Offshore vessels are often lumped together as "supply boats", but the types solve different problems. Choose the wrong one and you either pay for capacity you do not use, or lack capacity you need.
PSV — Platform Supply Vessel
The PSV is the workhorse of routine supply. It is built around a large open cargo deck with under-deck tanks for bulk: drilling mud, cement, fresh water, base oil and brine.
Typical work is rotating supply to fixed installations and rigs, plus backload of empty units and waste to shore.
AHTS — Anchor Handling Tug Supply
The AHTS is built for power. It carries winches and towing capability to handle anchors, run and recover moorings, and tow mobile units.
AHTS vessels are used in rig moves and anchor operations. They can carry cargo too, but the deck is smaller than a PSV because the winch arrangement takes space.
How to choose
- Routine supply with general cargo and bulk: PSV.
- Rig moves, anchor handling or towing: AHTS.
- Combined scope: consider whether two specialised sailings cost less than one vessel doing both jobs poorly.
The capacity that actually constrains you
Many plan on deck area alone. In practice the binding limit is often deadweight, tank capacity for the specific bulk type, or the number of lifting operations achievable inside the weather window.
Establishing which of these is the true constraint — before booking — is the simplest way to avoid a half-empty or over-booked sailing.
Frequently asked questions
What does OSV mean?
OSV stands for Offshore Support Vessel and is an umbrella term. PSV and AHTS are both OSV types.
Can a PSV tow a rig?
No. Towing and anchor handling require the winch and bollard pull capability of an AHTS.
Why is "supply" in the AHTS name?
AHTS stands for Anchor Handling Tug Supply — alongside anchor handling and towing it can carry supply cargo, but with less deck space than a dedicated PSV.
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