Comparison

PredictCurrent vs Slackwater

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

PredictCurrent

Navigate coastal waters with detailed tidal and ocean current maps. Access 10-day forecasts for currents, wind, waves, and sea temperatures. Essential for safe marine planning and exploration.

Highlights
  • Ultra-high-resolution 100m tidal current maps
  • 400m and 4km global coastline coverage
  • 10-day animated forecasts for currents, wind, and waves
  • Hourly tide chart data
  • Wind-against-current interaction analysis
  • Sea temperature tracking
Features
Currently charting
Read full description

Navigate coastal adventures with precision using real-time tidal current data from PredictWind. PredictCurrent delivers ultra-high-resolution 100m tidal current maps, plus 400m and 4km maps covering 90% of global coastlines. It also includes full ocean current coverage, empowering fishermen, sailors, and coastal explorers with essential tools for current tracking, tide planning, and marine navigation. Developed by PredictWind’s expert oceanographers, trusted globally for industry-leading forecasting, PredictCurrent supports confident and safe coastal navigation for boating, fishing, sailing, and kayaking. Why PredictCurrent - Unrivalled Precision: Ultra-high-resolution 100m tidal current maps provide unmatched detail for coastal tide planning, ideal for fishing, sailing, or paddle sports. Also includes 400m and 4km resolution maps. - Trusted Expertise: Built by PredictWind, pioneers in marine and ocean current forecasting, delivering professional-grade data. - Comprehensive Tracking: Monitor tidal currents, ocean currents, winds, waves, and sea temperatures with animated maps and hourly tide chart data for 10 days. - Coastal Navigation: Join fishermen, sailors, kayakers, and coastal explorers worldwide who rely on PredictWind’s marine weather and current data for informed navigation. Key Features - Ultra-High-Resolution 100m Tidal Current Maps: Visualise intricate nearshore water current movements with clarity, ideal for coastal navigation, route planning, and safety. - High-Resolution 400m & 4km Maps: Access tide and ocean current coverage for 90% of global coastlines, seamlessly integrated with live ocean current data. - Advanced Dashboard: Analyse wind-against-current interactions, wave heights, tide cycles, and directions using accurate ECMWF wind forecasts. - Animated 10-Day Forecasts: View dynamic tidal currents, ocean currents, wind, waves, and sea temperature forecasts on interactive marine maps. - Detailed Data Tables: Access hourly data on current speed and direction, plus alerts for wind-against-current situations. Tailored for fisherman, sailors, kayakers, and coastal adventurers, PredictCurrent offers essential tools for safe marine planning—backed by PredictWind’s proven ocean data and current tracking accuracy. Start with a 14-day free trial. Access ultra-high-resolution tidal current data, tide charts, ocean current forecasts, wind, waves, and sea temperature tools for your next coastal journey. Terms & Conditions: https://www.predictcurrent.com/terms-and-conditions Privacy Policy: https://www.predictcurrent.com/privacy-policy

About

Slackwater

This app provides tide and current predictions that work offline, even without a signal. It offers detailed information on tide times, current speeds and directions, and celestial events for thousands of stations worldwide. Users can access this data on their iPhone, iPad, and Apple Watch.

Highlights
  • Offline tide and current data
  • Tide predictions for 5,000+ stations
  • Current speed and direction
  • Sunrise, sunset, and moon phase
  • Apple Watch app and widgets
  • Siri integration
Features
Read full description

The tide and currents app that works without signal. Tides for more than 5,000 stations worldwide and currents across the US and Canada, already on your phone — on the water, on the beach, in the anchorage, with no bars and nothing to load. No spinner. No "no internet connection". You open it, and the answer is there: rising or falling, flooding or ebbing, and how long until the next high, low or slack. And it does the part most tide apps skip. Heights are the easy half. The harder question is the current: when does the pass go slack? How hard is it running at max? Can you get through before it turns? WORKS WHERE THERE IS NO SIGNAL Predictions are made on your phone, not fetched. Down a dead-end road, out at the point, in an anchorage, or with the boat's electronics down — you get the same answer you would have got at the dock. The map for your area and your favourite stations stays on your phone too. CURRENTS, NOT JUST TIDES Slack, max flood and max ebb on one curve, with speed and direction. Drag your thumb across the week to read any moment. Paired current stations link to the tide at their reference port. SUN, MOON AND THE TIDES THEY DRIVE Sunrise, sunset and twilight, the moon's phase, spring and neap tides explained, and solar and lunar eclipses, for every station. ON YOUR WRIST, HOME SCREEN AND SIRI An Apple Watch app that works without your phone: turn the Digital Crown to move through the day. Home screen widgets for the next event and today's curve. Ask Siri for the next low tide, high tide or slack window. On iPhone and iPad, in 16 languages. FREE, NO ACCOUNT, NO ADS Every station and every date is free and stays free. No account, no ads, no tracking, and the app is open source. Slackwater Premium is optional and funds development: lock screen widgets, Apple Watch complications, alerts before the tides and currents you care about, and station calendars. Choose a yearly subscription or a one-time lifetime purchase. WHERE THE NUMBERS COME FROM Tides for more than 5,000 stations across a hundred countries are built in, from NOAA, the Canadian Hydrographic Service, Norway's Kartverket, Toitū Te Whenua Land Information New Zealand (LINZ), Denmark's DMI, the Japan Coast Guard and the TICON-4 global tide-gauge catalogue, and checked against each station's published tidal datums wherever it has them. Currents cover the United States and Canada: more than 2,500 NOAA current stations, plus 23 Canadian passes from the Salish Sea to Haida Gwaii and Cape Breton. Canadian tide stations download their data from the Canadian Hydrographic Service once, then work offline. Seven Canadian current passes use downloaded harmonic models; the other sixteen fetch CHS predictions when you are online and keep the downloaded window for offline use. Where we cannot publish numbers we trust, the station is listed but blank instead of guessed. Predictions are not observations — conditions vary with weather and river flow. Not for navigation. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://slackwater.xyz/privacy/

Screenshots

PredictCurrent4 screens
Slackwater4 screens

Verdict

The call

The clearest difference is review sentiment: Slackwater at 100% against PredictCurrent's 57%. Slackwater also leads on rating (5.0 vs 4.5). PredictCurrent's advantage is ratings volume (272 vs 1) and chart position (#72 vs unranked). On price, update cadence, ads and in-app purchases there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. PredictCurrent sells 5 in-app purchases, starting at $15.00 per month and Slackwater sells 2 in-app purchases, starting at $7.99 per year. Whichever you choose, the download price is not the number that matters.

ReceptionRating · Positive reviews · Number of ratings

Slackwater holds the better App Store score, 5.0 against 4.5. That said, the two scores are not equally well evidenced: PredictCurrent has 272 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 57% of PredictCurrent's written reviews are positive against 100% of Slackwater's.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly monthly. The most recent releases landed on November 12, 2026 and November 11, 2026 respectively.

Scorecard5 real differences · 6 level
PredictCurrent versus Slackwater: the parameters behind the verdict, then further details
ParameterPredictCurrentSlackwater
PriceFreeFree
Rating4.5 (272 ratings)5.0 (1 ratings) — better
Positive reviews56.8% of reviews100.0% of reviews — better
Number of ratings272 — better1
Update frequencyMonthlyMonthly
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchasesFree with in-app purchases
Best chart rank#72 — better—
DevicesiPhone, iPadiPhone, iPad, Apple Watch — better
Requires iOS16.0 — better26.0
Further details — not scored
Size50 MB59 MB
Age rating4+4+
DeveloperPredictWind LimitedOpen Water Software LLC

Customer experience

PredictCurrent

All ratings255 ratings
Positive85.9%
Neutral2.7%
Negative11.4%
Written reviews81 reviews
Positive56.8%
Neutral0.0%
Negative43.2%

Slackwater

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Bugs and requests

PredictCurrent

Reported bugs

8 issues
  • Unable to add location error messages despite valid coordinates
  • Location setup fails to respond or complete
  • Password not saved correctly in database, preventing login
  • Account creation fails with character handling errors
  • App crashes when setting locations
Show 3 more
  • Free trial access inconsistent across devices
  • iPad version blocks access to charts despite iPhone trial access
  • Data unavailable errors at valid deep water locations

Requested features

9 requests
  • Extended forecast data for full 24-hour next day coverage
  • Smaller time increment stepping (sub-hourly) for racing
  • Exact tide turn time information beyond hourly data
  • Legend/symbol guide for app indicators
  • Improved coastal and estuarine modeling
Show 4 more
  • Better 100m resolution coverage beyond UK Solent region
  • Cross-platform synchronization between iPhone and iPad
  • Offline access to saved locations
  • Multi-language support (German, French, etc.)

Slackwater

Not enough reviews yet to summarise bugs or requests.

In-app purchases

5 purchases

PredictCurrent

Subscriptions5
  • PredictCurrent Pro 1-Month14 Days trial$15.001 Month
  • PredictCurrent Pro 3-Monthly14 Days trial$29.003 Months
  • PredictCurrent Pro 3-Monthly3 Days trial$29.003 Months
Show 2 more
  • PredictCurrent Pro 3-Monthly7 Days trial$29.003 Months
  • PredictCurrent Pro Annual14 Days trial$99.001 Year
2 purchases

Slackwater

Subscriptions1
  • Premium Yearly$7.991 Year
One-time1
  • Premium Lifetime$69.99

Questions

Is PredictCurrent free?
PredictCurrent is free to download, with in-app purchases available.
Is Slackwater free?
Slackwater is free to download, with in-app purchases available.
Which has better reviews, PredictCurrent or Slackwater?
Slackwater is rated higher. PredictCurrent averages 4.5 out of 5 from 272 ratings, while Slackwater averages 5.0 from 1 ratings.
Do PredictCurrent or Slackwater have ads?
Neither PredictCurrent nor Slackwater shows ads.
Which is updated more often, PredictCurrent or Slackwater?
PredictCurrent ships an update monthly, and Slackwater monthly. Most recently, PredictCurrent was updated on November 12, 2026 and Slackwater on November 11, 2026.

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