Boat Buying Test 102 – The Sea Trial

What to look for when sea trialing a boat you might buy.

We hope you’ve already read Boat Buying Test – 101: The Inspection, and are now ready to talk about leaving the dock for your sea trial. Great—for starters, shove that sales guy or owner out of the way and take the wheel. You’ll learn a lot more about the boat by operating it yourself (is the wheel “sticky” or does it turn smoothly? Do you have to fight it at high speeds, or in sharp turns? Is the throttle tough to move, or easy?) Operating the boat near the dock or ramp at slow speed is important, too, since some boats operate well at speed but are tough to handle at idle, or vise-versa.

boat buying

When sea trialing a boat don’t just go for a ride, take the wheel and run it for yourself.

Once you’re out on the water, make a chart on your notepad that lists out the different RPM ranges in increments of 500, from 1000 RPM to wide-open throttle RPM (usually 5500 or 6000, for an outboard boat). Write these down the left side of the paper. Then make separate columns along the top: two for speed, then one for GPH, running inclination, and sound level. Why make two columns for speed? So you can take two sets of readings in opposite directions and then average them together, to cancel out the effects of wind and current. Here’s what your empty chart should look like:

Make A Sea Trial Data Chart

RPM    MPH1 MPH2 GPH    LEVEL            DBA












Be Methodical

Set the throttles at 1000, and record your info—how fast you’re going on the GPS, fuel burn as per the engine monitors at the helm, how much bow-rise there is, and sound level in dB-A. (Note: there are plenty of free apps you can load onto your phone to measure inclination by degrees, and sound levels in dB-A). Then move up by 500 RPM, and repeat the process. And so on and so forth, until you reach wide-open speeds. Later, you can add columns and do some math to gain much more insight into the boat’s performance. Average the speeds together, divide by GPH, and you’ll have MPG. Multiple MPG by useable fuel capacity (always allowing for a 10-percent reserve, of course), and you learn the boat’s true range. For comparative purposes, knowing these details with data you gathered yourself is invaluable.

sea trial

How do the numbers shake out on a Robalo R302? Check out the chart, below.

Here’s a sample chart, collected on a sea trial of a Robalo R302 with twin Yamaha V6 four-stroke F300s, after adding the columns for MPG and range and doing the math:

Sea Trial Data For Robalo R302

RPM    MPH1 MPH2 GPH    LEVEL            DBA    MPG   Range

1000    5.5       5.7       2.7       0                      68        2.1       567

1500    7.6       7.8       4.4       1                      70        1.8       486

2000    9.4       9.6       7.2       3                      72        1.3       351

2500    14.0     14.0     12.0     5                      76        1.2       324

3000    22.0     23.0     14.0     2                      78        1.6       432

3500    30.1     30.5     17.5     2                      81        1.7       459

4000    35.5     35.7     22.0     1                      83        1.6       432

4500    41.0     41.2     29.8     1                      86        1.4       378

5000    46.0     46.1     40.1     1                      89        1.1       297

5500    51.5     51.6     52.5     1                      91        1.0       297

5750    53.0     53.4     56.5     1                      94        0.9       243

Once you’ve gathered your data, it’s time to put the boat through a series of “helm tests” that will tell you how well the boat handles. With the speed set at a reasonable cruise, carve some S turns. Make a sharp U turn. Hit waves in a head, beam, and following seas.

This is your chance to find out how the boat will handle rough terrain, so don’t be timid—run it hard. If you can get it to bang on a few big waves, so much the better. Later, when you re-inspect the cabin, you’ll see if a hard pounding will shake anything free down there. Finally, stop the boat and maneuver it as you would in close quarters; backing, opposing the motors (for twin-screw boats,) and “walking” the boat sideways. Go from a dead stop to full throttle and note the time it takes to get onto plane. Then back the throttle down slowly, and note minimum planning speed before the boat falls off of plane. This is a very important detail, as it tells you just how slowly you’ll be able to plod along in rough seas, while still getting reasonable fuel economy and making a decent speed. On boats with twins shut one engine down, tilt it up, and see if the boat can still plane at an acceptable “get-home” speed. Then ask yourself: do any flaws or stand-out attributes make themselves known? If so, note them down.

boat sea trial

A sea trial is no time to be timid – as you can see, the driver of this Edgewater 280 CC will get a real-world feel for how this boat can handle waves.

Next, put the boat into neutral and simply let it drift. Anglers will want to note whether it drifts beam-to or stern-to in the seas (usually beam-to for inboards and stern-to for stern drives and outboards, but this doesn’t always hold true), and everyone will want to note how much it rocks and rolls. Finally, sit in the passenger’s chair, lounge, or aft bench seat while someone else runs the boat. The helm is often one of the more comfortable positions to ride in, and getting a feel for how your passengers will fare at sea is something you’ll want to do now, not after you subject the wife and the kids to a hell ride.

boat buying

Run the boat, but don’t hog the wheel. You’ll want to discover what it feels like to be a passenger in the boat, too.

When your sea trial is complete, take the wheel again. Make sure you run the boat back to the dock, and try putting it in its slip or onto the trailer, to get a feel for just how tough these maneuvers will be in the future. Back at the dock, give the entire boat another once-over. Look for items that vibrated loose, hatches or cabinets that swung open, furniture that moved, and any other indications that the boat isn’t ready for prime-time. There, now—you’ve done it!

Consider that boat thoroughly tested. Here’s your diploma, you’ve graduated Boat Testing, 102.

Editor’s Note:  This is part 2 continued from Boat Buying Test 101 – The Inspection.

Get more great boating reviews and info from Lenny Rudow on BD.