Tug Horse Power

Bollard Pull Calculator
The app will calculate the required bollard pull and power to push or tow a barge or group of barges in open water or inland waterways (protected waters). The calculations can be certified by Det Norske Veritas (DNV) or for 3rd party surveyors.

App is useful for tug operators, captains, operational management, and Naval Architects and Marine Engineers involved in Marine Towing Operations for selection of tug for push/towing operations.

What does this App do?
This app uses data collected by the user to calculate the tug's power and bollard pull required to push a barge at a specified speed and environment. The app also calculates the tugs power and bollard pull required for a storm condition to hold a barge. The bollard pull is shown in MT and required Power of the tug is in HP and kW.

It is recommended to have a Bollard Pull certificate for the tug but is not required as it is already factored into the calculations.

The app should be used to select the appropriate tug (propulsion system) based on the required Bollard Pull. Alternatively, it can be used to check whether a selected tug is suitable before the towing operation proceed.

How to use this app?
The apps inputs are in red. The input requires barge dimensions (although this doesn't have to be a barge) and deck cargo dimensions to calculate the areas the environment will act upon. The calculations are in black and automatically update with each input. Once finished with the inputs, use the print button to air print, save as a PDF or email PDF. The input values will be saved on the app allowing the user to still take calls, email, etc. without losing their data entry. When the app is closed, the app will reset to the default values. No internet connection is required to save the output as a PDF or to use the app. The print output or pdf can be used in a report to submit to client. A 1" margin at top and bottom can be used for your company info using Adobe or similar PDF editor. Do not edit the calculated values in pdf editor and always save a PDF copy of the calculations for your records.

All calculations are done using DNV recommendations and Naval Architecture and Marine Engineering best practices. These calculations can be certified by DNV using the PDF printout. Additional details about the scope of work is provided by you such as the deck layout, selected tug, and vessel certificates.

The input units for this app are English. A SI (metric) version of this app is available in the App Store. All the calculations are in SI units and converted back to English units. This is required by most 3rd party certification agencies operating in the USA.

Limitations:
It is up to the user to input good data into the app. The hull of the vessel is input into the app and those calculations are already done for you. The area of the cargo requires the user to measure the front and side areas for input into the app. It is best to estimate it as a rectangle rather than measure every item and add their areas. This will save time and it is better to overestimate than underestimate wind area. Stability calcuations should be done separately to ensure vessel safety and proper seafastening is installed.

References
1. DNV-RP-H103, 2011, Sec 7.2.6
2. ABS Rules for Building and Classing Mobile Offshore Drilling Units, 2019, C 3-1-2/1.3.2