What kind of boat is it?
How much wind should it handle?
What's your boat's electrical system?
Not sure? Most boats under 12 m run 12 V. We'll confirm it with you.
Anything else we should know?
Have Luxfords confirm your sizing
A calculator can't see your hull. We'll check tunnel position, hull thickness, battery bank and the right control panel, then send a written quote.
Mon-Fri 8:00am-4:30pm · sales@luxfords.com.au
Thanks, it's with the team
We've got your BOW PRO BOWA0571 result. Someone from Luxfords will call you back during business hours, Mon-Fri 8:00am-4:30pm.
Can't wait? Call (03) 5973 6444.
What size bow thruster for your boat length?
Calculated with VETUS's published method at Beaufort 5 (the VETUS standard), using typical side windage for each boat type. Each cell shows the thrust needed and the smallest 12 V BOW PRO or BOW PRO Boosted model that meets it and suits that length. Your boat's real windage may differ, so use the calculator above or ask us to confirm.
| BOAT LENGTH | SAILING YACHT | MOTOR CRUISER | FLYBRIDGE / TRAWLER / CAT |
|---|---|---|---|
| 6 m (20 ft) | 11 kgf BOWA0301 · 30 kgf | 13 kgf BOWA0301 · 30 kgf | 17 kgf BOWA0301 · 30 kgf |
| 7 m (23 ft) | 14 kgf BOWA0301 · 30 kgf | 18 kgf BOWA0301 · 30 kgf | 23 kgf BOWA0301 · 30 kgf |
| 8 m (26 ft) | 18 kgf BOWA0361 · 36 kgf | 23 kgf BOWA0361 · 36 kgf | 29 kgf BOWA0361 · 36 kgf |
| 9 m (30 ft) | 23 kgf BOWA0361 · 36 kgf | 29 kgf BOWA0361 · 36 kgf | 37 kgf BOWA0401 · 40 kgf |
| 10 m (33 ft) | 28 kgf BOWA0361 · 36 kgf | 36 kgf BOWA0361 · 36 kgf | 45 kgf BOWA0571 · 57 kgf |
| 11 m (36 ft) | 34 kgf BOWA0401 · 40 kgf | 43 kgf BOWA0571 · 57 kgf | 54 kgf BOWA0571 · 57 kgf |
| 12 m (39 ft) | 41 kgf BOWA0421 · 42 kgf | 51 kgf BOWA0571 · 57 kgf | 64 kgf BOWA0651 · 65 kgf |
| 13 m (43 ft) | 48 kgf BOWA0651 · 65 kgf | 59 kgf BOWA0651 · 65 kgf | 75 kgf BOWA0761 · 76 kgf |
| 14 m (46 ft) | 55 kgf BOWA0761 · 76 kgf | 69 kgf BOWA0761 · 76 kgf | 87 kgf BOWB090 · 90 kgf |
| 15 m (49 ft) | 63 kgf BOWB090 · 90 kgf | 79 kgf BOWB090 · 90 kgf | 100 kgf BOWB110 · 110 kgf |
| 16 m (52 ft) | 71 kgf BOWB090 · 90 kgf | 89 kgf BOWB090 · 90 kgf | 113 kgf BOWB130 · 130 kgf |
| 18 m (59 ft) | 90 kgf BOWB110 · 110 kgf | 112 kgf BOWB130 · 130 kgf | 143 kgf BOWB150 · 150 kgf |
| 20 m (66 ft) | 111 kgf BOWB180 · 180 kgf | 138 kgf BOWB180 · 180 kgf | 175 kgf BOWB180 · 180 kgf |
| 22 m (72 ft) | 134 kgf BOWB210 · 210 kgf | 167 kgf BOWB210 · 210 kgf | 212 kgf BOWB285 · 285 kgf |
| 25 m (82 ft) | 172 kgf BOWB285 · 285 kgf | 215 kgf BOWB285 · 285 kgf | 273 kgf BOWB285 · 285 kgf |
The VETUS sizing method, step by step
- Windage (A): the side profile above the waterline, estimated from boat type and length unless you enter your own.
- Wind pressure (q): 30, 60, 100 or 157 N/m² for Beaufort 4 to 7.
- Turning moment: T = q × A × 0.75 × ½L, the wind trying to swing the bow around the stern.
- Thrust needed: F = T ÷ B, where B is the distance from the thruster to the pivot (about L − 0.5 m). 10 N ≈ 1 kgf.
- Model: the smallest thruster that meets F and suits your length, plus a stern unit one size smaller.
The method and the worked example (11 m, 18 m², Beaufort 5 → about 42 kgf) come from the VETUS Catalogue 2026-2027. Read more on how sizing works, or see every model on the range chart.
Bow thruster sizing FAQ
What size bow thruster do I need for a 30 ft boat?
Using VETUS's method at Beaufort 5, a typical 30 ft (9.1 m) motor cruiser needs about 30 kgf of thrust, which points to a 36 kgf BOW PRO (BOWA0361). A 30 ft flybridge or catamaran, with more windage, needs about 37 kgf, so a 40 kgf unit. Use the calculator above with your own boat type for a sharper answer.
What size bow thruster for a 40 ft boat?
A typical 40 ft (12.2 m) motor cruiser needs about 52 kgf at Beaufort 5, so a 57 kgf BOW PRO (BOWA0571). A 40 ft flybridge needs about 66 kgf, which moves you up to the 76 kgf class. A 40 ft sailing yacht needs about 42 kgf.
How is bow thruster size calculated?
VETUS sizes a thruster by the force it has to beat. Wind pressure for the chosen Beaufort force acts on the boat's side windage area to create a turning moment around the stern: T = q × A × 0.75 × ½L. Divide that by the distance from the thruster to the pivot (about the boat length less 0.5 m) to get the force the thruster needs, then pick the next model up.
Is a bigger bow thruster always better?
Not necessarily. A bigger unit needs a bigger tunnel, a larger battery bank and heavier cabling, and costs more to fit. Size to your calculated requirement with a little headroom, and choose Beaufort 6 instead of 5 if your berth is exposed. We'll tell you if stepping up a size is worth it for your boat.
Why does VETUS size thrusters in kgf instead of kW?
Thrust in kilograms-force is what actually pushes the bow sideways. Motor power in kW varies with propeller and tunnel design, so two thrusters with similar kW can deliver different thrust. The calculator works in kgf for that reason.
What size stern thruster do I need?
VETUS's rule of thumb is that the stern thruster can be one model smaller than the calculated bow thruster, because the stern sits closer to the pivot point. The calculator suggests a matching stern model automatically. See our stern thruster page for the transom kits.