If a manoeuvring aid is to be retrofitted, it is rarely possible to avoid the complex and therefore expensive installation of a tunnel. The installation of the external bow thrusters from Sidepower is much simpler. The motor and propeller are located under the hull. And only three small holes are required for the cable feed-through and the anti-rotation device.
A side effect of underfloor mounting is that the bow thruster can be installed very far forward, even on very shallow underwater vessels. This extends the lever arm and less power is required. The motor is also well cooled, which ensures significantly longer operating times. The propeller tunnel is also very short, which reduces the risk of cavitation of the bow thruster.
On the other hand, there is an increased flow resistance, but thanks to the new fairing called Hydropod, the braking effect should be limited. Sleipner states that the flow simulations predict an additional drag of less than five kilograms at a speed of 7.5 knots. Such a value is unlikely to be noticeable or measurable on most cruising boats, especially as it is unclear how much a conventional tunnel slows the boat down.
The bow thrusters run on 12 volts, are available with 30 and 50 kilograms of thrust and weigh 14 kilograms each. The SX35 model costs around 3400 euros and is suitable for boats up to 10 metres in length. The SX50 costs around 3600 euros and is designed to turn yachts up to 11 metres. Both are also available as Pro versions. The power can then be regulated and the control unit also offers a hold function, for example to push the yacht to the pier with the transverse thruster until the lines are handed over and occupied.
Further information from Manufacturer or with SVB which also has the bow thrusters in its programme.
