Kapal pemecah air batu

Kapal pemecah air batu Kawalan Pantai US berhampiran Stesen McMurdo, Februari 2002

Kapal pemecah air batu adalah kapal direka khusus untuk bergerak melalui persekitaran yang diselitupi dengan air batu. Kapal sebegini memecahkan air batu dengan menggunakan momentum dan kuasa mereka untuk menolak bahagian hadapan kapal di atas lapisan air batu. Berat kapal memaksa air batu ditolak turun yang mengakibatkan air batu itu pecah berkecai berketul-ketul. Bentuk badan yang direka khas membenarkan ketulan air batu ditolak ketepidengan itu membenarkan kapal pemecah air batu bergerak kehadapan. Kapal pemecah air batu memerlukan badan kapal yang diperkukuhkan khas bagi berfungsi dikawasan berair batu. Kapal biasa tanpa sebarang pengukuhan radak akan mengambil risiko menyentuh air batu sama sekali, walau sebagaimana perlahan sekalipun. Kapal moden seberat beribu-ribu tan bertembung dengan air batu seberat kemungkinannya dua kali ganda, atau sehingga seribu kali ganda, mampu mencetus kerosakan yang memerlukan pembaikpulih yang besar atau cukup besar untuk menengelamkannya. Air batu juga melobangi kapal yang tidak diperkukuhkan dengan mudah. Hasil ini dapat dilihat dengan jelas dengan tenggelamnya RMS Titanic.

Sejarah

Even in the very earliest days of polar exploration, ice-strengthened ships were used. These were originally wooden and based on existing designs, but beefed up. Particularly around the waterline with double planking to the hull, strengthening cross members inside the ship. Bands of iron were wrapped around the outside. Sometimes metal sheeting was placed at the bows, stern and along the keel. Such strengthening was designed to help the ship push through ice and also, in case the ship was "nipped" by the ice. Nipped describes the event when ice floes around a ship are pushed against the ship trapping it as if in a vise and causing damage. This vise-like action is caused by the force of winds and tides transmitted through ice formations that, although many miles distant, transmit the pressure.

At the beginning of the 20th Century several countries began to operate purpose-built icebreakers; most were coastal icebreakers, but Russia and later the Soviet Union also built several oceangoing icebreakers of around 10,000 tonnes displacement. Several technological advances were introduced over the years, but it was not until the introduction of nuclear power (icebreaker Lenin, 1959) that icebreakers develop their full potentials.

Function of icebreakers

Icebreakers are needed to keep trade routes open where there are either seasonal or permanent ice conditions. Icebreakers are expensive to build and very expensive to run, whether the icebreaker is powered by gas turbines, or is a nuclear powered icebreaker. They are uncomfortable to travel in on the open sea: Almost all of them have thick, rounded keels and with no protuberances for stability they can roll even in light seas. They are also uncomfortable to travel in when breaking through continuous thick ice due to constant motion, noise, and vibration caused by banging against the ice.

A modern icebreaker typically has shielded propellers both at the bow and at the stern, as well as side thrusters; pumps to move water ballast from side to side; and holes on the hull below the waterline to eject water bubbles, all designed to allow an icebreaker stuck amidst thick ice to break free. Many icebreakers also carry aircraft (formerly seaplanes and now helicopters) to assist in reconnaissance and liaison.

Future of Icebreakers

The shape which allows icebreakers to move through ice also make the ship uncomfortable in open water and have poor fuel effiency.

Icebreakers tend to roll side to side causing discomfort to the crew. Some new icebrakers such as the USCGC Healy make use of roll tanks. Roll tanks use computer controlled pumps to rapidly shift ballast water side to side to keep the vessel upright.

A greater concern is how well a ship cuts through waves. The ability of a ship to cut through waves can greatly affect its fuel efficiency and even its safety in a storm. Most ships use a sharp bow to cut through waves and help prevent waves from slamming the bow of the ship. Icebreakers with the round; sled-like bow used to ride up on the ice; tend to slam into waves and can be a risk in high seas. Recent advances in ship propulsion have produced new experimental icebreakers. Electrically driven propellers are mounted to steerable pods under the ship. These Azimuthing Podded Propulsors, or Azi-pods, improve fuel efficiency, ship steering, ship docking, and removes the need for rudders. Azipods also allow a ship to travel backwards as easily as it travels forward. The double acting icebreaker is unique beacuse its stern is shaped like an icebreaker's bow. Normally travelling forward, a double acting icebreaker uses a conventional ship bow for a more comfortable ride. When ice is encountered, the ship turns around and drives backward through the ice. The MT Mastera and MT Tempera are two vessels using this new technology.

Sesetengah kapal pemecah air batu

Argentina

tentera laut Argentine

• Almirante Irfzar

Australia

• Aurora Australis

Kanada

Pegawai Pantai Kanada

• Kapal pemecah air batu CCGS Alexander Henry
• Kapal pemecah air batu CCGS Amundsen
• Kapal pemecah air batu berat CCGS Louis S. St-Laurent
• Kapal pemecah air batu berat CCGS Terry Fox
• Kapal pemecah air batu CCGS Des Groseilleirs
• Kapal pemecah air batu CCGS Henry Larsen
• Kapal pemecah air batu CCGS Pierre Radisson
• Icebreaker CCGS Sir John Franklin
• Kapal pemecah air batu ringan CCGS Samuel Risley

Pedagangan

• MV Arctic
• Kapal pemecah air batu Arctic Kalvik (sekarang Kapal pemecah air batu Vladimir Ignatjuk)

Marine Atlantic

• MV Caribou (feri Gulfspan)
• MV Joseph and Clara Smallwood (feri Gulfspan)

Ontario Hydro

• Niagara Queen II

Finland

Finnish Maritime Administration

• MS Fennica
• MS Nordica
• MS Kontio
• Kapal pemecah air batu JSSkarhu

Commercial

• MV Sampo
• MT Tempera dan MT Mastera

Jerman

• PFS Polarstern
• Stettin

Antarabangsa

• • Greenpeace
    • Kapal pemecah air batu Arctic Sunrise

Jepun

• • Kapal pemecah air batu Shiraze

Russia

• Nuclear Kapal pemecah air batu Arctic (Icebreaker Arktika)
• Kapitan Dranitsyn
• Icebreaker Krasin
• Nuclear Kapal pemecah air batu Lenin
• Kapal pemecah air batu Saint Alexander Nevsky
• Nuclear Kapal pemecah air batu Yamal
• Kapal pemecah air batu Yermak
• Kapal pemecah air batu Vladimir Ignatyuk (dahulunya Kapal pemecah air batu Arctic Kalvik)

Sweden

• • Kapal pemecah air batu Oden

Amerika Syarikat

• • NSF
    • Kapal pemecah air batu Nathaniel B. Palmer
  • United States Coast Guard
    • Kapal pemecah air batu berat USCGC Healy (WAGB-20)
    • Kapal pemecah air batu berat USCGC Polar Star (WAGB-10)
    • Kapal pemecah air batu berat USCGC Polar Sea (WAGB-11)

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