Search around and every article on lift sizing gives you the same recipe: take the boat's dry weight, add 20 percent, buy the next size up. The arithmetic isn't wrong — but it leaves you with a lift that's just barely enough for the boat you own today, and almost certainly too small for the boat you'll buy next.
After years of installing lifts across Broward and Palm Beach County, the conversation we have most often with new customers goes like this: "I bought a lift a few years back for my old boat. I've since upgraded. Now the lift can't handle the new one." That call almost always ends in a full replacement — a cost nobody planned for.
We had exactly that call recently. A homeowner who bought a 20,000-lb lift from us three years ago — correctly sized for the boat he had then — asked us to pull it and install a 35,000-lb unit because he'd moved up to a much bigger boat. The original math was right. The forecast was wrong. Below is the standard 20% rule, and then the advice we actually give the owners who don't want to do this twice.
The 20% rule, done properly
The industry standard is simple: your lift's rated capacity should exceed your boat's fully loaded weight by at least 20 percent. The catch is in the phrase "fully loaded." That is not the number on the manufacturer's spec sheet — that's dry weight, and it quietly leaves out nearly everything that lives aboard a boat in normal use.
Here's what a spec sheet tends to ignore, and roughly what each item adds to a typical 30-foot center console:
- Fuel
- Gasoline runs about 6 lbs a gallon. Top off a 200-gallon tank and you've added 1,200 lbs before anyone steps aboard.
- Fresh water
- Roughly 8 lbs a gallon. A 30-gallon freshwater system tacks on about 240 lbs.
- Batteries
- Group 31 marine batteries are around 75 lbs each, and most consoles carry three or four — call it 225 to 300 lbs.
- Engines
- Outboards are increasingly left off "dry" specs. Twin 300s add ~1,200 lbs; quad 400s on a performance hull can add 2,200+ lbs.
- Tops & towers
- A T-top, hardtop, or tower adds anywhere from 200 to 600 lbs depending on how it's built out.
- Gear & electronics
- Tackle, rods, dive gear, coolers, anchor and chain, plus multi-screen helms and radar — easily 400 to 750 lbs combined.
A 30-foot console listed at 9,500 lbs dry routinely rolls onto the lift closer to 13,500 lbs fully rigged — a 40 percent gap between the brochure and reality. The takeaway: never size from the spec sheet. Size from your loaded boat.
How to size correctly for today
Work it in order: start with the manufacturer's dry weight, then add fuel, water, batteries, engines (if they aren't already counted), gear, electronics, and any top or tower. That total is your fully loaded weight. Multiply it by 1.20 for the safety margin, then round up to the next standard capacity your dealer offers.
A worked example on a Boston Whaler 280 Outrage: about 7,500 lbs dry with twin 300s, plus roughly 900 lbs of fuel, 250 lbs of water, 300 lbs of batteries, and another 500 lbs of gear and accessories lands near 9,450 lbs loaded. Add the 20 percent margin and you're at about 11,350 lbs — so the minimum lift is 12,000 lbs. That's the conventional answer. Here's why we don't stop there.
Why forecasting beats the 20% rule
Boat ownership follows a predictable arc. The 24-footer becomes a 28-footer. The 30 becomes a 34. Single engines become twins, and the casual weekend boat becomes a serious fishing platform. It isn't an accident — it's how boating works, and once someone has made one big upgrade the next one comes easier because they've already made peace with the cost.
The problem is that a lift is engineered to a fixed capacity. You can't "upgrade" it later. A 12,000-lb lift that fits your current 30-footer is the wrong lift for the 34-footer, the wrong lift for the twin-engine repower, the wrong lift once you add a tower. So the first question we ask on a site visit isn't about the current boat — it's "what do you expect to be running in two or three years?" Most people pause, because they hadn't thought about it. If you're the type who always wants a foot or two more length, size the lift for the boat you'll actually want.
What happens if you size too big?
Oversizing has a downside, but it's smaller than most owners fear. Bigger lifts use larger drive motors and pull a few more amps — negligible over the life of the lift. They can call for stronger pilings or added reinforcement to the seawall or dock, which is the one place oversizing can genuinely add cost. And a larger lift takes up more linear feet of dock. For most South Florida waterfront properties none of these are dealbreakers, and a good contractor will tell you upfront if your dock can't carry a larger unit — before you commit to it.
Typical lift sizes for South Florida boats
These are starting points — your actual loaded weight may land above or below:
- PWC / jet ski
- 1,200 – 1,800 lbA loaded Sea-Doo with rider is around 1,100 lbs.
- 20–24 ft bay boats & small consoles
- 4,500 – 7,000 lbLoaded: 3,500–5,500 lbs.
- 25–28 ft consoles & small cruisers
- 7,000 – 10,000 lbLoaded: 5,500–8,500 lbs.
- 29–32 ft consoles & cruisers
- 12,000 – 16,000 lbLoaded: 9,500–13,500 lbs.
- 33–38 ft consoles & performance boats
- 20,000 – 30,000 lbLoaded: 14,000–25,000 lbs.
- 40+ ft sportfish & yachts
- 30,000+ lbCustom engineering territory.
Most of the homes we work on end up in the 12,000–24,000 lb range. Not sure which tier your boat falls in? Our boat lift cost guide walks through how capacity drives the installed price.
What we tell owners here, specifically
Canals and the Intracoastal are different environments. Most canal-side homes have calm water and predictable tides, so sizing is straightforward. Intracoastal-facing docks take more wake and chop, which stresses the cradle under load — a capacity buffer matters more on that exposure.
Saltwater corrosion never takes a year off. Every lift down here lives in salt. Over a 15-to-20-year service life, frame and components lose some of their original strength to corrosion, so a lift sized right at the edge of its rating today will be undersized a decade from now.
Storm season rewards margin. A properly sized lift holds your boat well above surge during a named storm. Undersized lifts get pulled from service early — sometimes right when a hurricane warning goes up. Margin buys confidence the lift will still be doing its job the season it matters most.
On wake-prone water, watch speed, not just capacity. Homes on the Intracoastal or other high-traffic waterways deal with big boats throwing serious chop. There we often recommend a high-speed lift that can clear the water quickly when a wake is coming — a standard-speed unit can be perfectly rated and still let your hull bang the cradles while it crawls up. Speed is a separate spec from size. See how it factors into a full boat lift installation.