Delta Marine's 46m Zembra Launches With a Sub and a Seaplane

A three-year build ends at the Seattle waterline

Delta Marine launched Zembra on the Duwamish River on 21 August 2026, closing out a build that began when the owner commissioned the 46.3-metre full-displacement hull in 2023. The yard joined hull and superstructure in August 2025 and spent the following year outfitting the interior, a schedule that is unremarkable for a fully custom explorer of this size but still a reminder of what a bespoke commission actually costs in time: roughly three years from signature to splash, with delivery to follow later in 2026.

The finish sets Zembra apart at a glance. Delta Marine painted the hull a metallic Arizona bronze rather than the white that dominates the explorer category, paired with an angular composite superstructure and expansive glazing that keeps the interior visually connected to the water. It is a styling choice, not a technical one, but it signals a builder confident enough in its full-displacement platform to spend the differentiation budget on how the boat looks rather than on a novel hull form.

The equipment list is the point of an explorer yacht

What actually defines Zembra as an explorer rather than a large cruiser is the gear she carries to leave the anchorage: a two-seat ICON A5 amphibious aircraft and a three-passenger U-Boat Worx submersible, launched and recovered with a 3,500lb SWL boom crane on the bridge deck and a separate stern gantry crane, plus a helicopter landing area on the sundeck for owners who want a third way off the boat. Carrying a submersible and an amphibious aircraft together, not one for the brochure and a jet tender for everything else, is still unusual on a yacht under 50 metres, where deck and garage space is tight enough that most owners pick one toy class and commit to it.

The accommodation plan carries the same intent through to accessibility. Zembra has five cabins for ten guests, including a full-beam master suite on the main deck and a wheelchair-accessible cabin among the four below, served by an elevator that reaches all four decks. A sixth berth arrangement converts from a fitness cabin using Pullman berths, taking capacity to twelve when needed. Specifying wheelchair access from the keel up, rather than retrofitting a cabin after the fact, is a harder and more expensive design problem than it looks, and it is still rare enough in the explorer category to be worth naming.

Delta Marine's own record sets the expectation

Delta Marine's pedigree in this category goes back further than Zembra. The Seattle yard built commercial fishing vessels from 1967 before moving into custom motor yachts, and its two best-known full-displacement explorers carry genuine ocean-crossing numbers: the 163ft Triton is built for a 6,000-nautical-mile range at 13 knots on twin Caterpillar 3508 engines, and the 164ft Arianna is rated for 5,000 nautical miles at the same cruising speed. The 124ft Marama, delivered in 2008, backed the numbers with a real voyage, a three-month, 3,200-mile trip to Alaska and back that the yard still points to as proof its expedition hulls hold up away from a marina.

That history is the strongest argument for Zembra sight unseen: a yard that has repeatedly delivered five-figure-nautical-mile range on full-displacement platforms is a safer bet for an expedition commission than a builder doing its first long-range hull. It is also, for now, an inference rather than a published fact about this specific yacht, which is the gap the next section covers.

What is published, and what is not

Neither Delta Marine nor Northrop & Johnson, the charter broker appointed for Zembra, has released her range, top speed, fuel burn or engine specification beyond confirming twin Caterpillar power and zero-speed stabilisers. For a boat sold partly on expedition credibility, that is the number an owner comparing her to Triton or Arianna actually needs, and on launch day it simply is not on the record. A weekly charter rate has also not been disclosed; the broker's own framing, that Zembra is 'one of the hottest anticipated explorer yachts' coming to the market, is marketing language ahead of a tested price, not a market result yet.

Northrop & Johnson has pointed the charter programme at French Polynesia, Norway and the Caribbean, remote-water destinations that make sense for a boat carrying a submersible and a seaplane, but no guest has chartered her, no owner has logged a season aboard, and no independent trial has been published. Anyone reading the adventure-equipment story around Zembra today is reading the yard's and the broker's version of it, which is accurate as far as it goes but is not yet anyone's lived report from the water.

Zembra joins a small, real category, not a marketing invention

Pairing a submersible with an amphibious aircraft is unusual but not unique to Zembra. Pendennis built the 35-metre Fox to carry a submersible, amphibious vehicles and modular science labs alongside twin 2.3-tonne deck cranes, and the Silent 120 Explorer pairs a U-Boat Worx Nemo submersible with an Xcraft XP4 amphibious aircraft, charged in part from solar power. U-Boat Worx submersibles in particular now turn up across several yards' expedition builds, which suggests the equipment itself is maturing into a standard option rather than a one-off flex, even as the aircraft pairing stays rare.

What sets Zembra apart within that small group is size relative to accommodation: at 46.3 metres she carries the same aircraft-and-submersible combination as the smaller Fox while adding five staterooms, a wheelchair-accessible cabin and a four-deck elevator, a guest-comfort specification the more expedition-focused Fox does not prioritise to the same degree. For an owner comparing the two philosophies, that is the real choice Zembra represents: expedition capability without giving up the accommodation standard of a conventional charter yacht, at the cost of the unpublished performance numbers this article has already flagged.