Please select your home edition
Edition
Southern Spars - North Technology

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!

Festival of Sails 2017 660x82Ensign 660Wildwind 2016 660x82

Related Articles

Auckland On the Water Boat Show opens full of the Joys of Spring
The Auckland On the Water Boat Show enjoyed a beautiful Spring day for its opening. Despite the inclement weather that has been the New Zealand's daily fare for too long, the Auckland On the Water Boat Show enjoyed a beautiful Spring day for its opening. Today was the first of the four-day show and is also the first time that the Show has been held in the school holidays.
Posted today at 5:37 am
Knowing Harken takes years and years (Pt.II)
We looked at how Grant Pellew became the MD here in Australia, and how they rigorously go about testing their gear In Part One of getting to know Harken, we looked at how Grant Pellew became the MD here in Australia, and how they rigorously go about testing their gear. We also looked at some of the other brands Harken distributes in Australia and so we move on to the last category.
Posted on 25 Sep
Olympic Gold medalist and Volvo Ocean Race winner up for WS Board
Torben Grael (BRA) is amongst the 15 nominations for one of seven places on the Board of Directors of World Sailing Torben Grael (BRA) is amongst the 15 nominations for one of seven places on the Board of Directors of World Sailing in November. The five times Olympic medalist, Volvo Ocean Race winner and several times America's Cup competitor will bring a much needed sailing edge to the Board of World Sailing if he can navigate the politics of the controlling body of the sport.
Posted on 25 Sep
Amel - Do you fit the bill?
Perhaps it is equally as fascinating as the many features that go into either the Amel 55 or 64 It is certainly an interesting set of criterion. Perhaps it is equally as fascinating as the many features that go into either the Amel 55 or 64 and make them a definitive part of the quintessential bluewater cruiser armada. We’ll come to all of those in due course, but firstly we’ll tackle the hero image and why in so many ways, this explains, so, so much.
Posted on 21 Sep
Knowing Harken takes years and years (Pt.I)
You could imagine that being familiar with all that Harken produces and stands for is a lengthy process. You could imagine that being familiar with all that Harken produces and stands for is a lengthy process. So if you were going to be the person at the top in Australia, it would be best for you to have immersed yourself in sailing from an early age. When you grew up, being one of the technical service team would be more than a handy apprenticeship, as it were.
Posted on 19 Sep
Brookes and Gatehouse Videos with Knut Frostad
Navico, the parent company for Brookes and Gatehouse (B&G), Simrad and Lowrance have prepared some terrific videos Navico, the parent company for Brookes and Gatehouse (B&G), Simrad and Lowrance have prepared some terrific videos with Knut Frostad, the legendary Volvo Ocean Race sailor and former CEO. See him talk about sailing in general, the B&G product choices and placement he made for his own boat, and then why he loves his Outremer 5X.
Posted on 8 Sep
Boat Books of the Month - How to Read Water and False Flags
How to Read Water: Clues, Signs & Patterns from Puddles to Sea & False Flags: Disguised German Raiders of World War II. This month the Boatbooks Australia: Boat Books of the Month are How to Read Water: Clues, Signs & Patterns from Puddles to the Sea and False Flags: Disguised German Raiders of World War II.
Posted on 6 Sep
Soft Padeyes – light, strong and versatile
Several types of soft padeyes are now available and are proving increasingly popular over traditional stainless steel pa Several types of soft padeyes are now available on the market and are proving increasingly popular over traditional stainless steel padeyes. They all capitalise on the incredible strength to weight ratio and abrasion resistance of Dyneema® which offers a reliable, robust, flexible and safe termination.
Posted on 6 Sep
The X Factor starring X-Yachts
X-Yachts do indeed have plenty to sing about. X-Yachts do indeed have plenty to sing about. Testament to that is the three-year-old Xp38 on display at the recent Sydney International Boat Show still looked brand new. This was no mooring minder either, but rather a boat that had gone up to Hamilton Island Race Week for each of those years and campaigned hard.
Posted on 31 Aug
The C Beetle Project
Every now and then something comes along your way and you just have to read it. Every now and then something comes along your way and you just have to read it. Such is Phil Smidmore’s tale of Mick Miller and if I could be so bold as to implore you to read, then I know your life will be the better for it!
Posted on 30 Aug