What Is Polyethylene?
Polyethylene is a high density type of plastic. Comparing to other polyethylene materials, it is much more solid, stronger and also comparing to low density polyethylene (LDPE), it is a lot heavier and harder. Polyethylene’s density is less than water. It can be produced using moulding technology or with extrusion method. It is possible to merge the plates by special welding methods and it also can be processed on workbenches. It is very hard to merge them using and adhesive material. The appearence of polyethylene is mat, opaque and looks like wax. It is also a very clean material, it can contact with food without spoiling it.
Particulars Of Polyethylene
Durability: It is resistant to material aging. Lifetime of polyethylene is calculated as at least 50 years, but the performances prove that it is much higher in reality.
Light and Easy to Process: Carrying polyethylene plates are so easy that it gives an important advantage at production, comparing to heavier materials, like steel.
Flexibility & Endurance: Flexibility of polyethylene prevents deformity of material and cracking on surface. It is very resistant to collision damages and also resistant to tension cracks and crack expansion.
Adaptability: Polyethylene is not fragile, even at the low temperatures. It is resistant to freezing and also does not effect from freezing of the liquid it is in.
Good Welding Features: The tests show that, welding lines are much stronger than jointless pipe zones, especially the welding points merged with electro fusion and butt-welding, these points are extremely durable.
Resistance to Chemical Effects: Polyethylene material is highly resistant to chemical corrosive products. In different work areas, polyethylene is used for production of chemical tanks or acid tanks.
Easy Cleaning: Polyethylene does not get dirty easily, it does not contain toxic matter and very easy to clean.
Why Polyethylene Boats?
Polyethylene’s density is between 0,93 g/cm 3-0,97 g/cm3. This means it is 1/8 times lighter than steel and 1/3 times lighter than aluminium. It is even lighter than water, so this gives and enormous advantage to polyethylene for safety and carrying capaticy.
Polyethylene is a very convenient material for sea conditions. Because of its elasticity, it is very succesful to endure all kinds of sea conditions.
Resistance to Corrosion & Sea Creatures
Oxygen, salt and water does not affect polyethylene. It is possible to build polyethylene boats which is going to be in service for years without maintenance.
Polyethylene’s surface can stay bright and slippery always, as polyethylene does not corrode. So that frictional problems are very low, comparing to alternatives.
High Tension Resistance & Ability to Absorb Impact
Thanks to its high tension resistance, boat’s shell plates can easily absorb any impact and take minimum damage from impacts like collision or grounding. In case of any damage, it can be repaired very easily.
Polyethylene is an ideal material for boats which will work in shallow water or seashore.
It is possible to make local repairs for damaged parts of a polyethylene ship. Any repair or welding can be done easily and fast.
Low Invest & Running Cost
Polyethylene boats can be built very fast, because of characteristics of the material. Low investment cost and low manufacturing period are some of the most important advantages of polyethylene.
Polyethylene does not need any maintenance during working. It does not need to be painted or taken to drydock regularly. Boats can be used anytime, if there is no damage on the shell by outside factors.
Polyethylene boats are very light and adaptable to all kinds of propulsion systems. This gives polyethylene boats an important advantage for manouvering, for example while working at narrow seas.
Polyethylene boats are built as double hull and the space between hulls is filled with polistren foam, except engine room. This means, density of boat is lower than water, and there is not any possibility for the boat to sink.
Polyethylene Boat Types
The boats, which can be designed for various purposes of service, have the possibility of having different types of decks. It can be designed completely empty and ready to load cargo, or can be designed with a cabin and seats.
It is possible to build crew boat, pilot boat, agency boat, service boat, passenger boat, sea taxi, police boat, navy boat, ambulance boat, firefighting boat, waste cleaning boat, fishing boat, diving boat, tug boat etc. with polyethylene.
It is also possible to install different types of propulsion systems, such as inner or outer engines, water jet, surface propeller and conventionel shaft-propeller.
Comparing With Other Materials
• Polyethylene, is lighter than steel or aluminium, and plates of it is easier to merge. It gives much more construction convenience.
• Polyethylene is much more economical as a raw product, comparing to steel, aluminium and wood. A fiberglass, an aluminium and a polyethylene boat with same design and outfitting, have nearly similar weights. On the other hand, fiberglass is much more expensive and a harder material, which means it is more fragile to impacts, and it takes a long time to repair. Polyethylene is more economical, while at shipbuilding and in its lifetime in sea.
• Polyethylene is more resistant to corrosive effects of chemicals and seawater than other shipbuilding materials.
• Fiberglass and aluminium can be damaged and cracked easily when crashing to rocks or when a similar effect occurs. But polyethylene has a higher tension resistance, and can save itself with minimum damage. Also with it’s shape memory, polyethylene will take it’s original shape again.
• Fiberglas boats are constructed with moulding method and this does not give opportunity to modify the boat’s hull and deck when it is needed. However, polyethylene boats are constructed with cnc cutting and welding method, and can be shaped easily. For example, a closed area can be build quickly and without too much effort.
• At production, carbon emission values of polyethylene is 5 times lower than aluminium and GRP ships, and unlike them, polyethylene can be recycled %100.
|Tensile modulus of elasticity||1100||Mpa|
|Elongation at yield||9||%|
|Elongation at break||≥300||%|
|Impact strength||Without break (Kırılmaz)||KJ/m²|
|Notched impact strength||30||KJ/m²|
|Ball indentation hardness||40||Mpa|
|Shore hardness D (15 s)||65|
|Temperature range||-50 to +80||°C|
|Physiological safety in accordance with EU||Yes|
|Thermal conductivity||0,38||W/m * K|