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Fastnet Navigation. Nat Ives - RORC May 5 2009. AGENDA. Aim of the course The role of the navigator offshore Pre-race prep On the race track Routine and log Competitor tracking Weather and strategy updates Performance monitoring. Course to Sail Strategy Competitor tracking

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fastnet navigation

Fastnet Navigation

Nat Ives - RORC May 5 2009

  • Aim of the course
  • The role of the navigator offshore
  • Pre-race prep
  • On the race track
    • Routine and log
    • Competitor tracking
    • Weather and strategy updates
    • Performance monitoring
role of the offshore navigator
Course to Sail


Competitor tracking

Sailing Instructions

Notice of Race




Performance data

Start and nav software


Tides or currents

Class regs

Safety regs

VHF comms

Crew Weights

Sail crossovers

Sail hours


Shipping (lights)

Role of the offshore navigator
pre regatta prep admin
Pre-Regatta Prep - Admin
  • Notice of Race
    • Governing Rules – esp. Weather sources & IRPCS
    • Programme
    • Race Course
    • Registration
  • SI’s
    • Reporting
    • Time Limits
    • Penalties – esp OCS (two-turns penalty allowed, 50% place for OCS)
    • VHF and SSB channels
  • YC facilities
    • Start and End – Where are you berthing?
rorc comms regulations
RORC Comms Regulations


Sailing Instructions may request yachts to send position reports during a race. There is no limit on communication from a yacht provided the yacht does not receive information (other than that publicly available to all) which might help her in the race – see RRS41 - (outside help). A yacht may receive information about severe weather without infringing RRS41 (outside help).

pre regatta prep the race track
Pre-Regatta Prep – the Race Track
  • Waypoint lists for route, hazards, and lights
  • Weather
    • Forecasts sources - GRIB Files
    • Live Data
    • Historical Data - climatology
  • Topography
    • Roadmap?
  • Tides or Currents
    • Reference ports
    • Sources of data e.g. SHOM
  • Charts
    • Check up to date
    • Know symbols

Create a daily timetable based on the above, run preliminary routes to highlight key points of race area

waypoints other than obvious headlands
Waypoints – other than obvious headlands
  • Start and Finish lines
  • Shambles (E&W)
  • Eddystone
  • Runnel Stone
  • Longships
  • Wolf Rock
  • Seven Stones (light and rock)
  • Scilly Isles outlying rocks
  • Bishops Rock
  • Weather stations (Channel Light Vessel and Air Strips etc)
grib files
GRIB Files
  • Electronic compressed data file with forecasted or actual data on a grid
  • Important to know
    • Source – compare models
    • Forecast time and publish time usually in UTC
    • Resolution (1 deg, 0.5 deg, or hi-res)
    • Data height – normally 10m
    • How the data is calculated and displayed – beware interpolation
  • Sources
    • (free 1 deg and 0.5 deg GFS/AVN data) – check spaghetti plots
    • (free 1 deg data)
    • Higher res data is normally paid for e.g. Theyr, PRO-GRIB etc – if paid for then NOT in public domain so illegal for RORC races after start
    • Quik Scat analysis GRIBS
  • Global GRIB data can overestimate early and late in the day, does not account for topography and sea breeze
  • Check reference height for data – normally 10m
  • UKMO and MeteoFrance do not do free GRIB so use graphical output as reference
bermuda race daily schedule
Bermuda Race Daily Schedule


  • 0630 3 Day Basic + Sat Analysis
  • 0700 Posns
  • 0830 Avn Model
  • 1100 Gulf stream Sat Pic
  • 1200 Daily SSB Broadcast
  • 1230 3 Day Basic + Sat Analysis
  • 1430 AVN Model
  • 1500 Posns + Quikscat
  • 1830 3 Day Basic + Sat Analysis
  • 2030 AVN Model
  • 2300 Posns + Gulf Stream Satellite Pic
  • 0030 3 Day Basic + Sat Analysis
  • 0230 AVN Model + Quik Scat
live data sources
Live Data Sources

Use to update forecast and track features

  • UKMO
  • University of Wyoming -
  • CEFAS WaveNet buoy data
  • Satellite imagery – good for fronts
  • MCA VHF broadcast – Frank’s Weather pages –
  • YOU!! And a your instruments - barometer
pre race prep the boat
Instruments, GPS, Radar, Comms

Calibration (depth etc) & Operation (MOB Procedure, target tracking, charts, sunrise etc)


Polars and Sails

Nav polars

Sail Crossovers

Nav equipment

Compass & Binoculars

NavNotes & Log



Almanac & Tidal Stream Atlas

Pre Race prep – the boat.
the polar curve












The Polar Curve
  • Mathematical model of performance, Boatspeed vs TWA, TWS
  • Designer’s tool, modified with ‘real’ sailing data
  • Varies according to local conditions and situation
  • Consider bumps in curve



  • Tie them in with Sail Crossover chart
  • Think about VMC options.
  • Check actual performance againstpolars all the time.
  • VMC heavily affected by sea state
  • Is TWS at masthead
    • what is GRIB ref height?
    • Is polar for masthead height?
optimum route planning
Optimum Route Planning
  • Theoretical route that is fastest to the finish based upon
    • Weather forecast (GRIB)
    • Polars
    • Current (GRIB or Database
  • Cautions
    • Only as good as your inputs
    • Try to judge the sensitivity of the route by running with slower polar or shorter forecast
    • Can be driven equally by last day of forecast as much as first (where as forecast is more reliable for early on)
    • Use gut feel to estimate route first
sources of tidal data
Navico PowerPoint templateSources of Tidal Data
  • Winning Tides – Solent
  • UKHO and SHOM data for Channel and Irish Sea
  • Wiley Nautical Almanac
during the race
During the race
  • If you can be out of watch system then you can set your own routine. Link with tactician/skipper at key times to decide on course to steer.
  • Convey course to steer with context – e.g. Sea state etc, likely changes in conditions and sail changes. When you need to be called
  • Re-run routing after each forecast and update using observed conditions and satellite imagery
  • Track competitors online, visually or with radar (note bearings at dusk). Use this to help with forecast through implied winds.
  • Track performance of boat against predictions and adjust navigation polar accordingly or if you loose a sail.
fastnet navigation1

Fastnet Navigation

Nat Ives - RORC May 5 2009