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Avoiding Capsizing And Swamping

Three boaters are plucked from the water 25 miles offshore after their boat capsized. Learn how to prevent getting into this mess in the first place.

Capsized vessel

Photo: U.S. Coast Guard

A day out on the water led to three men being rescued by good Samaritans some 25 miles offshore of Hernando Beach, Florida, in the Gulf of Mexico. The trio, all wearing life jackets, were pulled November 2, 2019, from the overturned hull of a 26-foot Sea Fox center-console.

An EPIRB (Emergency Position Indicating Radio Beacon) set off from the capsized boat triggered a response from U.S. Coast Guard Air Station Clearwater. A C-130 aircrew dropped a life raft to three people, but a nearby good Samaritan aboard a power catamaran was first on scene and took the three men aboard. There were no reported injuries. Watch a video of the incredible rescue above.

A Look At The Numbers

A capsize is defined as a boat rolling over onto its side or completely over. Swamping typically means that a boat fills with water (often from capsizing) but remains floating.

What causes boats to capsize and swamp? In a word: instability. Boats are inherently stable until something causes them to become unstable. That something is weight — where it is and how much it is determines when a boat will tip over far enough to capsize or fill with water.

In an analysis of five years of GEICO | BoatUS Marine Insurance claims that involved capsizes and swampings, we learned what you can do to prevent this from happening in your own boat. Here's what we learned:

  1. Nearly all capsizes can be assigned to one of three causes: too much or poorly distributed weight, leaky vessels, and bad weather.
  1. The majority of incidents occur on small boats. Nearly 10% were 8-footers (such as dinghies). The largest group (41%) was in the 15- to 19-foot range. These boats were typically fishing boats with large, hard-to-drain cockpits, sometimes in poor weather, and sometimes overloaded. A quarter of the pie (26%) comprises boats 20 to 24 feet. Half of those were outboard-powered 22 footers. Larger boats tend to be more stable and rarely capsize.
  1. Life jackets can buy extra time until you're rescued, but they have to be worn to work. BoatUS Foundation tests showed that even modest waves can make it very difficult to don a life jacket when you're in the water — a job made harder still if you have to search for one after capsizing.
Swamped powerboat

Most power boats built before 1972 have no flotation and will sink out from under the crew if swamped.

Weighty Issues

  • Small boats are much more susceptible to an extra person or two or a couple heavy coolers aboard than larger boats.
  • Older boats may have gained weight over the years as more gear is stored aboard or the hull has absorbed water.
  • On boats with cockpit drains, a heavy friend or a second cooler might be all it takes to make the water come back in through the drains.
  • Most boats under 20 feet are required to have flotation. They also must have a capacity plate that states how much weight and how many people can be safely aboard.
  • Exceeding the capacity limits, even in calm water, is asking for trouble. In many states, operators can be ticketed for it.
  • Safe passenger loading is controlled by the number of "underway seating positions." So two slim adults taking four or five small children out for a spin on a boat designed to seat four is a big safety risk, even though the total passenger weight might be well under the boat's stated capacity.
  • Weight distribution is almost as important as the amount. Too many people on one side of the boat (Hey, look at that whale!) forces the gunwale too far down, potentially allowing water to pour in.
Unstable pontoon boat

Pontoon boats are generally more stable than monohulls, but even they can be capsized by an unbalanced load. (Photo: John Silver)

  • Some boat manufacturers label upper decks on larger boats to indicate how many passengers can be on them. Weight that is substantially above the waterline raises the boat's center of gravity and makes the boat less stable.
  • Installing a four-stroke engine on an older boat can add 10% to 15% more weight than it was designed for. Water can backflow into the cockpit.
  • Fishermen and hunters in small boats can make their boats unstable simply by standing up because their center of gravity rises.
  • Capsizes can be caused by modifications that affect the stability of the boat. Contact the manufacturer or a naval architect if you're unsure how a modification will affect stability.

Leaky Vessels

  • Sometimes it's as simple as forgetting to put the drain plug in. Other times it's leaking fittings. Tying the drain plug to your boat key is a simple way to remember the plug.
  • Water sloshing around the bottom of the boat affects stability, and waves or a wake can cause it to flip.
  • Leaking fittings are usually out of sight, often in livewells and bait boxes. Several claims were reported when an owner installed a livewell fitting using cheap PVC pipes and valves, and at least one livewell had no shutoff valve at all with no way to stop the ingress of water once it began leaking.
  • Any fitting that penetrates the hull needs to be closeable and should be made from stainless steel, bronze, or Marelon.
  • Some livewells are plumbed in such a way that they'll flood the boat if the valve is left open while underway.
  • Many older outboard-powered boats have low transom cutouts that can cause the boat to flood simply by slowing down too quickly, especially with extra wight in the stern. Newer boats have a well that reduces the risk.
  • Some boats have cockpits that drain into the bilge (generally considered a poor design), requiring the use of a bilge pump to even stay afloat. Bilge pumps are designed to remove nuisance water only, not to keep a boat from sinking. If you boat's cockpit drains into the bilge, be aware that if the bilge pump fails, your boat can fill with water and capsize or sink.
Large wave swamps powerboat

Large waves can overwhelm a boat and cause it to capsize. Keeping the bow into the waves can prevent the boat from rolling.

Bad Weather

  • Small boats are easily overwhelmed by modest waves or even wake, especially if they've got a full load and sit low in the water.
  • A sudden squall can flip even a larger boat. Check the weather forecast before you go out and keep a weather eye on the sky.
  • In most areas, NOAA broadcasts continuous weather via VHF radio. If you're within range, smartphone apps can show you detailed weather maps, including radar, which can indicate approaching storms.
  • Weather changes quickly on the water, so at the first sign of bad weather, head back to the dock. If you're caught out in a squall, have your passengers stay low near the center of the boat to maintain stability.

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BoatUS Editors

Contributor, BoatUS Magazine

Award-winning BoatUS Magazine is the official publication of Boat Owners Association of The United States. The magazine provides boating skills, DIY maintenance, safety, news and more from top experts.