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Catamaran thrusters: bow, stern or both, and whether you need one
Most catamarans do not have a thruster and do not miss it. Watch one come into a slip: one engine ahead, one astern, and she turns on the spot. The reason is built into the boat, so the answer on two hulls is different from every monohull answer on this site. This guide shows why most cats do without one, when the wind changes that, and what fits when it does.
The short answer
With twin engines in separate hulls, one ahead and one astern spins her in place. The cheapest fix is practice with the engines.
A big, tall cat in a tight slip with a crosswind can drift sideways faster than the engines can walk her. Then start at the bow.
No external unit fits a cat. A tunnel or a retractable goes in one hull. On a 42 ft cat, 28 tunnel units and 2 retractables are strong enough to steer her bow.
Our sizing puts a 42 ft cat at about 90 lb from a tunnel in a 15 knot breeze. The beam is not an input, so read toward the top.
No catamaran owner has published a fitted price. Our own estimate for a boatyard job is in what it costs.
Bow, stern, or both on a catamaran
In brief: with twin engines a full beam apart, most cats need neither, and the cheapest fix is practice with the engines. When the wind wins anyway, the bow is where to start.
At the stern, the engines already do the work. With the props in separate hulls, one ahead and one astern spins her in place. The section engines twenty feet apart explains it.
At the bow, a thruster goes in one hull as a tunnel or a retractable. External units do not fit a cat.
At both ends, some systems cover the whole boat. Jet Thruster offers one unit in one bow, one in each bow, and bow-and-stern layouts beyond that. The section where a thruster can go on two hulls covers the options.
Buying only one? Our page bow or stern first? helps you choose, and our page on what a stern thruster costs has the dated prices for the back of the boat.
A 42 ft catamaran, stopped, turning about her middle. The arrows point the way each unit pushes to turn her: the bow one way, the stern the other.
Engines twenty feet apart
A Two engines driving two propellers, set apart from each other. Running one forward and one in reverse turns the boat on the spot without any rudder at all. That is why twins need less help at the stern. monohull can steer at zero speed on its throttles. With one engine ahead and one astern, the boat turns about a point between two props a few feet apart.
A cruising cat does the same thing with far more leverage. Her props sit in separate hulls, the full beam apart. The turning lever is several times longer, and she spins in place without moving ahead.
Leopard says so on its own site. About its thruster option, it writes: “Leopard offers the optional bow thruster only on our flagship, the Leopard 58.”
Of the rest of its range, Leopard says: “With engines that are 20 or more feet (around 6 m) apart, and a bit of practice, you can dock a Leopard quite easily.” It is rare for a builder to explain why it will not sell you something, which is why it is quoted here.
If you have twin engines, practice comes before hardware on most cats. The thruster finder, the tool here that matches a unit to your boat, takes the twin-engine answer into account and says so on the result.
When the wind wins anyway
The throttles turn her. They do not stop her drifting. A cat is wide, and a bridgedeck cat (one with the cabin built across the deck between the hulls) is tall for her length. The side area the wind pushes on is large. All that resists it under the water is two thin hulls. A gust across the fairway takes the whole boat sideways, and the throttles can turn her all they like.
Jet Thruster sells water-jet thrusters for these boats. It puts the problem this way on its catamaran page: “Their broad beams and high profiles, while excellent for stability, make them prone to wind drift, especially during docking.”
Of twin engines, the same page adds that they “aren't always sufficient in tight marinas or gusty conditions.” A maker selling the cure has a reason to say so. Leopard's Leopard 58 exception says the same thing from the other side.
So the case for a thruster on a cat needs all of these at once:
- a big, tall boat
- a slip with no room to walk her on the engines
- a crosswind
A thruster is a steering control. It is sized to keep the bow where you want it at approach speed in a 15 knot breeze. It is not there to pin a big cat to a dock in a gale, and nothing sold for a cat will.
Where a thruster can go on two hulls
Not on an external unit. Most of this site's guides lean on external units that bolt on. Here they do not fit: an external unit bolts to the side of a single hull at the bow or to its transom, and a cat has two narrow hulls with a bridgedeck between them, so there is nowhere forward to hang one. That rules out every removable and bolt-on A thruster that bolts to the outside of the hull, up near the bow or on the back of the boat. Its propeller hangs in the water below it. Nothing is cut through the hull, so there is no tunnel., including the one I run on my own trawler. The thruster finder rules them out for a catamaran too.
A A tube bored straight through the hull below the waterline, with a propeller in the middle of it. It is the conventional thruster. Fitting one is mostly a labor job rather than a hardware one. goes in one hull, forward, where the hull has the depth for a tube. That puts it off the boat's centerline by half the beam.
The offset does not matter for steering. A sideways push turns the boat about its pivot by the same fore-and-aft The distance from the point the boat turns about to the place the push is applied. Double the distance and the same push turns the boat twice as hard. whichever hull it is in. The offset only means the unit is in one hull.
Jet Thruster's page offers one unit in one bow, or “one thruster in each hull of the bow for symmetrical control,” and bow-and-stern layouts beyond that. It names the Lagoon 450, Lagoon 46 and Lagoon 560 among the boats it has fitted. Our review of that system reads its manual, its prices in euros and its owner reports.
A A thruster that lives inside the hull and drops down through a hatch when you press the button, then pulls back up. It leaves no permanent hole in the water flow. drops a leg out of one hull and lifts it clear when you are sailing. That is why a sailing cat's owner pays more for one. A tunnel mouth is a permanent hole in the water flow along that hull. Our types page, the types compared, draws each mounting on one hull at one scale and says what each drills.
| Mounting | On a catamaran | Units that qualify |
|---|---|---|
| External | Does not fit two hulls | 0 |
| Tunnel, in one hull | The usual route. Published thrust runs 77–231 lb across the set | 28 |
| Retractable, in one hull | Lifts clear under sail | 2 |
What our sizing says, and what it cannot see
This site sizes every boat from the wind on her The sides of the hull above the water. at 15 knots. We have no catamaran hull type. So a cat is sized on that wind alone: we give her the height a light, fast hull has for its length, and the wind exposure of a tall boat, one that catches a lot of wind: a flybridge, a tall house or a tower.
That holds on this page, in the thruster finder and in the calculator, so all three give one answer.
| Boat | Side area we assume | Wind load at 15 kt | Thrust from a tunnel |
|---|---|---|---|
| 35 ft | 190 sq ft | 145 lb | 63 lb |
| 40 ft | 248 sq ft | 189 lb | 83 lb |
| 45 ft | 314 sq ft | 239 lb | 103 lb |
| 50 ft | 388 sq ft | 295 lb | 128 lb |
| 55 ft | 469 sq ft | 357 lb | 153 lb |
| 60 ft | 558 sq ft | 425 lb | 183 lb |
The beam is not an input. Our sizing reads the wind-facing height off the length. A wide bridgedeck cat can carry more side area than a monohull of the same length, so read toward the top of each range.
Run the calculator at your own length. It prints every step of the arithmetic and lets you change the wind exposure. That page also shows where the makers' own charts sit beside ours.
What it costs
No catamaran owner has published what a fitted thruster cost them. We found no quote, invoice or rough number in any thread this site has read. What is published is product prices.
The estimate below is this site's own. It prices a boatyard job on a 42 ft catamaran from published prices and current yard rates. There is no external figure, because no external unit fits two hulls.
| External | Tunnel | Retractable |
|---|---|---|
| Not possible on this boat | Tunnel thrusters for a 42 ft catamaran Most jobs cost $12,300–$14,600. The least expensive, fitted by a boatyard:
And 25 more models, up to $19,400 for the VETUS Bow Pro 764. The thruster itself, before fitting: $1,300–$8,800. The boat has to come out of the water for these. Find the right one for your boat | Retractable thrusters for a 42 ft catamaran Fitted by a boatyard, least expensive first:
The thruster itself, before fitting: $7,400–$18,000. The boat has to come out of the water for these. Find the right one for your boat |
A different length, or a different boat? The thruster finder prices your own, and the comparison by boat type puts this row next to every other kind of boat.
A tunnel job on a cat is the same job as on a monohull, done in one hull. You are paying for the tube, the glasswork either side of it, batteries and cable, and a Lifting the boat out of the water on a travel lift or a trailer so work can be done below the waterline. It is billed separately from the job itself. long enough to do it. The cost page takes that job line by line.
What this means when you dock
If you have twin engines and room to maneuver, practice one ahead and one astern before you buy anything. Leopard offers a thruster only on its flagship and says the rest of its range docks easily with a bit of practice.
If a big, tall cat drifts sideways in a gusty marina, that is the case a thruster is for. Start at the bow and size from the top of the sizing range.
If you were hoping for a bolt-on external unit, it will not fit two hulls. Price a tunnel or a retractable in one hull instead.
If you sail her, a retractable lifts clear under sail. A tunnel mouth stays in the water flow along that hull.
What we could not find
Any owner's fitted price on a catamaran. Not one, whether a quote, an invoice or a rough number.
Any builder besides Leopard stating on its own site which models offer a bow thruster. Jet Thruster names the Lagoon models it has fitted. Lagoon's own site was read on 18 September 2026. None of its eight model pages (the 46, for one) mentions a thruster. Its public configurator offers layout, cover, upholstery and deck choices and no equipment option at all. Whether a Lagoon can be ordered with one is a question for a dealer's option list, which is not published.
A sizing rule written for two hulls. The figures above size a cat on the wind alone, giving her the height a light, fast hull has for its length and the wind exposure of a tall boat.
Sizing figures are this site's own estimates, checked against the sizing the makers publish. Leopard Catamarans and Jet Thruster pages read 16 September 2026. The quotations are theirs.