We may earn a referral commission from some links on this page. It doesn't change your price or our recommendations.
Thruster specs
Lewmar 250TT GEN 2: specs, price and the boats it fits
The 250TT Gen 2 is the first Lewmar tunnel with twin counter-rotating propellers, built for big cruisers and trawlers. This is the 8.0 kW motor on 24 V with the bronze gearbox. The Gen 2 manual rates it at 308 lb of push and 46 kg, and gives it a 400 A fuse.
Defender, Fisheries and Lippert’s own store list no Gen 2 250TT, so the price here is Marinedeal’s, $4,949. Its listing prints 353 lb, more than the manual’s figure, so we follow the manual. The tube, the controls, the fuse and the battery switch are about $635 to $1,634 more, and a 24 V bank near the bow is the larger cost. See every part.
Lewmar also makes this motor with an aluminum gearbox, and a 48 V build at 9.6 kW; Marinedeal does not list them. The run rule is the same as the smaller units: three minutes one way and it goes into fault mode. Motors and controls carry one year of warranty inside the three.
The full spec sheet for a yard sits lower down, and the Lewmar thruster review covers Lewmar’s whole range.
Where this summary comes from (4 sources, read 15 October 2026)
- Marinedeal, Lewmar 250TT 8 kW 24 V Gen 2 (590024) listing
- 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
Key facts
- DIY level 2 of 5 Wiring prep only
- Thrust 308 lb 140 kgf, Lewmar's rating
- Boat length Not published See our sizing below
- Price $4,949 equipment only, marinedeal.com, 14 October 2026
- Fitted by a yard $12,883 to $23,371 Our estimate at 60 ft, unit and job
- Voltage 24 V As sold
- Mounts Tunnel Fixed mount, bow or stern
- To fit it Haul-out The boat comes out of the water
- Run limit 3 min In one direction, then fault mode
Every figure here is the maker’s or a dealer’s, except the fitted cost, which is our estimate. The full spec sheet is further down.
How much of the install is yours
DIY levels
- Level 5: Owner install. No yard, no electrician.
- Level 4: You fit 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 fits 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 h Yard: 32 to 70 h Electrician: 2 to 4 h Plus a haul-out.
- Cut, bond and fair the tunnel; fit the gear leg, motor and propeller Yard 32 to 70 h 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 h 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 h Our estimate. Nobody publishes a time for the final connections and test on their own.
Your part needs:Heavy battery cableCrimping big lugs
A qualified marine electrician should make the final connections and test them before first use. Hours are labor only.
Is it right for your boat?
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 houseboat gets full thrust to 44 ft, and a catamaran to 67 ft.
The table below tries the Lewmar 250TT GEN 2 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. Lewmar publishes no boat length, so thrust alone decides.
| Boat | Full thrust at 15 knots | Still 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 | 49 to 59 ft | 60 to 80 ftfull thrust to about 11 knots at 80 ft |
| Houseboat | 37 to 44 ft | 45 to 65 ftfull thrust to about 10 knots at 65 ft |
| Catamaran | 56 to 67 ft | 68 to 80 ftfull thrust to about 13 knots at 80 ft |
| Trawler | 49 to 58 ft | 59 to 80 ftfull thrust to about 11 knots at 80 ft |
| Motor yacht | 49 to 58 ft | 59 to 80 ftfull thrust to about 11 knots at 80 ft |
| 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 | 62 to 65 ft | None |
| Center console | No length. More thrust than the boat needs. | |
Reading the two length columns. 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 falls short of what the boat needs by no more than 10 percent, and gives the whole figure only in the lighter wind named. On a boat shorter than the first column’s shortest length, the unit is more than the boat needs.
It is sized for six kinds of boat here. For your own boat, the finder gives an answer that also counts your drive and who does the fitting. The compare page sets this unit beside others.
What it costs fitted
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 $660 to $3,860 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. Your own yard will have its own opinion. The cost page builds the same figures line by line.
| Boat length | The unit | Yard labor | Haul-out | Batteries, cable, charger | Other parts | Total |
|---|---|---|---|---|---|---|
| 37 ft | $4,949 | $5,120 to $6,84032 to 38 hours | $660 to $1,790 | $1,019 to $1,288 | $635 to $1,634 | $12,383 to $16,501 |
| 60 ft | $4,949 | $5,120 to $12,60032 to 70 hours | $1,160 to $2,900 | $1,019 to $1,288 | $635 to $1,634 | $12,883 to $23,371 |
| 80 ft | $4,949 | $5,120 to $12,60032 to 70 hours | $1,490 to $3,860 | $1,019 to $1,288 | $635 to $1,634 | $13,213 to $24,331 |
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 12 October 2026.
- At 24 V: two 12 V batteries in series, at least 500 CCA each (Lewmar’s minimum), $513 for both; Lewmar’s cable table gives 2 x 4/0 AWG: $360 to $629 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.
What else you buy
What follows comes 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 is the priced parts below, $635 to $1,634 at Fisheries Supply’s prices on 30 September 2026. The batteries, cable and charger have a line of their own.
| Part | What it is | What to ask for | Dealer price |
|---|---|---|---|
| Tunnel tube | The fiberglass, aluminum or steel pipe the thruster sits in, bonded through the bow. | 589501, 589502 (39 in, 59 in) | $307–$831250 mm fiberglass tunnel tubes up to 60 in (1.5 m) long (VETUS, Sleipner Side-Power, Lewmar), at Fisheries Supply, read 16 October 2026. |
| Control panel | The buttons or joystick at the helm. One helm, one panel: a second steering station needs a panel of its own. | 589268 single joystick, 589267 dual joystick, 589222 and 589223 pads | $219–$374Side-Power touch panel and single joystick, VETUS push-button panel, Lewmar single joystick, at Fisheries Supply. |
| Control cable, panel to motor | The thin cable from the helm to the motor. Sold by length. | Gen 2 AUX loom, 2 to 22 m | $29–$173Side-Power control cables, VETUS panel cables, Lewmar Gen 2 connecting cables, at Fisheries Supply. |
| Main fuse | A slow-blow fuse of the ANL type at the battery, in the size the maker prints for the model. | Lewmar ANL fuse, the rating in the yard table below | $18–$57Side-Power ANL fuses, Blue Sea ANL fuses, at Fisheries Supply, read 16 October 2026. |
| Fuse holder | The block the ANL fuse bolts into, with a cover. | 589006 (589010 for the T2 fuse) | $27–$93Egis and Blue Sea ANL fuse blocks, Side-Power ANL fuse holders, at Fisheries Supply, read 16 October 2026. |
| Main battery switch | The switch that cuts the thruster off from its battery when you leave the boat. | Gen 2 ABS 589810 (12 V) or 589830 (24 V), or any manual battery switch | $35–$107Egis m-Series 300 A, Blue Sea e-Series 350 A and HD-Series 600 A on/off switches, at Fisheries Supply, read 16 October 2026. |
| Battery cable and lugs | The two heavy cables from the battery to the motor, sized to the length of the run. The wiring calculator sizes them. | Lewmar names none | In the electrical line |
| Battery bank | A cranking-type bank near the motor, sized by the maker's cold cranking amps. The battery calculator checks it. | Lewmar names none | In the electrical line |
| Charger or charge feed | How the thruster bank gets charged: a shore charger of its own, a DC-to-DC charger or charging relay from the boat's system, or a charger built into the unit. | Lewmar names none | $146–$305NOCO GEN5X2 shore charger, Victron Orion-Tr Smart DC-DC charger, Blue Sea ML-ACR charging relay, at Fisheries Supply. |
| Glass, resin, filler and sealant | What bonds the tube or housing into the hull and seals the gear leg. | Lewmar names none | Not priced |
The cost page has the whole list with what every maker says about each part.
For the yard and the installer
The full spec sheet, grouped the way a yard reads it. Every figure is the maker’s or a dealer’s, with its source.
| Thrust and motor | |
|---|---|
| Thrust | 308 lb (140 kgf) As printed: "590024 TT 250 8.0 24v 250 8.0 10.8 24v Bronze Twin CR 5 Blade 140 308 46 101 400A 589010" - Lewmar Gen 2 TT manual 559231 Iss.3, section 6 |
| Motor | 8 kW |
| Voltage | 24 V |
| Fitting | |
| Type | Tunnel, fixed mount |
| End of the boat | Bow or stern |
| Tunnel diameter | 250 mm |
| What it does to the hull | Tunnel bore below the waterline |
| Haul-out to fit it | Yes |
| Maker’s boat length | Not published |
| The tunnel | |
| 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) |
| Price and ordering | |
| Price | $4,949 equipment only, a dealer's price, marinedeal.com, 14 October 2026 |
| Part number | 5900248.0kW 24 V, bronze gearbox, 24 V DC |
| Documents | |
| Manual | Installation manual (PDF)a dealer's copy (the maker publishes none we could find) |
| 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. Lewmar's Gen 2 installation manual |
| The site’s review | Lewmar thruster review |
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 |
|---|---|---|---|---|---|
| 24 V | 500 Anominal draw | 2 x 4/0 AWG per leg, the one size Lewmar gives for this model, for any run up to 65 ft of cable counted out and backGen 2 installation manual, Iss.3 | 400 AGen 2 installation manual, Iss.3 | Crank capacity at least the 500 A draw, Lewmar's ruleLewmar Gen 2 installation manual | 3 min in one direction, then fault modeGen 2 installation manual |
- At 24 V: size the cable for your run, or check the battery you have.
What holds up and what to weigh
Each point names the fact it rests on.
What holds up
- Lewmar sells it for either end, so it can go at the bow or the stern.The maker's listing
What to weigh
- The boat comes out of the water to fit it: it needs a tunnel bore below the waterline.The mounting: a bore through the hull, or a housing recessed into it
- Lewmar publishes no boat length for it. The boat table is our sizing alone.The maker's documents, as the database records them
What the manual and listings say
This is the note we keep on the Lewmar 250TT GEN 2 Tunnel Thruster, written from the maker’s manual, its product pages and the dealer’s listing.
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 250TT Gen 2 at 8.0 kW and 24 V: twin counter-rotating propellers in a 250 mm tunnel. The Gen 2 manual rates it 140 kgf (308 lb), 46 kg, with a 400 A fuse.
Videos
One of Lewmar’s own videos, from its YouTube channel: what changed in the Gen 2 tunnel units. It is the maker’s pitch. Watch it for what the unit looks like and how it goes in, and take any claim back to the figures above.
Other sizes and close alternatives
These are Lewmar’s next sizes in the same line, by thrust.
- One size down: Lewmar 185TT GEN 2 Tunnel Thruster, five sizes, 128 to 214 lb, $1,912 to $4,825.
- One size up: Lewmar 300TT GEN 2 Tunnel Thruster, two sizes, 550 to 616 lb, $7,339 to $10,499.
These are other makers’ units of the same style, for the same end, within a quarter of its published thrust. Each is that maker’s nearest match.
- VETUS Bow 125, two sizes, 275 to 308 lb, $4,589.
- Sleipner SE120/215T-24V, 306 lb, $4,905.
- Max Power CT125 (24 V), 254 lb, $2,947.
Every model with a page here is listed, maker by maker, on the thruster index.