Packing on the Pounds

Slow? Sloppy? Sluggish? Maybe your boat should go on a diet.

Packing on the Pounds
Packing on the PoundsBoating Magazine

Americans are big on supersizing -- and it shows. Although it's easy to see what we're doing to ourselves, it's not so apparent that we're doing the same thing to our boats. They come from the builder lean and ready to roar, but it's not long before we're bulking them up. From fishing tackle and watertoys to tools and electronics to those the-more-the-merrier passenger loads, our boats are getting heavier. And, if you believe the pundits, they're suffering from it just like us: giving up performance and becoming a danger to themselves.

But maybe it's not so bad. Sure, everyone talks about how weight is detrimental to boats, but we wanted to see if this is truly the case. So we got a boat, grabbed our test gear, and started packing on the pounds in search of answers. And while there were times where weight obviously had its ill effects, the results we got weren't always what you'd expect.

The Numbers Game
Like the suggested weight-for-your-height chart on a doctor's wall, we started with a similar guideline: the Coast Guard's maximum capacity label.

Next time you go aboard, look for the black and yellow capacity plate prominently displayed in the cockpit. If your boat is 20' or shorter, it's required to have one by the Coast Guard. If your boat is shorter than 26', the National Marine Manufacturers Association (NMMA) requires one to achieve certification. A plate will usually read like this: "8 PERSONS OR 1200 POUNDS." A confusing description that some may interpret as a hard-and-fast passenger number limit, and others an overall weight limit. In general, you should not exceed either the maximum weight capacity or the total number of passengers.

For decades boaters have been using these numbers as a safe guideline when taking on crew and gear. But now, those digits are being called into question -- and it's because of us.

Coast Guard capacity limits were last standardized more than 60 years ago, when the average boater was assumed to weigh 140 pounds. Sadly, in today's America, that estimate is way too low. The result is that we may be piling more pounds into our boats than they were designed to handle.

In our tests the weight we added was dead-on accurate. But be aware that when you go out with your beefy buddies, the plate that says the boat is safe for eight people may need to be adjusted down to six.

Taking on Ballast
Our test boat was a late 1990s 24' Sea Ray Sundeck powered by a 220-hp 5.7L MerCruiser. It has a common hull you see on plenty of boats and reasonable power. It's also a deckboat, which is a perfect test bed. Few boats get more people and gear piled into them than a deck. Ours had a capacity sticker rating for 12 passengers or 2,000 pounds.

To start we established baseline numbers at 800 pounds, the total weight of our test team and assorted gear. It's a common load for this boat. Based on the national average, a four-man crew would be close to this. Then we added weight in 400-pound increments until we reached the boat's 2,000-pound capacity. To do this we used Fly High water ballast bags, which are primarily used to boost wake size when wakeboarding. The bags were placed throughout the boat to mimic a safe passenger load.

For most of the experiment, we relied on our usual boat-testing tools. Fuel flow as well as running and banking angles were all noted. Speed and acceleration curves were obtained using the Stalker Acceleration System, the industry standard in radar-based testing. Finally, differences in stopping and turning distances were measured with GPS.

Then there was the more subjective part of the test, the seat-of-the-pants perspective from our crew and the boat's owner. From this, we noted any subtle handling abnormalities or safety concerns.

That's how we did it. Now here's what we learned.

The Power Principle
No shocks when we saw that adding weight increased fuel consumption. At a cruising speed of 3000 rpm, fuel consumption went from 7.8 gallons per hour (gph) at 800 pounds to 8.4 gph at 1,200 and 1,600 pounds to a high of 8.6 gph with the full 2,000-pound load. Consumption suffered less at wide open throttle but still showed an upward climb, starting around 17 gph and peaking at 18.2 gph when fully weighted.

We were all surprised, however, that loading the boat to its capacity not only failed to have a dramatic outcome on its top speed, but at one point actually had a positive effect. At our baseline of 800 pounds, the Sundeck topped out at 39.98 mph. At 1,200 pounds, the boat lost nearly a full mile per hour, dropping to 39.01 mph. The effect of another 400 pounds was less dramatic, losing only about 0.5 mph, with the boat doing 38.50 mph. Adding the last 400 pounds, to bring our weight up to the max load of 2,000 pounds, made us triple check the GPS. To our amazement it increased our speed just over a mile per hour to 39.66 mph.

A possible explanation for the jump in speed from 1,600 to 2,000 pounds may have to do with load distribution, which would have made for a better, more level running attitude for the hull.

There were no surprises with acceleration, which took a notable hit as more weight was brought aboard. At the 800-pound baseline mark, the boat reached 30 mph in an average of 9.00 seconds. At 1,200 pounds the time increased to 10.34 seconds, and at 1,600 pounds the time was all the way up to 11.21 seconds. Finally, with 2,000 pounds of ballast the time stretched to a full 12.46 seconds. Clearly, the additional weight was taking its toll as the boat labored -- taking nearly three more seconds or one-third more time -- to get on plane.

Even from a "seat-of-the-pants" perspective it became obvious that as we added more weight, the boat became notably more sluggish getting out of the hole, prolonging that dangerous period where a vessel's bowrise hampers a driver's visibility. With the base 800-pound load, bowrise reached 8 degrees before settling in at 3 degrees at our 3000 rpm cruising speed. At 1,200 pounds the bow rose to a view-blocking 10 degrees, eventually coming down to 3 degrees. This was followed by a dangerous peak of 13 degrees at 1,600 pounds, with a 4-degree cruise. At 2,000 pounds, bowrise came down slightly to a maximum of 11 degrees, which is still too high, and settled at 4 degrees.

Again, weight distribution played a role. We tried to load the boat in a way that 12 passengers would naturally settle. That final extra 400 pounds brought the bow down slightly but not near an acceptable level. Clearly, the more passengers you bring aboard, the more conscientious you'll have to be about their weight's effect on visibility. The added planing times will also affect the size of the wake you throw as well as your ability to tow someone on skis or a wakeboard.

An interesting note was that the owner told us his boat seemed to handle better with a medium amount of weight aboard, at around 1,200 pounds. One theory is that this settles the hull slightly lower into the water to its designed maximum waterline. Recreational boats are built to absorb a certain amount of loading with minimal effect. With a light load, our deckboat almost seemed to ride too high, feeling loose and slightly less stable.

Bodies in Motion
When it came to stopping, that same theory of not-all-weight-is-bad may help explain our results. Pulling alongside our designated mark at 30 mph, the driver abruptly chopped the throttle, maintaining a straight course as the boat settled back into the water. At 800 pounds, the stopping distance was 230'. As the load increased, at least initially, so did the stopping distance. With 1,200 pounds aboard, the distance increased to 255'. Loading another 400 pounds, our distance at 1,600 pounds climbed to 264'. Then came 2,000 pounds, and we were back to 250'. Why the sudden decrease?

Again, it came down to the way we distributed the load. At 2,000 pounds, the bow became noticeably heavier thanks to a full complement of "crew," more of whom occupied the forward cockpit. That meant more wetted surface and more friction between the hull and the water.

Weight also had an effect on the boat's turning radius, but not in a way you might expect. At the base 800-pound level, the distance between our starting mark and a point 180 degrees opposite was, on average, 55.6'. At 1,200 pounds, the turn tightened to 54.9'. The shrinking distance continued at 1,600 pounds to 54', followed by 2,000 pounds where it dropped to 49.9'. We credit the ever decreasing radius to there being more hull in the water, which gave more bite to the chines, strakes, and keel.

Studying the boat's banking angle in sharp high-speed turns adds credibility to this theory. As we added more weight, the banking angle came down. At both 800 and 1,200 pounds the maximum angle was 20 degrees. At 1,600 pounds it dropped to 15 degrees, and at 2,000 pounds it was a mere 10 degrees. Of course, the weight itself was a factor, making it harder for the hull to alter its lateral trim with all that extra ballast holding it down.

What We Learned
Weight does indeed affect a boat's overall performance, handling, and safety. Often it's for the worse, but sometimes it appeared to be for the better.

On a more uniformly negative note, with higher weight loads our boat, as would most, lost critical visibility -- and for longer periods of time -- when coming on plane. It also took much longer to accelerate and farther to stop. Translate those findings into your typical collision avoidance situation and the results should give you pause the next time you stuff your vessel to its capacity.

Credit this boat, and most others that are out there, for never pushing us past our comfort level. When staying within the recommended capacity limits, we never dipped the gunwale too close to the water during the tightest of turns, and never once did it feel like the boat was unstable or like there was the slightest chance of it capsizing. Surprisingly, adding weight often helped the boat maneuver through a turn and kept it from banking precariously.

It's important to note that our ballast bags were carefully secured so that they couldn't shift unexpectedly. However, during many accidents passengers and cargo get thrown about, resulting in a dangerous imbalance.

Likewise, we accurately measured our ballast, filling the boat to its certified 2,000-pound capacity, and distributed the load in a seaman-like fashion. Real life is rarely so predictable. Boaters notoriously overload the bow cockpit, stand up and move around while underway, and even ignore the capacity plate and load boats beyond their limits.

So the next time you're out on the water, watch your load. And the next time you're in the drive-through and are asked if you want to supersize your order, we suggest thinking twice before saying yes.

Weighing the Data
1. ACCELERATION: Just what you'd expect, an almost uniform increase in time to get from idling-in-gear to 30 mph.

2. SPEED: Everything went as predicted, until we added those last 400 pounds and got an unexpected speed jump.

3. STOPPING: Another surprise from those last 400 pounds: The stopping distance actually decreased.

4. TURNING: Things get interesting when you reach maximum capacity, and turns suddenly get a lot tighter, too.

Walking Ballast
According to the National Center for Health Statistics, between 1999 and 2000 the average American male weighed a whopping 190 pounds. Think that's offset by our female counterparts? Guess again. That same study said the average female tips the scales at 163 pounds. We're getting bigger -- fast -- and the capacity plates on our boats haven't kept up.

In 2004, the National Transportation Safety Board (NTSB) recommended that the Coast Guard revise its average body-weight standard of 140 pounds after a tour boat capsized in Maryland. One year later, the standards faced even more scrutiny after another capsizing in New York. In both cases the NTSB found that each passenger weighed nearly 30 to 40 pounds more than the average weight that the capacity limits were based upon.

Following the New York incident, then-Governor George Pataki demanded that the Coast Guard revise its weight standards and directed New York to raise its weight standard to 174 pounds per passenger for tour boats.

While the Coast Guard was initially slow to respond, in 2006 it recommended a new standard of 185 pounds per passenger for small commercial boats. This is still under review, and to date there has been no mention of amending the weights for recreational boats.

Until changes are made, which could be many years, think twice before going to the max on your boat's capacity plate. As a guide, on boats under 26', recalculate your capacity by using the suggested 185-pound average weight.