How to Choose the Right Electric Tunnel Thruster for Your Yacht

Max Power CT Series Selection Guide (With Specs & Installation Tips)

Why This Guide Matters

An electric tunnel thruster is one of the most valuable upgrades for safer, calmer and more precise manoeuvring. It helps you control the yacht at very low speed when the rudders are ineffective, especially in crowded marinas, strong crosswinds, current, tight berths and poor visibility.

The Max Power CT Series Electric Tunnel Thrusters are designed for motor yachts and deep-keeled sailing yachts, covering boat sizes from approximately 17 ft up to 150 ft. In this guide, we explain how to choose the correct CT model, what really affects thruster performance, and what installation details must be checked before ordering.

1) Tunnel Thruster vs Retractable Thruster — What’s the Difference?

Before choosing a model, it helps to confirm that you actually need a tunnel thruster:

Electric Tunnel Thruster (CT Series)

Best when:

you want the simplest and most proven design
your bow area has enough structure for a tunnel
you prioritise reliability and easy service access
you operate in marinas frequently

Retractable Thruster

Best when:

you want zero tunnel drag under way
the hull shape makes tunnel installation difficult
you need a stern thruster on a hull with limited space

For the majority of cruising yachts, a properly sized electric tunnel thruster remains the most effective solution.

2) The Biggest Selection Mistake: Choosing Only by Boat Length

Many owners choose a thruster purely by the “recommended boat length” range. It’s a good starting point, but it’s never enough on its own.

Two yachts of the same length may require completely different thrust depending on:

windage (side area above water)
displacement (weight and inertia)
hull shape and bow volume
keel type (especially for sailing yachts)
where and how you dock (wind/current exposure)

That is why Max Power provides selection charts, but final selection should always be confirmed using real operating conditions.

3) What Thrust (kgf) Do You Really Need?

Thruster thrust is usually shown in kgf (kilogram-force). Higher thrust means better holding power and safer docking, but it also requires:

larger tunnel diameter
more electrical power
heavier cabling and stronger battery supply

When to choose a higher model within the range

If your boat falls between two CT sizes, it often makes sense to select the more powerful thruster when:

your marina is exposed to crosswinds
you dock short-handed or with inexperienced crew
your yacht has a tall superstructure
you regularly berth alongside with wind pressure
you want a stronger safety margin for emergencies

4) Mono vs Duo Propellers — Which CT Thruster Is Better?

Max Power CT thrusters come in Mono and Duo propeller versions.

Mono (Single Propeller)

Best for:

smaller boats
simple installations
cost-efficient performance

Duo (Counter-Rotating Twin Propellers)

Best for:

smoother, more balanced thrust response
equal thrust to port and starboard
reduced vibration and noise
higher thrust efficiency in real conditions

For many owners, a Duo model is the upgrade that delivers the most “premium docking feel”.

5) Composite vs Bronze vs Aluminium Drive Legs

Most CT models use Max Power’s patented composite drive leg, which is known for being:

corrosion resistant
maintenance-friendly
lightweight
proven in long-term marine use

Selected larger models are available with bronze or aluminium drive legs for heavier-duty installations. These are typically chosen for larger displacement yachts, high-load use or project-based specifications.

6) 12V, 24V or 48V — Choosing the Best Voltage

The CT series includes 12V, 24V and 48V systems.

12V

common on smaller yachts
practical where cable runs are short
good for compact installations

24V

ideal for mid-size and larger yachts
reduces current draw compared to 12V
helps improve reliability under load

48V

significantly lower current for the same power
reduced cable losses and voltage drop
improved duty cycle performance
excellent for modern electrical systems and larger yachts

If the yacht already has a 48V bank (or hybrid power architecture), 48V thrusters are a very strong choice.

7) Technical Specifications — Max Power CT Electric Tunnel Thrusters

Performance data is given for thrusters installed at an immersion depth of one tunnel diameter.

Code	Model	Voltage	Max Thrust (kgf / lbs)	Tunnel Ø (mm)	Propellers	Drive Leg Material	Power (kW / hp)	Suitable Boat Length
636061	CT 25	12 V	30 / 66	110	Mono	Composite	1.8 / 2.4	17–28 ft
42529	CT 35	12 V	35 / 77	125	Mono	Composite	2.69 / 3.6	20–30 ft
317603	CT 45	12 V	45 / 99	125	Duo	Composite	3.23 / 4.3	20–34 ft
42530	CT 60	12 V	70 / 154	185	Mono	Composite	4.35 / 5.8	23–38 ft
42531	CT 60	24 V	71 / 158	185	Mono	Composite	4.4 / 5.9	23–38 ft
42532	CT 80	12 V	80 / 176	185	Duo	Composite	4.79 / 6.4	28–46 ft
42533	CT 80	24 V	89 / 195.8	185	Duo	Composite	5.28 / 7.1	28–46 ft
42534	CT 100	12 V	105 / 231	185	Duo	Composite	7.1 / 9.5	32–51 ft
42535	CT 125	24 V	115 / 253	185	Duo	Composite	8.58 / 11.5	34–59 ft
636660	CT 125	48 V	122 / 268.4	185	Duo	Composite	8.58 / 11.5	34–59 ft
317557	CT 165	24 V	165 / 363	250	Duo	Composite	11.88 / 15.9	40–66 ft
317558	CT 225	24 V	250 / 550	250	Duo	Composite	14.96 / 20	45–75 ft
317586	CT 225	24 V	250 / 550	250	Duo	Bronze	14.96 / 20	45–75 ft
317606	CT 300	24 V	300 / 660	300	Duo	Bronze	19.7 / 26.4	48–93 ft
636656	CT 300	48 V	275 / 606	300	Duo	Bronze	17.5 / 23.8	48–93 ft
42542	CT 325	24 V	325 / 715	315	Duo	Bronze	19.69 / 26.4	51–69 ft
634361	CT 325	24 V	325 / 715	315	Duo	Aluminium	19.69 / 26.4	51–69 ft
636657	CT 325	48 V	300 / 600	315	Duo	Bronze	17.5 / 23.8	51–69 ft
600138	CT 550 AC	380–440 V 3-ph AC	450 / 992	400	4-blade DUO	Composite	30 / 40.23	90–150 ft

8) Dimensions + Weight — Installation Planning Table

These dimensions help you check available installation space, tunnel size and tunnel wall thickness before ordering your thruster.

Model	Weight (kg)	A (mm)	B (mm)	C (mm)	D (mm)	E (mm)
CT 25	7	180	145	225	110	4–5
CT 35	9.6	190	140	210	125	4–5
CT 45	9.65	190	140	210	125	4–5
CT 60 (12V)	14.7	210	140	275	185	6–7
CT 60 (24V)	14.8	210	140	275	185	6–7
CT 80 (12V)	15.0	210	140	275	185	6–7
CT 80 (24V)	15.1	210	140	275	185	6–7
CT 100	24	250	200	356	185	6–7
CT 125 (24V)	24	250	200	365	185	6–7
CT 125 (48V)	24.26	250	200	365	185	6–7
CT 165	36	220	200	430	185	7–8
CT 225	37	270	200	405	250	7–8
CT 300 (24V)	58.5	250	250	480	300	9–10
CT 300 (48V)	64	250	250	480	300	9–10
CT 325 (24V)	59	250	250	480	315	9–10
CT 325 (48V)	64.5	250	250	480	315	9–10
CT 550 AC	300	—	—	—	400	—

9) What Do A, B, C, D, E Mean on the CT Drawing?

A — Overall length of the motor and leg assembly along the tunnel axis
B — Overall width of the motor housing
C — Overall height from the bottom of the tunnel to the top of the motor
D — Tunnel interior diameter (D Ø Interior)
E — Tunnel wall thickness at the installation area (recommended range)

Checking these parameters helps confirm that the selected thruster will fit physically before ordering.

10) Installation Tips That Make the Biggest Difference

Tunnel position and immersion depth

Install the tunnel as low as the structure safely allows
Tunnel centreline should typically be at least one tunnel diameter below the loaded waterline

Tunnel length and alignment

Keep the tunnel short and straight (preferably not exceeding 2 × tunnel diameter)
Ensure the tunnel is perpendicular to the hull centreline
Use smooth fairing on both tunnel ends to reduce turbulence, noise and cavitation

Structural reinforcement

Follow hull structure requirements and reinforcement around the tunnel
Always confirm tunnel wall thickness matches the recommended range

Electrical installation basics

Use correct cable sizing and fuse protection
Keep cable runs short to reduce voltage drop
Place batteries as close as possible to the thruster on larger systems

Conclusion — Choose the Correct CT Thruster the First Time

A correctly sized and properly installed tunnel thruster transforms docking from stressful to controlled. The Max Power CT Series offers a full range of electric tunnel thrusters that suit most motor yachts and sailing yachts, with multiple tunnel diameters, voltage options and Mono/Duo propeller configurations.

If you want the most confident results, focus on real conditions — windage, displacement and marina exposure — not only boat length.

Official Supply & Worldwide Support by Gaelix Marine Service

At Gaelix Marine Service, we supply original Max Power electric tunnel thrusters and configuration support for correct sizing and installation. We are an official Max Power representative worldwide, excluding Greece and Cyprus, where sales are managed by the local authorized distributor. For all other destinations, we provide international support and worldwide shipping options.

FAQ — Choosing Max Power CT Electric Tunnel Thrusters

1) My yacht length matches two CT models — which one should I pick?

If your yacht sits between two thruster sizes, the final choice should be based on windage, displacement and how exposed your marina is. For higher windage yachts, heavier cruising setups, or frequent crosswind docking, selecting the more powerful model usually provides safer control and more confidence.

2) Is a Duo propeller thruster worth it compared to Mono?

In most real docking situations, yes. Duo counter-rotating propellers typically deliver smoother thrust, better balance to port and starboard, and lower vibration. Mono models remain an excellent option for smaller boats, but Duo is often preferred when you want maximum control.

3) Can I retrofit a tunnel thruster on an existing yacht?

Yes. CT tunnel thrusters are commonly installed during refits. The main factors are tunnel placement, correct immersion depth, available internal space (A, B, C dimensions), and proper structural reinforcement around the tunnel area.

4) Should I choose 12V, 24V or 48V for my thruster?

12V is typical for smaller yachts with short cable runs. 24V is the standard for mid-size yachts because it reduces current draw and improves efficiency. 48V is ideal for larger yachts or modern power systems because it significantly lowers current, reduces voltage drop and supports better duty cycles.

5) What should I check before ordering a CT thruster?

Check tunnel diameter (D), available space for the thruster unit (A, B, C), and tunnel wall thickness (E). Also confirm cable run length, battery location and fuse protection requirements to avoid voltage drop and underperformance.

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