For most Admiralty lawyers most of the time, the question “what is a ship?” does not feature large on the radar. In the vast majority of cases there is no difficulty; the detailed working out of the question thus tends to be something left to law professors with time on their hands. Not always, however. An important recent battleground is ROVs. Although almost invariably controlled from ships, these can be pretty valuable pieces of kit in their own right, such that a right to arrest them and thus obtain security over them becomes worth having for a maritime claimant.
Yesterday the Australian Federal Court faced the issue in Guardian Offshore v Saab Seaeye 1702  FCA 273. The definition of a “ship” in the Admiralty Act 1988 (Cth) is very similar to that in s.313 of our own Merchant Shipping Act 1995: namely, a vessel of any kind used or constructed for use in navigation by water (though a few specifics are expressly incorporated). Colvin J had to deal with a purported arrest in Western Australia of a Saab Leopard, an electric underwater survey contraption looking a bit like an overgrown air-conditioning unit which could be made buoyant but only by the inflation through an umbilical cord of flotation bags attached to it.
His Honour, having gone through the English and Australian authorities going back to The Gas Float Whitton  AC 337, decided it was not used for navigation and hence not a ship. It was very small, lived a lot of time on the sea bed, had very little power of directed motion, and had little in common with any other kind of vehicle used in navigation. He therefore vacated the arrest.
One suspects strongly that the result would be similar in England. But note three things.
- This case does not hold that a ROV is not a ship: merely that this ROV isn’t. A miniature submarine with substantial power of directional travel and natural neutral buoyancy we suspect would be likely to be potentially classed as a vessel used in navigation, and hence liable to arrest. There’s nothing odd in saying some ROVs are and some are not ships, just as (probably) some jetskis are and some aren’t: compare Steedman v Scofield  2 Lloyd’s Rep. 163 (simple jet-ski not a vessel with R v Goodwin  EWCA Crim 3184;  1 W.L.R. 546 at  (more substantial jetski might be a vessel).
- An interesting issue remains unexplored. If the mother ship had been arrested, would a ROV operable only from and in connection with that vessel be regarded as part and parcel of it? (Compare Morlines Maritime Agency Ltd v The Skulptor Vuchetich  FCA 41; (1996) 136 A.L.R. 206). What if one person arrests the ship and someone else the ROV?
- A ROV can be not only a ship but something supplied to a ship under s.20(2) of the SCA 1981: The Sarah  CSOH 161,  1 Lloyd’s Rep. 546. This looks odd, but seems logically possible: compare the case of, say, a motor lifeboat.
One thing seems certain. We haven’t heard the last of this.