations: what’s actually happening

Current observations measure what’s actually flowing past a sensor at a specific moment. Unlike predictions, observations capture every influence—astronomical tides, wind effects, river discharge, atmospheric pressure changes, storm surge, and thermal expansion. Observations are reality.

NOAA maintains current observation stations at critical navigation points throughout U.S. coastal waters. These stations typically measure current speed and direction at multiple depths using acoustic Doppler current profilers (ADCPs). Some stations report every six minutes; others update hourly. The data feeds directly into Mariner Studio’s current observation features, giving you immediate access to actual conditions.

The value of observations lies in their immediacy and comprehensiveness. When a storm moves offshore and changes pressure gradients, observations reflect the effect within hours. When upstream rainfall increases river discharge, observations show the enhanced ebb current before predictions would suggest it. When wind piles water against one shore and creates asymmetric currents, observations reveal the pattern.

How current observations are measured

Modern current measurement relies primarily on acoustic Doppler technology. The sensor emits sound pulses into the water column and measures the Doppler shift in the return echoes. Water moving toward the sensor shifts the frequency higher; water moving away shifts it lower. By analyzing returns from multiple depth bins, the system builds a velocity profile showing current speed and direction throughout the water column.

Most NOAA stations measure currents at several standardized depths. Surface measurements capture the top meter of water where wind effects dominate. Mid-depth measurements represent the main current flow. Near-bottom measurements show where friction slows the current and where counter-currents sometimes develop. This vertical profile helps mariners understand how draft affects current exposure.

The best stations report data every six minutes with minimal dropout. Less reliable stations may update hourly or experience equipment outages during severe weather. Mariner Studio tracks station reliability and flags when data becomes stale or questionable.

The observation limitation: temporal coverage

Observations have one significant limitation—they only tell you what’s happening now or what happened recently. They don’t directly tell you what will happen in two hours when you arrive at the station. For future conditions, you still need predictions.

The solution lies in comparing recent observations to predictions for the same time period. If observations ran 20% stronger than predicted over the past six hours, there’s reason to believe predictions for the next few hours may also underestimate actual currents. If observations match predictions closely, you can use predictions for future timing with more confidence.

Professional mariners develop a sense for which deviations are temporary fluctuations and which represent systematic differences that will persist. A sudden spike in current during a wind gust represents temporary conditions. A sustained 30% increase in ebb current over multiple tide cycles suggests increased river discharge that will continue affecting the system.

When predictions and observations diverge

The gap between current predictions and observations reveals the non-astronomical influences on your waterway. Understanding common divergence patterns helps you anticipate when to rely more heavily on observations and when predictions suffice.

These patterns repeat across different coastal regions, though specific causes vary by location. Learning to recognize these scenarios improves your ability to interpret current data and make better navigation decisions.

Wind-driven deviations

Wind creates surface currents and piles water against downwind shores. In shallow water or narrow channels, sustained winds can enhance or oppose predicted currents by 20-50%. The effect varies with wind duration, fetch, water depth, and channel orientation.

A 20-knot southerly wind blowing for 12 hours into Chesapeake Bay enhances flood currents and diminishes ebb currents. Water piles up at the bay’s northern end, creating a hydraulic gradient that opposes the normal tidal exchange. Observations will show the effect clearly; predictions won’t capture it.

Conversely, a strong northerly wind pushes water out of the bay, enhancing ebb and reducing flood. The effect can be dramatic—a predicted 1.5-knot flood might become a 0.5-knot flood, while a predicted 2-knot ebb might reach 3 knots. These wind effects typically build over 6-12 hours and dissipate in similar timeframes after the wind drops.

River discharge effects

Increased freshwater discharge from rivers strengthens ebb currents and weakens flood currents throughout connected waterways. The effect extends far from the river mouth—Hudson River discharge affects currents 50 miles into New York Harbor. Savannah River flow influences currents throughout Wassaw Sound.

Spring snowmelt and heavy rainfall events can double or triple normal river discharge, creating current anomalies that persist for weeks. Predictions can’t capture these effects because they’re based on average conditions. Only observations reveal the enhanced ebb and diminished flood that characterize high-discharge periods.

The pattern is consistent—stronger ebb, weaker flood, and delayed slack water. Slack water may occur 30-60 minutes later than predicted during high-discharge periods because the residual downstream flow takes longer to overcome.

Storm surge and offshore weather

Offshore storms create surge that alters coastal water levels and modifies current patterns. A hurricane passing 200 miles offshore can raise water levels three feet along hundreds of miles of coastline. This surge enhances flood currents and diminishes ebb currents, similar to wind effects but potentially stronger and longer-lasting.

Nor’easters produce similar effects along the mid-Atlantic coast. Days of onshore winds pile water against the coast, creating anomalous currents that predictions can’t anticipate. The surge gradually relaxes after the storm passes, but effects may linger for 24-48 hours.

Observations capture these storm-related current modifications immediately. Smart mariners check current observations during and after significant weather events, knowing predictions will underestimate the impact.

Atmospheric pressure variations

Extreme barometric pressure creates an inverted barometer effect—high pressure pushes the ocean surface down; low pressure allows it to rise. The effect is approximately one foot of water level change per inch of mercury pressure deviation from normal. This water level shift translates into modified currents throughout connected waterways.

A deep low-pressure system (28.50″ Hg) passing through the mid-Atlantic creates about 1.5 feet of abnormally high water. This “pressure surge” enhances flood currents and diminishes ebb currents. The effect persists as long as the pressure anomaly remains over the region.

Combined with wind effects from the same storm system, pressure-driven current modifications can produce significant deviations from predictions—30-40% errors are common during extreme weather events. Observations provide the ground truth that helps you navigate safely through these conditions.

Using both data sources effectively in Mariner Studio

The most effective current planning synthesizes predictions and observations into a comprehensive understanding of conditions. Predictions provide your baseline plan and future timing. Observations reveal actual conditions and help you calibrate expectations. Together, they give you the complete picture.

Mariner Studio’s current features make this synthesis straightforward by presenting both data types in an integrated interface. You see predictions for planning future transits and observations for understanding current conditions. The workflow becomes natural—check predictions for tomorrow’s passage, verify with today’s observations to gauge accuracy, and adjust your plan accordingly.

The standard planning workflow

Start with predictions when planning a future transit. Identify predicted slack water times, maximum current speeds, and whether you’ll be working with or against the flow. This establishes your baseline plan—departure time, expected transit duration, and fuel requirements.

Next, check recent observations at the same station. Compare actual currents to what was predicted for those times. If observations matched predictions within 10-15%, you can proceed with confidence using predictions for your future transit. If observations ran significantly stronger or weaker than predicted, adjust your expectations for the upcoming transit accordingly.

The comparison becomes especially valuable 6-12 hours before your planned departure. Recent observations at that point provide strong indicators of whether predictions will verify for your transit time. A pattern of consistent overestimation or underestimation typically persists through the next tidal cycle unless weather conditions change dramatically.

Real-time navigation decisions

During actual navigation, observations take priority over predictions. Your speed over ground and compass course reveal the true current set and drift. If observations are available at stations along your route, they provide confirmation of what you’re experiencing and preview conditions ahead.

Professional mariners develop a routine of checking current observations at key waypoints during longer passages. A quick check halfway through a channel transit confirms whether conditions match expectations or require course or speed adjustments. Integrated waypoint current data in Mariner Studio makes this workflow seamless—as you approach each waypoint, current data updates automatically.

When observations show unexpected conditions, the question becomes whether to proceed, modify plans, or wait. Stronger-than-predicted favorable currents mean faster passages and fuel savings. Stronger-than-predicted opposing currents might make waiting for the next slack water the better choice. The observation data provides the information you need to make these real-time decisions.

Safety margins and contingency planning

The gap between predictions and observations defines the uncertainty in your current planning. Larger gaps require larger safety margins. When observations consistently exceed predictions by 40-50%, you should plan for actual currents to remain elevated and build contingencies accordingly.

Fuel planning exemplifies this approach. If you’re transiting 30 nautical miles against a predicted 1.5-knot current, standard planning assumes 1.5 hours of additional fuel consumption. But if observations show currents running 2.2 knots—50% stronger than predicted—you need to plan for significantly higher fuel consumption. The observation data prevents you from departing with insufficient reserves.

Time-critical transits require similar attention to prediction-observation gaps. If you must meet a tide gate 40 miles away and currents along the route are running stronger than predicted, you may not make the window. Observations reveal this reality early enough to delay departure and wait for the next favorable cycle.

Geographic patterns in prediction accuracy

Prediction accuracy varies significantly across different coastal regions and waterway types. Understanding these geographic patterns helps you know when to weight observations more heavily and when predictions alone suffice. East Coast and Gulf of Mexico waters show distinct patterns worth recognizing.

Open coast current stations

Current stations in deep water far from river mouths typically show excellent agreement between predictions and observations. These locations experience purely astronomical tides with minimal non-tidal influences. Predictions for stations like those off the Florida coast or along the Outer Banks rarely deviate more than 10-15% from observations.

In these locations, you can rely heavily on predictions for planning with minimal need to check observations unless extreme weather events are occurring. The currents follow regular patterns, and prediction algorithms capture those patterns well. Your primary planning challenge becomes timing—catching favorable currents and avoiding maximum opposing flows.

Narrow channels and passages

Constricted waterways amplify tidal currents and create unique hydraulic conditions. Places like Hell Gate in New York, the Cape Cod Canal, or Florida’s Intracoastal Waterway develop strong, complex currents that often exceed predictions. The prediction models understand the basic amplification but may not capture local variations caused by geometry, bottom features, or hydraulic effects.

In these locations, observations become essential for understanding actual conditions. A predicted 4-knot current might actually reach 5.5 knots at peak flow. Wind effects concentrate in narrow channels, creating additional deviations. Check observations religiously before transiting these waters—the difference between predicted and actual conditions can determine whether your transit is routine or hazardous.

Bay and estuary systems

Large bay systems like the Chesapeake, Delaware Bay, or Tampa Bay show moderate prediction accuracy that varies with weather conditions. During normal weather with average river discharge, predictions typically match observations within 15-20%. But wind events, rainfall, and storm surge create significant deviations.

The key skill in bay systems is recognizing when non-tidal influences become significant. If you’ve had three days of 20-knot winds from the same direction, expect observations to diverge from predictions. If the weather has been calm with light winds, predictions will likely verify. Build the habit of checking observations whenever weather has been unusual—you’ll often find meaningful deviations that affect planning.

River-influenced coastal areas

Areas near major river mouths show the poorest agreement between predictions and observations. The Savannah River entrance, the mouth of Chesapeake Bay, the Hudson River’s influence on New York Harbor—these locations experience highly variable currents that depend strongly on upstream discharge.

In river-influenced areas, treat predictions as rough guides rather than accurate forecasts. Observations may show currents 50-100% stronger than predicted during high-discharge periods. Conversely, during drought conditions, currents may run weaker than predicted. The only reliable approach is checking observations before every transit and expecting significant deviations from predictions.

Building your prediction-observation workflow

Effective current planning becomes intuitive once you establish a systematic workflow that incorporates both predictions and observations. The goal is making data synthesis automatic—something you do naturally without conscious effort for every passage.

The 24-hour pre-departure check

Start planning 24 hours before departure by reviewing current predictions for your entire route. Identify critical current stations where timing matters—channel entrances, narrow passages, areas where you must transit during favorable conditions. Note predicted slack water times, maximum current speeds, and whether currents will help or hinder your progress.

Next, check observations at those same stations for the current tide cycle. Compare observed currents to what was predicted for those times. Calculate the percent deviation—are observations running 10% high, 30% low, or matching predictions closely? This comparison provides your calibration factor for tomorrow’s transit.

If observations show systematic deviations from predictions, adjust your planned departure time accordingly. Stronger-than-predicted ebb currents might mean leaving an hour earlier to catch enhanced assistance. Weaker-than-predicted flood currents might mean you can afford to leave later without fighting strong adverse conditions. The 24-hour check gives you time to optimize timing without rushing.

The morning-of verification

On departure day, check observations again 2-4 hours before your planned departure. This final check confirms whether overnight conditions continued the patterns you observed yesterday or if something changed. New weather moving in, shifting winds, or changing atmospheric pressure can alter current patterns between your 24-hour check and actual departure.

This morning verification occasionally reveals that your 24-hour plan needs adjustment. If observations suddenly show much stronger adverse currents than yesterday’s pattern suggested, you might delay departure to wait for more favorable conditions. If observations show weaker currents than expected, you might advance your departure to take advantage of improved conditions.

The key is maintaining flexibility up until the moment you leave. Having a plan is essential, but being willing to modify that plan based on real-time data prevents forcing a passage under deteriorating conditions.

Underway monitoring

Once underway, your GPS provides continuous current observation through speed-over-ground and course-over-ground data. The difference between your speed through the water and speed over ground reveals actual current set and drift. This real-time information confirms whether conditions match your pre-departure expectations.

At key waypoints, check Mariner Studio’s current observations if stations are available along your route. A quick comparison between your GPS-derived current estimates and station observations validates your understanding of conditions. Significant mismatches might indicate local current variations or equipment errors worth investigating.

Professional mariners log current observations during passages, building personal experience that improves future planning. After a few transits through the same waters, you develop intuition for how predictions relate to reality in that specific location. This accumulated knowledge makes you faster and more accurate at synthesizing prediction and observation data.

Advanced applications: fuel planning and scheduling

The prediction-observation relationship becomes especially critical when planning fuel-efficient passages or meeting tight schedules. Small errors in current assumptions compound over long distances, turning minor miscalculations into significant problems. Understanding when to trust predictions and when to adjust based on observations prevents these issues.

Current-dependent fuel planning

A 100-nautical-mile passage at 10 knots normally requires 10 hours and consumes fuel at your standard rate. But if you face a 1-knot adverse current throughout the passage, your speed over ground drops to 9 knots, extending the passage to 11.1 hours and increasing fuel consumption proportionally. A 2-knot adverse current creates a 12.5-hour passage—25% longer than planned.

When predictions show adverse currents, you plan accordingly. But what if observations reveal those adverse currents are actually 30% stronger than predicted? Your 1-knot adverse current becomes 1.3 knots, and your 2-knot current becomes 2.6 knots. The fuel consumption difference between planned and actual conditions can become significant.

Smart fuel planning incorporates the prediction-observation gap. If recent observations show currents running strong, calculate fuel requirements using the actual observed values rather than predictions. Build a 10-15% reserve beyond that to account for continued variability. This approach prevents arriving at your destination with inadequate fuel reserves because you trusted predictions that underestimated adverse conditions.

Schedule-critical transits

Commercial operations often require meeting specific arrival times. A pilot boarding at 0600, a tide-critical bar crossing at 1400, or a berth assignment at 1800 creates hard deadlines. Missing these windows can cost thousands in delays, waiting time, and rescheduling fees.

For time-critical operations, the prediction-observation comparison becomes a go/no-go decision tool. If observations show conditions matching predictions, your calculated ETA stands. If observations show significantly different conditions—either favorable or adverse—you recalculate ETA using actual data and adjust departure timing to ensure meeting your window.

The most sophisticated operators maintain real-time ETA calculations throughout passages, updating their arrival prediction as observed currents reveal actual conditions. Mariner Studio’s ETA features can help automate these calculations, factoring current data into arrival predictions. This continuous refinement ensures you know whether you’re on track for your scheduled arrival or need to adjust speed to compensate for current deviations.

Common mistakes and how to avoid them

Even experienced mariners make predictable errors when working with current predictions and observations. Recognizing these common pitfalls helps you avoid them.

Treating predictions as guarantees

The most fundamental error is assuming current predictions represent what will actually occur. Predictions are models based on historical data and astronomical calculations. They represent the expected astronomical component of currents, not a guarantee of actual conditions.

Always view predictions as your starting point, not your final answer. Check observations to understand how local conditions are modifying the astronomical baseline. Even in locations where predictions are typically accurate, occasional meteorological or hydrological events create significant deviations. Maintaining a healthy skepticism about predictions and verifying with observations prevents unpleasant surprises.

Ignoring systematic deviations

When observations consistently run 20-30% different from predictions, that pattern typically persists until underlying conditions change. A common mistake is treating each observation as an isolated data point rather than recognizing systematic deviations that will continue affecting future conditions.

If observations have run 30% stronger than predicted for the past three tide cycles, assume the next cycle will show similar enhancement unless weather patterns change. Plan for those enhanced currents rather than hoping conditions will suddenly match predictions. Systematic deviations reveal fundamental differences between modeled and actual conditions—differences that persist until their causes resolve.

Overlooking the vertical current profile

Current speed varies with depth due to bottom friction and wind effects. Surface currents run fastest; bottom currents run slowest. Mid-depth currents represent the average flow. Your vessel’s draft determines which part of this profile affects your passage.

A shallow-draft vessel experiences primarily surface currents enhanced by wind effects. A deep-draft vessel experiences stronger bottom friction and averaged currents throughout the water column. When comparing predictions to observations, consider which depth bands matter for your vessel. Many ADCP stations report currents at multiple depths—use the depth range that matches your draft for the most relevant comparison.

Neglecting seasonal patterns

Some waterways show predictable seasonal variations in the prediction-observation relationship. Spring snowmelt enhances currents in river-influenced areas for weeks. Summer thermal stratification modifies circulation patterns in deep estuaries. Fall hurricane season creates surge events that persist for days.

Build awareness of seasonal patterns in your regular cruising grounds. If you know that April and May typically bring enhanced ebb currents due to snowmelt, check observations carefully during those months. If you understand that summer afternoon sea breezes consistently strengthen flood currents in your local bay, plan for that enhancement even when predictions don’t reflect it. Seasonal knowledge helps you anticipate when observations will likely deviate from predictions.

Frequently asked questions

How often are current predictions wrong?

Current predictions typically achieve 80-90% accuracy in locations dominated by astronomical forces with minimal non-tidal influences. In river-influenced areas or locations with strong wind effects, accuracy drops to 60-70% during normal conditions and can fall to 50% or lower during extreme weather events. The prediction error is usually conservative—predictions tend to underestimate actual current speeds rather than overestimate them.

Should I always trust observations over predictions?

For current conditions, yes—observations represent reality while predictions represent models. However, for future conditions, you still need predictions since observations only tell you what’s happening now. The best approach combines both: use observations to calibrate your confidence in predictions, then apply predictions for future planning with appropriate adjustment factors based on recent observation patterns.

What’s an acceptable deviation between predictions and observations?

Deviations within 15-20% are normal and generally don’t require significant plan modifications. Deviations of 20-40% warrant recalculating fuel requirements and ETAs but usually don’t prevent passages. Deviations exceeding 40% suggest significant non-astronomical influences are at work and may require reconsidering whether to proceed or wait for more favorable conditions. Always consider your vessel’s capabilities and the specific conditions of your passage when evaluating acceptable deviation levels.

Can I use yesterday’s observation-prediction comparison to predict today’s currents?

Yes, but with important limitations. If weather conditions remain stable and no significant changes in river discharge occur, yesterday’s deviation pattern typically persists through today’s tide cycles. However, changing weather, shifting wind patterns, or evolving pressure systems can alter the relationship. Always check current observations on the day of your passage rather than relying solely on yesterday’s patterns. Use historical patterns as initial guidance but verify with fresh observations.

Why do some current stations never match predictions?

Stations in river mouths, narrow channels with complex geometry, or areas with strong wind exposure experience non-tidal influences that predictions don’t capture. The prediction models are optimized for astronomical tides and may underweight or ignore meteorological and hydrological factors. These stations require heavy reliance on observations rather than predictions. After several transits through these areas, you’ll develop local knowledge of typical prediction-observation relationships that improves your planning.

How do I know if an observation is reliable?

Check the observation timestamp—data more than 30-60 minutes old may not represent current conditions. Verify the observation makes physical sense given tide stage and weather conditions. Look for smooth progressions over time rather than erratic jumps that might indicate equipment problems. Mariner Studio flags questionable data and indicates when stations are offline or reporting stale information. If observations seem inconsistent with predictions and weather conditions, treat them skeptically and consider navigating more conservatively.

Practical exercises for building skill

The best way to develop proficiency at using predictions and observations together is through deliberate practice. These exercises help you build the pattern recognition and decision-making skills that define expert current planning.

Exercise 1: Prediction-observation tracking

Choose a current station you transit regularly. For one month, record predicted current speeds and corresponding observations at the same time each day. Calculate the deviation percentage for each observation. Plot these deviations over time and look for patterns. Do deviations correlate with wind direction? River discharge? Atmospheric pressure? This exercise builds awareness of what drives prediction-observation gaps in your local waters.

Exercise 2: Blind ETA calculation

Before a passage, calculate your ETA using current predictions. Don’t check observations. Make the passage and note your actual arrival time. Then retrospectively check what observations showed during your transit. Calculate what your ETA would have been using observed currents instead of predictions. The difference reveals how much prediction-observation gaps affected your passage and whether checking observations would have improved your planning.

Exercise 3: Seasonal comparison study

Compare prediction-observation relationships during different seasons at the same station. Is spring different from fall? Does summer show different patterns than winter? Understanding seasonal variations helps you anticipate when predictions will likely deviate from reality. Most mariners discover that certain months consistently show enhanced or diminished currents relative to predictions—knowledge that improves planning throughout those seasons.

Exercise 4: Multi-station synthesis

For a longer passage involving multiple current stations, practice synthesizing prediction and observation data from all stations along your route. Check which stations show good prediction-observation agreement and which show significant deviations. Use this analysis to identify route segments where you can trust predictions and segments where you need to build larger safety margins. This exercise develops the skill of prioritizing data sources based on their reliability in specific locations.

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The gap between current predictions and observations contains critical information that prevents delays, saves fuel, and identifies hazardous conditions before you encounter them. Master this dual-data approach, and you’ll navigate with the confidence that comes from understanding both what should happen and what is actually happening in the water.

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Download Mariner Studio for iOS to access current predictions, real-time observations, and integrated current data at waypoints along your routes. All current features sync with your favorites for streamlined passage planning and underway monitoring.