The two terms get used interchangeably in marketing copy and they should not be. A support yacht and a chase boat solve different problems, sit at very different sizes, and run with very different crews and cost bases. This page draws the line between them, and walks through how to decide which one a programme actually needs.
The short answer
A chase boat is a separate-hulled small craft (typically 8m to 20m) that follows the mothership to extend its toy programme, range, or guest-shuttling capacity. It runs on owner-supplied fuel, carries 6 to 16 passengers depending on size, and is captained by one of the yacht's existing crew or an extra rotation hand. Capital cost runs from EUR 0.5m to EUR 3m for the upper end; operating cost is a meaningful but contained fraction of mothership opex.
A support yacht (or shadow vessel) is a substantially larger separate vessel, usually 35m to 80m, that operates as a logistics and mission platform alongside the main yacht. It carries helicopters, submarines, larger toy fleets, expedition equipment, and additional crew that the mothership cannot. It runs with its own captain and full crew complement, and capital cost is on the order of EUR 15m to 70m.
You do not "upgrade" from one to the other; they answer different questions.
Where the categories overlap
The grey area is the upper end of chase (16m to 20m) bumping into the lower end of support (sub-35m). At that overlap you find boats like the larger Anvera 55 carbon platforms, custom Hodgdon chase units, and the Brabus Shadow 900 Cross Cabin. These run with one to two dedicated crew, can sleep four to six, and carry a meaningful toy capacity, but they are still chase-class in the way they integrate with the mothership.
Once you cross into a 30m-plus shadow vessel (Damen YS, Lynx, Rosetti Superyachts), you are buying a second yacht, with everything that implies for crew, registration, refit cycles, and operating cost.
How to decide
The question to start with is what the existing or planned mothership actually cannot do, ranked by frequency:
- Toy capacity. If the limit is "we cannot fit a third tender, the jet-skis, and the dive compressor in one garage," a chase boat between 12m and 16m typically resolves it.
- Speed gap to guest experience. If the yacht is a 60m displacement hull cruising at 14 knots and the owner wants 50-knot day excursions, a chase boat fills the gap. A support yacht does not.
- Helicopter operations. If the mothership lacks a touch-and-go pad, the answer is a support vessel. A chase boat will not solve it.
- Submarine, expedition, or large diving programmes. Support vessel territory.
- Crew capacity for extended itineraries. Mostly support-vessel territory; chase boats add at most one or two berths.
- Range extension on long ocean transits. Support vessel; chase boats are not designed for ocean passages.
In short: chase boats extend what the mothership can do on a given day. Support vessels extend what the mothership can do across a season.
Cost framing
Order-of-magnitude opex per year, very rough:
- Chase boat (12m, 2 crew, EUR 1m capital). EUR 80k to 150k all in: fuel, dockage, maintenance, crew rotation. Negligible against the mothership.
- Support yacht (50m, 8 crew, EUR 30m capital). EUR 2m to 4m per year. A second yacht-sized line item.
If the operating-cost gap is uncomfortable, you are probably looking at a chase boat, not a support yacht.