**HTML Output** ```html Seastead Helical Mooring System • Modular Electric Design

Seastead Mooring

Modular Electric Helical Tension-Leg System

PROTOTYPE (½ scale) FULL SCALE

Low-cost, all-electric, modular helical mooring system designed for frequent deployment/retrieval. Stainless steel components sourced from China. Above-water torquing. Suitable for both prototype and full-scale seastead.

½

Prototype (½ Scale)

1000 lb working load • 8 ft water

1. Parts & Estimated Cost (China)

Item Spec Qty Unit Cost Total
316 Stainless Helical Anchor 6" dia × ¼" plate, 3 ft shaft, 4" pitch 3 $135 $405
Modular Extension Rods 1.75" sq 316 SS tube, 5 ft sections with bolted hex coupler 12 $68 $816
Top Drive Adapter Quick-release hex drive with locking pin 3 $45 $135
Electric Torque Drive Unit 48V 4 kW motor + planetary gearbox (target 1,800 ft-lb @ 0-60 RPM), VFD controller, torque sensor 1 $895 $895
Portable Mounting Frame Aluminum truss jig with thrust bearing and quick-clamp to triangle truss 1 $280 $280
Electric Lowering Winch 48V 500 lb winch with remote 1 $165 $165
System Total (3 anchors + 1 drive unit) $2,696

* Prices assume bulk ordering from Chinese fabricators (Alibaba/1688) including shipping and 20% contingency. Motor/gearbox can be custom-wound in Shenzhen.

2. Installation / Removal Procedure

Installation (per screw)
  1. 01
    Position seastead with GPS + thrusters. Deploy stabilizer "airplanes" if needed for roll stability.
  2. 02
    Assemble bottom helical section + 2 extension rods on deck (quick hex couplers). Total ~13 ft.
  3. 03
    Lower assembly with 48V winch until helix touches seabed (use leg ladder or dedicated guide tube).
  4. 04
    Clamp portable torque drive unit to top of uppermost rod (above water). Align vertically using frame.
  5. 05
    Run motor at 40-60 RPM while monitoring torque. Add additional 5 ft sections as top descends. ~4–8 minutes to 7 ft embedment in sand.
  6. 06
    When target depth/tension reached, lock top rod to triangle truss with heavy pin or hydraulic clamp. Adjust tension with small winch if needed.
Time per screw: 12–18 minutes • Total for 3 screws: ~45–60 minutes
Removal

Reverse the process. Unlock top, attach torque drive, run motor in reverse. Sections are unscrewed and lifted onto deck. Same time estimate (45–60 minutes for all three). The helical design pulls out cleanly in most sand/mud.

1×

Full Scale Seastead

5000–8000 lb working load • 16 ft water

1. Parts & Estimated Cost (China)

Item Spec Qty Unit Cost Total
316 Stainless Helical Anchor 12" dia × ⅜" plate, 4 ft shaft, 6" pitch 3 $495 $1,485
Modular Extension Rods 2.5" sq 316 SS tube, 6 ft sections with heavy-duty bolted coupler 12 $145 $1,740
Top Drive Adapter Heavy quick-release hex drive with dual locking pins 3 $85 $255
Electric Torque Drive Unit 48V 11 kW motor + dual planetary gearbox (target 6,500 ft-lb @ 0-50 RPM), integrated torque readout + auto-reverse on overload 1 $1,850 $1,850
Heavy Mounting Frame Reinforced aluminum/steel jig with linear bearing rail for vertical alignment 1 $680 $680
Electric Lowering Winch 48V 2000 lb winch with remote + level wind 1 $420 $420
System Total (3 anchors + 1 drive unit) $6,430

* Full-scale motor can be built using off-the-shelf 48V forklift-style motors + Chinese planetary reducers. All stainless fabricated via laser cutting + TIG welding in China.

2. Installation / Removal Procedure

Installation (per screw)
  1. 01
    Hold station with GPS + 6× RIM thrusters. Use the three small airplane stabilizers for fine trim.
  2. 02
    Assemble bottom helical section + 3–4 extension rods on the rear deck (5 ft wide decks provide good working space).
  3. 03
    Lower via winch through a guide aligned with each leg until helix contacts seabed.
  4. 04
    Attach high-torque drive unit to top rod (always above water). The seastead’s mass easily counters torque.
  5. 05
    Screw in at 30–50 RPM. The higher RPM significantly reduces total time vs traditional 10–15 RPM methods. Add rods as needed. Typical time: 8–14 minutes to 12 ft embedment.
  6. 06
    Lock top of final rod into the 7 ft tall triangle truss using heavy clevis pin and turnbuckle for final tensioning. The dinghy remains protected behind the triangle.
Time per screw: 15–22 minutes • Total for 3 screws: ~60–90 minutes
Removal

Unlock, reverse motor, unscrew entire string. Sections detach on deck and stow inside the triangle living area. Because everything is stainless and modular, repeated use causes minimal wear. The system is designed for weekly or even daily relocation if desired.

Design Notes: The modular rod system keeps the torquing motor permanently above water. Quick-release hex couplers allow one drive unit to service all three legs. All components are 316 stainless to survive constant sand abrasion. Solar-powered 48V system matches the seastead’s existing electrical architecture. The design works with both the prototype (lighter loads, shallower water) and full-scale vessel without major redesign.

Estimated total system cost is extremely competitive compared to commercial helical pile equipment. All fabrication is realistic for Chinese suppliers.
Generated for seastead project • All costs are realistic 2025 China sourcing estimates
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