Seaworthiness & Trailerable
By John Vigor

The following is reprinted with kind permission from Small Craft Advisor Magazine. Read the article below, including the side bars and then take the interactive test to help you assess your own boat.

Anyone who sails a small boat for any length of time will almost certainly be overtaken by bad weather at some stage. With the wind howling and the waves building, we often wonder: “How seaworthy is my boat?” There is no question that some boats survive bad weather better than others, even allowing for various degrees of experience among their crews. But what makes one boat more seaworthy than another?

We can’t answer that question, of course, until we define the word “seaworthy.” Experts agree it’s a nebulous term that does not lend itself to absolute definition.

It’s almost easier to define seaworthiness for sailboats intended to cross oceans than it is for boats designed to sail on rivers, lakes, and coastal waters. Seaworthiness for world cruisers means the ability to stay afloat, remain watertight, and keep crew safe in the worst conditions of wave and weather. It includes the ability to beat off a dangerous lee shore in heavy weather.

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The Heavily Ballasted Skipper 20

Displacement and Inertia

You may wonder why a whopping 25 bonus points is awarded to the heaviest boats in our seaworthiness quiz. Here’s why: Capsize is often as much the result of wave impact as the effect of a sudden gust of wind. Either way, the heavier a boat, the less likely it is to capsize, because of what’s called inertia.

Inertia is the resistance of a body at rest to being moved. It is also the resistance of a moving body to being stopped. It’s difficult to make a heavy boat with a tall mast heel suddenly. The mass of the hull and the leverage of the mast resist sudden changes in movement.

The deeper, heavier, and longer a boat, the more inertia she carries. Heavy-displacement boats are about five times as resistant to capsize as ultra-light-displacement boats of the same length, according to famed research scientist and naval architect Tony Marchaj.—JV


Cockpit Drainage

Cockpits are often disproportionately large on small boats. There is thus more need than ever for quick drainage. But very few production trailerables have adequate cockpit drains. Some have open transoms or outboard wells, but it’s a very rare boat that has better than two 1 1/2-inch scuppers. Two 2-inch scuppers would be a great improvement.—JV

Seaworthiness for boats that do not stray so far from land is a little different because they can often run for safety and reach land before wave conditions become too dangerous and before fatigue sets in among the crew.

Naval architect Ted Brewer says in his book Understanding Boat Design (International Marine): “Obviously it is unfair to compare the seaworthiness of a family daysailer with that of an ocean racer, and an outboard fishing boat does not need the seagoing ability of a bluewater motoryacht. However, all boats must meet a certain level of seaworthiness to suit their particular purpose, and they can and should be compared with others of their type.”

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Designer Warren Jordanís 15-foot Footloose Skiff favors simplicity. John Kohnen and his Pickle pictured.


The smaller the boat, the greater the need for simplicity. Complex systems all too often become liabilities when the weather gets rough. How often do we hear of a small-boat sailor caught out singlehanded in a sudden blow who can’t reef or start the outboard because he’s too scared to let go of the tiller and stop actively sailing?

Too many of us succumb to the blandishments of the purveyors of shiny marine equipment. We unwittingly follow the follies of fashion. We bolt on fancy fittings of expensive, hightech material where a good old-fashioned cleat or fairlead would do. Beware of the tendency to “improve” the piece of lanyard that’s doing an honest job. Sail safer by thinking simple.—JV


Vigorís Black Box Theory

Some boats seem to be more seaworthy than others. They survive storms unscathed where others get into serious trouble. Is this just luck? No, it’s work.

Every boat has an invisible black box that stores good-luck points. You earn a point every time you check the rigging before setting sail. You earn points for taking a shore bearing after you’ve anchored. Points pile up when you change the engine oil on time and buy new batteries for the GPS. In short, every seamanlike precaution you take, every little bit of maintenance or checking you do, especially on dark rainy nights when you’d rather be in your bunk, every bit of pre-planning on the chart, earns another point.

In times of stress, when you’re caught in a storm and you’ve done all you physically can, the points are cashed in as protection. You can’t control their withdrawal. They withdraw themselves as needed.

Boats that have no points in the black box will later be described as “unlucky” and “unfortunate.” But those with points to expend will survive the same conditions. The black box will take care of you. All you need to do is keep it topped up.—JV

The type we’re concerned with here is sailboats displacing no more than 3,500 pounds that are regularly trailered for afternoon daysails or weekends afloat. And what we’re looking at is their ability to perform safely in the sea areas and weather conditions for which they were designed. They should be able to cope with the conditions found in the protected and semi-protected waters typically frequented by trailersailors.

The accompanying quiz can’t give you a definite verification of your boat’s seaworthiness but it will certainly indicate its relative fitness for its designed purpose by comparison with other types of boats. And remember, it’s up to you to find out what your boat’s designed purpose is, and to sail it within those parameters.

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Capsize and Swamping

Two of the accidents most feared by small-boat sailors are capsize and swamping. You’ll sail with less angst if you’ve thought out in advance what you’d do if either of these things happened to you.

Dinghy sailors with wetsuits or drysuits can practice righting their craft by holding them head to wind and then standing on the centerboard, but what do you do about larger trailersailers? Luckily, the act of capsize in larger craft is slower, and if you haven’t cleated the mainsheet you’ll have a chance to spill wind before the mast hits the water. Further, a bigger boat’s metal centerboard will act as righting ballast. The quickest recovery will be made by boats with deep ballast keels.

Incidentally, many trailerables with fixed shoal keels or keel-plus-centerboard combinations are considered more seaworthy than boats with only a centerboard or daggerboard. There have been a number of reports of keel-plus-centerboard boats losing their boards, but still being able to sail to their destinations. And there are many instances of centerboard-only boats turning turtle and experiencing the board crashing back into the trunk, sometimes with great structural damage.

Swamping, that is the filling of the cockpit by a wave washing over the transom or side deck, is an ever-present hazard in heavy weather. You must give thought to the problem of getting rid of the water quickly, before another wave or swell comes along and swamps your heavily loaded boat even more. —JV


Elements of Seaworthiness

Seaworthiness is notoriously difficult to define, but we can reasonably expect the following characteristics in a seaworthy trailerable sailboat being operated in conditions for which she was designed:

• The ability to recover from a 90-degree knockdown without serious damage and without shipping a dangerous amount of water; or, in the case of open dinghies, the ability to recover and resume sailing after a knockdown and swamping.

• The ability to look after herself hove-to in sudden storms for at least short periods while you gather your wits, reef the sails, and/or start the engine.

• The ability to beat to windward in strong winds but reasonably calm waters toward a nearby weather shore. Alternatively, the ability to run safely downwind and beach herself on a nearby lee shore.

• The ability to keep her crew safe in all conditions. To achieve these desirable traits, you must be able to reduce sail area and still retain the good balance and helm docility that makes for a safe and efficient boat in heavy weather. —JV


How Seaworthy is your Trailerable Sailboat?

The quiz (click image at left) will give you an indication of the seaworthiness of your trailerable sailboat of not more than 3,500 pounds displacement, used in areas and weather conditions for which it was designed. In general, that means the conditions found in the protected and semi-protected waters typically frequented by trailersailors.

We take it for granted that you have a conventional rig such as a sloop, a ketch, or a yawl. If you sail a small cutter, a schooner, a junk, or something more exotic, you’ll have to play this game by ear. We also assume a reasonably normal ratio of displacement to waterline length and overall length. In awarding points to various characteristics, simplicity of design and operation has always won out over other considerations.

Choose one answer from each section, except where otherwise

Incidentally don’t jump off a cliff if your boat doesn’t come up to your expectations. There are certain to be seaworthy designs that fall through the cracks in our quiz.

What we hope is that taking the quiz will make you think more deeply about the many factors that constitute seaworthiness in a small sailboat, and pursue them diligently. Try to figure out why certain aspects of boat design earn more points than others, and discuss them with fellow boaters. Finally, we hope a good score will bring you improved confidence in your choice of boat and greater pleasure in sailing her.—John Vigor


There are a number of variables in our seaworthiness test, but here is an example of how three small boats with seaworthy reputations might score. For the sake of comparison, we’ve given each boat full credit for safety gear and reefing options and assumed their skippers were thoroughly experienced. Put your boat to the test and see how it compares. —Eds

The Drascombe Lugger: 134
The Cape Dory Typhoon Weekender: 170
The Santana 22: 182