How To Avoid Running Aground in SF Bay and What to Do When It Happens | Modern Sailing

How To Avoid Running Aground in SF Bay and What to Do When It Happens

As the salty old adage goes, "There are three kinds of sailors: those who have run aground, those who will run aground, and liars." So, as you might guess, running aground is not an uncommon experience among sailors - it can happen to anyone sooner or later!

When you've run aground, the feeling is unmistakable. You're sailing or motoring along when the boat suddenly lurches, falters, and stops... You may hear a thud, a grind, or worse, a crunch. Your heart plops into your stomach, which suddenly feels cold. If you're caught unprepared, you also might notice your heart beating faster.

If you've never run aground, this article can help you do your best to avoid (or delay?) this dreadful experience. If (or when?) you do run aground, knowing how to respond and a few techniques for getting unstuck can help you preserve your calm.

HOW TO AVOID RUNNING AGROUND

1. Consult the Chart

If you’re planning to sail or motor into unfamiliar waters, before you leave the dock, take the time to review a nautical chart of the areas involved in your itinerary. Blue-shaded areas on the chart indicate shallow water. Proceed with caution whenever you must navigate into these areas. The greenish-shaded areas must be avoided altogether. White areas on the chart indicate deep water that is safe for sailboats and most other vessels to navigate into. Also check the chart for underwater hazard symbols and depths along your route.

Note that NOAA chart depths are provided in Mean Lower Low Water (MLLW) measurements, which is the average height of the lowest tide recorded at a tide station each day during a 19-year recording period. An area that may look like safe water on the chart can become dangerously shallow during a low spring tide.

All MSC yachts carry a San Francisco Bay chart, usually stored in the navigation table. You can also purchase your own chart from a variety of online retailers or local marine supply stores. NOAA Chart 18649 – Entrance to San Francisco Bay is available for free download. The NOAA 18649 Booklet Chart, also free, is a more printer-friendly version.

Electronic chart apps such as Navionics can also be helpful for depth information. Keep in mind that apps also provide mean depths.

Most importantly, be aware that tidal currents within the Bay constantly reshape the seabed. Do not rely on apps or charts alone to keep you off the shoals.

2. Consult the Tide Tables

Be aware that common anchorages and channels in San Francisco Bay (even the Sausalito Channel leading into Richardson Bay) can become precariously shallow during spring tides (also known as “king tides”), which occur during full moons and new moons. 

During spring tides, high tides are higher and low tides are lower than average. In the Bay Area, spring tides can be especially extreme November through March. Exercise additional caution and avoid navigating into shallower areas during the low phase of a spring tide.

Ayala Cove at Angel Island and Paradise Cove (north of Point Chauncey on the eastern side of the Tiberon Penisula) can present a grounding risk during low tides. The same is true of the channel to enter Clipper Cove (between Treasure Island and Yerba Buena Island). Your safest bet is to plan your entrances and exits during a flood or high tide.

High and low tide times for areas within the Bay will vary widely from the tidal predictions at the Golden Gate station. Helpfully, NOAA’s website provides abundant detail for tides and currents all over the United States, including California and the San Francisco Bay Area. You can download and print tidal prediction tables for many stations within the Bay, which can be especially useful when planning your timing into or out of a tricky cove or channel. 

  • NOAA Tide Predictions for California – Scroll down to find San Francisco Bay and you will see dozens of stations where subordinate tidal predictions are available. Choose the station closest to your area of concern.

For a quick glance of the tide and current predictions for the present day and next two days at the Golden Gate station, check out www.windandtides.com

3. Know Your Depth Sounder Calibration

It’s important to know that the depth sounders on all MSC yachts are calibrated from the keel, not from the waterline. This means that if your depth sounder is reading 3 feet, there is 3 feet of water between the bottom of the keel and the sea floor.

If you're not on an MSC yacht, before you rely on a depth sounder, be sure to find out how it is calibrated, whether from the keel, the waterline... or not at all.

4. Maintain a Proper Lookout for Shoals and Buoys

When navigating into a shallow channel or anchorage, it’s a good idea to send a crew member to the bow to keep an eye out for shoals (if conditions permit). However, Bay water tends to be murky and depths can be difficult or impossible to gauge by the eye alone. Buoys and markers close to shore serve to warn boaters off shoal areas. For this reason, never sail between a buoy and shore.

5. Maintain a Safe Speed

When navigating into a channel or anchorage, take it slow. This will give you time to take evasive action should an underwater hazard or shoal be spotted or bumped. Also, if you happen to run aground, doing so at a slower speed can minimize the possibilty of damage to the vessel and make it easier to get ungrounded.

6. Know MSC Policies and Restricted Sailing Areas

Per Modern Sailing charter policy, charterers are restricted from entering the following areas:

  • Platinum Fleet and Catamarans: Pier 1.5 in San Francisco is restricted.
  • All Boats: Piers 39 & 41, Aquatic Park in SF, and Sam’s Café in Tiburon are restricted.
  • All Boats: Anchoring at China Cove (north side of Angel Island) is restricted due to underwater hazards.
  • Charterers may not sail outside of San Francisco Bay beyond the line of demarcation between Mile Rock and Point Bonita.

Note that the reason for some of these areas being off-limits to MSC charterers is due to a high risk of running aground. The policy also states: “Anyone sailing near shore or low water areas, through designated anchoring areas, or into/out of a marina who causes damage to the charter vessel or any other vessel or property is fully responsible for all claims of damage.”

If you happen to run aground during your charter, please be sure to report it to Modern Sailing so that we can send a diver down to check for possible damage. Unfortunately, the charterer is charged for the cost of the dive – but we hope this does not deter you from doing the right thing by reporting it. An inspection below the waterline after a grounding is necessary to ensure the safety of sailors who may charter the boat after you and prevent the possibility of further damage (such as by water intrusion).

WHAT TO DO WHEN YOU'VE RUN AGROUND

1. Change Direction

If you’ve run aground under sail, turn the wheel hard over towards deeper water and try to tack the boat. Allowing the jib to backwind will help push the bow around. This tactic only applies to when you’ve been sailing on a close haul or reach.

If you’ve come to a full stop, immediately depower your sails by easing the sheets. If you were sailing on a broad reach or run, bring the end of the boom in so it points directly into the wind and ease the jib sheet and allow the jib to luff while you start the engine. Then, quickly douse or furl in the sails. Take a deep breath and run the engine in neutral gear while you consider what to do next.

Hopefully you did not run aground hard, but if you have, start peeking into the bilge periodically to watch for rising water and check to see if the automatic bilge pump is coming on.

2. Motor Back

After the sails are doused, shift the engine into reverse gear. If you are certain there is deeper water behind you, gradually increase RPMs until you feel the boat backing up. Carefully observe any resistance you may feel. If you feel or hear any significant resistance or grinding, shift the engine back to neutral.

Much of San Francisco Bay’s bottom is covered in thick mud. The sticky nature of mud can create a suction effect around your keel. If you find yourself aground in mud, you can try to break the suction and dig yourself out by steering the boat gently from side to side while backing up. Once the boat starts moving backward, maintain RPMs until you’re floating free. 

If your initial attempt to back out doesn’t work, sit back and take a rest while you further assess your surroundings. There may be more deep water in another direction, so consult the chart to check for other possible escape routes. Also check the tidal situation.

Good news if the tide is low but flooding in - you can wait for the rising tide to float you off the seabed. If you're waiting for the tide to lift you off, maintain watch and be prepared to motor to deeper water the moment you are floating free. Otherwise, you risk being pushed into a shallower area and getting stuck again.

If you are stuck in a high-traffic area and think you might be there awhile, announce a "sécurité" radio call on VHF channel 16. Alert other boats in the area that you are aground and provide your location and/or GPS coordinates.

3. Heel Over

If motoring in reverse doesn’t get you ungrounded, the next step is to reduce your boat’s draft by heeling her to leeward. To induce heel, seat your crew on the lee rail and ease the boom out to leeward. A backwinded sail may also help heel the boat over. Once you’re heeled over as far as possible, try motoring in reverse again.

4. Kedge Off

This technique is prohibited for MSC charterers for several reasons:

  • MSC yachts are not equipped with dinghies.
  • Bay water is usually cold enough to present swimmers with a serious risk of hypothermia.
  • There is a risk of injury, rode breakage, prop fouling, anchor loss, and damage to the vessel.

However, the “kedging off” technique is worth a mention in case you one day find yourself aground in a non-MSC yacht in warmer waters and/or with a dinghy.

If all other attempts to move your boat to deeper water have failed, you can try to pull yourself free by kedging off with an anchor.

  1. Take an anchor out in a dinghy to deeper water far enough back to allow the anchor to set securely. If you have a strong swimmer aboard and the water isn’t too cold, swimming the anchor out is also an option. You can tie fenders or PFDs to the anchor to help carry some of its weight.
  2. After setting the anchor, bring the rode over the stern, wrap it on a winch near the center of the boat, and take up the slack.
  3. With the engine in reverse, winch up the anchor rode to pull the boat back toward deeper water.
    • There’s a risk of fouling the prop with the rode, so have a crew member handle the rode during this process to take up any slack.
    • Ensure that crew members are positioned away from the "snap back zone" to avoid injury in the event that the rode breaks.

5. Tow Away

In spite of your best efforts, sometimes a grounded boat will refuse to budge and you’ll need a professional towboat to come to your aid. Tows between private vessels are disallowed by MSC charter policy, so politely refuse any offers from passersby to tow you off. Instead, check your boat’s white binder for the SeaTow membership card and give SeaTow a call. You may also call for Vessel Assist on VHF channel 16. 


Please read our article Handling Emergencies Part III: Safety Under Tow to be prepared for any event in which you may need to receive a tow.

You can learn more about how to respond to a grounding emergency from an ASA certified instuctor in our ASA 106, Advanced Coastal Cruising and ASA 105/106 California Coastal Combination courses.

Want to learn more seamanship and safety tips? Check out the Member Resources section of our website. New articles are added frequently!


Photo © Gordon Brown (cc-by-sa/2.0) licensed for reuse.

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