Choosing a tender is rarely about finding the fastest boat on paper; it is about matching a small vessel's capabilities to the realities of your mothership and the experience you want to deliver guests at anchor. The evidence here supports a direct comparison of three production tenders—the SACS Strider 15, the Swan Shadow, and the Williams DieselJet 625—across the three metrics that most often decide the shortlist: top speed, guest capacity, and overall length. It also clarifies the more fundamental question lurking behind any tender purchase: whether a production model serves your program better than a fully custom build.
Superyacht Tender Performance at a Glance
The table below normalizes the published specifications for the three models into a single view, so the trade-offs become immediately visible. All figures are drawn from the builders' and marine media's published data for these specific configurations.
| Model | Top Speed (knots) | Max Guests | Length Overall (m) |
|---|---|---|---|
| SACS Strider 15 | Up to 42 | 16 | 14.97 |
| Swan Shadow | Up to 55 | 18 | 13.23 |
| Williams DieselJet 625 | Approximately 40 | 11 | 6.32 |
Read together, the numbers tell a clear story of positioning rather than simple hierarchy. The Swan Shadow, described by Yachts Croatia as carrying Nautor's design heritage into the powerboat category, is both the fastest and the most guest-capacious of the three, reaching up to 55 knots with its triple 250hp engine installation while seating up to 18. The SACS Strider 15 gives up roughly a third of that speed—up to 42 knots on twin Volvo Penta D6 440 units—but matches a day-cruiser layout for 16 guests across a longer 14.97-metre hull.
The Williams DieselJet 625 plays an entirely different role. Its published maximum of 74 kph, roughly 46 mph or about 40 knots, comes from a single 230hp Yanmar, and its eleven-person seating reflects a compact 6.32-metre hull that Williams Jet Tenders positions as a "reliable, dry riding and safe performance watersports workhorse." It is not competing with the two larger vessels on speed or capacity; it is competing on utility, stowability, and the ability to serve as a ship's tender where garage space and davit limits matter more than headline performance.
One practical observation follows directly from the juxtaposition: speed and capacity do not scale together in any predictable way across this selection. The fastest boat is not the longest, and the longest boat is not the most capacious. An owner who prioritizes guest throughput at anchor may find the Swan Shadow's 18-person capacity decisive; an owner whose program centers on watersports and shipboard convenience may find the DieselJet 625's proportions exactly right.
