For years, Imtra supplied the Brunswick Boat Group with Side-Power (now Sleipner) bow & stern thrusters for their line of Meridian Yachts models 341 through 459. The first systems were installed in 1999, and in 2002 Meridian began offering bow & stern thrusters as standard. While Brunswick has since discontinued manufacturing Meridians, there are hundreds of them still in operation with thruster systems that could be overdue for an upgrade.
Whether you’re looking for safer, simpler wiring and powering options, a newer and more powerful thruster motor, or a full system upgrade to proportional speed thrusters, Sleipner offers options for all of the above.
What to Look For
Locate the thrusters in the boat and look for a model number on the motor cover. The majority of Meridians from the 341 through the 459 model used the SP75 thruster, though some of the 40+ footers may have the SP95 and the 50+ foot models used the SP155. Knowing the exact thruster will determine what specific parts are needed for an upgrade.
The next thing to look for is whether or not the gear-leg of the thruster is oil-fed, or sealed. Between 2006-2008, Sleipner (then Side-Power) transitioned all their thruster gear-legs from needing an oil reservoir to being pre-filled and factory sealed. Determining which one you have is as simple as looking for an oil reservoir and hose that feeds into the motor mount bracket that sits on the tunnel below the motor. If you do have a sealed gear-leg, all upgrades can be done with the boat in the water and no need for a haul-out. If you have an older oil-filled gear-leg, an upgrade to proportional speed would involve replacing that as well, which would require the boat to be out of the water, but we’ll cover that in specifics below.
Thruster Upgrade Options
Wiring & Power
Many of the original thruster installations on Meridians were installed with a latching relay and separate rocker switch from the thruster control that turned power on & off to the thruster. While this worked in most cases, it made future troubleshooting service work more difficult as the extra wires and power circuit made identifying specific issues more difficult.
So the simplest and easiest upgrade to the old thruster system is to wire in a Sleipner Auto Main Switch, which controls the power to the thruster, and can be turned on and off with the power buttons on the control panel at the helm. Not only will this help in any future diagnostics and troubleshooting, but it is also a safety feature that allows the user to cut off all power to the thruster at the control, instead of having to find a manual battery switch mounted somewhere closer to the thruster.
READ MORE: Benefits of Having an Automatic Main Battery Switch for Your Thruster System
New On/Off Motor
Another simple upgrade that can be made is to swap the thruster motor out for a new one. The SP75 became what is now called the SE80, and the SP95 became the SE100, and all the motors and brackets are compatible, so swapping a motor out is as simple as disconnecting wires, removing 4 bolts, lifting the motor off, dropping the new one into place and reconnecting the bolts and wires.
This also means that an SP75 can be converted into an SE100, a ~30% more powerful thruster, just by replacing the SP75 motor with an SE100 motor. This upgrade is very simple to do and will provide more thrust instantly, but it does require one additional step of making sure that the batteries and wiring are sufficient for the new motor. The SE100 will draw more power, which could mean bigger batteries and thicker battery cables, depending on what is currently installed. It is always best to consult a manual and have an ABYC certified marine electrician verify the battery and cable sizing.
New Proportional E Series
Another upgrade option is to replace the existing on/off thruster system with a proportional speed control thruster system, by replacing the old thruster motor with a new E-Series motor. This upgrade option is certainly the most labor-intensive option, as it requires all-new control cabling so that the thruster and control can communicate, but the upside is an entirely new thruster system with variable speed control and several other benefits.
The first thing to check for before upgrading is for the oil-fed gear-leg. If the existing thruster is using the old oil reservoir, then the whole thruster, including the gear-leg would have to be replaced. However, if it is a sealed gear-leg, then the existing one can stay and only the motor, with an adapter plate and coupler, would need to be replaced and all work could be done with the boat in the water.
The new motor to use for a proportional system would be an E100 thruster motor, which is the world’s first electric motor designed and manufactured specifically for marine thruster use. It is a brushless motor that is ignition-protected and has the brains of the proportional system built right into the motor.
To make the transition, all of the wiring between the control at the helm and the thruster would have to be replaced. All Sleipner proportional thruster systems, as well as stabilization systems, use their proprietary S-Link cabling that is used for communication between the thruster and control, providing feedback like battery levels, thrust output and any faults or alarms when the system detects an issue. This of course means that the thruster control will have to be replaced as well, with a new PJC Panel, which includes the two paddles for control and an LCD screen for feedback.
While the most costly upgrade, it is certainly the most significant and completely overhauls the functionality of your thruster system. As one Meridian owner who completed the SP75 to E100 proportional upgrade in the summer of 2024 said,
“I love the new thrusters, they allow docking to be so simple. The system is so reactive and easy to use and the remote is also a blessing. This has made my boating experience so much better.” -Kevin, Meridian 411 owner.
Additional Upgrades
Beyond the thruster motors themselves, there are other bits of a thruster system that can be upgraded to modern technology. Since Meridian last installed a thruster on one of their boats, Sleipner has expanded the range of options for on/off thruster controls, so if you prefer a dual-joystick to the boat-shaped control, or vice versa, those can be swapped out with plug-and-play wiring, though some work to the cutout in the dash may be required. In addition, all Sleipner thruster systems can have a radio remote added in to the system for controlling your thrusters from anywhere on the boat, or even the dock.
While the focus on this article is on the extensive history of Meridian and Sleipner thrusters, these upgrades can be applied to any older Side-Power thruster. So if you have an existing Side-Power thruster system, particularly on an older boat, and you’re interested in improving the performance of the system, be sure to contact a dealer to quote the job, or reach out to us directly and we’ll help get you started!