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Thruster Installation

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Quick Thrust

A new thruster system offers an alternative to a conventional installation.

After ending yet another day on the water with a frustrating battle against wind and current while backing into your slip, you’ve made up your mind to get a bow thruster. It’s a decision you’ve made many times before, but the thought of cutting that big hole in your bow, laminating a tube in place, and then having to worry about improper sealing has always forced you to reconsider. So has the amount of time your boat might be out of the water.

Finally, an aternative has arrived, though. The same company that developed the Yacht Controller remote docking system is now importing a clever new kind of thruster—developed by the Austrian company Marinno—that mounts on the bottom of your boat’s hull, not in it.

“It’s the first thruster system designed from a clean sheet of paper,” says Gerald Berton, president of The Berton Group in Coral Gables, Florida, which owns the Yacht Controller and distributes Yacht Thruster in this country.

Bow thruster

Since the unit is constantly submerged, it’s in a sense water-cooled, at least where water temperatures are not overly high. This can prolong running time for up to seven minutes without overheating, according to Berton. Typical electric tunnel-style thrusters, most installers will tell you, tend to shut down in three to five minutes, depending on whether the unit has a temperature-based or time-based cutoff. (Overheating, of course, is not an issue with hydraulic thrusters, although such systems are usually found on boats larger than 60 feet.) In addition, the Yacht Thruster is housed in a stainless steel structure with a tapered shape. Berton says this reduces hydrodynamic drag significantly and also makes the unit rugged enough to withstand a grounding.

Also, because its motor is comparatively compact and light, the Yacht Thruster draws a nominal current that’s less than a more conventional unit’s, according to Berton. He has one on his 37-foot Intrepid and says he ran it for 30 minutes straight without depleting the battery. 

Generally speaking, customers are demanding better response from thrusters these days. So manufacturers of tunnel-style models have been developing ever-larger units. For the boat owner, this means less stowage space under a forward berth, where thruster motors are typically housed. Also, when engaged, these larger units are also much louder, which is unsettling for anyone relaxing belowdecks. Marinno recorded sound levels at the helm of a test boat. The Yacht Thruster was 14 decibels quieter than a tunnel thruster and 9 decibels less than a retractable model. And finally, power units for traditional thrusters are typically housed in a small confined area and may eventually succumb to corrosion caused by humidity and moisture buildup. On extremely hot days, they will also overheat that much more quickly.

While the price of the Yacht Thruster ($4,000 to $6,000 depending on the installation and size) might seem steep, you may save considerably in labor because there’s no fiberglass laminating required. Installation is fairly simple. For a bow-thruster application, one hole is cut with a holesaw for the through-hull as far forward as possible and then two more are cut for mounting studs that attach the unit to the hull bottom. Stern-mounted units are fixed low and as close to the boat’s transom as possible. It’s important for both to use the proper sealant between the running surface and the thruster and to properly tighten the bolts on the studs. The install kit comes complete with a backing plate and vibration dampeners.

The final steps are easy. You simply run a wire harness from the thruster to a set of relays and from there to a control panel on the dashboard (an optional remote is available) and connect the power cables to the batteries.

DIY? As a reasonably handy guy, I’d feel comfortable doing an installation myself. Several models are available, in both 12- and 24-volt versions. Configurations include bow thrusters, stern thrusters, and even a duplex thruster, which has two units in one housing, for larger boats. For smaller vessels (to 35 feet or so), Berton says you can simply piggyback off the power feed from an anchor windlass. Just remember to follow ABYC guidelines and use a marine-grade splash-proof bus or terminal strip in your anchor locker.

Bottom line? If you’re really getting tired of struggling with the elements while docking your boat at day’s end, but you’re a little leery about what you see as the complexities of conventional thruster installation, cheer up. The new Yacht Thruster may be your answer.

Yacht Thruster, 888-898-8608;

This article originally appeared in the July 2012 issue of Power & Motoryacht magazine.