A diving programme is the brief that exposes a chase boat's compromises faster than almost any other. The boat has to carry weight (cylinders, weights, rebreathers, compressor), it has to carry people (a divemaster, a few crew, six to ten divers in kit), and it has to do both in a sea state that's often borderline for the mothership's stern garage. Get the spec wrong and you end up using a SOLAS rescue tender as a dive boat, which works once and then stops working.
What the role actually demands
A dive-led chase boat is a working platform first. The deck has to swallow tanks in racks, regulators on hooks, weight belts on rails, and still leave room for two divers to kit up at the same time. Most superyacht programmes settle on something between 12 and 16 metres, which is enough to carry the kit and absorb chop on the run back, but small enough to launch from a dedicated shadow vessel or to follow the mothership without imposing on charter guests.
The four constants on every brief we've worked on:
- A flat working deck aft with non-slip, fresh-water washdown, and recessed tank racks
- A dedicated bench seat with stainless backrest for kitting up, ideally on both sides
- A swim platform low enough that a diver in full kit can step in and out without a ladder gymnastic
- A compressor and storage hold separated from the working deck, ventilated, with adequate sound attenuation
If the boat doesn't have those, you're retrofitting them. If you're retrofitting them, you've bought the wrong hull.
Powertrain and range
Diving rarely happens within a mile of the mothership. A reef worth visiting is often two hours away from the anchorage, sometimes more if the programme is moving between islands. The dive day is also long: a 6am departure, two morning dives, surface interval, an afternoon dive, then the run home. That puts a real number on range.
We brief 200 nautical miles at cruise as a working minimum. That usually means 1,500 to 2,500 litres of fuel and a twin or triple outboard package in the 1,200 to 1,800hp range, or twin diesel sterndrives if the programme operates in the Indian Ocean or the South Pacific where outboard servicing is sparse. Quad outboards on a 14m hull look impressive on a boat-show stand. They're also a maintenance bill that nobody reads carefully until the second season.
For programmes operating from a support yacht, the chase boat's autonomy matters less than its launch and recovery cycle. A boat that can be lifted in the swell at the end of a long day, with a divemaster who's been in the water four times, is a different specification problem.
Compressor, nitrox, rebreather support
Most serious dive programmes today run nitrox, and a meaningful minority run closed-circuit rebreathers. That means:
- An onboard high-pressure compressor (Bauer Mariner or equivalent) sized for the daily fill load
- A nitrox membrane or partial-pressure blending station, with O2 storage in a separate locker, vented, with the right flag-state sign-off
- A rebreather sorb storage area kept dry and temperature stable
- 240V power for chargers (handsets, scrubbers, lights, cameras)
If the chase boat is being asked to handle all of this, it has to be specified for it from the keel up. Compressor noise alone can drive a poorly thought-through chase boat off the brief; we've seen 20m boats where the compressor location made guest conversation on the foredeck impossible.
Crew, certification and operating envelope
A dive chase boat is operated by qualified crew, which means RYA Yachtmaster offshore as a baseline for the skipper, a divemaster (PADI or BSAC) as a minimum, and ideally an instructor for charter operations. The boat itself is usually MCA Workboat-coded under the Workboat Code, or operated under the tender's classification if it falls under 24m and stays inside the parent yacht's operating area.
Coding determines passenger numbers, operating distance from a safe haven, and life-saving appliance scope. A boat coded Cat 2 (60 miles from safe haven) is usually enough; Cat 0 (unrestricted) is overkill for almost every dive programme.
Builders worth the brief
For dive-specific or dive-tolerant chase boats, the names that come up regularly are Ribco, Pascoe, Hodgdon, Tecnorib (Pirelli), and Wajer. The choice depends on the parent yacht's geography, garage constraints, and whether the dive load is the primary brief or one of three or four jobs the boat has to share. If diving is the primary brief, we usually steer owners toward a purpose-built chase platform rather than a sport-tender derivative.
If you're scoping a dive-capable chase boat now, start with the brief before the hull, not the other way round.