Is this calculation free and private?

Yes, 100% of calculations execute locally in your web browser. No inputs or personal data are stored or transmitted.

What does the Boat Theoretical Hull Speed & Power Calculator give me?

It works out Theoretical Max Hull Speed, Theoretical Hull Speed, Required Engine Power and Displacement/Length Ratio, updating live as you change the inputs.

What do I need to enter?

Just Waterline Length LWL, Boat Displacement Weight and Target Cruising Speed. Every field has a sensible default you can start from.

Is my data uploaded anywhere?

No. The calculation runs in your browser with JavaScript — nothing you type is sent to a server or stored.

Does it work on a phone?

Yes. The layout adapts to small screens and needs no app or signup.

Boat Theoretical Hull Speed & Power Calculator

Calculate displacement boat hull speed in knots, speed-to-length ratio, and required inboard/outboard engine horsepower (Keith formula).

100% free
Private in browser
No signup
No watermarks

Waterline Length LWL (Feet)

Boat Displacement Weight (lbs)

Target Cruising Speed (Knots)

Theoretical Max Hull Speed (Knots)

7.1

Theoretical Hull Speed (MPH)

8.2

Required Engine Power (HP)

19.5

Displacement/Length Ratio (DLR)

173

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About Boat Theoretical Hull Speed & Power Calculator

Calculate displacement boat hull speed in knots, speed-to-length ratio, and required inboard/outboard engine horsepower (Keith formula). Enter Waterline Length LWL, Boat Displacement Weight and Target Cruising Speed and the tool works out Theoretical Max Hull Speed, Theoretical Hull Speed and Required Engine Power straight away. Everything runs in your browser, so your data never leaves your device.

How to use Boat Theoretical Hull Speed & Power Calculator

Enter Waterline Length LWL, Boat Displacement Weight and Target Cruising Speed.
Change any value to see the result update instantly.
Read Theoretical Max Hull Speed, Theoretical Hull Speed and Required Engine Power in the results panel — copy or download what you need.

Key features

Shows Theoretical Max Hull Speed (Knots)
Shows Theoretical Hull Speed (MPH)
Shows Required Engine Power (HP)
3 adjustable inputs, results update as you type
No signup, no limits

Frequently asked questions

Is this calculation free and private?: Yes, 100% of calculations execute locally in your web browser. No inputs or personal data are stored or transmitted.
What does the Boat Theoretical Hull Speed & Power Calculator give me?: It works out Theoretical Max Hull Speed, Theoretical Hull Speed, Required Engine Power and Displacement/Length Ratio, updating live as you change the inputs.
What do I need to enter?: Just Waterline Length LWL, Boat Displacement Weight and Target Cruising Speed. Every field has a sensible default you can start from.
Is my data uploaded anywhere?: No. The calculation runs in your browser with JavaScript — nothing you type is sent to a server or stored.
Does it work on a phone?: Yes. The layout adapts to small screens and needs no app or signup.

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