Sleipner Group (Side-Power)

Walk a marina and lift a few forward berth cushions, and the Side-Power name turns up a lot. Sleipner, the company behind it, says its tunnel thrusters have been installed in more than 350,000 boats. That installed base is one of the brand's biggest practical advantages: parts, manuals and technicians who know the product are easy to find.

The company

Sleipner started in 1908 and has had its headquarters and factory in Fredrikstad, Norway, since 1910. It began by making engines for leisure and fishing boats and has focused on thruster systems since the early 1980s. Today the group reports more than 230 employees across Norway and subsidiaries in Denmark, Finland, Germany, Italy, Poland, Sweden and the UK, and an annual turnover of about NOK 800 million.

Sleipner says it puts about 10% of turnover into research and development, does its manufacturing in-house from CNC machining to electronic assembly, and is ISO 9001 certified by DNV. Besides thrusters, it makes Vector Fins stabilizers, steering systems and anchor windlasses.

US distribution and support

In North America, Sleipner products are distributed by Imtra, an employee-owned company in New Bedford, Massachusetts. Imtra lists the full thruster range, including DC, eVision, AC and hydraulic units, plus parts and upgrade kits, and sells through dealers, boatyards and installers in the US and Canada. When you need a part or a technical document, Imtra is usually the route.

The thruster lines

Tunnel thrusters

The SE series is the on/off workhorse, running from the SE20 in a 110 mm tunnel to the 48V SE300. The SEP PRO adds variable speed and a hold function for bow-and-stern setups. Sleipner's newer eVision E-series uses a brushless motor with built-in speed control and is rated for continuous running at full thrust at 22°C; on Sleipner's site, several larger SEP PRO models now point to eVision replacements.

Retractable thrusters

The SR, SRL and SRV retracts cover mold-in, low-height and vertical installs, from the 80 class to the 48V SRV300, with PRO and eVision versions.

External thrusters

The SX, SXP and SXE transom units are built for twin stern-drive boats, with cowls that steer the water past the drives. The small SX35 and SX50 and the EX pods cover small boats and displacement hulls.

Hydraulic and AC

The SH hydraulic series runs from the SH100 to the SH2200 for large yachts and commercial craft, with SRHP hydraulic retracts. SAC units are AC-powered tunnel thrusters (230V, 400V and 690V versions are listed) for larger yachts and commercial vessels.

What sets Sleipner apart

• Conservative ratings. Model numbers are thrust at nominal voltage (10.5V on a 12V system). The figure at full battery voltage is higher.
• IPC. Sleipner's patented Intelligent Power Control adds a short delay between direction changes and stops the thruster if a solenoid sticks.
• Galvanic isolation. Underwater parts are isolated from the boat's DC system.
• S-Link. A CAN-based control bus that ties thrusters, panels and other Sleipner systems together.
• Q-Prop. A five-blade skew propeller upgrade that Sleipner says typically cuts noise by 20-40% in real installations.

Things to watch

The range is changing. Larger brushed PRO models are being replaced by eVision, and eVision is 24V or 48V only, so 12V boats need a separate thruster bank to use it. If you are buying a large proportional thruster, ask which generation you are getting.

Our take

Sleipner is the default choice for a reason: a huge range, sensible engineering, and support that is easy to find. It is not the only good brand, and Vetus in particular is a strong alternative. If you want a Sleipner thruster fitted or an old Side-Power unit replaced, get a quote or see our bow thruster installation page.

Questions people ask