Please select your home edition
Edition
Helm Events 728x90

Know your charts and sail clear of deadly rocks and reefs!

by John Jamieson on 6 Jun 2014
It pays to be so familiar that recognising the meaning is second nature .. .
How can you tell which rocks or reefs will cover or uncover with the tide each day? It pays to be very familiar with the symbols on nautical or electronic charts. For instance, what do the symbols that look like 'plus-signs' or 'asterisks' mean? Read this excerpt from John Jamieson's newest eBook 'Chart Symbols Made Easy' to find out more.

1. Look for 'Plus-Signs' Beneath the Waves

Scan your chart for plus signs or plus signs surrounded by a circle of dots. This indicates a dangerous underwater (submerged) rock. These rocks are never visible, even at the lowest tides. They may or may not show depths alongside the rock. Set your course well clear of the dangerous 'plus-sign' rocks.



2. Sail Clear of 'Dots-in-Four-Corners' Rocks

Beware of four distinct dots in all four corners of the plus sign symbol. These rocks are awash--which means they lie just at or below the surface of the water--at low tide. You may or may not see these rocks break the surface at low tide. That can depend on the charted sounding datum.

On NOAA charts that show a datum of mean lower low water (MLLW), rocks awash may be visible at some low tides. On charts for other countries, soundings are often given at a much more conservative datum called Lowest Astronomical Tide (LAT). Rocks awash on these charts will most often never be visible. Highlight dangers like these to avoid catastrophic damage to your small sailboat!



3. Avoid Contact with Deadly 'Asterisk' Rocks

Look for common asterisk symbols or asterisks surrounded by dots on your nautical chart or plotter. These rocks poke their deadly heads out of the water at low tide, but cover up at high tide. That's just one more reason to know the stage of the tide whenever you enter a harbor, anchor your boat, or make landfall along a coastline.



Scan and highlight dangers like these on your nautical or electronic chart. Keep your sailing crew or partner and sailing boat safe on the waters of the world throughout the sailing season. Use sailing tips like these for safer sailing--wherever in the world you choose to cruise!

Captain John Jamieson (Captain John) shows you the no-nonsense cruising skills you need for safer sailing worldwide. Visit his website at Skipper Tips. Sign up for the Free, highly popular weekly 'Captain John's Sailing Tip-of-the-Week'. Discover how you can gain instant access to hundreds of sailing articles, sailing skills videos, sailing tips newsletters and Free sailing topic e-Books!

Sail Exchange 660x82 Used SailsDoyle Sails NZ - Never Look BackMusto 2016 660x82 4

Related Articles

Fifth Blog from on board Perie Banou II
Jon Sanders is closing in on Reunion and Mauritius The west coast of Australia is now a long way behind. Then it was 3 reefs in the mainsail. Windy. A wind one gets in the region - history shows it has been the same over the past 400 years - Southerlies. Soon the wind bends. And we get the South East trades proper. For the first 1,000 Nautical Miles the Trades were what I expected. Very strong southerlies leaving the Australian shore (Shark Bay).
Posted on 2 Dec
Predictwind release improved racing and cruising routing function
PredictWind has released a major upgrade to its Routing function, taking a much more graphic and interactive approach PredictWind has released a major upgrade to its Routing function, taking a much more graphic and interactive approach to what has been a black art of weather routing, used to chose the fastest route for racers or most comfortable route for cruisers.
Posted on 28 Nov
Only room for one at the top
The results of RMIT's (Royal Melbourne Institute of Technology) independent testing are in. The results of RMIT's (Royal Melbourne Institute of Technology) independent testing are in. Zhik® is the market leader in waterproof durability with a new standard that replicates the real world sailing environment and conditions. It is an astounding four times more so than the previous leader.
Posted on 28 Nov
Beneteau Cup – A statement in family and time
Every other deity with a nautical interest seemed to sense the importance of the occasion and delivered in spades Flagstaff Marine delivered a terrific regatta to mark the 25th Beneteau Cup on Sydney Harbour. It seemed fitting that Beneteau had two factory representatives there as well, headed up by Director, Beneteau Group Asia Pacific, Thibaut de Montvalon and also Asia Sales Manager, Beneteau Group Asia, Vianney Guezenec.
Posted on 28 Nov
Parlier reigns supreme in Hydrofoil Worlds
The south westerly breeze kicks over the land mass over north facing beach, making for flat water despite strong wind. Whatever the shortcomings of the Fremantle Doctor on the first day of competition, were made up for in spades on day two, when the wind kicked in early at 15 knots and quickly built to 18 with gusts as high as 26. The Rockingham course is perfectly suited to such conditions. The south westerly breeze kicks over the land mass over the north facing beach, making for flat water despite strong wind.
Posted on 27 Nov
25th Beneteau Cup - Great weather. Great times. Great brand.
The 25th Beneteau Cup on Sydney Harbour was filled with a genuine sense of joy. The 25th Beneteau Cup on Sydney Harbour was filled with a genuine sense of joy. Flagstaff Marine, together with regatta partners Sydney City Marine, Mark Anderson’s Boat Transport and d’Albora Marinas, can be very proud of the achievement, but it is the owners and crews who make it all possible. Here then are some of the pics of their day! Full report to follow…
Posted on 26 Nov
Ensign want to sell your boat!
Ensign have had such a successful sales year that they are now looking for more pre-used stock to sell. Ensign, one of Australia’s largest yacht brokers, have had such a successful sales year that they are now looking for more pre-used stock to sell. At their head office location at Main Beach, Queensland, they can offer amazing rates on berthing while the boat is on sale at their Marinas Cove Marina and that means great exposure.
Posted on 24 Nov
Fourth Blog from on board Perie Banou II
Oh no - not the coffee cup Oh no - not the coffee cup - Jon keeps us all entertained as he approaches Reunion Island. The B&G chartplotter tells me since leaving the pleasant mid Western Australian town of Carnarvon (by world standards, an isolated town), that I have sailed some 2559 NM and have 751nm to go to Le Port Reunion Island. French. Reunion is a Suburb (department) of Paris. Population 844,000.
Posted on 23 Nov
Third Blog from onboard Perie Banou II
Wind over the last week has been quiet and mild - Trade Winds from South East and South South East. It is 0830am here. 1030 in Western Australia. Windy. Rather Windy. Wind over the last week has been quiet and mild - Trade Winds from South East and South South East. Barometer 1018 to 1020 whatever they are. Last night I tapped the barometer and it sorta went oops. 1015hPa. Blimey.
Posted on 18 Nov
Beneteau Cup - the 25th is the 25th
Beneteau Cup - the 25th is the 25th Flagstaff Marine will present the 25th Beneteau Cup on Friday, November 25. It is always a great day, both on and off the water, with loads of door prizes, great music and fantastic times assured. Of course, to be a part of it you do have to book in! You can enter this historic event right https://www.topyacht.com.au/db/aus/series_select.php?EventID=681!HERE!new and now - so hop to it...
Posted on 15 Nov