Moving the ship’s crane for trials – A unique project

Moving the ship’s crane for trials – A unique project

With a lead time of only 6 weeks, our client had an urgent request to fit out their 120 tonne catamaran diving tender SHORELINE ENGINEER, based in Portland, UK with new deck cradles and winches. She needed to handle and tow the customer’s new equipment for development trials in and out of the water, all from the port quarter. The problem was her crane was positioned amidships to starboard; so we needed to advise whether to install a second crane, or move the ship’s existing crane aft.

We held a meeting to discuss the requirements of the project and identify the likely problems.  The key need was to make these structural changes to the vessel in a manner both safe and compliant, in order that that the MCA’s Cat.2 coding was still met. It was clear from the outset that the proposed changes would have noticeable effects on both the structural integrity and the stability of SHORELINE ENGINEER (1).

With the very short time frame to the start date of the trials, the only realistic option was to move the existing crane. Purchasing and fitting a second crane would have taken longer, even if one was available. However, the problem of the strength of the deck and underlying structure still needed to be addressed.

C Data Marine’s team of experts, Clive Robinson, Bob Barnes and John Hall, attended on board and carried out a structural survey of the stern, concluding that the quickest and safest method would be to replace the port engine removal access plate (2) with a heavy 20mm plate serving as the crane base plate. This new plate was bolted down to twin, longitudinal deep beams, supported by cut frames and watertight bulkheads. Both the deep beams in way of the access plate, and the underside.

e of the replacement mounting plate were to be reinforced with webs; and the new plate secured with UTS bolts (3). Structural calculations showed this approach to have more than adequate strength for the weight of the towed equipment.

Quest quickly set to and fabricated the new base and strengthening, moved the crane and ran temporary hydraulic pipes,(4), in time to carry out a new load test (6), and re-inclining experiment,(5).  We re-calculated the six crane loading conditions produced as a supplement to the stability book six years previously, which remained compliant with the MCA stability criteria.

The structural report, inclining witness report and supplementary crane stability conditions, were filed with the vessel’s certification authority, SCMS.

Thanks to excellent team work and cooperation all round, plus a rapid response and advice from the  SCMS, the trial was carried out successfully, and met the original timetable. Subsequently, Quest were able to move the crane back to the normal place, and replace the ship’s own winch, leaving the kit of parts readily available to repeat any similar task in future.

Quest’s project director, Ned Wiltshire, said on conclusion, “We were very pleased with the quick service which we received from C Data Marine which ultimately meant that the we were able support our client safely, on time and on budget”.

C Data Marine’s naval architects and marine engineers, considered this to have been a most innovating and challenging project, completed successfully in a timely manner. Their highly experienced team, with in depth practice in energy efficiency, is now responding to enquiries about the rapidly developing technical challenges of propulsion and power generation conversions and newbuilds with alternative fuels such as ammonia and methanol, and hydrogen fuel cells.