Sea Trials Report:MY TangoFarm Cove, Sydney Harbour, AustraliaFriday 25th November 2016

Less Motion, More Ocean

Introduction

The sea trial described in this report was recorded on the 42.5m aluminium motor yacht Tango. MY Tango was built in 2006 by Oceanfast Yachts in Western Australia. The yacht cruises regularly on Sydney Harbour. VEEM is very pleased to have been selected to improve the comfort of the yacht at anchor in various preferred locations on Sydney Harbour.

MY Tango is fitted with traditional Naiad fins (i.e. there is no at rest stabilisation provided by the fins). The owner tasked VEEM Gyro with significantly improving the comfort of the yacht at anchor in various locations within Sydney Harbour. The challenge within Sydney Harbour is the frequent passing of various types of ferries. The mix of ferries on the harbour spans heavy displacement monohullsright through to high-speed catamarans. Each ferry type has a unique wake. Some of the fast catamaran ferries have a transverse stern wave as part of their wake. The rolling motion caused by this transverse wave were particularly problematic for MY Tango.

In very close conversation with the owner and his team, a Profile 1 gyro installation was selected. This is an unusually small gyro selection for a yacht of this size, but it was deemed appropriate given the very specific performance requirement. Following a very neat installation of the gyro in Brisbane by Matt Curtin-Andrews and his team, the gyro was commissioned by a VEEM team, and was ready for sea trials in her typical operating environment on Friday 25th

November 2016.

Sea Trials Report:Motor Yacht Tango, Sydney Harbour, Australia 25th November 20161 x VEEM Gyro 120 Installed

FerryRoute

VG120GyroLocation

Sea Trials Report:Motor Yacht Tango, Sydney Harbour, Australia 25th November 20161 x VEEM Gyro 120 Installed

The InstallationThe VG120 gyro was installed in what was previously the lazarette. Tango recently completed a refit during which a new beach club was added, increasing the length of the yacht by 6m. The installation was completed by MCA Marine in Brisbane, Australia as part of a larger refit workscope. The aft bulkhead of the lazarette was removed to allow the gyro to be rolled into place on specially built rails, and then lifted onto structural mounting beds designed by Austal Ships. Maintenance access for the gyro is excellent, with walk around access and clear access above.

The yacht was relocated to Sydney Harbour prior to gyro commissioning. Commissioning and sea trials were carried out in the yachts normal operating environment of Sydney Harbour.

The yacht went smoothly into service the following day. Reports from the yacht indicate that several specific improvements in the yacht were noted. These included a more stable swim platform making guest transfer from the tender faster and more comfortable, reduced sloshing in the fore deck pool as well as a general reduction in rolling motions making the onboard experience more comfortable. The yacht is now reviewing options for widening its operational area due to the improved comfort in waves.

The Installation… continuedThe photos below show the VG120 gyro happily in place within MY Tango. The enclosure panels have been removed to reveal the high spec finish, high quality fittings and beautiful looks of the VEEM Gyro 120.

Sea Trials Report:Motor Yacht Tango, Sydney Harbour, Australia 25th November 20161 x VEEM Gyro 120 Installed

Trials LocationThe sea trial was carried out in Farm Cove in Sydney Harbour. MY Tango was at anchor near the centre of the Cove. The wave environment was caused by passing ferries of various types and sizes. The waves caused by wakes from these ferries were acting directly on the yacht. In addition, reflected wake waves from the rock walls of the bay were acting on the yacht. The resulting wave environment was a confused slop from multiple directions. This is typical of the anchoring conditions in Farm Cove.

The requirement identified by the owner for the gyro stabilisation system was to significantly improve the comfort at anchor in various Sydney Harbouranchoring locations with frequent wake wave from passing ferries.

The trials area is indicated below.

SydneyOperaHouse

SydneyHarbour Bridge

TrialsLocation

FerryRoute

Sea Trials Report:Motor Yacht Tango, Sydney Harbour, Australia 25th November 20161 x VEEM Gyro 120 Installed

Roll Angle ResultsA strip chart and RMS spectrum (square root of the power spectral density) of the roll angle of the vessel with the gyro OFF and then ON is presented below. The reduction in RMS roll angle is 61%.

Roll motion measurements were recorded for approximately ten (10) minutes with the gyro locked in Standby mode (OFF) and then in Active mode (ON). This allowed in excess of 100 waves to pass under the vessel for each condition. The recording was not switched off between the ON and OFF tests. The chart below is a continuous data recording.

Sea Trials Report:Motor Yacht Tango, Sydney Harbour, Australia 25th November 20161 x VEEM Gyro 120 Installed

Elapsed Time [seconds]0 200 400 600 800 1000 1200

Gyro ON Gyro OFF

RollAn

gle

Roll Angle RMS SpectraThe RMS spectrum (square root of the power spectral density) of the roll angle of the vessel with the gyro OFF and then ON is presented below. In these conditions the VG120 reduced the RMS rolling angle by 61%.

The chart below indicates that the natural rolling period of Tango is around 5 seconds.

It can be seen that the resonant rolling has been virtually eliminated.

Period [seconds]0 1 2 3 4 5 6 7 8 9 10

GyroOFF

GyroON

61%RollReduction

5secondRollPeriod

Sea Trials Report:Motor Yacht Tango, Sydney Harbour, Australia 25th November 20161 x VEEM Gyro 120 Installed

RollRM

SSpectrum

Sea Trials Report:Motor Yacht Tango, Sydney Harbour, Australia 25th November 20161 x VEEM Gyro 120 Installed

VEEM Ltd, 22 Baile Road, Canning Vale, 6155, Western AustraliaTel: +61 8 9455 9355 Email: gyro@veem.com.au

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