Topic: How to manouver a boat/ship/canoe (Read 23823 times)

groennegaard · « **on:** July 16, 2007, 00:16:31 »

EDIT: Continued from discussion of P&O Berth at Rotterdam

No... not quite. I will put the bow to starboard to get it out... (

) then the starboard propeller ahead and the port propeller astern, and finally the rudders hard to port.

The arrows show movement - not thrust!

Setting the starboard propeller astern and the port propeller ahead will swing the stern towards the quay - and we do not want that. It is almost like driving a tank with two levers...

Regards
groennegaard

Stuart2007 · « **Reply #1 on:** July 16, 2007, 00:22:52 »

Thanks very much for that. It is appreciated.

OK... So I was actually talking about putting the ship through the quay.

That all makes sense now you put it like that. Having been on the bridge of a large ship leaving port, I really do have respect for you and your colleagues. Damned sure I couldn't do it.

Stu

EDIT: I've driven a tank. It is nothing like that. Driving a tank is easy. And if you hit something, you don't worry... The driver of whatever you hit worries instead.

mporter · « **Reply #2 on:** July 16, 2007, 02:28:24 »

Quote from: Stuart2007 on July 15, 2007, 19:22:47

Yes, but the rudder only works if it has fluid moving over it. In this case at slow speed, it isn't by forward movement. Only by propellor thrust. Problem is: lots of thrust= forward movement, which may not be what you want.

Take the mission to take PoR out of the berth; If you wind the engines up to get thrust, you will go through the harbour wall.

Stu

I agree with groennegaard, but as a further note, and as a comment to your earlier post -- when the ship is stationary a quick blast of throttle with the rudder hard over has almost no effect on forward motion but a considerable effect on swinging the stern. If this is not the case in SS08, then there is a problem in the dynamics.

Cheers,
Michael

groennegaard · « **Reply #3 on:** July 16, 2007, 06:53:15 »

Quote from: Stuart2007 on July 16, 2007, 00:22:52

EDIT: I've driven a tank. It is nothing like that. Driving a tank is easy. And if you hit something, you don't worry... The driver of whatever you hit worries instead.

He he..

I believe you. However, the tank thing was meant as a memory help to remember which way the ship will turn.

Ferrymaster · « **Reply #4 on:** July 16, 2007, 07:27:38 »

I have been on that ship.
And have seen that at the ship to the back a rope sits.
This has been confirmed to a pile and helps the ship to twist.

(what with difficulty to explain, I hope that the pictures helps)

biggeral88 · « **Reply #5 on:** July 16, 2007, 10:13:23 »

I hope the picture below will help answer the question above as to how a short burst of ahead power can be used to turn the vessel, without gathering significant headway.

The majority of large conventional ferries built today have what are variously known as Hi-lift or Becker rudders etc, and these have a large primary rudder , onto the trailing edge of which is attached a secondary surface, a 'tab' of sorts. Any rudder angle setting ordered is duplicated by BOTH the primary and secondary surfaces - ie. setting 20degrees of helm will move the main surface to that angle, and the trailing tab will then move 20degrees relative to the main surface, effectively giving 40degrees of helm. The ferries with which I am familiar have a rudder limit of 45degrees, effectively enabling thrust from the propeller to be vectored through 90degrees, thus having maximum turning effect with very little ahead movement.

Having possibly confused you with that 'description' I will let this photo do the rest of the explaining - it is of Irish Ferries' Ulysses when she was last in drydock, and it shows her rudders hard over to port. Imagine if you were standing directly astern of the prop (apologies for not having a photo to illustrate this!), you would in actual fact see only the tips of the blades, as the rudder diverts the vast majority of all thrust to the port side.

Hence, you can see why stern thrusters are less common than bow thrusters, simply because a similar job can be done with the equipment already in place, and it saves on the purchase and fitting of expensive thrusters!

I hope that has answered more questions than it has thrown up, but feel free to ask and I'll do my best to answer them and find a photo to illustrate.

AlexKall · « **Reply #6 on:** July 16, 2007, 11:07:26 »

Quote from: Stuart2007 on July 15, 2007, 18:46:44

I took 30 minutes

It is a bit tricky. That walkway to the mooring point on the starboard quarter is a bit too close to the ship and its akward to get past.

Stu

We might be talking about two seperate missions. I was leaving and I think you ware entering, correct?

James89uk · « **Reply #7 on:** July 16, 2007, 18:57:15 »

Quote from: Stuart2007 on July 15, 2007, 18:33:55

It looks hard, yes- but I don't think the other end in Santcruzzi looks much fun either (Have you seen the underwater obstructions buoys at the berth?)

I can't see why they won't use the stern thrusters- although I won't argue the point- seems a waste of money installing and 'ferrying' around heavy equipment for little use.

Hi Stuart,

I hadn't actually seen the underway obstruction buoys at Santurtzi but possibly that is because I hadn't been looking out for them! That's what happens when you spend too much time observing events on the bridge and not enough time watching what they are actually doing up there! None the less you are definitely right, manoeuvring there can't be easy either (especially not with a strong wind) as they don't really give you much space. Will look out for those buoys next time...

There is lots of good information in this thread so thanks to all for that. Was asking a few mariners about the point of the stern thrusters a few months ago and remember one person saying that at 4 knots they are approximately 50% effective, whilst for anything over 8 knots they have barely any effect on the ships course.

Groennegaard, interesting point you made regarding non existent stern thrusters on passenger ships - I think this entirely depends on what type of passenger vessel it is, its age and gross tonnage. We must remember that many new cruise ships in particular have "Azipods" which could carry out the same job as stern thrusters if required - thus, new ships with this technology don't need stern thrusters but do posses 2/3 bow thrusters.

As one person put it earlier in the year stern thrusters on ships with propellers are just another "superfluous gadget" and are just something else to go wrong - nevertheless there may be some occasions when they come in useful. Some ports do not allow officers to use thrusters within X metres of the berth and so have to rely on tugs, whilst others insist that you have a tug even if it just stays there doing nothing.

Argghhh, done too much research into all this...really must get a life...

James

Stuart2007 · « **Reply #8 on:** July 16, 2007, 22:43:03 »

No James, you carry on with your research.

I'm fascinated by this. People keep comparing rudder/props to the airflow over aircraft wings... Well, I'm half way through getting my pilots licence, and the theoretics of flight (and the learning to fly) is much less complicated than manouvering a 30,000 tonne ship to within 1/4 inch of the berth.

Anyway, we're getting away from the media part of this forum. I for one am fascinated and I'm sure others will be.

Stu

mporter · « **Reply #9 on:** July 17, 2007, 01:36:08 »

Quote from: groennegaard on July 16, 2007, 00:16:31

No... not quite. I will put the bow to starboard to get it out... ( ) then the starboard propeller ahead and the port propeller astern, and finally the rudders hard to port.

If I may offer an addendum in the interests of pedantry

: What the port propeller is doing here is keeping the ship from moving ahead, which it would eventually want to do if one had only the starboard prop or had only a single screw. The idea is to get all the various thrusts to combine into a single vector away from the wharf (as indicated by the red arrow).

Quote from: biggeral88 on July 16, 2007, 10:13:23

Having possibly confused you with that 'description' I will let this photo do the rest of the explaining - it is of Irish Ferries' Ulysses when she was last in drydock, and it shows her rudders hard over to port. Imagine if you were standing directly astern of the prop (apologies for not having a photo to illustrate this!), you would in actual fact see only the tips of the blades, as the rudder diverts the vast majority of all thrust to the port side.

Hence, you can see why stern thrusters are less common than bow thrusters, simply because a similar job can be done with the equipment already in place, and it saves on the purchase and fitting of expensive thrusters!

Again in the interests of pedantry (oh no, not again

): it is not the thrust that is diverted to port, but the water flow, and with the rudder hard over to port as shown the stern would be kicked to starboard and there is nothing left to drive the ship forward (which is where I started some many posts back but obviously with not enough explanation).

Cheers,
Michael

AlexKall · « **Reply #10 on:** July 17, 2007, 11:40:32 »

This is really interesting. I know very little of boats/ships, I've only taken a small boat out once and thats it. I'm slowly starting to lern the names of front/back left/right of ship now but it's slightly confusing as there seems to be different names for the same thing? Stern is the back, Bow is the front. That I do know. Can anyone go through all these names? I feel stupid asking for them but it's slightly confusing so I will take my chance of making a fool out of myself

Strangely I'm born by the sea unfortently it wasen't exactly lying by the water but a bit inlands so I never really saw that much ships.

LucAtC · « **Reply #11 on:** July 18, 2007, 02:08:24 »

Hello Stu,
I feel your lessons to fly airplanes inspired the title.

A very good introduction to manoeuvring ships can be found here:
http://www.ocp.tudelft.nl/mt/journee/Files/Lectures/ShipHydromechanics_Intro.pdf
or by googling "ship hydrodynamics MT519", and reading at least chapter 4.
Forget the formulas, or better, read and forget them (-> cut & run?).

If forgot also the references of a good "syllabus" of USCG, perhaps Michael knows about it?

Regards,
Luc

Stuart2007 · « **Reply #12 on:** July 18, 2007, 02:13:32 »

Hello Luc

It is really a fascinating subject. Whilst I had a good scientific reason for thinking a certain combination of propellor/rudder would achieve the result I wanted, I was exactly the opposite of what should have been.

When explained by Groeenegaard why- I realised my logic was 100% flawed. I tell you, airplanes are so simple by comparison. Point it at your destination and just go. (OK landing first time was not so easy)

Thanks for the weblink. I shall look tomorrow. Too tired to concentrate now (happens when you get to my age

)

Stu

mporter · « **Reply #13 on:** July 18, 2007, 03:03:19 »

Quote from: LucAtC on July 18, 2007, 02:08:24

If forgot also the references of a good "syllabus" of USCG, perhaps Michael knows about it?

Regards,
Luc

The USCG has a good manual on handling small craft -- I'll dig the link out tomorrow.

Chers,
Michael

Eemspoort · « **Reply #14 on:** July 18, 2007, 06:21:05 »

Now this is a very intresting thread. Much can be learned here for people with no or just few knowledge of "driving" ships!

Stuart: My geus is, you think flying is easier than driving a ship, because you can fly. I can't fly in real life, but i do know how to get from A to B in FSX. And trust me, handling a ship (of what size, theory is all the same, more or less) is much easier. Planes have much more "rudders" to stay on course and height. Rudder, Aillerons, etc. Ever tryied to taxi a plain sideways, or better, backwards? Can't do, right? Well, not without reverse-thrust.

On ships with a prop/rudder-conversion it's easy, you only have 1 rudder. Offcourse you can have more rudders (1 for every prop, 2 for every prop, i myself have a Hitzler-patent, 3 rudders and 1 prop), but you can turn them with one handle/joystick.
Pay attention on the movement of the plane, if you taxi next time. What happens if you give a bit forward throtlle and move your rudder hard port? You will go left. Allthough the prop on a conventional plane is in front, the thrust (wind?) goes backwards, hits the rudder (like water with ships) and the thrust/wind goes to port. Resulting in the planes tail moving to starboard!But the nose is going to port.

I hope, this is understandeble for you (and anyone else), since i'm Dutch, so my English might be a bit "strange"?

Like i said, i have a single prop with 3 rudders, the Hitzler-patent. 1 small rudder in centre of prop, 2 bigger ones besides the small one. When hard port, the port-rudder is a bit more over then 90 degrees, the midlle-rudder is 90 degrees, and the starboard-rudder is less then 90 degrees, resulting in a thrust-cut-off, bending all the water to port. When my rudder-patent is correctly adjusted, i can turn my ship without bow-thruster on the spot. With full throtlle (800 bhp for a 76 mtr long/8,2 mtr wide ship).
It would even go a bit backwards, if i don't watch out.

Hope this add's something to this thread.

alazose · « **Reply #15 on:** July 18, 2007, 18:09:31 »

So do you "drive" a boat and "pilot" a ship? What are the proper terms for taking the helm of each?

Eemspoort · « **Reply #16 on:** July 18, 2007, 18:59:10 »

Erm....well, i would like to know that to, how it is best said in English...

In Dutch we call it "varen", but i don't beleive there is a propper translation for it.
I just call it drive or sail or pilot in Englisch. Most people understand.

Karbine · « **Reply #17 on:** July 18, 2007, 19:06:57 »

Quote from: groennegaard on July 16, 2007, 00:16:31

EDIT: Continued from discussion of P&O Berth at Rotterdam

No... not quite. I will put the bow to starboard to get it out... ( ) then the starboard propeller ahead and the port propeller astern, and finally the rudders hard to port.

The arrows show movement - not thrust!

Setting the starboard propeller astern and the port propeller ahead will swing the stern towards the quay - and we do not want that. It is almost like driving a tank with two levers...

Regards
groennegaard

Its the same as driving a single screw boat..unless this ferry has bow thrusters? I dont have 2008 yet so i dont know.

You just do what you said kicking your stern out away from the jetty and then back away,once clear,you can then manouver and swing the ferry where you wish to go.

But i would have thought this size ship would have bow thrusters to get into that size of space in the photo..

groennegaard · « **Reply #18 on:** July 18, 2007, 19:51:23 »

Quote from: Karbine on July 18, 2007, 19:06:57

Its the same as driving a single screw boat..unless this ferry has bow thrusters? I dont have 2008 yet so i dont know.

You just do what you said kicking your stern out away from the jetty and then back away,once clear,you can then manouver and swing the ferry where you wish to go.

But i would have thought this size ship would have bow thrusters to get into that size of space in the photo..

The PRIDE OF ROTTERDAM has 2 Fincantieri 2,000kW bow thrusters. However, in SS08 you can only operate them together as one unit. I have never heard of a ferry of this size which did not have at least one bow thruster. Usually they have 2 bow thrusters.

Regards
groennegaard

Karbine · « **Reply #19 on:** July 18, 2007, 20:08:04 »

Ah ha!. Well its the same way of operating this ferry, you would put your bow thruster to starboard so its pushing the ships head away from the jetty.

This will cause the stern to swing into the pier. To overcome this you put the ships wheel into the pier and the starboard engine slightly ahead and the port slightly astern so it comes away sideways.

Attached is a picture of how to do it in ship sim 2006

Sam · « **Reply #20 on:** July 18, 2007, 20:17:44 »

Well, I allready used this technique since I started playing SS06.

It is verry effective for the patrol boat but with bigger ships it doesn't work so well.

groennegaard · « **Reply #21 on:** July 18, 2007, 20:28:04 »

Quote from: Sam on July 18, 2007, 20:17:44

It is verry effective for the patrol boat but with bigger ships it doesn't work so well.

That was for SS06. The dynamics have improved since then and I think it works quite well for the PoR (compared to the SS06 Mega Yacht and the Ocean Star). I'm still not happy about the rudder effect though...

But I think this is discussed somewhere else.

Regards
groennegaard

Bottman · « **Reply #22 on:** July 18, 2007, 21:27:34 »

Hey, there is no difference between the manoeuvres! Both vessels (Patrol and Pride) are using the same engine, rudder and thruster settings. (Guess the Patrol screenshot was mine.)

Cheers

mporter · « **Reply #23 on:** July 18, 2007, 22:55:10 »

Quote from: Sam on July 18, 2007, 20:17:44

Well, I allready used this technique since I started playing SS06.

It is verry effective for the patrol boat but with bigger ships it doesn't work so well.

This is not my experience. The technique works with all the vessels in 06 -- of course the amount of throttle vs. the amount of thruster has to be adjusted to the circumstances (eg. different ships, onshore wind, etc).

Cheers,
Michael

Stuart2007 · « **Reply #24 on:** July 18, 2007, 22:57:17 »

Eemspoort,

You may well be right in what you say. (I haven't finished my flying lessons yet...

) so maybe I find flying simple because I have experience.

Since Groeenegaard has explained the physics of manouvering- from a 'real world' perspective, it all makes total sense. However, flying a airplane is still very easy. Admittedly, I am talking about a single engined Slingsby Firefly and not an A380!

Put this way- 50 hours and you can be qualified with a pilots licence (single engined, VFR only/ non instrument). I think it takes more than 50 hours to qualify as a ship captain...

Stu

Author Topic: How to manouver a boat/ship/canoe (Read 23823 times)