Buying a Used Pontoon Boat- What to Inspect

Pontoons are the most popular boat on Southeast lakes, and they’re the boat buyers are most likely to buy on a handshake. It’s just tubes and a deck, the thinking goes. Then the new owner finds a tube full of water, a rotted deck under fresh vinyl, or a motor that won’t stay running.

We started out running a marina and repair shop on the Tennessee River, so we’ve seen a lot of pontoons from both sides of the work order. If you’re shopping for a used one, here’s what you should check before you hand over any money.

Start with the tubes

The tubes, or logs, carry the whole boat. Problems here are the most expensive to fix and the easiest to miss with the boat in the water, so ask to see it on a trailer or a lift. Once it’s up, look for:

• Water inside the tubes. Pull the drain plugs if the tubes have them. A boat that sits low on one side, or leans when it’s running, may have a tube taking on water.
• Dents and creases from beaching, hard landings at the dock, or poorly fitted trailer bunks. A deep crease can hide a crack.
• Cracked welds, especially where the brackets join the tubes, since that’s where the stress is greatest.
• Corrosion. Pitting, white powdery deposits, or thin spots in the aluminum can mean galvanic or stray-current corrosion, which is common on boats kept in the water at a marina. A dock with an electrical fault can do real damage in a single season. Copper-based bottom paint on aluminum causes the same problem.
• Nose cones and lifting strakes, plus the center tube on a tri-toon. Under-skins hide a lot, so look at whatever you can reach.

Then look underneath at the brackets

While you’re under the boat, follow the crossmembers that tie the tubes to the deck. Check for:

• Bent or cracked brackets
• Loose or missing bolts
• Corrosion where steel fasteners meet aluminum

Walk every foot of the deck

Most pontoons still have plywood decks under the vinyl or carpet. Plywood rots, and new vinyl can hide it. As you walk the deck, pay attention to:

• Soft spots or flex underfoot, anywhere on the deck
• The areas around anything bolted down: furniture, rail stanchions, and the helm. Water follows fasteners into the wood.
• Storage history. Rot is most common on boats stored uncovered, or where water sat under the furniture.

Composite decks don’t rot, but it’s still worth checking that the deck is fastened down solidly.

Check the fences, furniture, and Bimini top

These are part safety, part repair bill. Look for:

• Loose rail panels, broken gates, and cracked stanchion bases
• Split or mildewed upholstery. It’s cosmetic, but reupholstering a large pontoon isn’t cheap.
• A bent Bimini frame, broken fittings, or worn-out canvas

Look over the motor and controls

On most pontoons, the outboard is the most valuable part after the tubes. A proper engine inspection is a job for a mechanic (more on that below), but there’s plenty you can check yourself:

• Engine hours, from the gauge or the dealer’s printout, compared with what the seller told you
• Corrosion on the motor’s midsection and mounting bracket, and the condition of the pod or transom it’s mounted to
• Steering. It should turn smoothly lock to lock. A stiff cable or leaking hydraulic steering is common.
• Throttle and shift, which should move cleanly into and out of gear
• Leaks around the tilt and trim unit
• Serial numbers on the motor that match the paperwork

Trace the fuel and electrical systems

Fuel and wiring problems are hidden under the deck, so this is where an access panel and a flashlight earn their keep. Check for:

• A fuel tank that’s strapped down securely, whether it’s under the deck or in the console
• Fuel hoses that aren’t cracked, soft, or swollen, and that carry a Coast Guard rating
• Wiring under the deck without corroded splices or spots where it rubs against the crossmembers
• Batteries that are strapped down, with covers on the terminals
• Navigation lights and the horn, which should both work

Take it for a sea trial

The water tells you what the dock can’t. Never buy a pontoon without running it. While you’re out, notice:

• Whether it reaches the speed you’d expect for its tubes and motor
• Whether it runs level, or leans to one side
• How it handles in turns
• Whether the gauges read normal, and the motor holds its temperature at cruising speed
• Whether the trim works through its full range

Finish with the paperwork

Before you sign, make sure the boat matches its records:

• The HIN on the boat matches the title
• The motor’s serial numbers match the records
• The trailer, if it’s part of the deal, has its own title or registration, as your state requires

Is a survey worth it on a pontoon? Yes.

New tubes, a new deck, or major motor work can each run into the thousands, and any one of them changes what a boat is worth to you. Most buyers don’t have a lift, a moisture meter, or the time to crawl under a pontoon with a flashlight. And a lot of these problems only show up to someone who has seen hundreds of them.

That’s where we come in. A pre-purchase survey covers everything on this list: the tubes, brackets, deck, rails, fuel and electrical systems, and a sea trial. It comes with a written report and a fair market value you can negotiate with. If you’re financing or insuring the boat, your lender or insurer may require a survey anyway.

What a survey doesn’t cover is the inside of the motor. Compression testing, lower unit oil analysis, and a full diagnostic belong to a qualified marine mechanic, preferably one certified on that brand of outboard. On a pontoon, where the motor is a big share of the price, we recommend booking a mechanic’s inspection alongside the survey. Between the two, you’ll know exactly what you’re buying.