Thrusters

Welcome, Guest. Please login or register.

Technical Support

General Discussion

[Stuart2007]

Sarcasm? I'm shocked.  You'd never catch ME being sarcastic 

[The Ferry Man]

WHAT are you saying about us, Sir?

Angus, despite my earlier shock, I wonder now if this is similar to how the Wightlink (FASTCAT) boats cast off Portsmouth pier. I didn't actually see how they did it (or didn't pay attention!) but noted they don't have bow thrusters but still cast off as if they do (from a passenger perspective anyway)

Well....

They first turn towards the quay side, so they are diagonal with the bow closest, stern furthest. They then reverse before turning the other way to depart 

[Stuart2007]

Are you sure on that? I thought I had seen them doing as Capt Traddles described- that is pivoting on the stern, not the bow.

[The Ferry Man]

Are you sure on that? I thought I had seen them doing as Capt Traddles described- that is pivoting on the stern, not the bow.

Trust me I have watched them do it - I now use there method with RJ4

I will see if I have some pictures of them doing it

Edit: Sadly I don't, and no YouTube video

But they do do it that way

[Stuart2007]

Yes, I have seen it the way you describe... But I'm sure I've also seen it the way Angus has described it, I think.

[Traddles]

With reference to my little exercise. Marty (mvsmith) saw this done in a narrow river when he was on a research vessel. In the actual real case which he observed, the ship lay moored starb'd side to the jetty, bows pointing upriver, and the spring was led from the PORT fairlead right AROUND the bow and then to the jetty. The ship was thus able to complete a full 180⁰ turn and sail off down river. Sadly mooring ropes in the game will not go round corners so I had to make do as is.

Angus.

[TerryRussell]

With reference to my little exercise. Marty (mvsmith) saw this done in a narrow river when he was on a research vessel. In the actual real case which he observed, the ship lay moored starb'd side to the jetty, bows pointing upriver, and the spring was led from the PORT fairlead right AROUND the bow and then to the jetty. The ship was thus able to complete a full 180⁰ turn and sail off down river. Sadly mooring ropes in the game will not go round corners so I had to make do as is.

Angus.

Now that takes some skill!

Done wrongly, that vessel could have had bad scrapes on both sides and a crumpled bow. With really bad skills, they might have been able to wrap the hawser around the propellors and take them off. But that would need really bad skills! 

[eviss]

Hello Angus,

With reference to my little exercise. Marty (mvsmith) saw this done in a narrow river when he was on a research vessel. 
bows pointing upriver / to complete a full 180⁰ turn and sail off down river.

Luckely for me, the springline effect could be executed in favor of this exercise with the Northern Star.

Sometimes "the ship" (like the Vermaas) will not move at all, when a line is attached.

Adding to the presented example is the consideration where Marty is also refering to: the river 

It would be great to have a ShipSim version with effects like wind, wave and currents.

Spending a lot of my sailing times on rivers, there is a variaty of ways to use moring- or tow-lines to direct the ship without using of propulsion or thrusters.

The currents against the side of (loaded ships) and the rudders of course, can therefor be used to stear (within limmits) the ship.

vr. gr. / kind regards, Erik

[mvsmith]

I should add that R/V Argo was a converted US Navy diesel-electric ARS with twin screws and rudder. By skillful use of a backing screw, the bow can be kept clear of the dock while momentum carries the ship around. This is not really necessary for a small—214 feet—vessel that can stand being pressed gently against a wood-faced dock.

http://www.navsource.org/archives/09/37/3727.htm (http://www.navsource.org/archives/09/37/3727.htm)

[eviss]

Hello Marty,

Great moment, I'm happy, to hear / see you again.

By skillful use of a backing screw, the bow can be kept clear of the dock
This is not really necessary for a small—214 feet—vessel that can stand being pressed gently against a wood-faced dock.

I figured that to be the case, in order to stay clear of any structural damage !

vr. gr. / kind regards, Erik

[TerryRussell]

I should add that R/V Argo was a converted US Navy diesel-electric ARS with twin screws and rudder. By skillful use of a backing screw, the bow can be kept clear of the dock while momentum carries the ship around. This is not really necessary for a small—214 feet—vessel that can stand being pressed gently against a wood-faced dock.

http://www.navsource.org/archives/09/37/3727.htm (http://www.navsource.org/archives/09/37/3727.htm)

Hi Marty.

I still reckon that takes a lot of skill. 

[Aad The Pirate]

For those players who have an interest in this topic I attach a little exercise. The object is to take "North Star" off her berth and out into Red Hook Channel, New York harbour. The catch is that due to poor engine maintenance the astern linkage for the main engine is broken and you only have ahead power available. It is easy if you cheat and use astern power, but resist the temptation and don't This kind of emergency happens in reality and a good seaman will get round it. To do it correctly only takes a few minutes and illustrates the theme of this topic. I offer my thanks to mvsmith for the concept which he has witnessed in reality.

Angus.

Ahoy Agnus
And so I had to try it out, and off course, I made a movie:
http://www.youtube.com/watch?v=7Zwf9xxU8MU
Regards
Aad

[mvsmith]

Hi Aad,
Nice video, but I thought the object was to do it without the bow thruster.
Regards,
Marty

The geometry and physics are a clue:
The relative positions of the rudder pintle and the mooring bollard on the ship make it impossible to produce a significant turning moment with screw and rudder.

[Traddles]

Hi Aad,
As Marty says, I too like the video, but I do not see how to do it that way WITHOUT the magic bow thruster. The following 5 pictures show the way it is done. Sorry I cannot make a video but the pics. and their titles indicate the sequence. The "." use of the non existant thruster is cheating.

Angus.

[Aad The Pirate]

Ahoy Marty and Angus,
You caught me redhanded. Well, I'll make it up to you with this video:

http://www.youtube.com/watch?v=CJkaIoH3-kM

Regards
Aad

[Traddles]

Hi Aad,
Thanks for that one. It is easy when you know how, possibly a little paintwork scraped, but it is an emergency manoeuvre after all. You now qualify for this.
Regards,
Angus

[Stuart2007]

Angus/Marty

Thaks for the graphical translation, so we non-seafarers have an idea what you seadogs are actually talking about 

Marty, very nice to see you back. 'Hope you are well.