Thrusterpedia

Which boat thruster, what it costs, how to get it installed

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Drawing of a tunnel thruster: a tube through the bow below the waterline, the hull cut away to show the motor on top.
Our drawing of a tunnel thruster, the same for every maker. It is not Max Power’s own design.

Max Power · tunnel thruster · bow or stern

Max Power CT35: specs, price and the boats it fits

It gives 77 lb (35 kgf) of push. Max Power sells it for boats of 17 to 31 ft. It runs on 12 V.

The unit$1,276Equipment only, Marinedeal, read 26 October 2026
Installed by a yard, 30 ft boat$8,010 to $10,330Our estimate: the unit, labor, haul-out, battery and parts
  • Haul-out to install
  • DIY 2 of 5: wiring prep only
  • 3-year warranty

Quick stats

  • Thrust 77 lb 35 kgf, Max Power's rating
  • Boat length 17 to 31 ft Max Power's own range
  • Price per lb of thrust $16.58 Unit only. $104 to $134 installed
  • Voltage 12 V As sold
  • Battery at 12 V 800 CCA One battery, near the thruster
  • Run limit 2 to 3 min At a stretch, depending on the air temperature. The motor's S2 rating is 3 min
  • To install it Haul-out The boat comes out of the water
  • Mounts Tunnel Fixed mount, bow or stern

About the Max Power CT35

The CT35 is the way into Max Power’s range: a single-propeller bow thruster in a 125 mm tube for boats of about 17 to 31 ft. It gives 77 lb of push on 12 V, enough to swing a small cruiser’s bow in a breeze. Beneteau and Jeanneau installed Max Power units at the factory for years.

Marinedeal, a US online dealer, lists it at $1,276 for the thruster alone. The tube, a helm panel, a main switch and a fuse come to about $473 to $1,024 more. It runs from one strong starting (cranking) battery near the bow; we put that battery, its cable and a charger at $601 to $820. See every part.

Read more

The composite drive leg needs no zinc and is sealed for life, a plus for owners who dread hauling out to change one. Keep each push brief: the manual rates the motor for 2 to 3 minutes, depending on the air temperature. A spare propeller is about $72. Warranty: two years, three if registered.

Installers will find the wiring figures and dimensions further down. For the rest of Max Power’s line, read the Max Power thruster review.

Where this summary comes from (5 sources, read 12 October 2026)

Will the Max Power CT35 steer your boat?

34 FT TRAWLER · BOW · 15 KT WIND

Size forThis page always opens on Steering.

Every knot figure here is wind speed, not boat speed or current.

Steers her at 15 kt

On a 34 ft trawler the Max Power CT35 (77 lb) steers her in a 15 knot breeze. Her bow needs about 78 lb from a tunnel to steer her in a 15 knot breeze. Its 77 lb lands within 15 percent of that figure, which this site counts as enough.

The finder lists it for her.

11.9 FT LEVER Max Power CT35 pivot

A tunnel at the bow of a 34 ft trawler 78 lb ★ this unit · 1 to 3: the three cheapest others that steer her at 13 kt or more, installed

  1. ★ Max Power CT35 this unit 77 lb · tunnel from $8,080 Steers her at 15 kt
  2. 1 Max Power CT45 99 lb · tunnel from $8,277 Steers her at 17 kt
  3. 2 Lewmar 140TT Tunnel Thruster 82 lb · tunnel from $8,348 Steers her at 15 kt
  4. 3 VETUS Bow 45 99 lb · tunnel from $8,515 Steers her at 17 kt

The Max Power CT35 on a trawler, by length

  1. 25 ft20 kt
  2. 30 ft17 kt
  3. 35 ft14 kt
  4. 40 ft13 kt
  5. 45 ft11 kt
  6. 50 ft10 kt
  7. 55 ft9 kt
  8. 60 ft8 kt
  9. 65 ft8 kt
  10. 70 ft7 kt
  11. 75 ft7 kt
  12. 80 ft6 kt

Outlined: the finder does not list it at that length (under 13 kt, far more than she needs, or outside Max Power’s own length range).

  • Under 10 kt
  • 10 to 15 kt
  • 15 to 20 kt: the sweet spot
  • Over 20 kt: more than she needs

Prices are the low end of the installed total, from our estimate. For your own boat, drive and installer, the finder prices each unit.

Is it right for your boat?

What Max Power says 17 to 31 ft The maker's own range, from its listing
What our sizing says 34 ft Full thrust in 15 knots, across the kinds of boat it fits
Every kind of boat it fits, by length ten boat types
Which boats it fits, by length
Boat Full thrust at 15 knotsStill a fit, in lighter wind
Pontoon & tritoon Not listed. A pontoon has no hull body between the logs to bore a tunnel through, and nobody sells one for these boats.
Sailboat 25 to 34 ft None
Houseboat None 30 ft onlyfull thrust to about 13 knots at 30 ft
Catamaran 30 to 34 ft None
Trawler 25 to 34 ft None
Motor yacht No length. Outside the maker's length range.
Bass & flats Not listed. Nobody sells a tunnel kit for these hulls, and a bass boat’s shallow planing bow has almost no depth to hold one.
Wake & ski boats Not listed. Nobody sells a tunnel kit for these hulls.
Express cruiser 32 to 34 ft None
Center console No length. More thrust than the boat needs.

The Max Power CT35 against each kind of boat, in a 15 knot wind. Our sizing, from the finder’s own rules.

The first column is where one unit gives all the thrust the boat needs in 15 knots. The second is where the finder still lists it: the unit steers her in a 13 or 14 knot wind, within 15 percent of the 15 knot breeze this site sizes for. On a boat shorter than the first column’s shortest length, the unit is more than the boat needs.

How we size it

Our figure is the longest boat one unit can steer in a 15 knot wind. It is a range because each kind of boat catches the wind differently. Here every kind of boat it fits gets full thrust to 34 ft. The maker gives one range for every boat.

The table tries the Max Power CT35 on each kind of boat, at every length that kind of boat is built in. The wind is 15 knots and the rules are the finder’s own. A length counts as a fit when the unit gives the thrust that boat needs at the bow and the maker lists it for that length.

A boat up to 10 percent past the maker’s range still counts here, as it does in the finder. So the table runs up to 34 ft, just past Max Power’s own range (17 to 31 ft).

It is sized for five kinds of boat here. For your own boat, the finder gives an answer that also counts your drive and who does the installing. The compare page sets this unit beside others.

What it costs installed

A yard job, everything in. Our estimate.

Installed by a yard
Boat Total installed
25 ft $7,920 to $10,090$103 to $131 a lb of thrust
30 ft $8,010 to $10,330$104 to $134 a lb of thrust
34 ft $8,080 to $10,520$105 to $137 a lb of thrust

From the shortest to the longest boat it is sized for.

What is in each total five lines

These totals are our estimate of a yard job: the unit’s price, plus a yard’s hours at $160 to $180 an hour, plus the batteries, cable and charger, plus the other parts the box does not hold. 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. adds $450 to $1,640 at these lengths, with 5 to 7 days out of the water, worked from eight yards’ own rate cards. The hours come from what owners and yards report. The cost page builds the same figures line by line.

Each line of the estimate
Boat length The unit Yard labor Haul-out Batteries, cable, charger Other parts
25 ft $1,276 $5,120 to $5,760about 32 hours $450 to $1,210 $601 to $820 $473 to $1,024
30 ft $1,276 $5,120 to $5,760about 32 hours $540 to $1,450 $601 to $820 $473 to $1,024
34 ft $1,276 $5,120 to $5,760about 32 hours $610 to $1,640 $601 to $820 $473 to $1,024

For every length in the table above.

How the batteries, cable and charger add up. We price a battery bank close to the thruster, as the makers recommend, with 10 to 20 ft of cable out and back: red for the positive, black for the negative, cut to length. The low end is the cheapest battery that meets the figure and the shorter run; the high end is a sealed (AGM) battery and the longer run. The charger is a NOCO GEN5X2 two-bank shore charger.

Batteries and lugs are priced at Fisheries Supply and the cable and charger at Defender, read 26 October 2026.

  • At 12 V: one 12 V battery, at least 800 CCA (Max Power’s minimum), $360 for the battery; Max Power’s cable table gives 1/0 to 3/0 AWG, priced on 1/0 to 4/0 AWG, the nearest size cut to length: $95 to $314 for the red and black cable and the lugs; a GEN5X2 charger, $146.

The sizing and the costs on this page are estimates, for guidance only and without warranty. They are no quote, and nobody has inspected your boat. Check them against the maker’s manual and your yard before you rely on them. Terms of use.

DIY breakdown

DIY 2 of 5: Wiring prep only. The yard installs the unit and does the hull work; you do the wiring prep.

DIY levels

  • Level 5: Owner install. No yard, no electrician.
  • Level 4: You install it, electrician connects. You mount and wire it; a marine electrician makes the final connections.
  • Level 3: Split with the yard. The yard does the below-waterline part; you do the wiring.
  • Level 2: Wiring prep only. The yard installs the unit and does the hull work; you do the wiring prep.
  • Level 1: Yard job. A qualified professional does all of it.

You Yard Electrician. The bar is labor hours; a haul-out is a note.

How we rate DIY

You: 4 to 16 hours Yard: 32 to 70 hours Electrician: 2 to 4 hours Plus a haul-out.

Your part needs:Heavy battery cableCrimping big lugs

Every step, and who does it three steps
  1. Cut, bond and fair the tunnel; fit the gear leg, motor and propeller Yard 32 to 70 hours The low end is two crew over two days, the job as owners describe it on the forums. The high end rises with boat length between two real billed figures: 32 hours at 35 ft, and the largest invoice we hold, 70 hours at 47 ft.
  2. Mount the battery box, switch and fuse holder; run and secure the cables You 4 to 16 hours Our estimate. No maker times this step, and a first-time owner is slower than a yard, so the range is wide.
  3. Final connections at the battery and the motor, load test Electrician 2 to 4 hours Our estimate. Nobody publishes a time for the final connections and test on their own.

A qualified marine electrician should make the final connections and test them before first use. Hours are labor only.

Related videos

One from Max Power’s own channel and one from other channels. Each one is labeled. They play from YouTube only when you tap. Take any claim in a video back to the figures on this page, which are the ones we checked.

Bow thruster install!Owner install She’s the captain, February 2018
Max Power Hero ProductsMaker Max Power’s own channel

Know before you buy

What sets this model apart, what it costs to keep, and what to weigh.

Price per pound of thrust

$16.58 a lb The unit’s price over its published thrust. The bars are Max Power’s next sizes and the nearest other makers.

Controls

Delivered without accessories: the fuse, holder and control panel are bought.

  • Max Power 318200, no US price found.
  • The control cable your manual names, no US price found.

Service and warranty

Max Power's website gives 3 years. Its manual gives 2, and 1 more if the warranty is registered within 3 months of installation. Outside pleasure craft it is 6 months. It transfers to the next owner, and the first year covers up to 2 hours of labor in the field.

See Max Power’s warranty Max Power's warranty conditions.

Special mentions

Battery: at 12 V it wants one battery of 800 CCA or more, Max Power's figure. The cheapest that meets it is the Optima BlueTop SC27DM Group 27 AGM, $359.99. Check your own bank.

Charger: a NOCO GEN5X2 two-bank shore charger, $146.41. It is the one our estimate prices.

Gas engine room? Buy the ignition-protected Max Power CT35-IP, $2,456.

Max Power sells it for either end, so it can go at the bow or the stern.

Dealer prices at Fisheries Supply, read 26 October 2026.

What to weigh

The boat comes out of the water to install it: it needs a tunnel bore below the waterline.

Short pushes only: Max Power rates the motor for 2 to 3 min at a stretch.

Parts for the Max Power CT35

See the Max Power CT35 manual

Search for the number as printed here, with no spaces. Prices are each dealer’s on the day shown, before shipping and tax. Check the plate on your motor before you order: some parts change with the tunnel size, the voltage or the year.

For the install what the box leaves you to buy

11 parts

The manual button above opens it on the maker's site. It has the hull, wiring and fuse figures for this model.

From Max Power’s CT35 and CT45 installation manual, July 2024, read 25 October 2026.

In the box
The manual: "The thruster is delivered without accessories (fuse, fuse holder, control panel)." The motor comes with its relay and the electronic controller, and the leg with its screws, gasket and propellers.
Bought separately
The fuse and holder, a manual battery isolator and an electric one, the control panel, an 8 A control fuse, a breaker on the DC panel, the cable and the tunnel.
Charging
Max Power is the one maker that asks for both: the engine's alternator and a charger. A dedicated bank is optional and goes "as close as possible to the thruster". It wants starting-type batteries with high cold cranking amps.

In Max Power’s words, from its CT100 and CT125 installation manual, page 3: “The batteries used by the thruster must be charged by both the main engine's alternator and an appropriate battery charger.”

The “other parts” line in the estimate above covers these parts as a range, $473 to $1,024 at Fisheries Supply’s prices on 30 September 2026 and 26 October 2026, because the exact items depend on your boat. The batteries, cable and charger have a line of their own. The cost page has what every maker says about each part.

Tunnel tube

Fisheries Supply lists it as “Sleipner fiberglass tunnel tube, 125 mm bore, 600 mm”.

Sold in lengths from about 24 to 35 in. This is the shortest: the yard cuts the tube to the width of your hull at the thruster. No Max Power tube is listed at this bore. This one is another maker's.

Part number SM5001

Control panel

Ask for Max Power 318200.

Not sold at Fisheries Supply. Ask a Max Power dealer.

Part number See the line above.

Control cable, panel to thruster

Ask for The control cable your manual names.

Not sold at Fisheries Supply. Ask the panel dealer.

Part number See the line above.

Main fuse

Fisheries Supply lists it as “ANL fuse 175 A”.

The maker's figure: 125 A ceramic or 175 A ANL.

Part number 5128

Fuse holder

Fisheries Supply lists it as “ANL fuse block, 35 to 750 A, cable up to 4/0, with cover”.

Part number 3903

Battery switch

Fisheries Supply lists it as “m-Series 300 A battery switch, on/off”.

Rated at or above the 175 A main fuse. If your manual names its own switch, use that one.

Part number 2306

Control-circuit fuse holder

Fisheries Supply lists it as “Waterproof in-line ATO/ATC fuse holder”.

The maker asks for an 8 A fuse on the control supply.

Part number 5065

Batteries

Fisheries Supply lists it as “Optima BlueTop SC27DM Group 27 AGM”.

One at 800 CCA or more. The cheapest listing that meets it.

Part number BAT SC27DM

Battery cable, red and black

Defender lists it as “Ancor tinned battery cable 1/0 AWG, cut to length, red or black”.

This is the short run. A longer run takes heavier cable: the wiring calculator sizes yours. You need 5 ft of each color. For about 10 ft of cable in all, out and back. Measure your run and check it against the cable table in the manual: never go smaller than it asks for.

Part number None on the listing. Order it by name.

Cable lugs

Fisheries Supply lists it as “Tin-plated starter lugs, 1/0 AWG, bag of 10”.

This is the short run. A longer run takes heavier cable: the wiring calculator sizes yours. The listing runs $23.74 to $28.04 by stud size. Eight ends on one run, with two spare.

Part number 91066-P10

Charger

Fisheries Supply lists it as “GEN5X2 on-board charger, 10 A, 2 banks”.

Or a DC-to-DC charger from the house system: ask the electrician.

Part number GEN5X2

Outside the hull replacement parts in the water

4 parts

Propeller

The propeller on the drive. Max Power calls it “MAX POWER PROPELLER Ø125”.

Part number 35041
See it at Max Power No US price found

Propeller pin (drives the propeller)

The pin that locks the propeller to its shaft. Max Power calls it “Propeller Pin”.

Part number 312058
See it at MarineDeal$4.91 Price read 29 Oct 2026

Drive leg (complete)

The leg under the motor that turns the propeller. Max Power calls it “Embase Composite CT35 (includes N 9,10,12,14)”.

Part number 315318
See it at Max Power No US price found

Drive leg gasket (seals the leg to the tunnel)

The leg under the motor that turns the propeller. Max Power calls it “Leg Gasket”.

Part number 310255
See it at Max Power No US price found

Inside the boat replacement parts on board

13 parts

Motor brush

Carbon brushes inside the motor. They wear down with use. Max Power calls it “Motor Brushes (models after 2007)”. This one is for the models after 2007 version.

The CT35 and CT45 manual prints 312702 for models before 2007. The motor takes 8.

Part number 636077

Motor brush

Carbon brushes inside the motor. They wear down with use. Max Power calls it “Motor Brushes”. This one is for the models before 2007 version.

The CT35 and CT45 manual prints this brush for models before 2007 and 636077 for models after 2007. The motor takes 8.

Part number 312702

Drive coupling kit (spring and pivot)

They hold the brushes against the motor. Max Power calls it “Spring & Pivot-Coupling kit”.

Part number 315304
See it at Max Power No US price found

Relay (the motor switch)

A small switch in the motor’s control circuit. Max Power calls it “Relay 12V”.

Part number 312921
See it at MarineDeal$349.83 Price read 29 Oct 2026

Relay assembly (complete)

A small switch in the motor’s control circuit. Max Power calls it “Relay Assembly 12V”.

Part number 315325

Controller (control box)

The electronics that run the motor when you press the panel. Max Power calls it “Electronic Controller”.

Part number 315310
See it at MarineDeal$260.10 Price read 24 Oct 2026
See it at Defender$338.79 Price read 29 Oct 2026

Main fuse (125 A)

The main fuse at the battery, in the rating the maker gives. Max Power calls it “Fuse CT80 24V 125A”.

Max Power names this 125 A fuse for the CT80 24 V, but its pages and manuals give it for each model here. The holder is 35017.

Part number 35021
See it at Max Power No US price found

Main fuse holder

The main fuse at the battery, in the rating the maker gives. Max Power calls it “Fuse Holder T1”.

Part number 35017
See it at Max Power No US price found

Control panel, on/off dual joystick (bow and stern)

The control at the helm. Max Power calls it “Dual joystick, black (318205 gray)”.

The gray one is 318205.

Part number 318204
See it at MarineDeal$466.83 Price read 29 Oct 2026

Control panel, on/off single joystick

The control at the helm. Max Power calls it “Single joystick, black (318203 gray)”.

The gray one is 318203.

Part number 318202
See it at MarineDeal$232.19 Price read 29 Oct 2026

Control panel, on/off touch panel

The control at the helm. Max Power calls it “Touch panel, two buttons, black (318201 gray)”.

The gray one is 318201.

Part number 318200
See it at MarineDeal$219.91 Price read 29 Oct 2026

Motor heat sensor

The electric motor that turns the propeller. Max Power calls it “Heat sensor”.

Part number 311363
See it at Max Power No US price found

Replacement motor

The electric motor that turns the propeller. Max Power calls it “Electric Motor CT35”.

Part number 312863
See it at Max Power No US price found

The install parts are matched to Max Power’s own figures and priced at Fisheries Supply, with the battery cable at Defender, cut to length.

Spare part numbers come from Max Power’s parts pages and manuals. A dealer may sell a part we have not priced. Search for the number.

Other sizes and close alternatives

Compare them side by side

The other makers listed are the nearest match each makes, of the same style and for the same end, within a quarter of its thrust. The compare page lists every model, and the thruster index lists every model with a page here.

For the yard and the installer

Every published figure, with its source.

Full spec sheet thrust, motor, mounting, price, part number, documents
Full spec sheet
Thrust and motor
Thrust 77 lb (35 kgf) As printed: 35(kg) / 77(lbs)
Motor2.69 kW
Voltage12 V
Run limit2 to 3 min at a stretch, depending on the air temperature. The motor's S2 rating is 3 min
Installation
TypeTunnel, fixed mount
End of the boatBow or stern
Tunnel diameter125 mm
What it does to the hullTunnel bore below the waterline
Haul-out to install itYes
Maker’s boat length17 to 31 ft
Price and ordering
Price $1,276 equipment only, a dealer's price, marinedeal.com, 26 October 2026
Part number 42529Mono propeller, composite drive leg, 12 V
Documents
Manual Installation manual (PDF)on the maker's site
The site’s reviewMax Power thruster review

Every published figure the site holds for the Max Power CT35, with where each came from.

Draw, cable, fuse and battery at each voltage 12 V

These are the maker’s own figures, at each voltage it is sold at. The cable is the size for the shortest run in the maker’s table. A longer run may need heavier cable, and the wiring calculator works that out for your own boat.

Draw, cable, fuse and battery
Voltage Draw Maker’s cable Fuse Battery Run limit
12 V 250 Ameasured draw 1/0 AWG for up to 16 ft of cable counted out and back. Longer runs take heavier cableCT35/CT45 installation manual 125 A ceramic or 175 A ANLCT35 / CT45 manual Maintenance-free "starting" type batteries, with high CCA outputs. The manual's example is the Exide Maxxima 900, 800 CCA and 55 AhMax Power installation manual CT35 / CT45, July 2024 2 to 3 min at a stretch, depending on the air temperature. The motor's S2 rating is 3 minCT35 / CT45 manual

The Max Power CT35’s draw, cable, fuse, battery and run limit, as the maker publishes them.

The tunnel: length and depth rules

Depth below the waterline. The minimum acceptable position is 139 mm below the waterline. Ideally the top of the installed tunnel sits 185 mm below it. Shallower than the ideal, the manual says, performance falls off progressively. CT100 and CT125 installation manual (July 2024).

Our notes from the manual and listings

In the box: Delivered without accessories: the fuse, holder and control panel are bought.

Our note

A 125 mm tunnel. Max Power's own selection chart puts it on 17 to 25 ft boats with heavy displacement and high windage, and out to 31 ft on light, low-windage ones. The CT35/CT45 manual measures 250 A at 11 V and fuses it at 125 A ceramic or 175 A ANL.

The manual names an example starting battery of 55 Ah and 800 cold cranking amps rather than a figure. Standard on/off units are made for lead-acid, AGM or gel batteries. Max Power's FAQ says lithium will damage them unless specified correctly. Max Power publishes no price and sells through dealers. The figure here is one US dealer's listing for the unit alone. The same dealer's package with a control panel and 25 m of control cable costs more.

Where each point above comes from
  • Max Power sells it for either end, so it can go at the bow or the stern.The maker's listing
  • The boat comes out of the water to install it: it needs a tunnel bore below the waterline.The mounting: a bore through the hull, or a housing recessed into it

Not sure this is the one? The thruster finder asks about your boat and prices every unit that fits.

Where to go next

The specs are the maker’s and the dealers’, on the dates shown. The sizing and the costs are our arithmetic, done without seeing your boat.