見慣れない船がいるなぁと思っていたら
南極観測で活躍する「しらせ」が寄港しました。
さっそく港に見に行ってきました！
一般公開はコロナの関係で中止～
残念。中に入りたかったぁ
また11月には南極にでかけるそう。
このあとは舞鶴に寄るそうです♪
今度はいつ立ち寄るのかな？？
I was thinking that there was an unfamiliar ship, and then the Shirase, which is used for Antarctic observation, arrived. I went to see it right away! The public opening has been canceled due to COVID-19. Too bad. I wanted to go inside. They're going to Antarctica again in November. After this, they're stopping by Maizuru♪ I wonder when they'll stop by again? ?
[Updated Septeｍber 2024]
砕氷艦「しらせ」は世界的にも知られたフネであり、折々のニュースにも登場することから馴染みのある艦船だと思う。「しらせ」は、南極観測隊の人員や物資を乗せ日本と南極を往復している。
日本の南極観測の源流は先述した白瀬中尉の南極探検・学術調査にまで遡れる。明治40年代、1900年代初頭のことだ。そして現在の南極観測とは、国立極地研究所の科学観測・研究集団を観測隊として派遣することを指し、第1次南極地域観測隊の派遣決定が1956年（昭和31年）のことだったから、今日まで60年以上も継続されている国家事業となっている。
「しらせ」は南極観測船と砕氷艦、ふたつの肩書き各々で呼ばれることが多い。活動内容から見れば「南極観測船」であり、運航を担う海上自衛隊の分類では「砕氷艦」と呼ばれる。名称どおり、氷を砕く機能を持った艦という意味だ。
日本の南極観測船・砕氷艦には代々の歴史がある。初代は「宗谷（そうや：海上保安庁所属）」、2代目は「ふじ」。続く3代目となるのが現用の「しらせ」だ。
さらに言えば「しらせ」は、「初代・しらせ（AGB5002）」と現用の「２代目・しらせ（AGB5003）」と２隻ある。「初代・しらせ」は1981年に起工・建造され、翌82年に就役、2008年に退役している。そして「２代目・しらせ」は2007年に起工・建造され、09年に就役し、現用されている。初代しらせ退役と２代目建造の間に当たった08年の第50次観測隊航海にはオーストラリアの民間砕氷船をチャーターして行ったという。ちなみに「AGB」とは海自での分類と記号で砕氷艦を示すものだ。加えて、砕氷艦の英表記は「Icebreaker」とその機能性を表している。
現用の「２代目・しらせ」は南極昭和基地へ約1100トンもの物資を運ぶため大型化された。基準排水量は1万2650トン。海上自衛隊では補給艦「ましゅう」の1万3500トンに次ぐ大きさの自衛艦ということになり、世界でもトップクラスの高性能な砕氷艦だ。
その砕氷機能は次のとおり。まず、艦首下方の海面と接する船体角度は21度に設定した砕氷航行に最適なもの。厚さ1.5mまでの氷海なら時速3ノット（約5.6km/h）で連続した砕氷航行が可能だ。鋭角の吃水下船首が氷に乗り上げ、船体重量を使いながら押し分けるように砕氷する仕組みだ。外圧を受ける船体外板や後部ヘリ甲板などは高張力鋼を採用、喫水付近の船体は耐摩耗性に優れるステンレスクラッド鋼も使われている。水を移動させて動揺を抑える減揺タンクを内蔵、船体を左右に傾斜させるヒーリングタンク（タンク内のオイルを移動させ、船体を左右に揺らして氷を砕く）も併用し砕氷航行を効率化している。艦首には放射状に散水装置が取り付けられ、水を撒いて解氷しやすくする工夫もある。また、助走をつけて分厚い氷に突入し割る「ラミング」という砕氷手法も合わせ、氷の海を切り開いてゆく。
The name of the icebreaker Shirase of the Japan Maritime Self-Defense Force is said to come from the Shirase Glacier near the Showa Station in Antarctica. The Shirase Glacier is named after the first Japanese to reach the Antarctic continent, Lieutenant Shirase Nobu of the Imperial Japanese Army, so the name of the ship can be interpreted as coming from Lieutenant Shirase. However, since the instruction that sets the standards for naming JMSDF vessels does not include any personal names, it is not a direct reference to Lieutenant Shirase's name. The icebreaker Shirase is a world-famous ship, and is often featured in the news, so it is probably a familiar ship. The Shirase travels back and forth between Japan and Antarctica carrying personnel and supplies for the Antarctic Research Expedition. The origins of Japan's Antarctic research can be traced back to the Antarctic exploration and academic research of Lieutenant Shirase mentioned above. This was in the 1900s and early 1910s. And today's Antarctic observation refers to the dispatch of scientific observation and research groups from the National Institute of Polar Research as observation teams. The decision to dispatch the first Antarctic Research Expedition was made in 1956, and it has been a national project that has been ongoing for over 60 years. The Shirase is often called by its two titles, Antarctic observation ship and icebreaker. In terms of its activities, it is an Antarctic observation ship, but the Maritime Self-Defense Force, which operates it, classifies it as an icebreaker. As the name suggests, it means a ship with the ability to break ice. Japan's Antarctic observation ships and icebreakers have a long history. The first was the Soya (belonging to the Japan Coast Guard), the second was the Fuji, and the third was the current Shirase. There are two Shirases: the first Shirase (AGB5002) and the current second Shirase (AGB5003). The first Shirase was laid down and constructed in 1981, commissioned the following year in 1982, and decommissioned in 2008. The second Shirase was laid down and constructed in 2007, commissioned in 2009, and is still in use. In 2008, between the retirement of the first Shirase and the construction of the second, a private Australian icebreaker was chartered for the 50th research expedition voyage. Incidentally, "AGB" is the classification and symbol used by the MSDF to indicate icebreakers. In addition, the English name for icebreaker is "Icebreaker" and indicates its functionality. The current second Shirase has been enlarged to carry about 1,100 tons of supplies to the Showa Station in Antarctica. Its standard displacement is 12,650 tons. This makes it the second largest ship in the MSDF after the supply ship Mashu, which has a displacement of 13,500 tons, and one of the most high-performance icebreakers in the world. Its icebreaking functions are as follows: First, the angle of the hull where the bow touches the sea surface is set at 21 degrees, which is optimal for icebreaking navigation. In seas with ice up to 1.5m thick, continuous icebreaking navigation is possible at a speed of 3 knots per hour (about 5.6km/h). The acute angle of the draft bow rides up onto the ice, and the weight of the hull is used to push it aside and break the ice. High-tensile steel is used for the outer hull plate and the rear helicopter deck, which receive external pressure, and stainless clad steel, which has excellent wear resistance, is used for the hull near the waterline. Icebreaking navigation is made more efficient by incorporating anti-rolling tanks that move water to suppress rocking, and heeling tanks that tilt the hull left and right (moving oil in the tank and rocking the hull left and right to break the ice). Water sprinklers are attached radially to the bow, and there is also a mechanism to spray water to make it easier to melt the ice. In addition, an icebreaking technique called "ramming", in which the ship takes a running start and enters thick ice to break it, is used to cut through the icy seas.
オリジナル投稿：2020年9月12日
