Comparison

PredictWind vs Slackwater

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

Head to head
About

PredictWind

Access highly accurate marine weather forecasts and advanced tools for wind, waves, and currents. Plan your voyages, optimize routes, and stay informed with real-time data and alerts for safer and more enjoyable time on the water.

Highlights
  • Accurate marine weather forecasts
  • Wind, wave, and current data
  • Weather Routing for optimal routes
  • Departure Planning summaries
  • High-resolution forecast maps
  • Live wind observations and webcams
  • Weather alerts
Features
Read full description

Accurate marine weather forecasts and powerful tools utilizing wind, wave and currents, save you time, keep you safe and ensure you get the most out of every day on the water. Access the world’s top-ranking forecast models for reliable and accurate wind and weather data, including ECMWF, AIFS, ICON, UKMO, GFS, and more. Our very own PWAi, PWG & PWE models deliver unmatched accuracy in the short-to-medium range. View high resolution marine weather maps for wind, gust, CAPE, wave, rain, cloud, pressure, air temperature, sea temperature, ocean data and solunar. Suitable for sailing yacht, powerboat and any other marine weather activity. In addition to marine forecasts, PredictWind also provides a suite of powerful marine weather tools to save you time and keep you safe at sea using Wind, Wave, Tidal and Ocean currents. Weather Routing takes your start and end points then calculates your route factoring in tides, currents, wind and wave data, depth and your Sailing Yacht or Powerboats unique dimensions to give you the best route for comfort or speed. Departure Planning quickly summarizes the forecast marine weather conditions you’ll encounter along your route if leaving on day 1, 2, 3, or 4. Use this data to select the perfect departure date, every time for your Sailing Yacht or Powerboat. ADDITIONAL FEATURES - Daily Briefing: Powerful marine weather data condensed into a simple text forecast. - Maps: High resolution forecasts maps with animated streamlines, wind barbs or arrows. - Tables: The ultimate dashboard for detailed analysis of Wind, Wave, Rain and more. - Graphs: Compare multiple marine forecasts at the same time. - Live Wind Observations and Webcams: Know what’s happening with the weather right now at your local spot. - Local Knowledge: Hear about the best marine spots, amenities and activities at your destination. - Weather Alerts: Set your preferences then get alerts when conditions are just the way you like them for Wind, wave and other parameters. - Ocean Data: See what’s happening under the waves with ocean and tidal currents, and sea temperature. - GPS Tracking: Get a free customized GPS tracking page for your blog or website showing wind data overlaid. - AIS Data: View over 280,000 vessels worldwide on the AIS network to see marine traffic. Terms and conditions: https://www.predictwind.com/about-us/terms-and-conditions
 Privacy policy: https://www.predictwind.com/about-us/privacy-policy

About

Slackwater

Access tide and current data for thousands of stations worldwide, even without an internet connection. View predictions for rising/falling tides, slack times, and current speeds and directions. Includes sunrise, sunset, and moon phase information.

Highlights
  • Offline tide and current data
  • 4,700+ tide stations worldwide
  • Currents across US and Canada
  • Sunrise, sunset, and moon phase
  • Apple Watch app
  • Home screen widgets
  • Siri integration
Features
Read full description

The tide and currents app that works without signal. Tides for more than 4,700 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. Every current station links to the tide at its 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 scrub 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 14 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 4,700 stations across a hundred countries are built in, from NOAA, the Canadian Hydrographic Service, Norway's Kartverket 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 22 Canadian passes from the Salish Sea to Haida Gwaii and Cape Breton. Canadian stations download their data from the Canadian Hydrographic Service once, then work offline. A few Canadian passes sit in water the on-device model cannot predict; those fetch predictions when you are online, and say so. 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

PredictWind4 screens
Slackwater4 screens

Verdict

The call

The clearest difference is in-app purchases: Slackwater at none against PredictWind's 10. Slackwater also leads on rating (5.0 vs 4.8). PredictWind's advantage is ratings volume (33K vs 1) and chart position (#21 vs unranked). On price, ads, monetization model and device support 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. PredictWind sells 10 in-app purchases, starting at $6.99 per month. Slackwater asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Slackwater holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: PredictWind has 33K ratings behind it against 1, so its average is the more settled of the two.

Scorecard5 real differences · 6 level
PredictWind versus Slackwater: the parameters behind the verdict, then further details
ParameterPredictWindSlackwater
PriceFreeFree
Rating4.8 (33K ratings)5.0 (1 ratings) — better
Positive reviews84.4% of reviews—
Number of ratings33K — better1
Update frequencyEvery 9 days—
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree with in-app purchases
Best chart rank#21 — better—
DevicesiPhone, iPad, iPodiPhone, iPad, Apple Watch
Requires iOS15.0 — better26.0
Further details — not scored
Size50 MB53 MB
Age rating4+4+
DeveloperPredictWind LimitedOpen Water Software LLC

Bugs and requests

PredictWind

Reported bugs

3 issues
  • App crashes or freezes on some devices
  • Inconsistent performance across different locations
  • Subscription issues and billing problems

Requested features

5 requests
  • Improved integration with other apps and charts
  • More frequent weather model updates
  • Earlier weather forecast updates
  • Ability to customize alert settings
  • Improved offline functionality

Slackwater

Not enough reviews yet to summarise bugs or requests.

In-app purchases

10 purchases

PredictWind

Subscriptions10
  • Basic - Monthly7 Days trial$6.991 Month
  • Basic - 3 Monthly7 Days trial$12.003 Months
  • Basic - Annual7 Days trial$29.001 Year
Show 7 more
  • Standard - Monthly7 Days trial$49.001 Month
  • Standard - 3 Monthly$99.003 Months
  • Professional - Monthly7 Days trial$99.001 Month
  • Standard - 3 Monthly7 Days trial$99.003 Months
  • Standard - Annual7 Days trial$249.001 Year
  • Professional - 3 Monthly7 Days trial$249.003 Months
  • Professional - Annual7 Days trial$499.001 Year
None

Slackwater

No in-app purchases

Questions

Is PredictWind free?
PredictWind is free to download, with in-app purchases available.
Is Slackwater free?
Slackwater is free to download, with no in-app purchases.
Which has better reviews, PredictWind or Slackwater?
Slackwater is rated higher. PredictWind averages 4.8 out of 5 from 33K ratings, while Slackwater averages 5.0 from 1 ratings.
Do PredictWind or Slackwater have ads?
Neither PredictWind nor Slackwater shows ads.

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