What causes boats to capsize?

Our friends at BoatUS had a great article on the causes.

In a word, instability. Boats are inherently stable until something causes them to become unstable. And 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.

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. So to simplify, we'll use the term capsize from here on. As mentioned, boats capsize because they become unstable, but there are three main reasons for that instability: too much or unbalanced crew or equipment weight; leaking water, which also creates too much weight; and bad weather, which causes instability as a boat is rocked and filled with water.

We Hope It Floats

There is always a very real possibility of injury when passengers unintentionally go in the water with nothing to hold onto. The U.S. Coast Guard (USCG) has addressed this by requiring monohull powerboats built after 1972 under 20 feet in length to float when filled with water. This is a good thing, because without it, most of the small boats in the study would have sunk out from under the crew, leaving nothing to hang onto while waiting for rescue. The bad news is that boats larger than 20 feet that don't have built-in flotation will eventually sink if capsized, and even smaller boats with flotation can still sink if grossly overloaded. (Note: Boats up to 26 feet built to the American Boat & Yacht Council (ABYC) standards adopted by the National Marine Manufacturers Association (NMMA) also have flotation). Inboard and sterndrive boats have less rigorous basic flotation requirements than outboard-powered boats. If your boat was built before 1972, it wasn't required to — and probably won't — have flotation at all.

Which Boats Are More Likely to Capsize?

Small boats are most likely to capsize. Almost 10 percent were 8-footers, mostly dinghies, and capsizes here often didn't cause much damage. But the biggest group, according to a BoatUS study were the 15-19 footers, representing 41 percent of all capsizes. These boats were typically fishing boats, often with large, hard-to-drain cockpits, sometimes out in poor weather, and were sometimes overloaded.

The next most common group are boats in the 20-24-foot range, representing a quarter of the total; half of those were outboard-powered 22-footers. Larger boats tend to be more stable and rarely capsize, though there were several boats over 38 feet that capsized.

Why They Capsize

Nearly all capsizes can be assigned one of three causes. The most common is too much or poorly distributed weight. Small boats are much more susceptible to an extra person or two or a couple of heavy coolers aboard than larger boats. Older boats especially may have gained weight over the years as more gear is stored aboard. On boats with cockpit drains, an extra beefy friend or a second cooler might be all it takes to make the water come back in through the drains, filling the boat. While most of these under-20 foot boats are required to have flotation, they also must have a capacity plate that states how much weight and how many people can safely be aboard. Pay attention to this number, and keep in mind that the number of seats in a boat is not always an indication of the number of people it can carry safely. Exceeding the capacity limits, even in calm water, is asking for trouble; and in many states, operators can be ticketed for it. All it takes is a stiff wind, a large wake, or an unbalanced load to flip over.

The bottom line is that loading too much cargo or too many passengers in one part of the boat can affect its stability, even if the total load is within the boat's maximum capacity. Weight needs to be evenly distributed, especially in smaller boats. One other thing worth mentioning is that capsizes can also be caused by modifications that affect the stability of the boat. Even a small tuna tower can severely change the center of gravity, especially on a smaller boat.

The second major cause of capsizing is leaks. Sometimes it's as simple as forgetting to put the drain plug in; other times it's leaking fittings. Water sloshing around in the bottom of the boat affects stability and waves or a wake can cause it to flip. Tying the drain plug to your boat key is a simple way to remember the plug. On the other hand, leaking fittings that can fill the boat with water 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 shut-off 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. One more thing the claims revealed: 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 excess weight in the stern. Newer outboard 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 your 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.

Weather is another major cause of capsizes, sometimes in concert with overloading. 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.

Troubleshooting Tips

What good is all the fancy electronics you spent a fortune on, if they don't work? Sometimes, as is often the case in many things in life, simple is the solution. Continuing on the previous blog, here's a continuation on tips for keeping your equipment functioning.

Pull the plug! Just like your computer, when your GPS/chart plotter, fish finder, radar or other gear locks up or fails to respond to the controls, sometimes disconnecting the power cable or switching off the set’s circuit breaker and reapplying power can restore normal operation.

 In extreme cases, when all else fails, you can perform a “master reset.” Follow the instructions in the owner’s manual for the unit. Be advised that this is a last-resort procedure. A master reset can also delete all your waypoints, routes and custom settings.

 Quick tip: Regularly back up your waypoints and other entered data on a blank data card (refer to the unit’s owner’s manual for instructions on how to back up your waypoint list and other valuable data).

Be sure you know the location of every fuse for every electronics instrument you have. And keep an adequate supply of each fuse size on board.

Redundant Systems

Consider installing a second VHF radio and GPS/chart plotter. With a modest investment you can have independent redundancy for these essential instruments.

Keep a handheld VHF and GPS as part of your electronics lineup. Basic models are very affordable, serve as portable second stations and stand ready to go with you if you ever have to leave your boat in an emergency.

 The bonus is that the radio and GPS are already connected internally, so the set’s DSC emergency button is ready for use as soon as you obtain, register and enter your personal Mobile Maritime Service Identity (MMSI) number These sets are waterproof and floatable and will operate even in the event you find yourself in the water.

Always keep fresh batteries for every portable device you carry on board. And, if you don’t already have one, install a 12-volt cigarette lighter outlet to charge all of your handheld devices that have rechargeable batteries.

Midseason Boat Maintenance Tips

Mask and Fins I
While you’re at the sandbar or rafted with friends, dive overboard and inspect the boat’s bottom. Usually, the transom can stand a scrub to remove fouling, since not much “washing action” occurs there. Ditto for the scum line above the painted waterline. You may also have a layer of slime on your boat’s bottom. The trick is to remove the growth without removing too much bottom paint. We use a scrap of shag carpet with good results. It removes soft growth without scuffing off too much paint. For hard growth, like barnacles, use a paint scraper with the corners filed round to prevent gouging.

Lights
Before buying a new fixture, clean the socket and contacts using 220-grit sandpaper wrapped around a stick. You can also purchase replacement sockets. If you do replace the fixture, consider upgrading to energy-saving LED lights

Air-Out
On a dry, windy day, open the hatches, pry off deck plates and let the boat breathe, to reduce moisture and the chance for corrosion and mildew.

Seacocks
Open and close seacocks regularly. Besides an annual disassembly and lubrication, constant use will keep them in shape and will alert you to problems before they become catastrophic.

Some of the best ideas are cheap but will save you loads in the long run. Here are a few you can bank on.

It's In The Bag

A crisp, neat, straight paint line is a delight to the eye and is easy to achieve with careful application of masking tape. Your efforts unfortunately can be marred by paint creeping under the edge of the tape, ruining the effect. This is often caused by minute pieces of dirt sticking to the edge of the tape as it is laid down. Avoid this by storing tape in a resealable zipper storage bag when not in use. The bag will keep dirt off the tape and prevent half-used rolls from drying out between uses.

Zap The Tape

Nothing is more maddening than a roll of masking tape that won't unroll, but only comes off in little bits. Before tossing it in the trash, an ornery roll of tape can often be brought back to life with a quick blitz in the microwave. Don't overcook it: 5 to 10 seconds is often more than enough to revitalize the adhesive and return the roll to taping nirvana.

Keep It Solvent

Boat owners use lots of expensive caulks and compounds in cartridges. Half-used tubes that sit for more than a day or two often dry up, then get thrown in the trash. To avoid wastage, cover the end of the cut nozzle with a good dollop of petroleum jelly. It will keep the air out and prevent the contents of the tube from hardening. Next time you need the caulk, thoroughly wipe off the jelly and squeeze out a little bit of caulk to be sure the inside of the nozzle is clear of jelly.

Cheap Hand Cleaner

Many jobs on the boat can leave your hands filthy. For a fast-and-effective hand cleaner that's good at removing grease and grime, pour a little olive oil on your hands along with a sprinkling of sugar. Wipe with a paper towel, then wash your hands with soap and water.

Shaft Nut Configuration

Want to start an argument in most any boatyard?

Find a boat where the shaft nuts are in this configuration (thick nut first, thin nut last) and tell the owner or yard manager who installed it that they're backward. It seems like a no-brainer that the larger nut against the prop would do most of the work and that the smaller nut should go on second, to kind of hold it in place.

In truth, however, it's the smaller nut that should always go against the load because it is the "jammed" nut, not the "jam" nut. When the second, outer nut is tightened down, it compresses and deforms the inner nut a tiny bit, rotating it a fraction of a turn. This effectively unloads the threads of the first nut and engages the threads of the second nut. Thus, the top or outer nut actually takes all the load. As the larger nut has more thread area (and more holding power), that's the one you want as the outer nut. I see prop nuts installed backward all the time while surveying. Will the prop fall off because of it? Not likely. But who wants to find out?

Corrosion

Photo: Mark Corke

Anodes are essential to protect submerged underwater metals from galvanic corrosion. Normally they should be replaced every year or when they are 50 percent wasted. How long anodes last depends on many factors, such as where you keep and use your boat and whether it stays in the water between uses or is stored on a trailer. Inspecting anodes on a trailered boat is pretty easy, but for boats stored in the water, things are a little more complicated. And because you can't easily see the anodes that are clamped to things such as shafts, line cutters, and bow thrusters, they tend to get forgotten. In some cases, it makes sense to hire a diver to check the condition and, if necessary, replace worn anodes. Doing so may be even more cost effective than hauling the boat out of the water.

Wrapping It Up

Get a rope or even some fishing line wrapped around the prop and it can be more than just a little aggravating; it can land you in big trouble and calling for a tow. The majority of ropes and lines are made from synthetic fibers, and while these may be great at tying things up, like your boat to the dock, they can be a real headache if they get wrapped around the prop. A moment's lack of concentration and fishing line can get wrapped around an outboard's propeller, where it will swiftly work between the gear housing, damaging critical oil seals and melting into a solid lump that will require considerable time and effort with a sharp knife to remove. It's bad enough on an outboard, but wrapping a rope around the shaft of an inboard-powered boat may require an expensive haulout to get things sorted. Be aware of lines on your boat that may be trailing in the water, just waiting for a spinning prop. And watch the water ahead for floating line as well as other problems.

Boat Cooler Basics

Here's an article by Michael Vatalaro in BoatUS about coolers, the unsung staple of boating.

No matter the size of your boat, a cooler is essential.

Here are a few ways to get the most out of yours.

Nothing shouts Summer Boating! like an ice-cold drink on a sticky-hot day. But if you find yourself short of ice after a long day on the water or constantly shelling out for a fresh bag from the dockside store each morning of a long weekend, you may need to upgrade your chill chest. Four factors determine the effectiveness of your cold spaces aboard: Size, insulation, gasketing, and drainage. Let's tackle them one by one.

Size

Bigger isn't necessarily better. The more volume your cooler or insulated box has, the more ice you'll need to chill down all the stuff in it, and all the air in any empty space. This is why a full cooler holds ice better than one that's mostly empty — you're not wasting thermal energy cooling down all that air, some of which, by the way, gets exchanged every time you open the lid. The ideal cooler or box will be just big enough for your normal weekend's use. If you need more space on occasion, you can always employ a soft-sided cooler bag as needed.

Coolers with wheels and handles, like this new 80-quart Elite from Pelican, make it easier to get your food and drink from the car to the boat.

Insulation

This might seem obvious, but more is better in this case. Ideally, it's thick foam, and the lid is as thick as is practical. If you don't have an insulated box on board currently and you're considering adding insulation yourself, the first consideration is how much space there is around the box (on all sides) to add foam — without it contacting the hullsides or the bottom of the boat. The second issue is drainage.

Gasketing

Just like the weather stripping around the doors of your house, a good thick gasket prevents air from leaking in or out of your cooler, in this case, stealing your precious cold air and melting your frozen H2O. If the lid of your box or cooler doesn't have a gasket, consider using a $4 roll of foam tape or door kerf to seal the gap. It won't hold up as well as the proper rubber gasketing of a high-end Yeti or Engel cooler, but it should get you through a season or two.

No livewell? No problem! An old cooler makes a great portable livewell. A simple 12-volt
aerator kit, which can be bought for around $30, will transform a cooler into a bait keeper. (Photo: Dan Armitage)

Drainage

Yes you need to be able to drain your box or cooler, but not at all times. You want a removable plug so you can spill excess water and weight at the end of the weekend, or leave it open to melt and drain in your absence, but until then, that chilled water is your beverage's best friend. Water transfers thermal energy way more efficiently than air, so when your ice melts and becomes an icy bath, your drinks will never be colder. The flip side of this is that your sandwich will never be soggier. But rather than drain that cold water away to keep your foodstuffs dry, pack them in zip-top bags instead.

If you're considering adding insulation to a box on board, make sure it drains overboard, but also figure out how you're going to plug that drain while the box is in use. And while you're at it, figure out a way to stow the plug so you always know where it is when you need it on Saturday morning