Navigating the people and weight on your boat ensures safety for all. Here are suggestions for coordinating the weight onboard.
Supervising the load onboard your boat starts before you take off and continues throughout your entire time spent out on the water. Keeping an eye on your boat’s load is essential, and your safety, efficiency, and handling will increase and improve. Some boats carry a yacht certification which the National Marine Manufacturers Association provides to confirm that a particular boat model has been manufactured to meet all ABYC standards of safety, design, and construction—this will help you organize the load on your boat. However, if that’s not your case, apply this formula: The recommended number of people equals boat length (in feet) and boat width (in feet) divided by 15.
Rule number one is never to exceed the capacity rating of your boat. Find the capacities listed in pounds and persons, engraved or imprinted upon a plaque or sticker near the helm. Know that for the purposes of capacity, a person equals 150 pounds. So, if your linebacker-sized guest comes on board, count them as two people.
Weight distribution on your boat starts with the center of gravity and trim. Trim is the running angle of the boat as it makes its way through the water. The boat’s center of gravity (CG) is the point where downward (gravitational) forces focus. The center of buoyancy (CB) is where the upward (floating) forces focus and should always line up vertically under the CG while at rest.
According to Dave Gerr, noted naval architect and dean of the Westlawn Institute of Marine Technology, you can assume that the center of gravity and buoyancy is 60 to 65 percent aft of the bow on almost any planing hulls. Putting the CG on the aft third helps a boat quickly plane but makes it more sensitive to trim and weight issues. When the weight distribution is focused around the calculated CG, it will find its best speed, fuel economy, and handling. But that’s only sometimes practical. Sometimes adding weight in the wrong place will alter a boat’s CG or CB away from the ideal spot.
Rough water, engine power, weather forecast, tide schedule, and wiggle room for all aboard to coexist should also play a part when configuring the layout of the load going on your boat to help the weight distribution. For example, while your boat may hold so many guests, how well will it run through the inlet when heavily loaded if the tide turns? Always take a minute to consider the possibilities and err on the side of caution.
Along with the math, experience-based indicators tell you when your boat, or a boat you happen to be aboard, is overloaded. A boat that heels or rolls excessively may be overloaded, mainly if it shows a very deep, slow roll (heavily ballasted displacement craft excepted). Struggling to achieve a plane is another indicator of excess weight aboard, though a weak or underpowered engine could also be the culprit. In addition, a boat that shows its waterline below the water’s surface, or one in which the cockpit drains are entirely submerged, is another indication that the boat may be overloaded. Hopefully, your boat is not slow to rise to the waves, which is often an indicator of too much weight aboard.
As explained, these commonsense overload indicators come with caveats. Use them as part of a greater awareness—an expansion of your boat sense. If one crops up, investigate, read the capacity plate, and alert the captain or owner.
Another tip is if you load the stern with heavy gear, store some equipment in the bow to neutralize it. Keep all the big guys from sitting to port; try to place them on opposing cushions. And if you add aftermarket items, consider how they’ll alter weight distribution and make adjustments.
Another rationale for managing weight can be financial. Excess weight costs more fuel to carry along the water. So, avoid filling the livewell until necessary. Carry spares and backups of equipment, but don’t store enough to stock an entire marine store on board and leave the beach gear and toys on the dock if the seasons don’t permit it.
Before setting sail, take an inventory of your gear, heed capacity plates, trust your boat sense, and, in all cases, when loading a boat, place safety first.