Why She Floats
A wooden box, full of engine.
It is a fair question, and children at the dock ask it more honestly than adults do: why doesn’t she sink? Wood floats, sure — but she is also carrying an outboard, two batteries, a klaxon, six gallons of fuel and, on a good day, seven people. Here is the whole answer, in three moving parts, using her real measurements.
- Length overall
- 14′3″
- Beam
- 7′at the rail
- Draft
- ~17″how deep she sits
- Her speed limit
- 4.8 kn5.6 mph, and that's physics
Part one · Buoyancy
She doesn’t float because she’s light
Two thousand years ago Archimedes worked out the only rule that matters here: a floating thing pushes aside exactly its own weight in water. Not its own volume — its own weight. AWOOGA weighs whatever she weighs, and she settles down into the harbor until she has shoved that many pounds of Long Island Sound out of the way. Then she stops. That’s floating.
Which leads to the fun part. Put something heavy aboard and she has to shove aside more water, so down she goes — but only far enough to displace the new weight. And because she is a wide, flat-bottomed boat, that turns out to be almost nothing. Load her up:
- A grown adult180 lb
- A small passenger60 lb
- A dog with opinions45 lb
- A loaded cooler55 lb
- A full fuel tank45 lb · 6 gallons
- Anchor & rode35 lb
People aboard 0 of 7
Show your work
Push a boat down by one inch and she displaces one inch’s worth of extra water. How much that weighs depends on one thing only: the area of the slice the water makes across her hull — the waterplane area.
waterplane = waterline length × beam × fullness = 13 ft × 7 ft × 0.82 ≈ 75 sq ft per inch = 75 sq ft × 1/12 ft × 64 lb/cu ft ≈ 400 lbSo roughly 400 pounds sinks her one inch. A 180-pound adult moves her waterline by under half an inch. Her full rated load of 7 people is about three inches — on a boat with well over a foot of freeboard.
Which of these numbers are real: her 7-foot beam and 17-inch draft are published measurements. Her waterline length (13 ft) and the 0.82 fullness figure are honest estimates for a hull of this shape — nobody has taken a tape to the waterline. Both live in one constant at the top of floats.js; measure them properly and every number on this page follows.
Part two · Speed
Why 20 horsepower is plenty
A boat like AWOOGA doesn’t skim over the water — she pushes through it, shouldering a hole in the sea and dragging it along behind her. And a hole in the water has a top speed. As she goes faster, her bow wave gets longer, until the wave is as long as the boat and she is effectively trying to climb up her own hill. That’s hull speed, and no amount of engine gets you meaningfully past it.
It depends on one measurement: how long she is at the waterline. Not her overall length — the bit actually in the water.
4.8knots
— that’s 5.6 mph
● That’s AWOOGAThe same formula, run on some other hulls:
- AWOOGA
- Cruising sailboat
- Lobster boat
- Harbor tug
- Container ship
Past a certain size the formula stops being the binding constraint — a container ship could theoretically make 35 knots and instead runs at 20, because the fuel bill to get there is monstrous. For small boats, though, it’s a wall.
Show your work
Now the satisfying bit. Her published cruising speed is about 5 mph — roughly 90% of the theoretical maximum for a hull her length. She is already going very nearly as fast as a 14-foot displacement boat can go.
Bolting on a bigger motor wouldn’t make her faster; it would make her squat, dig a deeper hole, burn more fuel and arrive at the same time. The 20-horsepower Tohatsu on her transom isn’t a compromise. It’s the right answer.
Part three · Shape
Tugs are not built to go fast. They’re built to push.
Everything a tug does happens at almost no speed at all: leaning on the side of a ship, holding a barge against a current, dragging something enormous away from a pier at walking pace. The number that matters isn’t top speed, it’s bollard pull — how hard she can haul while standing still.
That’s a shape problem, not a horsepower problem. Push sideways on something and it wants to roll over; the cure is beam. A wide hull resists the heel, keeps the propeller buried, and gives the crew a deck that stays flat while all that force goes through it. So tugs are fat. AWOOGA is very fat.
Every hull above is drawn to the same length so you can compare their beam directly — a racing shell laid alongside AWOOGA at true scale would be four times as long as this page is wide. Ratios for the other boats are typical of their type.
At 2 : 1, AWOOGA is proportionally beamier than the working tugs she imitates. Seven feet of boat across fourteen feet of boat. She is, geometrically speaking, almost a square — and that is exactly why seven adults can stand up in her and nothing interesting happens.
The short version
Three sentences, if you’re in a hurry
She floats because she’s wide
Not because she’s light. A wide waterline means every extra 400 pounds only costs her an inch of freeboard.
She’s slow because she’s short
A 13-foot waterline caps her at about 4.8 knots no matter what’s hanging off the transom. She already cruises at 90% of it.
She’s fat on purpose
Tugs trade speed for stability, because their whole job happens at zero knots with something enormous on the other end of the line.
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