The 4 Types of Marine Vessels
Cargo/Freighter Vessel: A cargo vessel is generally a ship that carries simple cargo. The cargo is usually packed into rectangular-prism shaped containers. The containers (after loading) can way anywhere from 2Tons to even 100/200Tons depending on the load. Some cargo ships carry oil in their built-in tanks and these ships are known as Oil Tankers. The hull of a cargo freighter is usually flat-bottomed with a bulbous hull at the front. The vessel is made out from sheet metal which is riveted together to form a watertight hold. The vessels are made with a low waterline in mind so the vessel (when empty) might be 2-5 meters above the water while when full, it might be just 1 meter above due to the heavy load. When most of the water is underwater, the extra metal would create a lot of drag therefore we have a bulbous bow, the bulbous bow will guide water around the hull. The second function of the bulbous bow is that it creates a wave in front of the boat so when another wave is coming towards the boat, the wave produced from the bulb will collide with the other wave cancelling it out. This vessel is propelled by a high Horsepower but low RPM engine as the vessel needs to go forward at a steady speed in order not to damage the cargo.
______________________________________________________________
Navy Combat Vessel: This type of vessel, as the name states, is used by the military. Navy vessels are usually 100-250 meters long depending on their use. Navy vessels are designed to carry guns, other weapons, ammunition and/or even relief cargo. The vessels are also designed to cruise at high speeds at around 20-30Knots but these days there are navy ships which can cruise at 40-50Knots. The worlds fastest navy ship is the U.S.S. FREEDOM which is a Littoral Combat Ship capable of reaching speeds of up-to 45Knots/52mph. . The hull of a Navy ship can be flat or V-bottomed. Vessels designed for cargo and combat are usually flat with a bulbous hull while vessels made for pure combat can even be V-bottomed with/without a bulbous hull. The vessels are propelled by high horsepower – high RPM engines so that they can reach their desired speeds. Some ships like HAMINA ATTACK CRAFT of the Finnish navy uses water-jets (similar to ones on Jet-ski’s) to propel it forward. They are usually made from light weight aluminum alloy. ____________________________________________________________________
Speed Boats: Speed boats are usually made for the purpose of pleasure. People sometimes want to get outside and have the ride of a lifetime. A speedboat is a boat that is quite small usually carrying 2-5 people and can reach speeds of upto 80Knots. The hull on a speedboat is usually a V-bottom and is made so that it allows the boat to skim over the water so that it has less water resistance. Normally, speedboats are propelled using medium horsepower and VERY high RPM engines and in some cases water jets. The engine of a speedboat provides a great deal of power and has a huge acceleration power compared to that of a cargo ship. Speedboats are made out of high-grade carbon-fiber or even fiberglass. ____________________________________________________________________
Tug Boats: (In the picture you can see a huge cargo vessel being pushed by tugboats.) When a huge vessel such as an oil tanker is coming to dock/berth (more correctly: Berth), there are normally other vessels in front and behind the berth so the vessel has to maneuver and fit itself on the dock without crashing into the dock or into other ships. Of-course, a huge vessels has no ways of doing the safely and accurately, that’s when the Tug boats come into play. There are normally two boats to aid a ship but in some cases there are even 4 or 8 depending on the size of the vessel and the complexity of the maneuver required. The tug boat is usually has a V-bottomed hull and has a rubbery edge just like bumper-cars. They have the rubbery edge because they need to actually PUSH and PULL the ships without damaging anything so the rubber proves as a shock absorber. The propulsion on the ship is usually from a High Horsepower and Medium RPM engine. The High horse power to aid the ship in pushing other huge vessels and the RPM to help it push the vessel faster. Tug boats are made from sheet-metal, plastic, in rare cases wood or even high grade plastic (carbon etc), the rubbery edge is made from high grade rubber and is filled to a very high air pressure.____________________________________________________________________
What influenced our choice of design?
Hull: When we wanted to design our hull, we were initially thinking of making a speedboat with a V-bottom, but later on as we came to know about the small difficulties in making a V and it's purpose on our lives, we decided to make a Freighter as most of our things (Computers, cars, oil etc) come by ship and it would be good to have an improvement in the ship design. We chose a Flat bottom hull as it would be easier to make. To make the vessel cut through the water, we added a pointed tip and it did a very good job. We also chose a flat hull as it could hold huge amounts of weight.
Materials: We chose our materials carefully as we also has to scale down the weight of the material. Metal would be too hard to cast in the DT lab and is not at our skill level. Then we came to acrylic, light (in scale) and easy to bend! So we chose acrylic. Acrylic also never rusts and it is waterproof so our model could last for years and would be a role model to ships of the future.
Propulsion: We planned on using a High Horsepower and High RPM motor but due to the time restraint, we just made the hull and used human propulsion for the tests. In the future we could scale up our ship and put inplace an actual engine if we could get the funds for it.
____________________________________________________________________
Evaluate Stage
Investigate : In this stage we did a thourough investigation. It was really good and we got a full six marks. We all had different tasks to do and one day we sat together and compiled it all together and presented sir ONE document which had all our input. This time this was very Successful and next time to make it better, we should do an investigation of the tools and materials available in the DT lab.
Design : In this stage we made various designs on Google Sketch Up and presented them to sir. We also got very high marks in this stage. We also justified our choices and the materials to be used. Next time we should create various small models out of styrofoam so that we can actually FEEL it and it would aid our thinking better.
Plan : In this stage, we created a Gantt chart and a production plan. It was really successful only that we did not include the alternative tools to be used because this time we did not have soldering irons but we found it later on.
All in all, we did get a 5 but we want a six next time and we will give alternatives to our tools.
Create : This was the best part of it all, here we made a change ans swithched out design to a flat bottomed freighter due to the difficulty in making a Vee and the time we had was also running out. Our boat functioned really well and during our high speed tests it actually CUT through the water and made me wet in the process as the tip of the boat created a huge splash. Next time we should incorporate a bulbous hull so that we can have a smoother ride with less rocking.
Attitudes In Technology : I worked very cooperatively with my colleagues and we all worked together as a team to produce a very wonderful boat which will hopefully be improved and will help the future generation of boat design.
THE END
