Great Lakes Winter Layup: Peak Season for Hull Work
By Ray Whitfield, ADCI-certified commercial dive supervisor. Reviewed by Dana Whitcombe, technical reviewer.
Hull & Bottom Cleaning | Marine Salvage & Recovery I cut a hole through the ice on the St. Marys River in the middle of January. It was 18 below zero air, the water at 32.5 degrees, and my job that morning was to inspect the sea chest on the port side of a 730-foot laker. I dropped through the opening, and the murk closed over me like a curtain. Layup is the cold season. Most people think the Great Lakes dive industry rolls up its hoses when the ice comes. The truth is the opposite. The winter layup window is when the biggest, slowest, most deliberate hull work happens. Vessels tied to the dock for months, with no cargo and no current, are the perfect work platform. We've got time to run ultrasonic surveys, mount repairs, and clean sea chests before the seaway opens in late March, give or take. The seaway closes around mid-January, and most of the fleet is tied up by the first of February. That's when we ramp up for six to eight weeks of non-stop underwater work.
Why Winter Is the Busiest Time
The work every owner wants is a full hull survey. That's divers walking the entire hull and recording plate thickness. We run an ultrasonic gauge over the steel—a Krautkrämer, but we all call it a UTG. We plot readings in a 10-foot grid, and the surveyor tracks them on the chart. A typical laker has a wetted girth of, call it 60 to 70 feet, so that comes out to a lot of man hours. The unexpected part is what we find. In the last two weeks of January everything gets quiet, and owners get nervous. They know they had a strange vibration in December, or they heard something scrape when they hit the sea wall. So they call us to have a look. That's when we find the rope wraps, the cracked rudder web, a missing bolt on an anode. The layup is the only chance to fix these things while the boat sits still.
Under-Ice Diving: The Actual Job
Cutting a hole through the ice is the easy part. We pick a spot near the work area, score a rectangle about 4 by 6 feet with a chainsaw, and then break it out with a heavy bar. The hard part is keeping it clear. Ice re-freezes overnight, so every morning the tender chips it free. If you're working from the ship's deck, you go off the side into that little pool. You wear a dry suit under a thick undergarment, plus a hot water supply from a surface boiler. That's the only reason you can stay down long enough to get anything done. My Kirby Morgan helmet has a clear faceplate the size of a dinner plate, and the comms sit right at my ear. We aim for 30 to 45 minutes in the water, sometimes three to four dives a day depending on the cold. The thing people don't expect is the visibility. It's usually clearer in winter because there's no runoff and no boat traffic churning up the bottom. On a good day you can see 15 or 20 feet. You can watch a zebra mussel shell slowly spin through the water column. That's the part I like, even after 28 years. Of course, there are days when it's all black below the surface, and you work by touch and by the sound of the comms, patting the steel to find the crack. That's when you really earn the day rate.
Repairs Below the Waterline
Once the survey tells us where the steel is thin, we go to work. Underwater welding is the standard for cracks or small pits. We use a wet-welding rig—an AWS E6012 rod and a waterproof stinger—and a clear dome on the helmet lets you see the arc. It's not as pretty as a dry-dock weld, but it's plenty strong for most hulls. For bigger damage, we'll bolt a steel patch over the hole with a marine epoxy like Belzona 1111 as the gasket. That patch can be 1/4-inch plate, round or rectangular, with holes drilled through the original steel. We torque the bolts to spec, grind off the edges, and test the seal with a vacuum box. It's honest work. The less glamorous jobs are just as important. Replacing anodes is routine: unbolt the old zinc or aluminum, bolt on the new ones. Sea chests get clogged with sand and debris, so we clear them with a high-pressure hose. And sometimes we have to deal with a prop wrapped in wire or rope. You'd be surprised how often that happens. You take a knife and a saw, and you just work at it, piece by piece, until the prop is clean. It's cold, tedious work, and there's no way to rush it.
The Business Side and Safety
This kind of work doesn't happen without contracts and planning. Most owners book us well ahead—like in November—for a window in January or February. The contract is typically a day rate for the dive team, which includes the supervisor, two divers, and a tender, plus the hot water unit, a diesel boiler, and the surface air supply if it's not breathing off bottles. That day rate is not cheap, because we've got to pay for the gear and the insurance. But compared to the cost of dry-docking a laker for a week, it's a steal. Owners like it because they can lock in a schedule and have the work done before the spring breakup. We also operate under strict safety rules. Any commercial diving in the U.S. Falls under OSHA 1910.401, and most of us carry ADCI certification. The dive supervisor—that's me—is responsible for the dive plan, the emergency drills, and making sure nobody stays down too long. We run a standby diver in the water or suited up at the hole, and we watch the bottles. When you're in winter conditions, hypothermia is the real enemy, not just the cold. The safety rules exist for a reason. I've had buddies who've gotten caught under ice, and they're alive because someone followed those protocols.
Frequently Asked Questions
What is the Great Lakes winter layup? It's the period from January to late March when commercial bulk carriers stop running due to ice and tie up at docks for the season. Divers do inspections, clean sea chests, replace anodes, and repair hulls during this window. Why is winter the best time for hull work? The ships sit still for months, so there's no current, no schedule pressure, and we can do detailed surveys and repairs that would be impossible during the summer sailing season. How do divers work when the harbor is frozen? We cut a hole through the ice with a chainsaw and keep it open with aeration or hot water. The dive team works from that opening, and the surface crew stay in a heated shanty. What kind of certification do Great Lakes hull divers have? Commercial divers in the U.S. Work under OSHA 1910.401 and most are trained and rated by ADCI (the Association of Diving Contractors International). For cold water jobs, the supervisors are usually ADCI-certified as well.