Sizing a Boat Lift: Why the Number on the Sticker Isn't the Number

Boat lifts are sold by capacity, and the temptation is to compare that number against the weight in the brochure for your boat. That comparison is where most undersized lifts come from, because the brochure weight is a dry hull and the lift has to carry the boat as it actually sits.

Start with dry weight, then add what is permanently aboard. Fuel is the big one: petrol is roughly six pounds a gallon, so a full 60-gallon tank is another 360 lb. Water tanks, batteries, an outboard or two, the bimini, ground tackle, safety gear, a cooler nobody has taken out since spring, tubes, boards, tools. On a mid-size pontoon this routinely adds fifteen to twenty-five per cent to the number you started with.

Then add rain. A boat left on a lift for a week in a Florida summer can collect a serious amount of standing water if the cover holds it or the scuppers are above the waterline while lifted, and water is over eight pounds a gallon. This is the load that catches people out, because it arrives when nobody is watching.

The second half of the calculation is the part that gets skipped entirely: the structure. A lift rated to 10,000 lb is rated on the assumption that what it is bolted to can take 10,000 lb. If the piles were driven for a walkway and the beams were sized for foot traffic, the sticker on the motor is describing the weakest part of the system incorrectly. That is why we work out the real wet weight and then engineer the piles, beams and cradle for it, rather than fitting a rated lift and hoping.

One more thing worth knowing: most lifts warn you before they fail. Cables fray visibly, sheaves start to squeal or bind, and a frame that has gone out of alignment chews one cable faster than the other three. If you replace the cable without correcting the alignment, the new one wears out the same way on the same schedule.

Not sure what your lift is actually carrying, or whether the dock under it can take what you want to put on it? Call Sunrise Deck & Dock at (407) 530-7796 for a free estimate.