# Propeller Calc vs iVSP

The clearest difference is rating: iVSP at 5.0 against Propeller Calc's 3.0. iVSP also leads on iOS requirement (13.0 vs 17.0). On price, review sentiment, ratings volume and update cadence there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

iVSP holds the better App Store score, 5.0 against 3.0. Both are backed by a comparable volume of ratings — 1 and 1 respectively. Written reviews split almost evenly too, at 100% and 100% positive.

Both ship on a similar rhythm, roughly every 21 months. The most recent releases landed on September 9, 2026 and September 11, 2026 respectively.

## The numbers

| Metric | Propeller Calc | iVSP |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.0 (1 ratings)](https://appshunter.io/ios/app/propeller-calc/id478119478/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/ivsp/id1451717453/reviews)** |
| Number of ratings | 1 | 1 |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 21 months | Every 21 months |
| Monetization | Free | Free |
| Size | 3 MB | 384 MB |
| Requires iOS | 17.0 | **13.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Frode Rørvik](https://appshunter.io/developer/478119481) | [Voith Digital Solutions Inc](https://appshunter.io/developer/1281566238) |

## What reviewers say

### Propeller Calc

[App page](https://appshunter.io/ios/app/propeller-calc/id478119478)

This utility calculates propeller performance metrics like pitch, gear ratio, RPM, slip, and speed. Input any four values, and the app computes the fifth, helping users understand the relationship between propeller design and boat performance.

**Highlights:** Calculate pitch, gear ratio, RPM, slip, and speed, Enter any four variables to find the fifth, Understand propeller slip and its impact, Supports iPhone and iPad, Free to use

**Features:** macOS Compatibility

**In-app purchases:** none


### iVSP

[App page](https://appshunter.io/ios/app/ivsp/id1451717453)

Experience ship navigation with Voith propulsion systems. Explore the mechanics and hydrodynamics of Voith Schneider Propellers (VSP) and their unique thrust capabilities on various vessel types. Learn about the innovative technology behind this propulsion system.

**Highlights:** Steer ships with Voith propulsion, Explore Voith Schneider Propeller mechanics, Understand VSP hydrodynamics, Simulate various vessel types, Learn about VSP thrust generation

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Propeller Calc free?

Propeller Calc is free to download, with no in-app purchases.

### Is iVSP free?

iVSP is free to download, with no in-app purchases.

### Which has better reviews, Propeller Calc or iVSP?

iVSP is rated higher. Propeller Calc averages 3.0 out of 5 from 1 ratings, while iVSP averages 5.0 from 1 ratings.

### Do Propeller Calc or iVSP have ads?

Neither Propeller Calc nor iVSP shows ads.

### Which is updated more often, Propeller Calc or iVSP?

Propeller Calc ships an update every 21 months, and iVSP every 21 months. Most recently, Propeller Calc was updated on September 9, 2026 and iVSP on September 11, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*