A sea trial is not a pleasure sail, and it is not a formality after the survey. It is the only chance you get to run the boat as a system, under load, with the seller aboard and the money still in your account. Most buyers waste it by going for a nice reach in ten knots and coming back smiling.
Go with a written list. Sail in enough breeze to load the boat, ideally twelve to fifteen knots rather than a drifter. Bring your surveyor if they will come, since many will attend the trial as part of the job, and bring one experienced friend who is not emotionally invested in the purchase.
Start at the dock, cold
Insist the engine is cold when you arrive. Watch the start: how long it cranks, whether it needs glow plugs, what comes out of the exhaust. A puff of smoke at start is normal on an older diesel, continuous black smoke is over-fueling or a load problem, white is unburned fuel or coolant, and blue is oil.
Confirm cooling water is flowing at the exhaust within the first seconds. Look in the engine space while it runs at the dock and put a hand near, not on, the hoses and the exhaust elbow. Check for exhaust smell below, which means a leak somewhere in the system and is a safety item.
Maneuvering under power
Before you leave the slip, agree that you will be driving for part of the trial. Then use the harbor properly.
Run the engine up to full cruise rpm in open water and hold it. A boat that will not reach its rated rpm under load has a problem: fouled bottom, wrong propeller, tired engine or a partly blocked exhaust. Watch the temperature gauge through several minutes at load, not just at idle.
Back the boat down hard and hold it, both to test the gearbox and to see how she handles astern, which is most of docking. Do a full-lock turn each way. Do at least one crash stop from cruise into reverse. Listen for vibration through the hull at various rpm, which points at shaft alignment, a bent shaft or a damaged propeller.
Then check the steering itself: how many turns lock to lock, whether there is slack at the wheel, and whether the emergency tiller is aboard and actually fits. Ask to see it fitted, not just stowed.
Under sail
Hoist everything, including the sails the seller did not plan to use. A headsail that has not been unrolled in three seasons is exactly the one that is blown out.
Sail on both tacks, upwind and downwind, and look aloft rather than at the water. Watch the leeward shrouds for slack, the mast for pumping or an unfair bend, and the chainplates and deck for any movement. Go forward and look at the furler, the tracks and the deck hardware while they are loaded.
Feel the helm. A well-balanced boat has light, moderate weather helm and will hold a course briefly with hands off. Heavy helm may be rig tune, may be sail shape, and may be the boat.
Reef the main and shake it out, which tests the reefing system and tells you how much work the boat is to sail shorthanded. Tack repeatedly and gybe at least once, watching the winches and the traveler. Run the autopilot if there is one, both upwind and downwind, and give it long enough to show whether it wanders.
Systems, while everything is running and heeled
Heeling is when leaks appear. Check the bilge before you leave and again after an hour on each tack, which is the single most informative test on the list.
While underway, exercise everything: the electronics and instruments against reality, the VHF with a radio check, the windlass with the anchor down and back up, the head, the stove, the refrigeration, the battery charging under engine, the bilge pumps, and the navigation lights if you can get out at dusk.
Open lockers and lift floorboards while the boat is heeled and look for water where there was none.
Back at the dock
Do not leave immediately. Sit down with your list and write your observations while they are fresh, before the conversation turns to price.
Sort the findings into three piles as you would with a survey report: safety, structural, and the ordinary list every boat carries. Negotiate on the first two.
Run the numbers on what you saw with the sailboat ratio calculator, which tells you whether the boat's behavior matched what its design should do, and price the offer honestly with the what should I pay calculator.
For the boats we cover, there is a model-specific inspection checklist to take aboard and a full owner's reference manual written around that model's systems and known issues. Start with the inspection checklists or browse the boats catalog.
