大型船舶操纵性能特点概要

大型船舶操纵性能特点概要

由于超大型船舶的尺度和载重量极大而主机相对单位吨位所具有的马力反而变小，从而使超大型船舶与一般1 –2 万吨级船舶在操纵性能上具有了很多需要注意的不同特点。

一．操纵性能下降

1．舵效差，反应迟钝，甚至3 – 4 节船速时已无舵效；

2．追随性差，故在改向或过弯曲航道时，需予以充分估计，及时施舵；

3．航向稳定性（方向稳定性）差，施舵后，一旦船首开始偏转则需注意及时压舵驶上新航向；

4．保向性能差，在风浪中航行因B/L.D值较高，易产生偏航；

5．旋回性相对好，虽旋回圈较大，但其D/L值较低，呈良好旋回性能；

6．启动，停车惯性大，呈显出变速操纵较为呆笨，停船性能较差；

7．转向惯性大，故需施大舵角，早施舵，早回舵，施大压舵角；

8．紧急停船性能下降（停车惯性大）。

二．浅水，狭水道中受限水域中产生的效应更为明显

1．阻力增大，船速下降；

2．船体下坐，产生纵倾；

3．旋回性变差；

4．振动加剧，产生异常振动；

5．舵力产生变化；

6．航向稳定性提高；

7．因纵倾与横摇，要求足够的富裕水深；

8．沿岸航行，易产生侧壁效应；

9．因风，流压差，要求足够的海底宽度；

10．追越与对驶时，保持必要间距，以防船吸效应。

三．港内操船特点

1．由于港口码头水域有限，超大型船舶的操纵港作拖轮是主力；

2．靠离码头，横向移动需要使用多艘拖轮；

3．所配拖轮位置应据不同作业状态而应有所不同；

4．回转中需注意本船船尾的反移量。

四．操纵用锚上的受限

1．锚泊时，几乎都是抛单锚锚泊；

2．如抛锚调头等操纵用锚时，应倍加注意，因锚机制动力不足，船速必须小于1/4节，否则有危险；

3．因船舶动量特大，一般不可应用锚来制动，最忌违的是航行中下锚；

4．一般均采用深水抛锚法，用锚机倒至海底，松出一定长度锚链后，再用常规方法松链。

超大型船舶的船型均肥胖而粗短，其方型系数多高于0.8，船越大C B亦越大，即是压载时C B也可达0.75以上，其长度比L/B为6.0 – 6.7，比一般货船小，而宽与吃水之比多大于2.5，比一般货船大，其舵面积比A/Lpp * d多低于1/65，但却具有良好的旋回性，从而使得超大

型船舶的追随性和航向稳定性能较差，而旋回性能较好，主机功率随船型的增大而增大，但并不与其吨位成比例，其单位吨位马力值有较大降低，且其全速倒车速度也仅能达到全速前进时的30%左右，一般均在6节以下。

Outline of Manoeuvre Characteristics of VLV

Owing to the large measures and great DWT of VLV and relatively smaller main engine horse power per ton, there are many characteristics different from those of the 10,000 ton to 20,000 ton vessels.

1. Ship’s Manoeuvrability Coming Down

1.1Bad steering: slow reaction, no rudder effect, turn at the 3-4 kt speed.

1.2Bad yaw quick responsibility: make enough estimate and make rudder in time when

altering course or passing the bend channels.

1.3Poor course stability (directional stability): after making rudder pay attention to make

opposite rudder in time the ship head being to slant.

1.4Bad course keeping ability: in the storm weather, easy to be off course, because of low

B/L *D value.

1.5Good steady turning ability: although there is a big turning circle, D/L value is small

good turning ability appearing.

1.6Big starting and stopping inertia: changing speed appear duller, stopping ability is not so

good.

1.7Big turn inertia: in order to make big rudder angle, make rudder early, make early return

rudder, make big opposite rudder angle.

1.8Because of big stopping inertia crush stopping ability comes down.

2. More evidence effects in Shallow and Narrow Channel

2.1 Resistance increase, speed coming down.

2.2 Trim happening because of ship body sinking.

2.3 Steady turning ability becoming not so good.

2.4 Vibration intensifying, abnormal vibration appearing.

2.5 Course stability being better.

2.6 Rudder force changing.

2.7 Require enough U.K.C, because of trim and heel.

2.8 Bank effect easy to happen in narrow channel sailing.

2.9 Require enough breadth of sea bottom for leeway.

2.10 Keep necessary distance from other ship while is going to overtake or head-on.

3. In the Harbor Manoeuvre Characteristics

3.1 Tugs become main force to maneuver VLV because of limited harbor water area.

3.2 Need several tugs to go alongside or leave berth or move transversely.

3.3 Need different tug disposition according to different tasks.

3.4 In turning process pay attention to the kick of own ship stern.

4. Restricted to use Anchor in Manoeuvring

4.1 Almost use single anchor at anchorage.

4.2 Pay special attention to using anchor in maneuver, ex. Turning with anchor, speed have

to be less than 1/4 KT, otherwise there are dangers because the brake of windlass has no

enough break power.