# Hull Speed Calculator — Boat Waterline Knot Guide

> Boat Waterline Knot Guide (iPhone/iPad app by Shanghai Sheyuan Network Technology Co., Ltd..)

- Source: https://appshunter.io/ios/app/hull-speed-calculator/id6761676564 (this page in markdown: same URL + `.md`)
- Developer: [Shanghai Sheyuan Network Technology Co., Ltd.](https://appshunter.io/developer/1560626858)
- Category: Utilities, Productivity
- Price: $1.99
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English
- Released: 2026-04-08
- Data updated: 2026-07-25
- User reviews in markdown: https://appshunter.io/ios/app/hull-speed-calculator/id6761676564/reviews.md

## What is Hull Speed Calculator?

Need to know if your boat can outrun its own bow wave? Hull Speed Calculator tells you the maximum efficient speed for any displacement hull based on waterline length — so you stop wasting fuel pushing past physics.

Enter waterline length, beam, and displacement to instantly see theoretical hull speed in knots, mph, and km/h. The app calculates Froude number, speed/length ratio, displacement/length ratio, and whether your hull can realistically plane.

HULL SPEED CALCULATOR
Enter waterline length and displacement to calculate theoretical hull speed. Shows speed/length ratio, Froude number, and hull speed in knots, mph, and km/h.

SPEED TABLE
Reference table showing hull speeds for waterline lengths from 15 to 60 feet at speed/length ratios of 1.0 (cruising), 1.2 (fast cruise), 1.34 (hull speed), and 2.0 (semi-planing).

POWER GUIDE
HP per ton requirements by hull type: displacement (under 40 HP/ton), semi-displacement (40-100), and planing (over 100). Includes example vessel types for each category.

SPEED CONVERTER
Bidirectional speed unit conversion: knots to mph, km/h, and m/s. Enter any value and see all conversions instantly.

Built for naval architects, boat builders, and sailing enthusiasts. Works offline.


## Version history (last 3 releases)

### 1.0.2 — 2026-07-07

Added a More Pro Tools section to discover related field calculators.

### 1.0.1 — 2026-04-12

Bug fixes and performance improvements.

### 1.0 — 2026-04-08

No release notes.

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All apps by Shanghai Sheyuan Network Technology Co., Ltd.: https://appshunter.io/developer/1560626858

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-25.*