```html 1/10th Scale Trimaran Seastead Specifications

Trimaran Seastead: 1/10th Froude Scale Model Specifications

Scale Factor (λ): 10

Environment: Caribbean Sea Water (Density ≈ 64 lbs/ft³)

1. Dimensions (Full Scale vs. 1/10th Scale)

Component	Full Scale	Scale Model (Feet)	Scale Model (Inches)
Triangle Frame - Sides	80 ft	8 ft	96 inches
Triangle Frame - Back	40 ft	4 ft	48 inches
Leg Length (Height)	19 ft	1.9 ft	22.8 inches
Leg Wing Chord	10 ft	1 ft	12.0 inches
Leg Wing Width (Thickness)	3 ft	0.3 ft	3.6 inches

2. Weights & Displacement (Target Weight at 50% Submerged)

Calculation Assumption: A standard NACA teardrop/elliptical profile has a cross-sectional area of roughly 0.68 × Chord × Thickness. At full scale, the area is approx. 20.4 sq ft.

Full Scale Submerged Volume (3 legs, 9.5 ft deep): ~581.4 ft³
Full Scale Target Weight: 37,210 lbs (18.6 tons)
1/10th Scale Model Target Weight: 37.21 lbs
(Weight scales down by λ³, which is 1000)

3. Expanding Foam Mix Requirements (Per 1 Scale Leg)

To calculate the amount of 2-part liquid needed to fill your leg mold:

Volume of 1 scale leg mold: 0.3876 ft³
Expanded Foam Mass Needed: At 2 lbs/ft³, you need 0.775 lbs of foam per leg.
Liquid Volume Equivalent: Assuming standard unexpanded liquid foam specific gravity (~9 lbs/gallon), 0.775 lbs requires about 1.38 cups of total liquid.
Mix Ratio (1:1 by volume): Adding a 10% safety margin for waste left in the mixing cup and trimming:
Part A Needed: ¾ Cup (0.75 cups)
Part B Needed: ¾ Cup (0.75 cups)

4. Tow Testing Speed (Froude Scaling)

To simulate a full-scale velocity of 5 knots (8.439 ft/s), Froude scaling dictates that model speed scales by the square root of the scale factor √λ = √10 ≈ 3.162.

Target Tow Speed: 2.67 ft/s (approx. 1.8 mph)

5. Model Force to Full-Scale Electrical Power Conversion

You want to multiply the drag reading on your scale model (in lbs) by a single constant to get Full Scale Electrical Watts to maintain 5 knots.

The Math:

Force scales by λ³: Full Scale Drag = Model Lbs × 1000
Mechanical Power (ft-lbs/s) = Force × Full Scale Velocity (8.439 ft/s)
Convert ft-lbs/s to Watts = Multiply by 1.3558
Mechanical Watts = Model Lbs × 11,442

However, electrical motors and propellers are not 100% efficient. A standard marine thruster operating efficiently is typically around 50% efficient from electrical draw to actual thrust.

The Multiplier Constant: 22,884

Formula: Model Drag (lbs) × 22,884 = Full Scale Electrical Power Draw (Watts)

Note: If you have exceptionally efficient thrusters (e.g., 60%), use 19,070. If you have inefficient thrusters (e.g., 40%), use 28,605. The constant 22,884 assumes an industry-standard 50% overall propulsion efficiency.

6. Natural Roll Period

Time variables in Froude scaling relate by the square root of the scale factor (√λ).

Multiplier: 3.162
Formula: Model Roll Period (seconds) × 3.162 = Full Scale Natural Roll Period (seconds)

```