Here’s some great advice from Skipper Tips about how to spot, and avoid, submerged jetties or piers or other underwater dangers:
What two little known sailing hazards could damage your boat’s hull, crack your keel, or mangle your propeller shaft or rudder? Make sure that you mark these dangers of the deep on your nautical chart or electronic chart plotter.
Scan any chart in sheltered waters and you might see submerged jetties, sunken piers, or hidden ‘groins’ (more on this later). Set your sailing course to clear these dangers by a mile or more if possible. Note the slight differences between the International and ‘Other’ symbols above. International symbols are basic symbols for all maritime nations.
Some nations make slight modifications to the International symbol for more clarity. For example, here in the U.S., the National Oceanic and Atmospheric Administration (NOAA) charts might show a simpler version of the international symbol. You can find all chart symbols used on paper and electronic charts in Chart No.1 (free download).
Highlight These “Ruins” on Your Chart!
Sailing in San Francisco Bay has to be one of the greatest adventures I can recall. You have a virtual “smorgasbord” of challenges from high winds to choppy seas to swift current to shipping traffic.
And you will be faced with hidden obstructions like submerged piers and ruins. When I sailed out of Berkeley marina, one such submerged pier was a major concern for all sailors. It extended a good two miles from the shore out into the Bay.
Sailors were warned to stay at least 100 yards (300 feet or 91 meters) to the north of this “sailboat snagger.” You could experience a strong southerly set onto the pier. Give submerged ruins like these a wide berth. Consider your leeway–or set downwind or down-current–to avoid serious damage to your sailboat.
If you see a solid (not dashed) outline of a pier accompanied by the words “Ruin”, “Ruins” or the abbreviation “ru”, this indicates a structure which is unsafe for mooring and in a state of disrepair.
Solid outlines indicate objects or parts of an object that will be visible at all stages of the tide. Any part of a pier or ruin symbol that shows a dashed outline indicates that part of the pier will be covered at higher stages of the tide. Read more:
https://www.skippertips.com/public/2520.cfm
