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Lewmar · tunnel thruster · bow or stern
Lewmar 140TT Tunnel Thruster: specs, price and the boats it fits
It gives 82 lb (37 kgf) of push. Lewmar's own chart puts it on boats of 30 to 35 ft. It runs on 12 V.
- Haul-out to install
- DIY 2 of 5: wiring prep only
- 3-year warranty
Quick stats
- Thrust 82 lb 37 kgf, Lewmar's rating
- Boat length 30 to 35 ft Lewmar's chart, by windage. See below
- Price per lb of thrust $18.12 Unit only. $103 to $171 installed
- Voltage 12 V As sold
- Battery at 12 V 270 CCA One battery, near the thruster
- Run limit 3 min In one direction, then fault mode
- To install it Haul-out The boat comes out of the water
- Anodes $18.37 A change. More than twice another maker's
About the Lewmar 140TT
The 140TT 2.0 kW is a workhorse bow thruster for small cruisers and sailboats: one propeller in a 140 mm tube gives 82 lb of push on 12 V. Lewmar’s own selection chart puts it on boats of about 30 to 35 ft in a 15 knot wind. Two owners installed one to a 1985 Bayfield 32 themselves and wrote up the whole job.
Defender lists the thruster alone at $1,486. The tube, a control panel, a fuse and the required battery switch add about $549 to $1,223. It runs on one starting battery near the bow, and the battery with cable and charging comes to $583 to $717 by our figures. See the full list.
Read more
The brushes are its weak point by owner accounts. One owner changed three 140TT motors after the brushes seized, and Lewmar sells no brushes, only a whole new motor. Brush the carbon dust out of the motor at each service. Run it in short spells: three minutes one way trips fault mode.
Installers will find the wiring figures and dimensions further down. For the rest of Lewmar’s line, read the Lewmar thruster review.
Where this summary comes from (8 sources, read 13 October 2026)
- Defender listing (the database’s price)
- Lewmar Thruster Selection Guide (boat length by windage)
- Good Old Boat, 2023: two owners fit a 140TT to a Bayfield 32C
- Trawler Forum, 2023: three 140TT 2.2 kW motors changed for seized brushes
- Tugnuts, 2025: a Cutwater C-32’s 140TT motor, sold only as an assembly
- Lewmar Gen 2 TT installation manual 559231 Iss.3 (three minutes one way, then fault mode; warranty one year on motors and controls)
- Lewmar, About (making boat hardware in Havant, England, since 1946)
- Lippert Components acquires Lewmar Marine Limited, 1 August 2019
Will the Lewmar 140TT Tunnel Thruster steer your boat?
36 FT TRAWLER · BOW · 15 KT WIND
Every knot figure here is wind speed, not boat speed or current.
On a 36 ft trawler the Lewmar 140TT Tunnel Thruster (82 lb) steers her in a 15 knot breeze. Her bow needs about 88 lb from a tunnel to steer her in a 15 knot breeze. Its 82 lb lands within 15 percent of that figure, which this site counts as enough.
The finder lists it for her.
The Lewmar 140TT Tunnel Thruster on a trawler, by length
- 25 ft21 kt
- 30 ft18 kt
- 35 ft15 kt
- 40 ft13 kt
- 45 ft12 kt
- 50 ft10 kt
- 55 ft10 kt
- 60 ft9 kt
- 65 ft8 kt
- 70 ft8 kt
- 75 ft7 kt
- 80 ft7 kt
Outlined: the finder does not list it at that length (under 13 kt, far more than she needs, or outside Lewmar’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?
Every kind of boat it fits, by length
| Boat | Full thrust at 15 knots | Still a fit, in lighter wind | Lewmar’s chart |
|---|---|---|---|
| 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 36 ft | 37 to 41 ftfull thrust to about 13 knots at 41 ft | 30 to 35 ftas the 140TT 2.0, class B |
| Houseboat | None | 30 to 31 ftfull thrust to about 13 knots at 31 ft | 30 to 30 ftas the 140TT 2.0, class C |
| Catamaran | 30 to 41 ft | 42 to 47 ftfull thrust to about 13 knots at 47 ft | 30 to 30 ftas the 140TT 2.0, class C |
| Trawler | 25 to 36 ft | 37 to 41 ftfull thrust to about 13 knots at 41 ft | 30 to 30 ftas the 140TT 2.0, class C |
| Motor yacht | 35 to 36 ft | 37 to 41 ftfull thrust to about 13 knots at 41 ft | Off the chart |
| 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 46 ft | 47 to 52 ftfull thrust to about 13 knots at 52 ft | 30 to 35 ftas the 140TT 2.0, class B |
| Center console | 35 to 40 ft | None | 30 to 35 ftas the 140TT 2.0, class A |
The Lewmar 140TT Tunnel Thruster against each kind of boat, in a 15 knot wind. Our sizing, from the finder’s own rules, beside Lewmar's chart.
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 a sailboat gets full thrust to 36 ft, and an express cruiser to 46 ft.
The table tries the Lewmar 140TT Tunnel Thruster 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. The listing prints no boat length, so thrust alone decides. Lewmar's own figures are in the opening lines.
Reading Lewmar’s chart. Lewmar publishes a selection guide, checked 15 September 2026, on a dealer’s copy. It names a model by boat length, from 30 to 90 ft, for a The area of the boat the wind can push on: the hull sides, the cabin, the mast and rigging, or the canopy. A tall, boxy boat has a lot of it, and wind force does not care how slowly you are moving. class and a wind band. Our 15 knots falls in its lightest band, 11 to 16 knots.
The Lewmar 140TT Tunnel Thruster is not on the chart by name. Lewmar rates it at the same 82 lb (37 kgf) as the 140TT 2.0. That tunnel unit is on the chart, so the column shows what the chart says for it. Which class a kind of boat falls in is our reading of its windage. The chart starts at 30 ft.
It is sized for seven 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.
| Boat | Total installed |
|---|---|
| 25 ft | $8,188 to $10,396$100 to $127 a lb of thrust |
| 40 ft | $8,448 to $13,996$103 to $171 a lb of thrust |
| 52 ft | $8,758 to $18,536$107 to $226 a lb of thrust |
From the shortest to the longest boat it is sized for.
What is in each total
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 $2,510 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.
| Boat length | The unit | Yard labor | Haul-out | Batteries, cable, charger | Other parts |
|---|---|---|---|---|---|
| 25 ft | $1,486 | $5,120 to $5,760about 32 hours | $450 to $1,210 | $583 to $717 | $549 to $1,223 |
| 40 ft | $1,486 | $5,120 to $8,64032 to 48 hours | $710 to $1,930 | $583 to $717 | $549 to $1,223 |
| 52 ft | $1,486 | $5,120 to $12,60032 to 70 hours | $1,020 to $2,510 | $583 to $717 | $549 to $1,223 |
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 270 CCA (Lewmar’s minimum), $257 for the battery; Lewmar’s cable table gives 3/0 AWG, priced on 4/0 AWG, the nearest size cut to length: $180 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 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 DIYYou: 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
- 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.
- 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.
- 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 Lewmar’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.
Know before you buy
What sets this model apart, what it costs to keep, and what to weigh.
Price per pound of thrust
$18.12 a lb The unit’s price over its published thrust. The bars are Lewmar’s next sizes and the nearest other makers.Controls
The solenoid, the ICU control box and a 2 m motor loom are in the box. The panel, its loom, the fuse and holder are bought.
- Lewmar Simple joystick, for 591101 and 591482 only (589094), $324.43 at Fisheries Supply.
- Lewmar 4-wire control cable, 2 m (589021), $38.46 at Fisheries Supply.
Pricey wear part: anodes
$18.37 a change- Anode kit (589150): $18.37 at Fisheries Supply.
A change costs $18.37. That is twice the $9.00 for Sleipner’s anode on the same 140 mm tunnel (SM31180A, Defender). An anode is a plain block of metal that wears away by design, so you will buy it again.
They sit below the waterline, so a change means a haul-out or a diver.
Service and warranty
Lewmar gives 3 years, but 1 on electric motors and their electrical equipment and on electronic controls. Service by anyone but an authorized Lewmar representative can void it. Removal, transport and installation costs are not covered.
See Lewmar’s warranty Lewmar's Gen 2 installation manual.Special mentions
Battery: at 12 V it wants one battery of 270 CCA or more, Lewmar's figure. The cheapest that meets it is the Lifeline GPL-1400T AGM starting, $256.72. Check your own bank.
Charger: a NOCO GEN5X2 two-bank shore charger, $146.41. It is the one our estimate prices.
Lewmar 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.
Lewmar prints no single length band for it. Its selection chart gives one by windage: 30 to 35 ft at 15 knots, across the kinds of boat in the table. The boat table is our sizing alone.
Short pushes only: Lewmar rates the motor for 3 min at a stretch.
Parts for the Lewmar 140TT Tunnel Thruster
See the Lewmar 140TT manualSearch 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
The manual button above opens it a dealer's copy (the maker publishes none we could find). It has the hull, wiring and fuse figures for this model.
From Lewmar’s Gen 2 TT installation manual 559231 and the RT manual 55110070, Iss.3 and Iss.4, read 30 September 2026.
- In the box
- The motor, the solenoid and its loom, the ICU control box, a 2 m motor loom, the saddle, gasket, hub, propeller, anode kit and fixings. The RT ships with its own housing and actuator.
- Bought separately
- Under Accessories: the control panels, the panel looms, the fuse holders and ANL fuses, the automatic battery switch. "The installation MUST have a battery switch". The tunnel fits a Lewmar saddle.
- Charging
- The manual sizes the battery by cranking amps and says to "ensure batteries are fully charged before switching on the main power". It gives no rule on a charger, a feed or a bank of its own.
The manual’s words, page 12: “Battery crank capacity should be at least equal to the thruster current.”
The “other parts” line in the estimate above covers these parts as a range, $549 to $1,223 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 “Lewmar fiberglass tunnel tube, 140 mm bore, 750 mm”.
Sold in lengths from about 30 to 59 in. This is the shortest: the yard cuts the tube to the width of your hull at the thruster.
Control panel
Fisheries Supply lists it as “Lewmar Simple joystick, for 591101 and 591482 only”.
Control cable, panel to thruster
Fisheries Supply lists it as “Lewmar 4-wire control cable, 2 m”.
Sold in lengths from 2 to 22 m. This is the shortest: measure the run from the helm to the thruster and buy the length that reaches.
Main fuse
Ask for 200 A (Lewmar 589012).
Lewmar's figure for the 590002, TT 140 2.0Kw 12v (Gen 2 installation manual, Iss.3). Not listed at Fisheries Supply; ask a Lewmar dealer.
Fuse holder
Ask for Lewmar fuse holder 589006 (T1) or 589013 (T2).
Ask the dealer who sells the fuse.
Battery switch
Fisheries Supply lists it as “m-Series 300 A battery switch, on/off”.
Rated at or above the 200 A main fuse. If your manual names its own switch, use that one.
Batteries
Fisheries Supply lists it as “Lifeline GPL-1400T AGM starting”.
One at 270 CCA or more. The cheapest listing that meets it.
Battery cable, red and black
Defender lists it as “Ancor tinned battery cable 4/0 AWG, cut to length, red or black”.
You need 10 ft of each color. For about 20 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.
Cable lugs
Fisheries Supply lists it as “Tin-plated starter lugs, 4/0 AWG, bag of 10”.
The listing runs $47.52 to $49.44 by stud size. Eight ends on one run, with two spare.
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.
Outside the hull replacement parts in the water
Anode kit
The metal that wears away in the water so the drive does not. Lewmar calls it “PROPELLER ANODE KIT”.
The 110TT and 125TT parts lists show no anode.
Propeller
The propeller on the drive. Lewmar calls it “PROPELLER AND WASHER”.
Drive pin (breaks to protect the drive)
The pin that locks the propeller to its shaft. Lewmar calls it “DRIVE PIN”.
The 125TT and 140TT use the same pin. The manual lists the 125TT as 591251; Defender sells it as 590101. Both are the 2.0 kW 12 V 125TT.
Tunnel gasket
It keeps water out of the joint it sits in. Lewmar calls it “TUNNEL GASKET”.
Inside the boat replacement parts on board
Solenoid (the motor switch)
The heavy switch that sends battery power to the motor. Lewmar calls it “SOLENOID 2.0”. This one is for the 1.5 kW and 2.0 kW version.
The 140TT 2.2 kW takes B11126 instead. The 110TT list prints it as SOLENIOD.
Controller box (the ICU)
The electronics that run the motor when you press the panel. Lewmar calls it “GEN2 TT ICU”.
The 250TT parts list prints its ICU as 589834, the same number as its solenoid loom, so we list no ICU number for the 250TT.
Main fuse, 200 A
The main fuse at the battery, in the rating the maker gives. Lewmar calls it “200 A ANL TYPE FUSE”.
The rating the manual gives for each model it fits. Lewmar sells it as an ANL fuse.
Control panel, dual joystick (bow and stern)
The control at the helm. Lewmar calls it “Controller, Dual Joystick”.
Control panel, dual pad (bow and stern)
The control at the helm. Lewmar calls it “Controller, Dual Pad”.
Control panel, single joystick
The control at the helm. Lewmar calls it “Controller, Single Joystick”.
Control panel, single pad
The control at the helm. Lewmar calls it “Controller, Single Pad”.
Replacement motor
The electric motor that turns the propeller. Lewmar calls it “MOTOR ASSY 2.0KW 12v”. This one is for the 2.0 kW version.
The standard motor. The manual lists a separate IP (ignition protected) motor. The manual lists the 125TT as 591251; Defender sells it as 590101. Both are the 2.0 kW 12 V 125TT.
No part matches. Try the number without spaces, or the part’s name.
The install parts are matched to Lewmar’s own figures and priced at Fisheries Supply, with the battery cable at Defender, cut to length.
Spare part numbers come from Lewmar’s parts pages and manuals. A dealer may sell a part we have not priced. Search for the number.
Other sizes and close alternatives
- Size down Lewmar 125TT 77 lb · $1,846
- Size up Lewmar 140TT Gen 2 Package 92 lb · $2,754
- The kit Lewmar 140TT Kit 82 lb · $1,965
- Other maker VETUS Bow Pro 361 79 lb · $3,188
- Other maker Max Power CT35 77 lb · $1,276
- Other maker Sleipner SE30/125S DC 88 lb · $1,755
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 and motor | |
|---|---|
| Thrust | 82 lb (37 kgf) As printed: 37 kgf |
| Motor | 2 kW |
| Voltage | 12 V |
| Run limit | 3 min in one direction, then fault mode |
| Installation | |
| Type | Tunnel, fixed mount |
| End of the boat | Bow or stern |
| Tunnel diameter | 140 mm |
| What it does to the hull | Tunnel bore below the waterline |
| Haul-out to install it | Yes |
| Maker’s boat length | 30 to 35 ftLewmar's selection chart, by windage; the listing prints none |
| Price and ordering | |
| Price | $1,486 equipment only, a dealer's price, defender.com, 26 October 2026 |
| Part number | 59148212 V |
| Documents | |
| Manual | Installation manual (PDF)a dealer's copy (the maker publishes none we could find) |
| The site’s review | Lewmar thruster review |
Every published figure the site holds for the Lewmar 140TT Tunnel Thruster, with where each came from.
Draw, cable, fuse and battery at each voltage
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.
| Voltage | Draw | Maker’s cable | Fuse | Battery | Run limit |
|---|---|---|---|---|---|
| 12 V | 270 Anominal draw | 3/0 AWG, the one size Lewmar gives for this model, for any run up to 45 ft of cable counted out and backGen 2 installation manual, Iss.3 | 200 AGen 2 installation manual, Iss.3 | Crank capacity at least the 270 A draw, Lewmar's ruleLewmar Gen 2 installation manual | 3 min in one direction, then fault modeGen 2 installation manual |
The Lewmar 140TT Tunnel Thruster’s draw, cable, fuse, battery and run limit, as the maker publishes them.
- At 12 V: size the cable for your run, or check the battery you have.
The tunnel: length and depth rules
Tunnel length. A minimum suggested tunnel length of twice the diameter. Lewmar’s installation manual.
Depth below the waterline. One tunnel diameter below the waterline to keep air out of the tunnel, with 0.75 of a diameter the minimum. Gen 2 TT installation manual, 559231 Iss.3 (2018).
Our notes from the manual and listings
In the box: The solenoid, the ICU control box and a 2 m motor loom are in the box. The panel, its loom, the fuse and holder are bought.
Our note
The 2.0 kW 140TT on its own, single propeller in a 140 mm tunnel. A boat owner installed one himself on the DIY page. The Gen 2 manual rates it 37 kgf (82 lb), with a composite gearbox, 13 kg and a 200 A fuse. It gives 270 A at 12 V on at least 70 mm² cable to 14 m of total run, battery to thruster and back.
That fuse sits below the stated draw, as on every row of the manual's table. Lewmar's whole battery rule is that crank capacity should at least equal the thruster current. Run it in one direction for more than three minutes and the system enters fault mode. A thermal switch stops a hot motor, and the manual says wait 20 minutes. The panel powers itself down after 15 minutes idle.
The tunnel goes one diameter below the waterline (three quarters at minimum) and at least two diameters long. The anode is checked after three or four months on a new install, then yearly. The manual says brush the carbon dust out of the motor, especially on an aluminum boat. Three years' warranty on paper, but one year on electric motors, associated electrical equipment and electronic controls.
Service by anyone but an authorized Lewmar representative voids the warranty, and removal and reinstalling are not covered. Lewmar publishes no boat length. Fisheries Supply's listing says a typical boat up to 35 ft. The same part number is dearer at Fisheries Supply and dearer still at Lippert's own store. Defender's is the lowest of the three. Defender quoted a lead time of 24 to 28 days.
Where each point above comes from
- Lewmar 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
- Lewmar prints no single length band for it. Its selection chart gives one by windage: 30 to 35 ft at 15 knots, across the kinds of boat in the table. The boat table is our sizing alone.Lewmar's Thruster Selection Guide, checked 15 September 2026
Not sure this is the one? The thruster finder asks about your boat and prices every unit that fits.