Both vessel types are offshore support vessels. The daily work, the schedule and the required skills are different enough that officers who have done both consistently describe them as distinct careers rather than variations on the same job.
What Each Vessel Does
PSV, Platform Supply Vessel: runs cargo between shore bases and offshore installations. The defining operational activity is DP cargo transfer alongside rigs and platforms. The vessel carries deck cargo and bulk liquids. It transits, it arrives, it works alongside the installation, it returns. Repeat, indefinitely.
AHTS, Anchor Handling Tug Supply Vessel: does the supply function but adds the anchor handling capability. When a semi-submersible drilling rig needs to move location, AHTS vessels recover the rig’s anchors, attach towlines, tow the rig to the new position and re-set the anchors. Between rig moves the vessel does supply runs like a PSV.
The anchor handling work is in a different category of operational intensity from supply runs. Moving a drilling rig involves heavy equipment, high loads on winches and towlines, close-quarters work around a large floating structure and conditions that are often challenging. AHTS vessels operating in the North Sea in winter during a rig move are working in one of the more demanding environments in commercial shipping.
Size and Power
PSVs are typically medium-sized vessels designed around deck cargo capacity and tank volume. The power plant needs to support DP operations but the vessel is not built around raw bollard pull.
AHTS vessels are built around power. The anchor handling winches are enormous. Bollard pull, the measure of towing force, is a primary specification for AHTS vessels. Large North Sea AHTS vessels have bollard pulls of 200 tonnes and above. This requires substantial engine power and the vessels are larger and more powerful than most PSVs.
Skills and Certificates
Both require DP certificates for officers. The anchor handling work on AHTS vessels requires additional competency that is typically built through sea time and company-specific training rather than a separate certificate.
AHTS deck officers develop skills in heavy lift operations, towline management and anchor pattern operations that PSV officers do not routinely work with. This makes AHTS experience distinctive on a CV in a way that straightforward supply vessel experience is not.
Pay
North Sea monthly rates at senior levels:
PSV Chief Officer: $8,000 to $12,000. AHTS Chief Officer: $9,000 to $14,000.
PSV Master: $10,000 to $15,000. AHTS Master: $12,000 to $18,000.
The AHTS premium reflects the more demanding operational requirements and the smaller pool of officers with relevant experience. Large AHTS master positions with North Sea operators at the top of the pay scale are among the better-compensated positions in offshore shipping.
Career Implications
Starting on PSVs is more accessible. Entry into offshore is easier through supply vessels where the core requirement is DP competency and watchkeeping experience. Officers without offshore backgrounds find PSV positions more available than AHTS positions at entry level.
Building AHTS experience after establishing a PSV career is a natural progression. The pay premium and the operational interest of the anchor handling work motivate many officers to make this transition after a few years on supply vessels.
Officers who build substantial AHTS experience, particularly with large vessels in demanding environments like the North Sea, have a career profile that is recognisably different from general offshore officers and tends to command better pay and more options.