I have analyzed your seastead design parameters. The comparison between RIM drives and submersible mixers is a classic trade-off between **hydrodynamic efficiency** (thrust per watt) and **packaging efficiency** (size/weight).
You are correct that submersible mixers have superior thrust/kW numbers. This is because thrust is a function of the mass of water moved times the velocity squared. A large propeller (like the 2.5m one you mentioned) moves a *large mass* of water at a *low velocity*. A smaller RIM drive propeller must move a *smaller mass* of water at a *higher velocity* to achieve the same thrust. Since velocity is squared in the energy equation, the high-velocity (small prop) approach requires more energy for the same thrust.
However, for a seastead, the mixer's weight and bulk are problematic, while the RIM drive offers a sleek, integrated solution.
Below is a comparison table in HTML format. I have included the Yamaha HARMO, a true Industrial RIM Drive (Thrustmaster), a high-end ROV RIM Drive (Hydromea), the Submersible Mixer (Xylem/Flygt), and a high-value standard electric drive (ePropulsion) for context.
**Note on Links:** As an AI, I cannot browse the live web in real-time to validate if a specific e-commerce "add to cart" link is currently active. I have provided links to the **manufacturer's official product pages**, which are the most stable and reliable sources. From there, you can find their "Contact Sales" or "Where to Buy" sections. Be wary of "RIM Drives" on general marketplace sites (like Alibaba) that are just standard motors in a tube; the manufacturer links below are for verified RIM technologies.
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Seastead Propulsion Comparison
Seastead Propulsion Options Analysis
Comparing RIM Drives, Submersible Mixers, and Standard Electric Drives for a 30,000 lb seastead.
Key Metric: High Lbs/kW is best for efficiency; Low $/Lb-thrust is best for budget.
| Type |
Lbs Thrust |
Watts |
Lbs/kW (Efficiency) |
$ Price (Est.) |
$/Lbs-thrust (Cost Eff.) |
Manufacturer URL |
| RIM Drive (Yamaha HARMO) |
227 lbs |
3,700 W |
61 |
~$3,500 |
$15.40 |
Yamaha HARMO Official |
| RIM Drive (Thrustmaster RDT) |
~550 lbs |
7,500 W |
73 |
~$6,000* |
$10.90 |
Thrustmaster of Texas |
| RIM Drive (Hydromea LUMA) |
~220 lbs |
4,000 W |
55 |
~$6,000 |
$27.00 |
Hydromea LUMA |
| Submersible Mixer (Flygt/Explo) |
~720 lbs |
3,200 W |
225 |
~$1,800** |
$2.50 |
Xylem Flygt (Mixers) |
| Electric Outboard (ePropulsion Navy) |
~350 lbs |
6,000 W |
58 |
~$2,900 |
$8.28 |
ePropulsion Navy 6.0 |
| Industrial RIM (Schottel RDT) |
Varies (High) |
Varies |
~70-80 |
$$$ (Custom) |
N/A |
Schottel Electric |
*Notes on Pricing:
- Thrustmaster: These are industrial grade (Oil & Gas/Salvage grade). They are robust, repairable, and have excellent efficiency for RIM drives. Prices vary by distributor.
- Submersible Mixer: Price listed ($1,800) is for a high-quality Chinese industrial clone (e.g., Liancheng or similar brands on Alibaba/Global Sources). A Western brand like Xylem Flygt would cost ~$8,000+. The efficiency is unmatched for low-speed pushing.
```
### Analysis and Recommendations
1. **The "Mixer" Efficiency Hack:**
You are absolutely correct that submersible mixers blow RIM drives out of the water regarding **Lbs/kW** (225 vs 60). For a seastead moving at 1 MPH, this is actually the most scientifically sound solution. At such low speeds, drag is high, but you don't need speed—you need raw pushing power.
* **Pros:** Unbeatable efficiency, rugged, designed to run 24/7 submerged.
* **Cons:** Heavy, physically bulky (hard to mount cleanly on a pontoon), and not designed for hydrodynamic gliding (they create a lot of turbulence).
* **Recommendation:** If you mount these, consider placing them inside a "duct fairing" on your pontoon to smooth out the water flow behind the large prop.
2. **The RIM Drive Option (Thrustmaster):**
I included **Thrustmaster of Texas (TMOF)** in the table. This is likely the "Larger RIM Drive" you are looking for. They specialize in azimuth (steerable) RIM drives for workboats and oil platforms.
* **Why it's good:** It is much more efficient than the Yamaha (73 lbs/kW vs 61 lbs/kW) because the propeller diameter is larger. It is built for industrial saltwater use.
* **Price:** It is more expensive than the Yamaha, but it is a true commercial unit.
3. **A Word on Chinese RIM Drives:**
Finding a direct "Buy Now" link for a large Chinese RIM drive is difficult because most are sold via B2B trade sites (Alibaba/Made-in-China) and the links expire. However, the technology is widely used in Chinese ROVs and small ferries. I recommend searching specifically for **"Hubless Rim Driven Thruster"** on Alibaba. If you go this route, ask the seller for the **Thrust (N)** vs **Power (kW)** curve.
* *Warning:* Many vendors list "Tunnel Thrusters" as RIM drives. Look for the motor stator coils visible in the duct ring. If it has a central hub with a shaft, it is **not** a RIM drive.
4. **Vibration:**
RIM drives are indeed vibration-free because the motor is decoupled from the hull and integrated into the water stream. If vibration is a major concern for your living area, the RIM drive (or a high-quality standard electric like ePropulsion) is superior to the Mixer. Mixers have large blades and can sometimes transmit a low-frequency "thrum" into the hull structure.