Lewmar Proportional Thruster 140-250TT — Owner's Manual

Location & Tunnel

• Boat out of the water, levelled and secure. Hull work by a competent marine engineer.
• As far forward as possible; 1 × tunnel Ø below the waterline (0.75 × Ø minimum); suggested minimum tunnel length 2 × Ø.
• Use the IP (ignition protected) version in a damp or wet location; otherwise the thruster must sit in a dry space.
• Radius the tunnel ends (r = 0.1 Ø) to improve thrust and reduce noise.
• Drill pilot holes both sides with a jig, cut, fit the tube, grind back the gel coat, fix the tunnel leaving room for the saddle, then gel coat and antifoul.

Hub, Saddle & Motor

• Any angle within 90° of vertical; support the motor if it is more than 30° from vertical. Normal install: propeller to port (single-propeller units; LH propeller to port on the 250TT).
• Cut the hub hole with the template and a GRP hole saw, light pressure; seal the cut edge with resin.
• Gasket on the hub (needed for correct propeller position), zinc chromate paste or marine grease in the bore, saddle on; Blue Loctite 243 on the bolts and full torque within 10 minutes. 250TT: tighten each bolt alternately.
• 185TT gearbox stem in the saddle: below 2 mm (1/16") remove tunnel material; above 3.5 mm (1/8") pack under the saddle.
• Propeller stack: large washer, propeller, anode, small washer, nyloc nut. Check it spins centred and does not touch the tunnel. Do not antifoul the zinc anode.
• 140/185: align the motor drive pin with the shaft slot, grease, do not remove the plastic retainer tie. 250TT: remove the key retaining tie, grease the shaft. Loctite 243 on the motor bolts.

Panel & Safety Features

• On: press and hold ON for 1 second (LED green). Off: press ON once. In fault mode (solid red) pressing ON turns the system off.
• Thrusting one way for more than 3 minutes puts the system in fault mode (LED red).
• A PORT/STBD signal present at switch-on puts the system in fault mode (protects against wiring faults or a second joystick held on).
• PORT and STBD together stop thrusting. Pressing the opposite button on a second panel cancels thrust; the same button has no effect.
• Auto power-down after 15 minutes of inactivity (TT).
• Motor and controller over-temperature puts the system in "limp-home" mode.
• Never run the thruster out of the water.

LED Diagnostics

Service Schedule

• New install: check the anode after about 3–4 months to set the replacement interval.
• Annual service: clear debris from tunnel, propeller and hub; replace the anode; replace a damaged or fouled propeller; grease the exposed seal and shaft; new tunnel gasket whenever the hub comes off; check leads, bolt torques and that the compartment is dry; brush the carbon dust out of the motor.
• Drive pin (140TT & 185TT): cut the cable tie, punch out the pin parts, tap in a new pin and secure with a new plastic cable tie.

Fault Finding

• Thrust in wrong direction: switch on the PCB rear.
• Fuse keeps blowing: wrong rating, or propeller jammed/restricted; check the propeller washer is fitted.
• Panel does not light: hold ON for 1 second; battery connected; main switch on and fuse; control loom connections; thermal switch tripped after long use: wait 20 minutes, do not cool the motor any other way.
• Lights but no thrust: batteries charged? motor connections tight?
• Poor thrust or one direction only: batteries/cables undersized or flat (minimum 21V at the motor on 24V units); debris in the tunnel; propeller washers wrong; brush springs seated.
• Motor turns, no drive (140TT/185TT): stop. Shear pin broken (remove the 4 motor bolts and replace the pin) or propeller blades broken.
• Noise and vibration: propeller touching the tunnel; on 140–185 check hub height.