Comparison

Propeller Calc vs Haidi Classic

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Propeller Calc

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
Read full description

This calculator can determine pitch, gear ratio, RPM, propeller slip and speed parameters. Enter any four variables, and it will calculate the fifth. Use the toggle switch to choose which field to calculate. Pitch is the theoretical forward movement for one complete turn of the propeller. Every inch of the boat in contact with the water induces drag. Therefore, the distance travelled differs since the propeller is "slipping" behind the theoretical distance it should travel with each rotation. The difference between theory and reality is called slip. Depending on your application, slip typically ranges between 5% and 20%. A lower number is only sometimes what you are after. Slip of a prop changes with operating conditions and is not a direct measure of efficiency. Please consult professionals for guidance. Happy powerboating

About

Haidi Classic

Features
Read full description

1. Connect the BMS Bluetooth module through the mobile phone Bluetooth to read the status information of the lithium battery pack; 2. You can view the voltage, total voltage, remaining power, real-time current, cycle times, temperature, pressure difference, etc. of each string of the battery pack, and you can set the protection parameters according to your own needs; 3. An alarm is issued when the battery pack is abnormal, which is convenient for users to check and repair, and provides historical alarm records;

Screenshots

Propeller Calc2 screens
Haidi Classic2 screens

Verdict

The call

The clearest difference is iOS requirement: Haidi Classic at 11.0 against Propeller Calc's 17.0. On price, ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

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

Scorecard1 real difference · 9 level
Propeller Calc versus Haidi Classic: the parameters behind the verdict, then further details
ParameterPropeller CalcHaidi Classic
PriceFreeFree
Rating3.0 (1 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings1 — better—
Update frequencyEvery 21 months—
AdsNoNo
In-app purchasesNoNo
MonetizationFree—
DevicesiPhone, iPadiPhone, iPod
Requires iOS17.011.0 — better
Further details — not scored
Size3 MB68 MB
Age rating4+17+
DeveloperFrode RørvikHaidi Energy Tehcnogy Co., Ltd

In-app purchases

None

Propeller Calc

No in-app purchases

None

Haidi Classic

No in-app purchases

Questions

Is Propeller Calc free?
Propeller Calc is free to download, with no in-app purchases.
Is Haidi Classic free?
Haidi Classic is free to download, with no in-app purchases.
Do Propeller Calc or Haidi Classic have ads?
Neither Propeller Calc nor Haidi Classic shows ads.

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