TideTutor

Day Skipper tidal calculations · iPhone · iPad · Android

Teaches,
doesn’t tell.

TideTutor is a patient tutor for the tide sums every sailing student dreads. You do the working. TideTutor nudges you with a hint, catches the classic slips, and shows every step once you’ve earned it.

Have a go ↓

Coming soon to the App Store and Google Play

Real question · 222-227A

Have a go.

This is one of the app’s free questions, checked by the same engine. Get it wrong on purpose if you like: try 1.2, the most common slip there is.

No pencil? Take a hint. There are three, and each one gives a little more away.

Wyvern QuayStandard port
LW07231.2 m
HW13236.0 m

Using the rule of twelfths, find the height of tide at Wyvern Quay at 0923, during the second hour after low water.

m

    Common mistakes,
    corrected.

    Wrong answers aren’t just marked wrong. TideTutor recognises the classic slips and tells you what you did, without telling you the answer.

    • Rule of twelfthsGave the rise, not the height of tide
    • Rule of twelfthsTook twelfths of the HW height, not the range
    • Rule of twelfthsAssumed the tide rises at a steady rate
    • Tidal hoursHW−2 or HW+2? Got the sign the wrong way round
    • Tidal hoursStarted the tidal hour on the hour, not 30 min before
    • Tidal curvesUsed the springs curve on a day between springs and neaps
    • Tidal curvesRead the wrong side of high water
    • Secondary portsUsed the nearer time difference instead of interpolating
    • Secondary portsForgot to apply the height difference
    • Course to steerSteered the water track and ignored the tide

    Passage plan

    Five topics, in the order you’ll meet them.

    1. WP1Rule of twelfthsHeight of tide on the hour, by the 1, 2, 3, 3, 2, 1 rule.
    2. WP2Tidal hoursBuild the HW−6 to HW+6 table, and pick the right hour.
    3. WP3Tidal curvesRead the standard-port curve, between springs and neaps.
    4. WP4Secondary portsTime and height differences, interpolated, one box at a time.
    5. WP5Streams & course to steerRead the diamond, then draw the vector triangle on a practice chart.

    On iPad

    Made for the chart table.

    The question sits beside the chart. Drag the tide vector, set the track, walk the dividers along the latitude scale, and see the triangle come together. Longer questions are checked a stage at a time, so you know exactly which step went wrong.

    TideTutor on iPad: a course to steer question beside the practice chart

    No signal in the marina?
    Doesn’t matter.

    TideTutor's progress screen, showing each topic as secure, getting there or learning

    Everything works offline. There’s no account, no ads and no tracking, and your progress never leaves your phone.

    TideTutor keeps score for you, though: what you’ve mastered, what needs work, and a revision mode that brings your mistakes back until they stick. Set your exam date and the countdown starts.

    Free to try

    Two questions in every topic, on us.

    Then one purchase unlocks every topic, unlimited questions and revision mode. Pay once, keep forever. No subscription, ever.

    Full Access £29.99 once

    UK price; your store shows your local price.

    TideTutor: Day Skipper tidal calculations practice for iPhone, iPad and Android.

    TideTutor is for training only, not for navigation. All ports, places, charts and tidal data in the app are fictional; any similarity to real places is coincidental. TideTutor is independent: it is not RYA material and is not endorsed by the Royal Yachting Association.