Hi Joe, Quick email to let you know that the recent dredging project in Brunei was completed without a single minute downtime on the 4” Vortex dredge. 316hrs dredging for the 32 day project. Please see comments in the email below from the ROV Supervisor.

We all think its great, no problems with it, worked really well and was reliable. Exactly as the last project, the 4” hoses started to show signs of wear which was understandable. This year we requested a spare 4” hose to be included with the equipment to be ready for this. Perhaps spare hydraulic hoses may be included in future hires.

Only down side is a small one, after using it approx. 22hrs a day for 3 weeks, the intake hose wore through and needed to be patched up. The 4” Vortex Unit from Vortex International was integrated onto our Quasar ROV for a pipeline damage survey for BSP in Brunei. 120 locations were dredged over a 30 day period without incident or breakdown.

System was professionally packaged and much thought was put into the dredge mounting by Vortex. System integration was fast and simple. Unlike previous dredge systems, no water found its way into the ROV hydraulics system over the entire project, which I have to admit would be a first in my experience of working offshore.

Although the system was rented through a third party organization, the team at Vortex made themselves available should any issues come to light. Feedback was also taken on board as we wore out a suction hose during the project.

Very impressed with the Vortex Equipment and would definitely use it again next season.

This item of equipment has been used extensively on the TAQA Causeway project UK – P768 and was for the vast majority of the time fitted to TXLS 25.

The kit is excellent, performance is far beyond what was expected for such a compact item. The system achieved 100% operational time, no breakdown whatsoever. On a couple of occasions we had to recover to unblock the suction hose, but considering the oil based mud and small items of debris that the dredger was having to deal with, this is not at all surprising.

Perhaps the most refreshing thing about the kit is the way it is transported. The transit case has a hinged lid with inbuilt rams that prevents the lid from dropping closed. This is an excellent safety feature.

Once opened, the layout is well designed. Cargo straps secure items in place, information regarding the equipment is pasted on the inside of the lid, operational and service manuals are included.

All in all we would have to say A1 equipment, A1 research and development and A1 for safety and design.

Vortex worked quickly to mobilise the dredger onto our Triton XLX ROV with a minimum of fuss.

The company was proactive in arranging for the required adaptor frame to be fabricated and during operations the dredger worked flawlessly, with no down time. The Vortex 6" dredger comfortably exceeded our expectations in very sticky, highly cohesive soil, with an incredible amount of suction power for such a small unit.

We don't know of any other 6" system in the marketplace that can compete. This operation reaffirms our commitment to selecting Vortex dredgers whenever possible for our subsea operations.

We found the Vortex Dredge Skid fast and efficient to interface to the ROV due to the adaptor skid manufactured to fit an XLX frame. The skid was neutrally buoyant eliminating the need to add further floatation.

The operation of the 6" Vortex Dredge was excellent throughout which decreased the expected time to complete the dredging operations. 

DOF Subsea regards performance, reliability and service as paramount when hiring equipment. We will use the Vortex Skid again and would recommend its hire to any company in the future.

All in all we were very impressed with the TORNADO 4 inch dredge unit. We thought that the sand it was moving was soft and silty, but the divers informed us it was a hard packed seabed.

They could not drive a pick into the ground more than 1 ft. The dredge didn't have any problem fluidising it and moving it. You could not stall it either. Punch it into the ground with the 7f, and watch a hole appear in front of you.
It was quite therapeutic to watch the sand collapse into a hole. I suppose what we were moving was pretty much beach sand type composition, which had the odd large shell in it.

It took around 5 mins to form a hole which the 7f could not reach to the bottom off, which measures around 500mm deep, and 1m across. We spent more time relocating and waiting for the viz to clear so we could see where we were at, and then could carry on the dredging in the right direction. Nothing you can do to help that.

Marine Growth Sample Tool & Seabed Sample Grab Tool

We used the marine growth sampling tool a couple of days ago. Took six samples from one face of the first location, from about -10m down to about -70m. It was a success collecting samples. The scraper worked well, but some of the sample which was sucked into the hose did get lost so not all of the sample made it into the bag. But enough was retained that the scientists were happy with the results. Gary on the 7-function impressed us all by catching a couple of larger chunks which were falling having escaped the suction!

The seabed grab has been a great success. We have completed about 70% of the sampling around the second location & 75% around the first location. Progress has been slow, only because we've been doing it in SIMOPS with ROV inspection. But the mechanism has been very reliable. There have been a couple of mis-triggers where we have sampled some seawater instead of mud, but we've pushed the limits to 3m+ swell and 30kts of wind and it has kept producing the results. The only reason we haven't used it in worse conditions is because above those limits we can't use the crane and there is no other method to safely deploy it, so we have in no way been limited by the tool which was the intent of the design.

The Vortex unit was extremely efficient in removing the top layer of sediment, but the lower more consolidated sediments proved to be more difficult with a reduced rate of progress. 

 he Vortex 4” dredge system still removed this material without having to break up the clumps of clay first. Some clogging of the suction nozzle guard occurred as shells were picked up and could not pass through the constriction. These blockages were cleared by the ROV at seabed without any significant inconvenience.

Conclusions & Recommendations:
The general consensus of personnel involved was that the Vortex 4” dredge system out-performed other self contained ROV dredge systems previously used.

Subsea oil absorption tool:

The sampling went well. The pump is just a smaller version of the zip pumps we already use minus the circuits for blow or suck or jet. The tubing lenths were adequate to mount the pump on the porch and the filter rack on the back of the ROV. I didn't take pics of the install due to the comp issue taking all our time. The only issue we had was not having 1" cam lock plugs to run less than 10 filters at a time if we wanted too. We did manage to locate 5 cam lock plugs from the vessel but if they had them in the kit it would make the kit more flexible to the end user.

Overall I would say it's one of the better kits I've seen. All the hoses and pump fittings were blantantly marked so we didn't have to spend time in the manual. The installed PRV was already set up so we could run the IHPU to 100% if there was a reason to.

This is as close to a true plug and play setup that I've seen in a while.

We offer a wide range of dredging solutions to suit most deep sea applications. The below graph shows our current selection of dredge solutions from the Electric 2 1/2 inch, to the larger BLACK HOLE 8 inch dredge.


We can also tailor a dredge solution to specifically suit your hydraulic supply if by chance your requirements are not covered by our extensive range. If you require a custom dredging solution please contact us directly.