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Boat Design – Find 5 Collaborative and Ready-To-Use Simulations

SimScale Boat Design

Boat design and shipbuilding is one of the oldest human activities. The entire history of civilization is marked by the human desire to sail, to discover new territories, to conquer or defend rich islands, to trade or, very recently, to feel the pure pleasure of sailing.

A long history of boat design

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The Oldest Boat Design – Gobustan Petroglyphs, Smithsonian Institution

History sources show us the boats served as transportation long time before antic carriages. It seems the oldest archaeological evidence is coming from Indonesia where people were sailing between islands using ancient canoes [1]. Probably the earliest evidence of sailing activities in the Mediterranean area was discovered in Crete and consist of various quartz tools dated 130,000 years ago [2].

A Mesolithic petroglyph from Gobustan National Historical-Artistic Preserve, Azerbaijan (12,000 – 7,000 BCE) is considered as one of the first boat designs [3]. Probably the oldest recovered boat is a monoxylon canoe – made from a single Scottish pine trunk, discovered and exposed in Netherland. The Pesse canoe constructed during the early mesolithic period somewhere between 8200 and 7600 BC [4]. The first mentions for wheels used in transportation are coming from Mesopotamian chariots built in 3200 BC period [5].

The Art of Building Boats

Following the traditions of the ancient Phoenicians, Egyptians, Vikings, Greeks, Spanish or Dutch boat builders, the construction of military vessels or commerce has become an art. Consequently, boat design and construction is today a preserved tradition for generations. Ships are designed primarily according to their destination. Depending on their capacity, and the navigation conditions that will have to face, there are ships designed for river and flowing fast vessels, as well as for marine vessels backwaters. Finally, boats design should face the waves, rocks, and currents in oceans and seas.

Boat engineering based on simulation methods

From the ship engineering perspective, the boat design is just one of the key secrets of a successful boat series. The ship’s materials are very important as well. Floating capacity, flexibility, ease of processing, but also the hardness and water resistance were always selection criteria for the favourite materials in shipbuilding. Until now we can find almost the same building design and construction methodologies during the history.

The big difference shows when we start looking at the prototype testing conditions before launching the ship in the water. We know from history and even old movies that the new boats were directly launched in small basins or directly in the docks waters. And the probability that a ship will immediately float was quite small, as many hazard factors influence its success.

In modern boat engineering, we have the possibility to test the materials and boat profile in laboratory conditions or in a virtual mode, using computer simulation tools. Testing laboratories are good for the physical analysis of different materials and boat structures’ behaviour in different sailing scenarios.

Computer simulation, known as engineering simulation, offers the digital version of qualitative testing on thousands of models. Its purpose is to test the boat early in the design process, make the design changes based on the simulation’s results, and develop the least amount of physical prototypes needed, saving money and time.

Ship hull shapes in boat design

Between the most important factors influencing the ship hull’s shapes and affecting the boat’s buoyancy and stability in water are [6]:

  • Flare – water launch increases the boat’s displacement and creates a positive buoyant force to float the boat;
  • Tumble home – is the reverse of flare and is the shape of the hull as it moves outgoing from the gunwale to the water line;
  • Camber – a deck usually curves athwartships, making it higher at the centerline than at the gunwales so the water flows off the deck;
  • Sheer – the curvature of the main deck from the stem to the stern;
  • Length on the waterline (LWL) – is the distance from the bow to the stern, measured at the waterline when the boat is stationary. LWL changes as the boat ride high or low in the water.
  • Length over all (LOA) – is the length of the craft from its stem to its stern in a straight line. LOA does not change according to the way the boat floats  in the water;
  • Draft – is the depth of the boat from the actual waterline to the bottom of its keel;
  • Draft appendage – is the depth of the boat from the actual waterline to the bottom of its keel or other permanent projection.

5 boat design simulations

Other key factors in boat design analysis are the water flow properties. But a better way to see the simulation features and advantages in boat design is to discuss the real models. SimScale Public Projects library is the better source to share simulation projects. This is a free place where you can find an already completed boat design simulation, copy it and change the CAD model or setup with your own specifications.  This saves time and also make it easier to perform a simulation. But let’s see a few examples:

The waves’ impact on a ship

This is one of most frequent engineering issues, associated with any kind of ship, from small boats for agreement purposes, to giant transportation or cruise ships.

In this project we can see how we can simulate the behavior of sea waves around a frigate. The ship’s oscillating motion is modelled using the 3DOF solid body motion option, through which the ship’s roll (x-rotation), heave (z-translation) and sway (y-translation) can be specified. The geometry was uploaded to the SimScale platform and meshing was done using snappyHexMesh. Finally the simulation results can be used to study the impact of waves on the ship.

CFD Analysis of a Floating Boat in a Wave Tank

In boat design from traditional shipyards is usual to simulate the wave effects on different hull shapes and dimensions in artificial conditions trying to reproduce natural environments. One such physical testing is the wave tank, a special water reservoir able to host a small-mid size boat.

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The water phase fraction and velocity along with the orientation of the boat at 3-time instances.

Our proposed project is simulating the free movement of a floating boat under the influence of a head-on wave via a Multi-phase 6-DOF (degree of freedom) transient analysis. The model considers the boat as a stationary floating body in a water tank with an open top. A single wave is generated to create disturbance in the water and simulate the motion of the boat. For simplicity of the analysis, a laminar model is used also.

The simulation analysis the instantaneous flow of water and the free motion of the boat under the wave disturbance. The results processed on ParaView show the transient changes in phase fraction of water and flow velocities along with the free motion of the boat due to the fluid forces. This simulation shows also how the free floating body motion can be predicted via simulation to provide insight and aid in Marine vehicle design and development.

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Transient wake formation behind a boat.

Transient wake formation behind a boat

Here is another interesting subject for engineering simulation using a CFD analysis. In the proposed projects we can see how we can simulate the transient wake formation behind a moving boat.

The model is therefore highlighting the capability of local time-stepping in the multiphase solver used on the platform. The boat simulated in this case is 4 meters in length. It sails at 3.5 m/s at a heeling angle of 5 degrees. The simulation enables analysis of Kelvin wake formation times and wake patterns also within reasonable computation time. Finally we can clearly see the pattern in the snapshots.

Collaborative simulation project: Multiphase flow around a boat hull

Another very interesting project is simple simulation scenario: multiphase flow analysis around a boat hull. In this case, the simulation results are not so important. Most important is the collaborative efforts between 4-5 co-participants in this project.

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Animation of the air-water interface color-coded by velocity approaching steady-state:

Resuming scenario: one engineer wants to test the capabilities of the SimScale simulation software by performing a CFD analysis on his own CAD model of a boat. The initial model is analyzing a free surface flow around a boat hull to predict the waterline, drag etc. But consequently any model is subject of improvement.  Two other engineers try also to help the project initiator, running parallel simulation sessions on the same CAD model.

After few iterations, one of SimScale engineers proposed finally a better alternative for the initial model, having many chances to perform the proposed simulation. Interesting is the moment a boat design experienced engineer joins the forum topic and shared his expertise with the other project participants, improving the model and obtaining also better results for the multiphase flow analysis.

You can see the initial modelling conditions here, and the collaborative steps watching the dialogues from the forum here.

Interested to find more about the collaborative facilities offered by SimScale? Read these 2 blog articles with related topics:

A Powerboat trim angle study

The main purpose of this powerboat study is to predict the resistance and trim angle of a planning hull. In the current sailing activities, one of the most important thing for a powerboat driver is to try different trim settings in different sea conditions. Obviously every boat is different, and the reactions to various trim changes are very different in varying conditions. Efficiency, speed, trim angle, and the smoothness of the boat’s ride are also subjects of such studies.

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Powerboat trim angle simulation

Although the model is still in early stages, this project is definitively important for the multitude of approaches. No less than nine different users have chosen this model and made eight simulations to test their own terms of analysis. Want to see them? Nothing more simpler…

Go to the SimScale Public Projects library and insert the title “Powerboat trim angle study” in the Search window. Finally the search result shows all the project with the same title opened on the SimScale platform. Therefore not all the projects are a successful simulation. Also some users preferred only to load 1 or 2 CAD models and to study the meshing facilities offered by SimScale.

Try your own powerboat trim angle study! SimScale offers a 14-day free trial.


References:

[1] – First Mariners, Archaeology Magazine, May/ June 1998

[2] – Plakias Survey Finds Mesolithic and Palaeolithic Artifacts on Crete, The American School of Classical Studies at Athens (ASCSA), January 2010.

[3] –Gobustan Petroglyphs, Smithsonian Institution

[4] – The Pesse canoe, Wikipedia

[5] – Fascinating facts about the invention of the Wheel by Mesopotamian’s in c3500 BC., Wheel History – Invention of the Wheel – The Great Idea Finder.

[6] – Boat Construction, Overview, Boat Crew Seamanship Manual, US Coast Guard


This case study shows a flow analysis of a ship propeller performed with the SimScale simulation platform. 

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