Seakeeper’s drive to expand their gyroscopic technology to an ever wider section of the boating population has taken a big leap with their launch of the Seakeeper 2. Making its debut at the Miami Boat Show, the Seakeeper 2 has pushed this technology boundary down to just 27ft. What was only recently the luxury of a 50ft motor cruiser is now small enough to fit inside the seat console of an open boat.
Since the introduction of the Seakeeper 5 in 2015 (PBR Issue 127) and the arrival of Seakeeper’s compact DC-powered Seakeeper 3 the following year, the benefits of gyroscopic stabilisation have been stretching downwards. However, the Seakeeper 2, weighing just 188kg and with dimensions of 24.8in x 25in x 20in, is 25% lighter than the SK3 but capable of getting to grips with a 7-tonne boat. It is aimed at boats between 27ft and 32ft, and is powered by 12V DC, so no genset required, just a decent domestic battery bank.
This is a proper DC system that does not require an inverter to convert DC into AC. It needs 900 watts of power to spool up to its maximum operating speed of 9000rpm, where it produces 3871ft/lb (5249Nm) of torque. It takes 35 minutes to reach this speed, though it is effective after 24 minutes. Its normal operating power is between 300 and 650 watts (depending on the sea). If you had a 3 x 100ah battery bank you could spend four hours at anchor without running the engines, and without discharging your batteries to a harmful level. The sound levels are 68dBc at 1 metre. Encased in a soundproof cavity, this would not prove intrusive.
Like any gyroscope it resists any lateral force to move it off its spinning axis. If you push the top of the gyro forward in an action known as ‘precession’, it will exert force on the port side of its mounting. Pushing it aft will reverse this effect to the starboard side. With the gyro in its locked position, unable to rock either way, it is ineffectual. The key is the timing of its fore and aft precession. Like any modern stabilisation system it is controlled by a roll sensor, or in this case two integrated roll sensors. An ECU then controls the whole operation via a control panel interfacing electronic intelligence with hydraulic power, which comes in the form of a hydraulic pump controlling four hydraulic rams. These rams control the direction in which the gyro tilts, as well as how far and how fast it tilts. The system has the ability to assess the wave pattern in order to act proactively rather than reactively. The limit of the fore and aft precession is determined by the amount of travel permitted by the hydraulic rams, so there is a limit to the duration of each stabilising thrust of the gyro. The precession speed also affects the amount of stabilising force produced, so if the gyro precedes fast it will have a short but powerful effect. To reduce the operating temperature and increase efficiency, the gyro chamber is a sealed vacuum, thereby removing air friction. A seawater cooling system runs through a freshwater heat exchanger while temperature sensors keep track of both the gyro motor and its shaft bearings.
UK agents Osmotech will have the first units ready for fitment around April/May this year, and we have been offered the opportunity to test one of the first systems fitted then. The cost is anticipated to be about £25,000 to £27,000 fitted.
www.osmotech.co.uk (UK South coast agents)