Taking a Boat for a Sea Trial – Know Before You Buy

cobia bilge
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boat sea trial

A sea trial is the final piece of the boat buying puzzle.

In the past two weeks we’ve looked at how to gain insight into a boat’s quality by inspecting inside the anchor locker and bilge. Assuming you’ve liked what you’ve seen, now it’s time to leave the dock and take the boat for a sea trial.

boat sea trial

A sea trial is the final piece of the boat buying puzzle.

First off, don’t be a mere passenger on this trip. 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 high speed but are tough to handle at idle, or vise-versa.

Once you’re out on the water, make a chart on your notepad (of course you brought a notepad!) that lists out the different RPM ranges in increments of 500, from 1000 RPM to 6000 RPM (or as appropriate for the boat). Write these down the left side of the paper. Then make separate columns along the top: two for speed, one for GPH if the boat has fuel flow information at the dash, and a final column for MPG. (You need two columns for speed so you can take two readings in opposite directions then average them together, to cancel out the effects of wind and current). Set the throttles at 1000, and record how fast you’re going, and how much fuel you’re burning. Then do the same at 1500, 2000, and so on. Spin the boat around, and do your second run in the exact opposite direction. Later, you can do the math to determine MPG. when you sit down and think about how different boats you looked at performed, having records of cruising speeds and fuel efficiency will give you good hard facts to use for comparative purposes.

One note – if you’re looking at a modern boat built by a relatively large manufacturer with a Yamaha powerplant, you may be able to find this data in Yamaha’s library of performance reports. Experience has shown that these reports are dead-on accurate, and after comparing numbers I’ve collected with those in Yamaha’s reports, I have yet to find any major differences.

Once you’re done dealing with data, 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 ginger—run it hard. If you can get it to bang on a few big waves, so much the better. 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. Then ask yourself: do any flaws or stand-out attributes make themselves known? If so, note them down.

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 not always!) 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 you friends and family to rough conditions.

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, and any other indications that the boat isn’t ready for prime-time.

Do the inspections we discussed in the past few weeks and complete this sea trial, and you have all the info you need to make a well-informed decision about that boat.


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