Please select your home edition
Edition
Pantaenius - Worldwide Support

Know these seven danger nautical chart symbols!

by John Jamieson on 6 Mar 2013
Deadly Danger Symbols Captain John Jamieson http://www.skippertips.com
Could you glance at your chart or plotter and identify--in just seconds--the seven vital danger symbols that could rip a hole in your hull, damage your keel, bend a propeller shaft, mangle a propeller, or cause you to go aground?

There are dozens of danger symbols used on nautical charts today, but here are some of the more common ones. Know these 'ship killers' to stay safer on the waters of the world wherever you choose to sail or cruise.

1. Rocks
Note how the basic rock symbol looks like a plus sign. This means a rock that's beneath the water surface all the time. A symbol that looks like an asterisk means the rock will uncover (become visible) at low tide. A plus sign with dots in the corners means the rock lies just beneath the surface, even at low tide.

2. Islets (small islands)
Small islands--called 'islets'--are common in the Bahamas, Caribbean, and Pacific. Islets surrounded by a solid line are visible at all tidal stages. A number indicates the maximum height at high tide (or charted datum). Islets surrounded by a wavy, squiggly line cover and uncover with the tide. At higher tides, the islet will be covered. A number indicates its height above water when uncovered at lower tidal stages.

3. Breakers
Breakers form when ocean swell meets a sea bottom that's only one to two times their height. For example, if a two foot swell travels over a bottom two to four feet deep, it will break.

Breakers are dangerous to any small craft because they can cause loss of rudder or propeller control.

Stay clear of any symbol like that shown in the illustration above. You may also see the abbreviation 'Br' used alone without the symbol.

4. Coral Reefs
The world's most popular cruising grounds--Bahamas, Caribbean islands, and Pacific atolls--also contain some of the most dangerous waters. Study your navigational chart with care and look for the 'Co' abbreviation close to any rock or islet symbol.

5. Obstructions
Easy to miss on a nautical or electronic chart display, obstructions can cause damage to propellers, shafts, and keels. Many charts use only an abbreviation 'Obstn' to warn mariners. Dots around a circle mean an unknown hazard lurks beneath the surface. Tiny enclosed circles could be broken stumps, old piling remnants, or submerged poles and posts.

6. Wrecks
Fish-bones and sunken-hull illustrations make up the most common wreck symbols. Fish-bones without dots are safe to sail across. Cartographers put these on charts to warn commercial fishing trawlers not to drag nets and to caution ships not to anchor. Give fish-bones surrounded by dots or sunken-hull symbols a wide berth to avoid hull damage.

7. Spoil Area
Deadlier than the plague, identify, highlight, and stay clear of dashed outlines with descriptions like 'Spoil Area', 'Fish Haven', 'Fish Traps', or 'Dumping Ground'. Ever wonder where all those old cars and trucks, building material, or garbage goes? Now you know! Spoil areas never show soundings because depths change all the time.

Danger Abbreviations You Need to Know
Familiarize yourself with the danger abbreviations used with or without the symbols described above. Study these until you know them at-a-glance:

Rk, R or Rks - Rock or Rocks
Hk or Wk - Hulk or Wreck
Obstn - Submerged Obstruction
Co - Coral

Foul - Foul Ground
These additional abbreviations may be found alongside any danger symbol, or they may stand alone. For instance 'Shoal Rep' means that shallow water was reported ('Rep') at that position by a mariner, but it has not been surveyed. Stay clear of any area on your navigation chart marked by these abbreviations.

PA - Position Approximate
PD - Position Doubtful
ED - Existence Doubtful
Rep - Reported
SD - Sounding Doubtful

Now you know how to identify any of the seven danger group symbols on any sailing chart in the world. Use these chart navigation secrets to give you the edge and keep your crew safe and sound wherever you choose to cruise.

Learn more about nautical chart symbols and abbreviations. Download the free publication 'Chart No. 1: Nautical Chart Symbols, Abbreviations and Terms', here.

John Jamieson (Captain John) with 25+ years of experience shows you the no-nonsense cruising skills you need for safer sailing worldwide. Visit his website at www.skippertips.com. 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, videos, and e-Books!

Related Articles

From Olympic flag to Olympic Gold and maybe another
The Sydney Olympics was a Sailing double 470 Gold event for Australia. Having won the 420 World Championship in 2000, the feeder class to the 470, while still at school in Australia young Matt Belcher was given the honour of carrying the Olympic flag during the closing ceremony of the Sydney 2000 Olympics.
Posted on 28 Apr
Pantaenius – Smooth sailing is more than a favourable weather forecast
Pantaenius get ready to launch into their fourth year operating in Australia As Pantaenius get ready to launch into their fourth year operating in Australia, we get to see why they continue to grow their happy crew of customers. Sitting down with Pantaenius Australia’s MD, Jamie MacPhail, you immediately get a sense that the smooth sailing is a direct result of both their unique product and the marketplace’s willingness to embrace the better mousetrap
Posted on 27 Apr
100 days to Rio, are there potholes and bumps ahead?
The Road to Rio 2016 still has a few curves, bumps and potholes for teams battling to win in Hyeres. The Road to Rio 2016 still has a few curves, bumps and potholes for teams battling to win in Hyeres, at some World championship events and Weymouth World Cup but for most crews.
Posted on 26 Apr
Is George Lucas a sailor?
He’s very famous for a lot of things, and justifiably so. One of them is Industrial Light and Magic He’s very famous for a lot of things, and justifiably so. One of them is Industrial Light and Magic, which has been instrumental in the making of many of the special effects that have made the digital world so impressive. Gone are the smears of Vaseline along the bottom edge of the clear filter to hide the trolley that was actually transporting Luke Skywalker’s Speeder, for instance.
Posted on 25 Apr
America's Cup - Oracle Racing win in Court but with collateral damage
Oracle Racing have had another claim against them by a former crew member dismissed. Oracle Racing have had another claim against them by a former crew member dismissed. Mitchell focussed largely on the circumstances of the matter and introduced into the public arena some interesting documents to support his claims.
Posted on 23 Apr
Thou doth protest too much, me thinks
And no, we’re not off to analyse Hamlet right away. There’ll be no surtitles popping up on the top of your screen And no, we’re not off to analyse Hamlet right away. There’ll be no surtitles popping up on the top of your screen about now. At any rate, it is simply an adaptation of Lady Gertrude’s original line. We merely seek to use it as a way to demonstrate that when there is a lot of brouhaha going on, the smoke screen ultimately ends up as a lovely, colourful flag as to the real intent behind it.
Posted on 18 Apr
Children of the Internet, Rio and Hong Kong
I have four daughters, the youngest, who in her mid 20's is a true child of the Internet. I have four daughters, the youngest, who in her mid 20's is a true child of the Internet. The kind of conversations I have with her run along these lines.... In the olden days we did not have television until I left school and they had a thing called print magazines, that reported events between two weeks and four months after they happened. And her sceptical response... Hoh! Daddy, Hoh!
Posted on 14 Apr
Can World Sailing learn from dear old Oz?
Why just lay the drop sheets out and tape up the edges of the windows for a splash of paint Some time ago now, Sail-World proposed that ISAF had a really good opportunity at hand when it morphed into World Sailing (WS). Why just lay the drop sheets out and tape up the edges of the windows for a splash of paint, when you could bring out the jackhammers and do a proper reno??? A call was issued for 200,000 sets of goggles and earmuffs to be supplied and for the real work to be commenced.
Posted on 11 Apr
World Sailing Cup V3 - A Dead Rat in a Shoe or Spring Daffodils?
While a host of major sailing events go from strength to strength, the Sailing World Cup has very major issues. Last night my Irish better half was sitting beside me on the sofa watching an Australian version of the popular TV Cooking Program My Kitchen Rules on a tablet with her headphones while I was watching Diehard II for the seventeenth time (it’s a boy thing) on TV. She suddenly spluttered and laughed, took off her headphones and motioned for me to mute Diehard. (Seriously!!)
Posted on 9 Apr
TeamVodafoneSailing nosedive and win double before heading offshore
TeamVodafoneSailing has had more than their share of action over the past month TeamVodafoneSailing has had more than their share of action over the past month, involving both high-performance multihulls in their stable.
Posted on 9 Apr
Lancer 40 yearsBarz Optics - Kids rangeKilwell - 1