求资深世外船人答疑解惑·····

Crash/Cargo rail of 200mm N.B. heavy pipes shall be provided on main deck (P&S) as shown on drawing. Vertical rails fabricated from 250 x 250x9/14, H beam.
1、请问一下，“200mm N.B. ”是什么意思是？该怎么翻译呢？

A stern  roller about 5.0m long by 1.6m diameter (S. W. L. 200mt) with Forge steel or equal shaft and roller bearings. Horizontal separation between stern roller and rudders shall be such as to allow 30-

35◦ angle of inclination (to the vertical) tangent to aft of stern roller and bottom ends of trailing edges of rudders.

2、请问一下，“Stern Roller”是什么东西？这段话该怎么翻译？

One (1) set  hydraulically operated anchor handling fork-hydraulic retractable  shark jaws  of  approved make to be installed in centreline on  main  deck  aft.  The stopper to be able to take 50mm to 75mm dia. wire and 28mm to 75mm dia. chain.

SWL to be 200 tonnes.  Stopper and towing pins with common power unit and to be remotely controlled from the wheelhouse aft console and local control station at the stern control station with talkback and speaker facility.

3、请问一下，“Shark Jaws”是什么东西？作用是什么的？能否附真实图片？这段话应该怎么翻译？

Two (2) bow anchors with high holding force together with shackle and stud link chain cable are to be installed in accordance with the rules.

For guidance, they are as follows:-

•         Two (2) high-hold-type anchors, stowed in anchor-pockets, each of 1305 kg.

•              Total length of 440M x 40mm / Grade U2 stud-link-chain cables, divided to port and starboard side with swivel and shackle.

·                  •         Two (2) chain-stoppers, spindle compressor type.
4、请问一下，“spindle compressor type”指的是什么类型？能否附实物照片？

以上四个问题，请各位大侠帮忙解答一下，小弟不胜感激········