We may earn a referral commission from some links on this page. It doesn't change your price or our recommendations.
Thruster specs
Sleipner SX35 Compact Stern: specs, price and the boats it fits
The SX35 is Sleipner’s answer for a smaller boat that has no room for a tunnel at the stern. It bolts to the outside of the hull through three small holes below the waterline and gives 93 lb of push, for boats of about 20 to 33 ft that want steering help at the back end in a crosswind.
Defender sells it for $3,870 in the version for a hull up to 50 mm thick; the 150 mm version, for thicker hulls without glass work, costs a little more. Add about $307 to $642 for the panel, main switch and fuse, and about $498 to $574 for a starting battery near the stern, its cable and charging. The boat has to come out of the water to fit it. See every part.
Sleipner recommends its external units for displacement and semi-planing boats running under 20 knots, because a planing hull can slam a pod hard in waves. The control box mounts close to the thruster inside the hull. Pushes of 2 to 3 minutes are the limit before it rests. Two-year warranty, transferable.
Installers will find the wiring figures and dimensions further down. For the rest of Sleipner’s line, read the Sleipner (Side-Power) review.
Where this summary comes from (4 sources, read 12 October 2026)
Key facts
- DIY level 3 of 5 Split with the yard
- Thrust 93 lb 42 kgf, Sleipner's rating
- Boat length 20 to 33 ft Sleipner's own range
- Price $3,870 to $4,167 equipment only, defender.com, 12 October 2026
- Fitted by a yard $6,575 to $10,673 Our estimate at 35 ft, unit and job
- Voltage 12 V As sold
- Mounts External Fixed mount, stern
- To fit it Haul-out The boat comes out of the water
- Run limit Not clear Sleipner's page prints "4 duty cycle" with no unit
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: 4 to 8 h Electrician: 2 to 4 h Plus a haul-out.
- Drill, seal and bolt the unit below the waterline Yard 4 to 8 h Our estimate. No maker times it; one owner paid his yard about a day of labor to mount two units. Source.
- 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 every kind of boat it fits gets full thrust to 36 ft. The maker gives one range for every boat.
The table below tries the Sleipner SX35 Compact Stern 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 where it mounts 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 36 ft, just past Sleipner’s own range (20 to 33 ft).
| Boat | Full thrust at 15 knots | Still a fit, in lighter wind |
|---|---|---|
| Pontoon & tritoon | Not listed. Its maker does not name this kind of hull. | |
| Sailboat | 33 to 36 ft | None |
| Houseboat | Not listed. Its maker does not name this kind of hull. | |
| Catamaran | Not listed. An external unit bolts to the side of a single hull at the bow or to its transom, and a cat has two narrow hulls with a bridgedeck between them, so there is nowhere forward to hang one. | |
| Trawler | 33 to 36 ft | None |
| Motor yacht | 35 to 36 ft | None |
| Bass & flats | Not listed. This site does not list it for this kind of boat. | |
| Wake & ski boats | Not listed. This site does not list it for this kind of boat. | |
| Express cruiser | Not listed. This site does not list it for this kind of boat. | |
| Center console | Not listed. This site does not list it for this kind of boat. | |
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 three 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 $590 to $1,740 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 |
|---|---|---|---|---|---|---|
| 33 ft | $3,870 to $4,167 | $1,280 to $3,6008 to 20 hours | $590 to $1,590 | $498 to $574 | $307 to $642 | $6,545 to $10,573 |
| 35 ft | $3,870 to $4,167 | $1,280 to $3,6008 to 20 hours | $620 to $1,690 | $498 to $574 | $307 to $642 | $6,575 to $10,673 |
| 36 ft | $3,870 to $4,167 | $1,280 to $3,6008 to 20 hours | $640 to $1,740 | $498 to $574 | $307 to $642 | $6,595 to $10,723 |
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 12 V: one 12 V battery, at least 380 CCA (Sleipner’s minimum), $257 for the battery; Sleipner’s cable table gives 1/0 AWG: $95 to $171 for the red and black cable and the lugs; a GEN5X2 charger, $146.
- At 12 V: one 12 V battery, at least 380 CCA (Sleipner’s minimum), $257 for the battery; Sleipner’s cable table gives 1/0 AWG: $95 to $171 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 Sleipner’s SE80 to SE150 installation guide, document 2687 rev 30, 2025, read 30 September 2026. That manual is written for the tunnel units. An external unit has no tunnel to buy.
- In the box
- The gasket, bolts and anode come with the unit. The SEP guides call the power controller "the included PPC unit".
- Bought separately
- The ANL fuse and a main switch ("must include"), the control panel with its own guide, the panel cable and the battery cable.
- Charging
- The word "charging" is not in any of the Sleipner guides we read. The battery is sized by cold cranking amps, and a battery near the thruster is suggested. How it gets charged is left to you and your installer.
The manual’s words, page 19: “For installations on large vessels with bow and stern thrusters or catamarans a dedicated battery for each thruster should be considered.”
The “other parts” line in the estimate above is the priced parts below, $307 to $642 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 |
|---|---|---|---|
| Control panel | The buttons or joystick at the helm. One helm, one panel: a second steering station needs a panel of its own. | SM8960G single joystick, SM8950G touch panel | $219–$374Side-Power touch panel and single joystick, VETUS push-button panel, Lewmar single joystick, 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. | Side-Power 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. | SMANLHOLD (SMANLHOLD-C with a cover) | $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. | Side-Power manual main switch, 350 or 600 A, or the automatic AMS | $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. |
| Control-circuit fuse and switch | A small fuse, and often a switch, on the thin wire that powers the panel or control box. | Sleipner names none | $8–$12Blue Sea in-line ATO fuse holders, 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. | Sleipner 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. | Sleipner 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. | Sleipner names none | $146–$305NOCO GEN5X2 shore charger, Victron Orion-Tr Smart DC-DC charger, Blue Sea ML-ACR charging relay, at Fisheries Supply. |
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 | 93 lb (42 kgf) As printed: Thrust at 12V: 42kg / 93lbs; Thrust at 10.5V: 35kg / 77lbs (sleipnergroup.com, SX35 external stern thruster 12V w/controller unit, read 2026-09-18; Defender printed "43 kg (93 lbs) at 12/24V; 35 kg (77 lbs) at 10.5/21V") |
| Thrust under load | 77 lb at 10.5 V |
| Motor | 1.8 kW |
| Voltage | 12 V |
| Fitting | |
| Type | External, fixed mount |
| End of the boat | Stern |
| What it does to the hull | Three small holes, below the waterline |
| Haul-out to fit it | Yes |
| Weight | 15.3 kg (34 lb)Sleipner’s product page |
| Maker’s boat length | 20 to 33 ft |
| Price and ordering | |
| Price | $3,870 to $4,167 equipment only, a dealer's price, defender.com, 12 October 2026 |
| Part number | 883348for a hull up to 50 mm (2 in) thick, 12 V 883348for a hull up to 150 mm (6 in) thick, 12 V |
| Documents | |
| Manual | Installation manualon the maker's product page |
| Warranty | Sleipner gives 2 years for leisure use and 1 for commercial use. It transfers to the next owner, and it starts no later than 18 months after the boat's first launch. Sleipner's warranty statement, effective 1 April 2022 |
| The site’s review | Sleipner (Side-Power) 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 |
|---|---|---|---|---|---|
| 12 V | 245 Anominal draw | 1/0 AWG for up to 22 ft of cable counted out and back. Longer runs take heavier cableinstallation guide | ANL 150installation guide | 200 CCA DIN minimumSleipner installation guide, SX35 and SX50 external, document 8086 rev 3 (2026) | "4 duty cycle", as the page prints itproduct page, "Motor cycle duty" |
- At 12 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
- Sleipner also prints a second, lower thrust figure for when the battery sags under load: 77 lb at 10.5 V.The maker's published rating
What to weigh
- The boat comes out of the water to fit it: it needs three small holes, below the waterline.The mounting style
What the manual and listings say
This is the note we keep on the Sleipner SX35 Compact Stern, written from the maker’s manual, its product pages and the dealer’s listing.
In the box: Gasket, bolts and anode with the unit. The panel, its cable, the fuse and main switch are bought.
for a hull up to 50 mm (2 in) thick
It bolts to the outside of the hull through three small holes below the waterline. The variant this row links is the 150 mm one, which fits a hull up to 150 mm thick without glass work. Sleipner's external page puts its external units on displacement and semi-planing boats up to 60 ft. The boat comes out of the water to fit it.
It is rated 42 kg (93 lb) at 12 V and 35 kg (77 lb) at 10.5 V. The figure here is the 12 V one, as on every Sleipner row. The unit weighs 15.3 kg and draws 245 A, with an ANL 150 fuse and a minimum battery of 200 cold cranking amps DIN. It is for boats of 20 to 33 ft.
The page prints its duty as "4 duty cycle at 20 C", as written. Defender's price sits below Imtra's list. Since the 2025 tariffs, that list carries a separate tariff line. This row is the 50 mm (2 in) hull-thickness version; Defender prices it separately, read 12 October.
for a hull up to 150 mm (6 in) thick
This row is the 150 mm (6 in) hull-thickness version; Defender prices it separately, read 12 October.
Videos
One of Sleipner’s own videos, from its YouTube channel: an owner’s Sealine 35 with the compact external units, on the water. 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 Sleipner’s next sizes in the same line, by thrust.
- One size up: Sleipner SX50 Compact Stern Thruster, 137 lb, $4,365 to $4,658.
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.
- DockStar Smart Thruster, stern, 90 lb, $4,270 to $4,570.
- Max Power CT45 stern pod, 99 lb, $3,275.
Every model with a page here is listed, maker by maker, on the thruster index.