BitterRadishPASSAGE PLANNERSTHE HOW & THE WHY
Two planners answer different questions: will the current help or slow my passage? and how much tide will there be when I reach the places that matter? This guide walks through both.
Compare time underway on a fixed passage course between the C&D Canal entrance and Nantucket Harbor entrance, including Delaware Bay, offshore New Jersey, New York Harbor, Long Island Sound and the eastern sounds.
Open current planner →Estimate water level at your arrival along the recorded Cape May–Toms River inside passage. Compare departures using six priority tide checkpoints, a cruise speed and adjustable bridge waits.
Open tide planner →The start and finish choices select a stretch of an existing course. These pages do not generate a new navigable route, select a marina berth, or add a detour to a dock. A named town or inlet is a passage position on that course.
Press Show whole route when you deliberately want to fit the selected passage to the screen. Calculate, Swap and Pick on map preserve your current map view. Changing the start or finish can reset the inspected trip position because it is a different passage.
NOAA nautical chart loads chart tiles separately over the internet. Zoom in to see available soundings and navigation marks. Simple coastline uses saved land shapes and is helpful if the chart service is slow. It has no soundings. Map colors describe predictions at your arrival time, not a single snapshot of conditions everywhere.
Select a passage that crosses the eastern Sound and click near the Race. Then click several positions on the departure graph. The boat reaches that same place at different times, so the current there can change from following to opposing even though your route stays the same.
The horizontal axis is departure time; the vertical axis is total time underway. Lower is faster. The search samples every ten minutes from ten hours before to ten hours after the departure entered when you last pressed Calculate. It can cross midnight and includes nighttime departures.
Fastest means shortest passage duration. It does not mean earliest clock-time arrival or best weather. Choosing a graph result keeps that original comparison window. Pressing Calculate again centers a new window on the current input time. Departures the model cannot complete are excluded; the note below the graph reports them.
Following and opposing colors describe the component of current along your course at the estimated arrival. Near slack means very little modeled current. Arrows point in the direction the water flows, in true degrees. A cross-current can reduce forward speed even when the along-course component is favorable. Gray means current is unmodeled, particularly on the offshore New Jersey legs; it does not mean slack water.
The boat advances along the course in steps of at most one minute. At each step the planner evaluates saved NOAA current predictions at the boat’s changing position and time. Nearby station current vectors are blended along modeled course segments. The calculation accounts for following, opposing and cross-current, assuming the boat steers to stay on the course.
Harmonic station data are saved at six-minute intervals. Subordinate stations use smooth estimates between predicted slack and maximum-current events. Station depths and sources appear under Sources, station depths & calculation assumptions; a station’s prediction depth is not the depth of water under your boat.
A passage is rejected if the model cannot maintain forward progress or exceeds 120 hours. Unmodeled segments use the entered boat speed without a current adjustment. Wind, waves, river discharge, traffic, stops and actual throttle changes are outside this calculation.
The planner first estimates your arrival at Wildwood Crest, then Nummy Island, Ludlam Bay, All Seasons Marina, the rail bridge and Main Marsh, in northbound travel order. Those are six different tide times. A longer Margate wait shifts the rail-bridge and Main Marsh arrivals later; it does not shift places you have already passed.
At this point shows estimated tide in feet MLLW, rising/falling water level, next high and low tide, arrival time, elapsed time and the timing section. Rising or falling describes water level; it is not a current direction. A dashed connector identifies the prediction source used for a nearby-station estimate.
Gold labeled markers identify the six priority checkpoints. A red outline flags a priority checkpoint below your alert level. Route colors give a broader estimate blended between nearby tide sources. Use the checkpoint table to read the actual values used for ranking and alerts.
For each candidate departure, the planner computes the estimated tide at each included priority checkpoint’s individual arrival. It then takes the lowest of those heights. The best departure maximizes that lowest value; the lowest tide window minimizes it. The graph’s vertical axis is this minimum in feet MLLW, so higher gives the larger modeled tide margin across your checkpoints.
The alert compares each arrival estimate against Flag arrival tide below. Equality is at the alert level; only values below it trigger the warning. The notice names all flagged checkpoints, and the table labels each one. Changing the alert level updates the notice and markers immediately, without changing the route timing or recommendation ranking.
The best departure can still have a low-water alert: it is the best among the sampled departures, not a promise that all six have enough water. Check the selected departure’s notice after choosing it. A passage with no priority checkpoint has no best/lowest tide recommendation, but the other station arrivals remain available.
These are on-page planning notices. They do not send texts or emails, monitor a live gauge, or notify you while the page is closed.
Mean Lower Low Water is a tidal height reference used for many nautical chart depths. A tide of 1.2 ft MLLW is water level 1.2 feet above that datum; it does not say there are 1.2 feet of water at the checkpoint.
If a verified charted depth were 4.0 feet at MLLW, adding a predicted 1.2-foot tide would give a nominal 5.2-foot water column. This planner does not supply that verified depth or subtract draft, squat or a clearance margin. Wind and weather can move actual water levels away from astronomical predictions, especially in back bays.
The controls and bridge table list, north to south: Atlantic City railroad bridge, Route 40 / Albany Avenue Bridge, then Margate City Bridge. The calculation processes them in your actual travel order.
Arrival is the time you reach the crossing, before that bridge’s wait. Clear bridge is arrival plus its slider delay. Earlier bridge waits are included in the arrival at later bridges. Each listed delay adds the same amount to final arrival; the summary reports total moving time plus all bridge waits.
Move a slider to recalculate bridge times, downstream tides, alerts and the departure comparison automatically. Try 0 minutes if you expect no wait, or 30 for a longer hold. The map view and your inspected point stay selected. The rail-bridge priority tide is checked on arrival, before the rail bridge’s own wait; a wait can change water level while you are there.
Sliders are assumed delays. They do not predict bridge openings, train movements or required notice. Boat height is not used to decide whether an opening is needed. If a bridge requires no wait for your boat, set its delay to zero; check actual opening requirements separately.
Checkpoint markers show the places being checked. The original four use nearby NOAA tide stations projected onto the recorded passage. The two added locations use explicitly labeled station proxies; no unverified local time shift or height correction has been applied.
| Checkpoint | Prediction source | How to interpret it |
|---|---|---|
| Atlantic City rail bridge | NOAA 8534638 · Absecon Channel, State Route 87 bridge | Marker at the rail crossing. Source is about 1.56 nm away. Nearby-station proxy at your rail-bridge ETA, before its wait. |
| Main Marsh Thorofare | NOAA 8534393 · Main Marsh Thorofare | Station estimate at the closest pass-by position. |
| All Seasons Marina · Ocean City | NOAA 8534975 · Great Egg Harbor Bay / Beesleys Point | Checkpoint beside the marina near the 34th Street / Roosevelt Boulevard bridge. Source is about 2.08 nm away. Nearby-station proxy, not a measured level at the marina. |
| Ludlam Bay | NOAA 8535221 · Ludlam Bay, west side | Station estimate at the closest pass-by position. |
| Nummy Island | NOAA 8535661 · Nummy Island, Grassy Sound Channel | Station estimate at the closest pass-by position. |
| Wildwood Crest | NOAA 8535838 · Wildwood Crest, Sunset Lake | Station estimate at the closest pass-by position. |
Nearby waterways can have different tide timing and range. Source distance is shown beside each checkpoint in the table and inspection panel. A marker at your requested spot is not a claim that NOAA measures or predicts that exact spot. USGS location record identifies the gauge location beside All Seasons Marina; this planner uses the supported NOAA prediction source above rather than that gauge’s live observations.
The inside passage follows a timestamped August 29, 2022 track from Canyon Club in Cape May to Dillon’s Creek on Toms River. Obvious stationary time at the start and finish and bridge-area holds were removed. The cleaned moving pattern is reused in reverse for southbound trips.
Open-water sections scale from the 26-knot reference cruise. Slower sections retain their recorded timing as a proxy for restricted or no-wake travel; increasing cruise speed does not make those sections run faster. A lower cruise speed also limits them when it is below their inferred speed. These sections are inferred from recorded progress, not a verified map of legally designated no-wake boundaries. Actual restrictions and conditions take precedence.
Bridge waits are added after the cleaned moving timing. Planned stops, docking, refueling and marina detours are not added. Unlike the current planner, the inside tide planner does not alter passage duration for tidal currents.
Saved NOAA high and low tide events supply times and heights. Between those events, a smooth cosine curve estimates the height. At a checkpoint, the selected source is evaluated at that checkpoint’s arrival. Along-route color blends nearby source heights at the same time. Neither is a live observed water level.
Prediction reference: NOAA CO-OPS data API. More background and the reason this project exists: About BitterRadish passage planners.