Max Power CT325 HYD Hydraulic Tunnel Thruster (Models 250 & 325) — Installation Manual

Tunnel

• Tunnel as low and as far forward as possible; propellers must not protrude beyond the hull line.
• Ideally at least one tunnel diameter of depth from the waterline to the top of the tunnel; poor immersion can be compensated by moving the tunnel further forward.
• Hydraulic units can be fitted vertically, horizontally or tilted.
• With tunnels of a different wall thickness (e.g. metallic), the zone between drive leg/gasket and motor support must match the thickness in the Positioning & Measurements table, with a stable motor support. Under 8 mm thickness, fit an extra hard rubber gasket between motor support and tunnel.
• Mark the tunnel centre, drill Ø 10 mm and trace the elliptical cut-out with a compass made from 8 mm rod. Disc the inside of the hull 10 to 15 cm around the holes.
• Laminate with at least 8 coats of mat and roving with isophthalic resin, filling the hull/tunnel gap with reinforced filler. No fibreglass on the motor support area; lightly sand it.
• Fair the tunnel ends with reinforced filler for clean water flow, then seal the whole area with epoxy or gel-coat.

Drive Leg, Motor & Propellers

Drive leg & motor support

• The leg gasket and the motor support can be used to mark up the drilling position; in some cases it is easier to mark out and drill before the tunnel is stratified.
• Fit the leg with its gasket in the tunnel and check the propeller tip clearance all round (folded cardboard works); slight adjustment to align the leg may be needed.
• Remount the assembly with the gasket coated in an oil- and salt-water-resistant jointing compound; remove all excess. The gasket goes between leg and tunnel, not between motor support and tunnel.
• Mating faces of leg and motor support must be dirt free with a light film of grease. Graphite grease must not be used.
• Torque: screw Ø 12 mm = 80 Nm; tighten the two fixing screws alternately. Once tightened, the propellers must turn freely without touching the tunnel.
• Use only the original leg screws (part 22) delivered with the drive leg: longer screws risk damaging the leg and letting water in.

Hydraulic motor

• Do not separate the motor from its adapter.
• Lightly grease the leg drive shaft and fit the lower drive coupling; position the red plastic coupling (piece 10 on the spare part diagram) on it.
• Push the lower coupling all the way down on the drive leg shaft before tightening its 2 × 6 mm Allen fixing screws.
• Position the motor and tighten the 4 × 10 mm screws to 40Nm. The coupling may need adjusting if a tunnel other than a Max Power tunnel (thickness 9mm) is used.
• Top and bottom coupling pieces must fit tightly together. The motor-side coupling is in place on delivery: do not touch it.
• Check the propellers turn freely with no tight spot (some motor resistance is normal), then recheck all motor bolts.

Propellers

• Check the oil drain screw (8 mm Allen key) and the anode (10 mm key) are tight.
• Apply silicone grease to the shaft and seals before fitting the propellers, to prevent limestone deposits.
• Fit pins and propellers with the blades opposed, not in line. Tighten the screws (3 mm Allen key): only 2 mm should show above the hub; more means the screws are not in the shaft groove.
• In a shallow tunnel, horizontal protection grills are recommended; they do modify thruster performance.

Using an Electro-Hydraulic Pump

• Thruster battery bank (high CCA, starting type), power circuit fuse, electric battery isolator (optional with electro-hydraulic pump) and power relay.
• Electro-hydraulic pump with N/O heat sensor; hydraulic oil reservoir with N/O alarm sensor; service valve (DCV).
• Independent battery bank for the control circuit supply, through the yacht's main DC breaker board with an 8 A fuse.
• Electronic thruster controller (control box 315311) linked to the control panel by the 6-wire control cable and cable connectors A, B and C.

Using a Motor with Clutched PTO

• Clutch or bypass driven through a bi-polar clutch relay.
• Hydraulic oil reservoir with N/O alarm sensor and service valve (DCV).
• Independent battery bank for the control circuit, 8 A fuse on the main DC breaker board.
• Electronic thruster controller and control panel, same cable connectors A, B and C.

Full colour-coded wiring and the hydraulic diagram are in the manual PDF.

Maintenance

• Keep tunnel, leg and propellers clean.
• Before fitting the propellers, clean the shaft and oil seals and apply a layer of silicone oil to prevent chalky deposits.
• Annually: change the anode if necessary; change the drive leg oil on a classic (bronze) leg; check the oil and the hydraulic filtration circuit (only if necessary).
• Every 5 years: drain the hydraulic oil, change the filter and refill.
• Keep this manual on board.

Warranty

• Two years from purchase by the end user, transferable; it starts 6 months after the boat is delivered to the dealer.
• Register within 3 months of purchase for one extra year (3 years in total), with proof of purchase.
• Non-pleasure use: limited to six months.
• Excluded among others: installation contrary to published specifications, lack of normal maintenance, unauthorised repairs, normal wear and tear, cost of hauling the boat.