Asset datasheet
Skimmer-class hydrobot — general arrangement
Skimmer-class hydrobot: an uncrewed torpedo craft that stands on its own weapons. A low faceted hull is carried over the water on 8 composite legs, and each leg ends in a detachable AUW that serves as a float until it is sent. The legs work the swell so the body holds still, which is what lets a swarm of them keep low-power lasers focused on one target.
Key figures
| Hull | 5.6 m long, 3.6 m in beam |
|---|---|
| Float ring | 8.5 m by 6.3 m, 8 floats at 0, 42, 84, 132, 180, 228, 276, 318 deg |
| Float | 1.72 m long, 0.68 m across, splayed up to 9 deg |
| Deck above the water | 2.1 m; top of the deck houses 3.0 m |
| Leg lift | each leg independently, up to 35 deg |
What it is (preliminary)
This is the author's concept as it stands, written down ahead of the model. Only the geometry is modelled so far: the hull, the deck houses, the legs, the floats and how far each leg lifts.
The hydrobot is an uncrewed surface craft that carries torpedoes by standing on them. It is a spider: a hull held clear of the water on composite legs, resting on a swarm of six or eight detachable AUWs. The model is drawn with 8, each 1.72 m long and 0.68 m across, on a ring 8.5 m by 6.3 m.
On station
| Holding the horizon | In its ordinary state on patrol the craft uses the AUWs as its means of holding the horizon: the legs work against the sea and the hull stays level. A level hull makes it much simpler to point the laser air-defence head at what it has to hit. |
|---|---|
| Unloading the gyro | The same support takes a serious share of the load off the craft's control-moment gyro. |
| The heaviest parts of the system | The AUWs are the most massive elements of the craft. Each carries hydrogen fuel and the generation that runs on it, batteries for bursts of manoeuvring acceleration, and motors powerful enough to drive it at 90 knots. |
Attack
Against a serious target the craft lets its AUWs go two at a time, a symmetric pair at each release, and settles into the water as they leave.
- With every pair released the craft sits lower in the water.
- Its power-to-weight ratio falls with each release.
- It loses the ability to use the laser head actively.
The AUW as a weapon
Each AUW carries a shaped-charge head, and its attack is meant to go in three stages.
- The shaped charge burns through the hull of the ship attacked.
- Part of the hydrogen fuel the AUW still holds is driven through the hole it has made. Burning inside, it is expected to raise the temperature within the hull.
- The main charge detonates.
The fuel that brought the weapon to its target is thus part of what it delivers.
Not in the model yet
- The release of an AUW from its leg, and the craft's trim and freeboard as pairs leave.
- What an AUW holds: fuel, generation, batteries, propulsion, the shaped-charge head and the main charge.
- The six-legged variant.
- The laser head and the control-moment gyro as units of their own; the deck houses are drawn as an envelope.
Concept art
artPencil concept art: the current best, and the one used in the chapters
artThe original style reference the model was calibrated against
artAn intermediate study
Assembly sheets
Arrangement and structure
arrangementSkimmer-class hydrobot — general arrangement
skeletonSkimmer-class hydrobot — structural skeleton
Interactive and sources
- Model sourcesmodel.json, adapters.py and checks.py: the parametric model every sheet on this page is built from.
- Where it appears: chapter 11, Return to the IslandThe escort of the strike group.
Meshes
Meshes are cheap to rebuild and are not kept under version control: build.py --obj and --stl write them to mesh/ beside this page.
Every sheet, figure and mesh on this page is generated from one parametric model, and nothing is written until its geometry checks pass. Lengths in the sheets are in centimetres unless a dimension line says otherwise.