Beautiful weather has allowed the iXblue survey team to achieve great progress on the joint LINZ/Marlborough District Council survey project, since arriving onsite in the beautiful Marlborough Sounds region five weeks ago.
The crew and daily operations
The vessel Karen D is crewed by two Pacific7 personnel who share the driving, engineering and cooking duties to keep the operation running smoothly.
iXblue is using two survey personnel at a time on this project, and for the second time in recent years we are fortunate to welcome a NIWA scientist onboard to assist with scientific record keeping.
The team has been working daylight hours from 7am to 6pm most days. Being able to anchor or moor in close proximity to the survey area has reduced the downtime we usually experience when we have to transit daily from an alongside facility.
Interesting facts about the Marlborough Sounds region
I was fortunate to spend a half day on the vessel recently and gain an appreciation of the size of the area being surveyed, and the operational environment the team is working in.
Early in the project, the team surveyed the notorious French Pass region. This is a narrow choke point between two large bodies of water. The tidal stream and current in this region is quite extraordinary and well worth a look should anyone be fortunate enough to be visiting the area. It is one stretch of water that warrants extreme navigational care for any mariner.
For the trip out to the Karen D survey vessel, we caught a water taxi from the town of Havelock. The driver had spent many years working in the local mussel industry and was a fountain of knowledge. I was amazed to learn that there are approximately 550 tonnes of scallops harvested from over 600 mussel farms in the Marlborough Sounds region every day of the year.
At the moment, the scallop farmers are selling their produce at about NZD$1,300 per tonne. It is easy to understand the value of this important industry to the NZ economy and the important role played by the Marlborough District Council to properly manage and protect this industry and resource for future generations.
The best quality data we’ve ever seen
The new Kongsberg Em2040 dual head, dual swath system and iXblue HYDRINS sensors have performed faultlessly from day one, and are producing the best quality data we have ever seen.
The resolution and data density generated by this system is next level when compared to our recent projects. It is another great example of what is possible when a large number of world leading OEMs continually strive for technical perfection.
A big thankyou to all of the teams at Kongsberg, iXblue, Valeport, Fugro (MarineStar), QPS and Caris for providing us with such outstanding sensors and software.
New fairing design not fairing so well
In our last blogpost Equipment Choices for our New Survey in Western Marlborough Sounds, NZ we mentioned that we had designed and built a new mount for the EM2040 system which is considerably larger than the Em2040 Compact system we’ve used in the past. We decided to experiment and build an over-the-side mount that offered a low drag, hydrodynamic design. It is always preferable to minimise the flow of turbulent water across the face of the sonar and to reduce the inherent drag and vibration on the pole that secures the sonar to the vessel.
If you’re interested in how it is performing, the answer is that it is not.
During our initial sea-trials and testing of the system, we were experiencing excessive movement and vibration on the pole. Subsequent tests with the fairing removed significantly reduced the movement on the pole. So it was an easy decision to undertake the survey minus the fairing.
It has once again highlighted for us the complexity and challenge associated with designing and building multibeam mounts that are fit for purpose on small boats. It is back to the drawing board for this mount design! Whilst the outcome was both interesting and disappointing, the fact that the system is generating such high-quality data without any hydrodynamic fairing whatsoever does go to show that a little luck never goes astray in this business!
I certainly enjoyed my brief sojourn into the real world of surveying, and look forward to having the opportunity to escape the office and do it again.