Single-turn (Anderson turn):
- Anderson turn is suitable for immediate action situation.
- In this technique you place the rudder hard over to the side of MOB and once you have deviated from your original course by 250 degree you bring your rudder amidship and perform a stopping manoeuvre.
- On the positive side its a fast recovery method and it works well for the ships with tight turning characteristics.
- However its difficult to approach as you are not on the straight course.
The main advantages of single-turn manoeuvre are that the vessel quickly returns to the victim and the turn is relatively simple and easy to execute. At the end of the single turn manoeuvre, though, the ship is approaching her reciprocal course almost perpendicularly. This means that the location of the POB should be well known because otherwise only a small portion of the reciprocal course will be crossed and therefore the probability of detecting the person is quite low.
- This is suitable for an immediate action situation where the individual has just fallen over the side.
- you place the rudder hard over to the side of MOB.
- After you have deviated from course by 60 degree, you place the rudder hard over to the opposite side and finally when you are 20 degree short of the opposite course. You put the rudder amidship position.
- The key positive feature of technique are –
- It makes good the original track.
- Works well in reduced visiblity
- Its simple
- On the negative side it takes vessel further away from the MOB and its a slow process.
The above points are enough for exam purpose, Below you will find same thing written in a bit different way so its your choice to read or directly skip to Scharnow turn
Williamson Turn aims to turn the vessel to her reciprocal course from
where the POB location is approached directly. The turn is executed by turning the rudder hard over and once the vessel has deviated 60 degrees from the original course, the rudder will be switched hard over to the other side. When the course is 20 degrees from the original course, the rudder will be put back to neutral position.
The advantages and disadvantages of this turn are quite the opposite to that of Anderson’s turn. The execution time will be longer than in the case of single-turn and it’s more difficult to perform. On the other hand, if there’s an uncertainty of the victim’s
location, Williamson turn is superior since it returns to the reciprocal course where the
POB will most likely be. Moreover, during the time the vessel is returning to its original position and travelling on the straight line, the time can be used to observe the POB and adjust the course whereas in Anderson this would be difficult because of the reciprocal course is approached indirectly.
- This action is not suitable to use in immediate action situation where the individual has just fallen overboard.
- You place the rudder hard over and when you have deviated by 240 degrees from your original course you place the rudder hard over to the other side. When you are only 20 degree from opposite course the rudder should be placed amidship.
- Advantage –
- Auto recovery as the ship is brought back to opposite course.
- Victim always in view of rescue team on bridge.
- Disadvantage –
- Not suitable for immediate action.
The two previous manoeuvres excel when performed as immediate actions, whereas Scharnow turn is advantageous when used as a delayed response. In fact, Scharnow turn cannot be performed as an immediate action since after the manoeuvre the vessel will be only a few ship’s lengths behind the original position.
The turn is executed similarly to Williamson turn but now the goal is to arrive on the reciprocal course behind the vessel. The underlying idea is the same as in Williamson turn; return quickly to the reciprocal course and attempt to detect the POB from there.