Resistance and Powering Design

How big to make the engine?  That innocent question reveals a complex field of study.  Resistance and powering require multiple methods of calculation to obtain an accurate prediction for engine size.



Get Your FREE Technical Briefing

Learn about the technical risks before you commit to a project.

To predict the engine size, we handle the propeller and the hull separately.  This typically consists of two stages:

  1. Resistance estimate
  2. Propulsion design

The resistance estimate determines the total thrust required for each speed.  This produces a curve of thrust and power requirements, accounting for water, wind, waves, fouling, and several other factors.  DMS has multiple methods available for a range of accuracy and budget needs.  

Next, the propeller must develop that required thrust by converting the power of a spinning shaft.  Most propellers vary from 50% – 70% efficiency, which profoundly impacts your fuel bill.  This is where DMS focuses intensely on selecting the right propeller.

The best propeller requires DMS to specify several variables.  Diameter, blade pitch, blade area, and other geometry features.  The ultimate goal is peak efficiency, but the engineer must also consider cavitation, vibration and noise, operational profile, engine matching, and several other factors.  It becomes a balancing act.

Want to Learn More

Ready to discuss your next project.  DMS is ready to join your team.

Relevant Ship Science Articles

Ship Model Scaling

The physics of model scaling make it impossible to perfectly convert between model scale and ship scale. Learn how to get around the scaling correlation problem and convert from model scale to ship scale measurements.

read more

Next Level Hydrodynamics

Time for an upgrade! Far beyond the single purpose testing facility, the modern towing tank expanded into a Swiss Army knife of experiments. Armed with new gadgets and advanced capabilities. Time to see what new tricks the tank holds for us!

read more

The Ship Towing Tank

It may look like a swimming pool, but towing tanks exist for a different purpose. Dragging models down the tank propelled the science of ship design forward across the years. These pools deliver critical measurements for ship hydrodynamics. Discover why we pay such a high price for a fundamental tool of ship design.

read more

How to Cut the Bunker Bill: Preparing for IMO 2020

Ready or not, here it comes! No matter who you talk to, IMO 2020 promises to be a time of uncertain fuel prices. If fuel prices will go up, your fuel consumption needs to go down. Here are eight practical ways to reduce your fuel consumption.

read more

How to Design a Waterjet: Key Elements of Waterjets

What makes a waterjet work? What is the difference between a good and bad waterjet? Waterjets may appear to be brutes of power, but they rely on delicately balanced design equations. Learn the common elements that go into all waterjets and discover the best practices that you should expect from any decent waterjet design.

read more