crossing coastal river bars disaster inbound damage outboundhelp page bar dynamicsdamage inbound...

CROSSING COASTAL RIVER BARS

Disaster inbound

Damage outboundHelp page

Bar Dynamics Damage inbound

Vessel handling

(Ranger Hope © 2005/14) (Chart extracts courtesy of AHO)

Open as Ppt show

The NSW East Coast is renowned for its formidable river bars.

Safe passage requires both the vessel and the skipper’s experience

to be adequate for the conditions encountered.

All small vessels and all skippers have their limitations.

If in doubt don’t go out

All small vessels and all skippers have their limitations.

Never turn your back to a wave.

PORT MACQUARIE BAR

DIAMANTINA ROCKS

BARS OF THE NORTHERN RIVERS

As the river water meets the sea it spreads out, slows and drops its load of silt. The East Australian Current continually erodes the seaward side forming a steep edge where waves can suddenly form.

THE PORT MACQUARIE BAR

PORT MACQUARIE BAR 2013

DiamantinaRocks

EAST AUSTRALIAN CURRENT

DAYTIME LEADS

NIGHTIME LEADS

VARIABLE LEADS - AVOIDS SOUTHERN HAZARDS2013 approx 250º T

2013 approx 245º T

2013 approx West T

2013 approx 265º T

Breaks

This chart extract is not for navigationclick here for charts

CAMDEN HAVEN BAR

FORSTER TUNCURRY BAR

OTHER BARS

TWEED BAR


RICHMOND RIVER BAR


THE CASUALTIES OF PORT MACQUARIE BAR

The Mermaid, the Prince Regent and the Lady Nelsonwere all damaged on the barwhen they brought the firstconvict settlers in 1821.

The “safe and commodious harbour…of a type familiar to experienced seamen of this coast” as promoted by the explorer John Oxleyin 1818, has since claimed thirty more shipwrecks and countless small vessels.

Ben Boyds topsail schooner WANDERER

On 14th November 1851, in huge seas with 14 crew and 14 foot of draught, the rakish craft was spotted desperately searching for entry. The townsfolk fearing she was a pirate signaled warning not to cross the seven foot depth over the on the bar.

The next day she foundered the seven foot depth as she attempted to run the bar.

In 1879 the outbound paddle steamer the Ballina was swept sidewayswhere she stuck fast on the sand. Cargo and passengers

were taken off but attempts to refloat her failed.

The outer northern breakwall was built over her remains.

F.V. NERANGI

In 1933, the attempts of the Pilot Master Capt. Liley were unsuccessful in towing the trawler off the Southern Breakwall.She became a total wreck.

Captain Liley considered the new double ender pilot boat the “Hastings” unsuitable for bar work. In 1937, while piloting the SS

Nambucca inbound, a freak wave capsized her and he was drowned.

Here she is seen washed up on the North Shore.

His crewman, with a lifebuoy, Jim Fitchett, survived.

PORT MACQUARIE WATERFRONT IN 1890

THE EVER CHANGING BARThe signature of a bar is that it is always unpredictable, changing by act of man, nature or conditions of the moment. History shows

that changes can be dramatic and sudden.

Royal HotelThe Bar Clarence St Kooloonbung Ck

Royal Hotel

THE SWASHWAYS OF THE BAR

Goal Point

Copy of an original painting courtesy of the Hastings Council Art Collection

PORT MACQUARIE 1824-1880

THE SWASHWAYS OF THE BAR

BALLINA WRECK

ROYAL HOTEL

WANDERER WRECK

NORTHSHORE

NORTHERN

BREAKWALL

BALLINA WRECK

SOUTHERN

BREAKWALL

PELICAN ISLAND

ROYAL HOTEL

CLARENCE ST WHARF

RESCUE SHED

RSL

THEN AND NOW - 2004 SHORELINE OVERLAID

BAR

PORT MACQUARIE 1880-1930

1943

In 1929 a one hundred year flood washed away the North Shore, the new entry was shoals & shallows until consolidated by the Northern Breakwall constructed in 1930-1940

Ballina Channel

Southern Breakwall 1899

Ballina channel

PORT MACQUARIE 1970

PORT MACQUARIE 2004

Outer Northern Breakwall

By 1970 sand build up on the NorthShore has reduced the bar to 5 feet.In 1976 the outer Breakwall was built to create northerly sand migration andpush a crescent bar out to sea. The wreck of the Ballina and the Ballina Channel were covered by the new wall.

By 2000 swell was often found to be less heavy to the north of the charted(recommended) track sown above.


The Crescent Bar

Flagstaff Hill

PORT MACQUARIE 1984

PORT MACQUARIE 1998

The Crescent Bar

BARS ARE EVER CHANGING

Advice received must be weighed against your observation of present conditions

PORT MACQUARIE 1998

PORT MACQUARIE BAR 2013

DiamantinaRocks

EAST AUSTRALIAN CURRENT

DAYTIME LEADS

NIGHTIME LEADS

VARIABLE LEADS - AVOIDS SOUTHERN HAZARDS2013 approx 250º T

2013 approx 245º T

2013 approx West T

2013 approx 265º T

Breaks


THE DYNAMICS OF RIVER BARS

Swell Wind

Seas Current

Tide Flood

EVER CHANGING BAR CONDITIONS

Ocean waves rotate within their wavelength. Squeezed upward on the shoaling bar, they slow down, the wavelength shortens and they may become top heavy and break.They become waves of translation (pushing forward).

WAVE ACTION ON THE BAR

18 knots on the bar25 knots approach 25 knots after

The bar

Steep edge

The seaward edge is kept steep

by the East Australian Current.

Typical speeds of the swell

Lagoon

SeasSwell

Wavelength Sea and swell coincide

SWELL AND SEASSeas are whipped upby the local wind.

Swell is created by distant storms,persistent winds or seismic events.

Seas + swells of different frequencies interact to form sets.

Typically 50 to 200mtrsSpeed 15-30 knots

SWELL AND SETSCORAL SEA CYCLONE

LOW IN THE TASMAN

Swells of different frequencies may interact to form sets of largerwaves or lulls. The period betweensets may be up to 20 minutes or more.

EFFECT OF WIND ON THE BAR

Increase of wavelengths and breaking of waves

flattens waves inshore, but raises them offshore

Swells slow down and their wavelengths shorten on the bar

Offshore wind

Onshore wind

EFFECTS OF ONSHORE WINDS

More white water

Higher waves, longer swellMore spray, less visibility

EFFECT OF TIDE ON THE BAR

Increase of wavelengths & progressiveincrease of bar depth

shortening of wavelengths & raising of wave height

Swells slow down and their wavelengths shorten on the bar

Ebb tide

Flood tide

PORT MACQUARIE 2004

The Crescent Bar 2004

PRESSURE WAVES

Strong run out tide can create standing waves by shortening the wavelengths and raising of wave height. These are usually inside the bar but particularly “wet” for small vessels to cross.

RUN OUT & FLOOD

Northerly longshore current

Southerly East Australian current

The overflowing saucer effect of run out

South West Rocks

Southerly swelloffshore

The leading edge ofswells slow as they hitshallow water causingwaves to land parallel

along the beach.

Northerly waves into Arakoon

Arakoon

Easterly waves in the break

COASTAL REFRACTION

COASTAL REFRACTION

SE on the South

Easterly on the leadsNE on the North

Refraction on the crescent bar moderates

swell direction.

THE REGULATIONS

Commercial vessels require operational permit and are ill advised to operate on bars in conditions above

winds of 20 knots and waves of 2 metres

In approved lifejackets (PFD1) must be worn over bars

Disaster inboundDamage outbound

Photos courtesy of RMS

FAST PDV OUTBOUND PLANPrepare your vessel and crew Forecast, fuel, mechanics, stowage, Pfd 1

Watch and wait Lulls and Sets may be 20 minutes apart Radio an ETR Tell someone where you are going

Look for saddles of lower wave height and avoid white water.

Anticipate tackling at least three waves on the bar & don't turn around.

Slow down to reduce the impact forces of the swell

HIIGH TIDE & RUN IN

TIMING IS EVERYTHING

DON’T GET AIRBORNE

ASSUME NOTHING

Show me how not to exit a bar

Swells may travel at 25 knots.A vessels approach at 20 knotscreates an impact at 45 knots.

You cannot slow the swell.

Becoming airborne results indamage to vessel and crew.

Slow down to reduce

impact forces

Show me a small vessel outbound

Photos courtesy of NSW Maritime Authority

PREPARE YOUR VESSEL TO GO OUT

POOR TRIM GOOD TRIM

Overloading aft encourages becoming airborne, level trim punches through the waves.

LOW MOTOR TILT GOOD MOTOR TILTHIGH MOTOR TILT

Poor tilt trim encourages becoming airborne or punches under the waves.

SLOWER VESSELS OUTBOUND

Show me a large vessel outbound

AVOIDING THE WORST OF THE RUN OUT PRESSURE WAVES

Show me a Parallel running exit

This technique is only relevant to Marine Rescue Personnel who may be required to exit in unfavourable conditions in order to save life. If you need to use such methods to get out then you shouldn’t go out!

INBOUND PLAN -ASSUME NOTHING

Don’t turn around

HIIGH TIDE & RUN IN

TIMING IS EVERYTHING

Stay on the backof the wave

Watch and wait Lulls and Sets may be 20 minutes apart

Prepare vessel and crew Forecast, fuel, mechanicsl, stowage, Pfd 1

Radio sign off on return Tell the rescuers that you are back

Disaster inbound

No water flow over the rudder whilst surfing down the wave face.

Ineffective prop thrust due to cavitation in the aerated white water.

The stern being pushed forward by the wave crest as the bow bottoms in the contra-rotating trough.

BROACHING IS PROMOTED BY :

NEVER RUN DOWNTHE WAVE FACE

as it slows on the bar


PREPARE YOUR VESSEL TO COME IN

POOR TRIM GOOD TRIM

Slight trim by the bow up, improves buoyancy and stops the bow digging into the holes.

TOO LOW MOTOR TILT LOW MOTOR TILTGOOD MOTOR TILT

Sight an object or compass bearing as the river mouthmay disappear behind the wave.

STAR

CLOUD

COMPASS

BACK OFF THE REVS IF WHITE WATER CAVITATION OCCURSGently reapply only the power at which the prop will grip the water.


PRESSURE WAVES

Dealing with pressure waves inbound

Prepare for heavy weather, Pfd 1Stowage & free surface effect limitationWatertight doors, deadlights & hatchesClear freeing portsConsider a drogue

DON’T TURN AROUND

SLOWER VESSELS INBOUND

Tell me more about preparing for heavy weatherPhotos courtesy of RMS

SHOULD YOU WAIT UNTIL CONDITIONS IMPROVE?

SLOWER VESSELS INBOUND

Photos courtesy of RMS

PORT MACQUARIE BAR

TOWING OPERATIONS

ADVICE & HELP IS AVAILABLE FROM YOUR LOCAL SEA RESCUE

TELL THEM WHO YOU ARE AND WHEN YOU EXPECT TO BE BACK

Many volunteer rescue unitsmaintain a radio watch and operate safety schemes for protecting vessels in their area.

AUSTRALIAN HYDROGRAPHIC OFFICE

CHARTSThe sample of chart AUS 219 is not safe for navigation but for demonstration only. Accurate charts are available from:

BUREAU OF METEOROLOGY

SATELLITE WEATHER COLOUR

NSW MARITIME RMS

4 DAY FORECASTTIDAL PREDICTIONS

MORE HELP IS WAITING AT:Aus 219

FOSTER TUNCURRY

CAMDEN HAVEN

HASTINGS RIVER

WEATHER WATCH

LOCALCONDITIONS

RESCUE

TIDES

PORT MACQUARIIE SEA RESCUE

MARINE RESCUE NSW

AUST. VOLUNTEER COASTGUARD

ROYAL VOL. COASTAL PATROL

http://www.hydro.gov.au/

http://www.bom.gov.au/

http://www.bom.gov.au/products/IDX1124.shtml

http://www.maritime.nsw.gov.au/index.html



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