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Rolex Fastnet Race 2021: Winning is in the Details

Posted by Penny Haire on 21 June 2021 5:39:52 PM
Penny Haire

TID Fastnet Race blog header

The prestigious Rolex Fastnet Race is just a few weeks away, and competitors who have the most accurate data on hand will be able to make the best possible decisions for the fastest route.
The Fastnet is genuinely a navigators' race, as it challenges competitors to negotiate some very tricky tidal situations - such as whether to head offshore for pressure or tuck inshore to avoid the worst of an adverse tide. This year's race is exciting because it's finishing in France for the first time, and the last section involves negotiating the notorious Alderney Race, with currents of up to 9 kts.

By popular demand, Tidetech is again providing an exceptional package for this year's race, with 400m resolution tidal current GRIBs for the whole race area and 100m GRIBs for the Solent and Dorset Coast. In addition, GRIB's are available before the start of the race for pre-planning and strategy, and historical GRIBs for the last six races are also available so that navigators can run multiple scenarios based on historical wind and tidal data.
With validated model accuracy, this unprecedented level of detail gives you the best chance against competitors who rely on less detailed data.

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Where Tidetech's High-resolution models beat the rest:


1.   Unprecedented Detail

Tidetech's 400m and 100m resolution GRIBS give far better detail than MyOcean Copernicus model or Admiralty Tidal Streams:

Example A: St Albans Head - resolution

St Albans Head MyOceanUKHO St Albans Head

MyOcean Mercator / Copernicus 2km resolution                                                        AdmiraltyTidalStreams

Tidetech St Albans Head tidal currentsTidetech St Albans Head 100m

Tidetech 400m resolution                                                                Tidetech 100m Resolution

Example B: Detailed Tidal Gradients

The below image shows samples of the current, past St Albans Head, and the high precision detail from our model shows you where the tide is strongest. So, for example, if you're only a few hundred meters from a competitor, they might have 2 knots more wind, but you might have 3 knots more tide. If you use this level of extreme detail in the data to make strategic decisions, a small separation from a competitor can significantly impact your result.

Tidal Gradient St Albans Head

Example C: Alderney Race to Cap de la Hague

Negotiating Alderney and its Race (Le Raz Blanchard) will be very tricky - boats will make significant gains or losses here. Make sure you have the best possible data at hand.

MyOcean Copernicus AlderneyAdmiralty Alderney

MyOcean Mercator / Copernicus 2km resolution                                                     Admiralty Tidal Streams

Cap de La Hague tidal Streams 2Tidetech Alderny 400m

Tidetech 400m resolution GRIBS

2.  Validated Model Accuracy

Tidetech models are validated against all available observations and harmonic predictions.

Validation against all Admiralty Tidal Stream locations in the race area - here is a sample:Validation UKHO

There's lots of buzz around this race, and for a good reason, because this year's race will bring some fresh new challenges for teams and having the most accurate data could put you at the front of the fleet!

Fastnet Special Package



  1. 100m resolution Solent Model for the race period- available early July

  2. 400m resolution model of the entire course for the race period - available from June 24th

  3. Immediate access to our English Channel, Solent and North-West European models to use in the race build-up.

  4. Historical GRIBs for the last six Fastnet races, from 1000 UTC for five days - available from mid July



The price might seem high at first sight, but building, validating and running a new model takes time and much scientific expertise. However, at less than the cost of a new sheet and way less than a new sail, it's is a small investment considering the detailed and accurate information you'll have access to before and during the race and its potential to put you on the podium!

Sign up now


Topics: sailing, tides, English Channel, Tidemap, grib, yacht race, yacht racing, Fastnet

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