2022-Feb-21

Stability Letters Explained

For small vessels, the major problem with stability letters is explaining it to the captains. Today I will review a stability letter and give plain English interpretation of all the boring mumbo-jumbo.
2021-Jan-18
shipwreck. Capsized ship.

Free Surface Moment

Without proper management, the shifting liquid in a ship’s tanks can create a lethal scenario. Free surface moment (FSM) is one of the most frequently misunderstood elements in ship operation. The deck officer that values their life wants to understand free surface moment. The physics behind it, and how it applies to ship operating limits.
2020-Nov-02

Practical Stability Test: Naval Architect’s Guide

Every naval architect learns the theory of how to perform a stability test. But a well executed stability test employs very little theory, and a great deal of practical experience. This guide imparts some of that hard earned experience to make your next stability test go well.
2020-Oct-19

Stability Test Theory

What science could possibly link moving a few weights on deck with calculating the light ship weight? Armed with knowledge, we carefully exploit physics to achieve high quality science without the fancy equipment. Today I explain some of the theory behind the stability test.
2020-Sep-07
Extendable knuckle boom crane

Practical Stability Test: Chief Engineer’s Guide

A stability test requires extensive work to prepare the vessel. Where do you go to find that work list? This guide should give you some advanced warning of what to expect. It covers all the practical matters for a Chief Engineer to prepare for their next stability test.
2020-Aug-17
shipwreck. Capsized ship.

Practical Stability Test: Master’s Guide

Smooth stability tests require planning, and practicality. As the vessel Master, you want to prepare for this thing that completely disrupts vessel operations. But you are a busy person, and engineers are very long winded. Instead, this guide provides a brief overview, focusing on the major elements that concern you with a stability test.
2020-Jul-06
Extendable knuckle boom crane

Practical Stability Test: Owner’s Guide

What are the practical steps necessary to execute a stability test? How to avoid the pitfalls? Who do you call to arrange everything? This guide gives advice to the vessel owner on how to prepare for a stability test, from start to finish. Instead of theory, we focus on the logistics and coordination.
2020-Jun-22
When Need Stability Test - Title Slide

When You Need a Stability Test

Certain as the sea, ships will require stability tests at some point in their life. Or maybe not. This article discusses the different types of stability tests and when regulations require them.
2020-May-11
Stability Test Title Pic

What is a Stability Test

Stability tests do not arrive instantly after you order one. It takes time and planning, and you should expect extensive coordination with several different organizations. But the ultimate benefit justifies the expense: a ship with reliable stability performance. This article unravels some of the mystery behind a stability test and why you want one.
2020-Feb-03

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.
2020-Jan-13
Next Level Hydrodynamics

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!
2020-Jan-09

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.
2020-Jan-06

Guts of CFD: Multiphase Modeling

In computational fluid dynamics (CFD), we often need to model scenarios that involve more than one fluid. Volume of fluid modeling (VOF) expands the capabilities of CFD to allow limitless combinations of different fluids. The world of VOF encompasses everything from droplets of diesel spraying in cylinder all the way up to tsunami waves crashing against the city of Tokyo. How does VOF achieve this, and what are the implications for CFD modeling?
2019-Dec-09

Practical CFD Modeling: Mesh Deformation

Mesh deformation is incredibly frustrating, complicated, unstable . . . and unavoidable if you want to incorporate body motions into CFD. Modeling body motion demands mesh deformation, changing the mesh on the fly, while using it to solve transport equations. As you might expect, that brings a host of new challenges. This reviews several new strategies that the CFD engineers needs to consider.
2019-Nov-18

Practical CFD Modeling: Time Variation

When we add the time domain, simulations change from modeling steady scenarios to unsteady, where boundary conditions change over time. Beyond the physics, modeling unsteady flow requires a few changes to the CFD solver. Inner iterations, timestep, Courant Number, and data management all enter into the strategy for the CFD engineer. Today we discuss each of these.
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