Seastead Convoy Mode Systems Architecture

1. Convoy Mode Overview

Convoy Mode allows multiple seasteads to transit or hold station in a precise, rigid grid formation. Leveraging the unique design of the trimaran-style seasteads—specifically the NACA foil legs and 6 RIM drive thrusters providing 6-DOF maneuverability—station-keeping in dynamic sea states becomes feasible. By operating as a swarm, the convoy creates a distributed sensory and computational network, vastly improving safety, watchstanding, and situational awareness.

Dynamic Grid

The formation is a virtual grid moving through the water. Grid spacing (e.g., 200 feet) ensures the 80x40 ft structures have safe clearance while remaining within high-bandwidth directional communication range.

Moving Base RTK

Instead of a fixed land base, one seastead (typically the lead) acts as the RTK base station, broadcasting correction data. All other seasteads (rovers) achieve centimeter-level relative positioning.

Swarm Autopilot

The RIM drives and "little airplane" stabilizers are continuously adjusted by the autopilot to maintain the exact RTK coordinates assigned to that grid cell, factoring in wind, current, and wave action.

2. Joining Protocol & Activation

Joining a moving convoy is a critical evolution. The process must be highly automated to prevent collisions, utilizing the precise RTK positioning and RIM drive agility.

Request & Assignment: A lone seastead requests to join via Starlink long-range channel. The Convoy AI calculates an available grid position on the perimeter (to avoid crossing through the middle of the formation) and transmits the target RTK coordinates.

Approach Vector: The joining seastead navigates to a staging point outside the grid using its standard GPS and AIS. It approaches from outside the convoy, ensuring it does not cross the path of other seasteads. The dinghy is secured against the railing to prevent snags.

RTK Lock: As the seastead approaches the staging point, it locks onto the convoy's Moving Base RTK signal. The autopilot transitions from absolute GPS navigation to relative RTK navigation.

Convoy Mode Activation: Once the seastead crosses the threshold (e.g., within half a grid spacing of its target cell) and RTK fix quality is confirmed, the system announces "Convoy Mode Activated." The autopilot assumes station-keeping control.

Integration: Directional antennas align to the nearest neighbors. The seastead's cameras and AI are added to the distributed watch network.

3. Distributed Watch & Parallax Tracking

With multiple seasteads spaced precisely on a grid, the convoy functions similarly to a phased-array radar or a distributed astronomical telescope. By synchronizing camera feeds using RTK timestamps, the system achieves highly accurate passive ranging.

Parallax Ranging Mechanics

Because the exact RTK coordinates (down to the centimeter) of every seastead are known, when two or more seasteads detect an object (e.g., a ship on the horizon), the system computes the distance via triangulation. For example, two seasteads 200 feet apart looking at the same target will see it from slightly different angles. The AI matches the object in both video feeds and calculates the exact range and velocity of the contact, adding it to a shared database without needing active radar.

Human-AI Watchstanding

AI Night Watch: Thermal/IR cameras and visual cameras run object detection (YOLO or similar) 24/7. They look for lights, vessel profiles, floating debris, and squalls.
Distributed Human Watch: A rotating duty roster assigns humans across the convoy. A web-based "Dead Man's Switch" requires watch-standers to click a confirmation button every 10 minutes.
Failover: If a human misses the prompt, the AI escalates an alarm to other human watch-standers in the convoy, and autonomously adjusts the convoy's course if an imminent collision is detected.

4. Local Communications & Mesh Network

While Starlink provides backhaul to the internet, the convoy relies on a localized, high-speed, low-latency mesh network for RTK corrections, parallax computation, and swarm control. This network must operate seamlessly over water, which presents unique RF challenges (multipath reflection, ducting).

Why Directional WiFi 5/6 (5 GHz)?

Your intuition is correct. 5 GHz WiFi is ideal for this use case for several reasons:

Bandwidth: Parallax video processing, RTK corrections, and AIS data require significant bandwidth (10-50 Mbps per link). 5 GHz provides this easily.
Interference Resistance: The 5 GHz band has more non-overlapping channels than 2.4 GHz, which is critical when operating a dense grid of transmitters.
Line of Sight (LoS): Because the seasteads are on the open ocean, LoS is guaranteed. 5 GHz struggles with obstacles but excels in clear LoS.

Antenna Layout: The 4-Directional Grid

Each seastead should be equipped with 4 directional antennas, mounted on the 7-foot high truss roof (above the solar panels to avoid obstruction). Because the convoy maintains a fixed heading (the blunt NACA foils forward), the antennas can be aligned to the grid:

Bow Antenna: Points to the seastead ahead.
Port Antenna: Points to the left.
Starboard Antenna: Points to the right.
Stern Antenna: Points to the seastead behind.

Hardware Note: Use PTMP (Point-to-Multi-Point) or PtP (Point-to-Point) links with highly directional sector or dish antennas. The narrow beamwidth reduces "noise" from other convoy members and maximizes range.

Mesh Routing Software

Standard WiFi needs to be converted into a mesh. Because the topology is relatively fixed (a grid), proactive routing protocols work best.

OLSRd (Optimized Link State Routing): The gold standard for maritime mesh networks. It calculates routes proactively, ensuring low latency for RTK data.
BATMAN-adv: A layer-2 mesh protocol that works well with standard WiFi hardware, treating the entire convoy as a single local network.
Proprietary (Ubiquiti/Mikrotik): Using vendor-specific PTMP modes (like Ubiquiti airMax AC) provides hardware-level polling, eliminating WiFi collision issues and ensuring deterministic latency for navigation data.

5. Recommended Hardware, Range, & Costs

Keeping costs down while ensuring reliability means leveraging commercial-off-the-shelf (COTS) terrestrial wireless hardware, mounted in marine-rated enclosures.

Component	Recommendation	Specs / Data Rate	Est. Cost per Unit
Primary Directional Radio	Ubiquiti NanoStation 5AC Loco (or Mikrotik SXTsq 5)	~450 Mbps throughput 45° Beamwidth	$50 - $100
Long-Range Directional Radio	Ubiquiti LiteBeam 5AC Gen2	~450 Mbps throughput Narrow beam, higher gain	$100 - $130
Mesh Router / Compute	GL.iNet GL-MT6000 (Flashed with OpenWrt for OLSRd)	WiFi 6, Dual-core, handles mesh routing	$80 - $120
Marine Enclosure	Custom 3D printed ASA or NEMA 4X box with UV-resistant dome	Protects ethernet connections from salt spray	$40 - $80
Omnidirectional Backup	Mikrotik mANTBox 2 15s (2.4GHz)	Fallback mesh if directional links drop	$100

Expected Performance

Range: Over water with clear Line of Sight, a NanoStation 5AC Loco can easily maintain a stable link at 2 to 3 miles (10,000 - 15,000 feet). If the convoy grid spacing is 200-500 feet, you have massive link margin, meaning the connection will remain rock-solid even in heavy rain or fog.
Data Rate: At close grid distances, these radios will link at their maximum rates (400-500 Mbps). This is more than enough to stream multiple 1080p or 4K camera feeds for parallax processing alongside RTK correction data (which is only a few kbps).
Total Cost per Seastead: 4x Directional Radios ($400) + 1x Mesh Router ($100) + Enclosures/Cabling ($150) = ~$650 per seastead. This is exceptionally cost-effective for enterprise-grade maritime networking.

                Marine Deployment Tips
                Antenna Height: Mount the antennas on the roof of the 7-foot truss. Even a few feet of elevation drastically improves the Fresnel zone clearance over waves.
Corrosion: Use dielectric grease on all Ethernet connectors. Use UV-resistant zip ties and stainless steel mounts.
Redundancy: The 4-directional setup provides inherent redundancy. If the "Bow" radio fails, data can route "Port" then "Bow" via the neighbor, maintaining the mesh.

            