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Author Topic: Cratus tug?  (Read 2534 times)

geosub1978

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Cratus tug?
« on: June 25, 2023, 16:30:46 »

Hello to all!

Urgent: Can someone please provide me a link for the CRATUS tug or a broader patch that includes it inside because I can't find anything working?

Idealy, I am looking for an in-game model which would be something like 80m long with two azipods and bow thruster but I don't think there is any.

Thank you in advance!

George
« Last Edit: June 25, 2023, 17:50:19 by geosub1978 »
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LucAtC

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Re: Cratus tug?
« Reply #1 on: June 26, 2023, 22:13:11 »

Hello geosub1978,
I am not sure, what are you exactly looking for ? Cratus is part of the game, and I changed its behaviour to match ufolev's request as in  http://forum.shipsim.com/index.php?topic=31627.0 but you should perhaps have a look at this Unofficial Patch board, in fact a board where moderators proposed improvements to the ships, some of which could have been made from the very beginning, had we had enough time.
Fairmount Sherpa is about 75 m loa, and in CP1.4 I modded her with 2 azimuth thrusters and bowthruster, if my memory is correct.
http://forum.shipsim.com/index.php?topic=31068.0
I hope this is more or less an answer to your question, if need be I can still make other changes, as long as it improves realism.
Regards,
Luc
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geosub1978

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Re: Cratus tug?
« Reply #2 on: June 27, 2023, 00:18:20 »

Hi! A big thank you is less than enough! The adjusted Fairmount Sherpa is excatly the ship I want!

However, could you please reduce the lagging between the ordered RPM and the ordered angle? I think the response time of both is two slow and it has to be x1.5 - x2.
Furthermore, I believe that the bow thrusters are too powerful against the RPM setting and need to be reduced by 1/2.

Anyway, many thanks!!!

George
« Last Edit: June 27, 2023, 00:19:58 by geosub1978 »
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LucAtC

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Re: Cratus tug?
« Reply #3 on: June 27, 2023, 17:31:13 »

Good afternoon, geosub1978

In the attachment, FairmountSherpa is modified like your proposition, wit the following specifications:
Azimuth Thrusters Angle control now a fixed turn rate 45 deg/s (8 s the 360°)
Power 2 x 775 kN max (Total 158 t BP) fixed pitch in tunnel prop., mechanically driven,  now clutch.
Thrust control 5.6 s from 0 to 100% (350 RPM) up, and 0.5 s down, clutch.
Bow thrusters, 0 to 100% in 8.6 s, reduced to 2 x 900 kW

The thing is untested, as I usually do, waiting for your suggestions/critics.
The bridge controls are unchanged, meaning they don't face each other, and also no transverse arrest capability.

Regards,
Luc
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geosub1978

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Re: Cratus tug?
« Reply #4 on: June 27, 2023, 21:55:43 »

Hello LucAtC!

The RPM, rotation response and the bows are much better now I think.However rolling is extremely high and has to be reduced to 50% (maybe more) of what it is now. Finally I believe that the inertia in matters of rotation  and acceleration, decelerationis is also overestimated. I believe that the ship should be able to speed up and slow down more easily (50%) and rotate with less ease (50%). This is my personal view.

Best Regards

George :)

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geosub1978

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Re: Cratus tug?
« Reply #5 on: June 28, 2023, 04:26:19 »

One thing more

Is it possible to enable the use of keyboard commands when on camera?

Thank a lot!
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LucAtC

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Re: Cratus tug?
« Reply #6 on: June 28, 2023, 16:40:43 »

Hello geosub1978,

My previous modification restored the bowthruster engine and main engines data to their original values, as was indeed needed.
What I don't understand is what you mean by inertia, as the displacement is set at 4775 mt, and the yaw, pitch and roll are computed and should have matched the mass moment of inertia values of the ship. But indeed there was a mistake in the yaw radius of gyration, 21.65 m ipv 19.22 m, which is now corrected in the attached file, you have been right about it.
Speeding faster would mean higher thrust, which is quite improbable: The peak thrust is 775 kN for each propeller, 1550 kN both, the mass of the ship is 4775 mt, so 1,550,000 N divided by 4,775,000 is 0.325 m/s² at start time, of course propeller efficiency changes with speed, so does water resistance. By the way, the static wetted surface is some 1800 m².
I do agree that improvements are needed, I think because this version of Sherpa doesn't exist, such pods aretoo heavy at her stern, 80 t each probably. But why not? The best way to have correctly set values is that you would give me the name, particulars or specifications of the ship that you intend to simulate, as rolling data and accelerations, maximum values to be expected under the developed thrusts seem to be not far off in the FairmountSherpa model.
Videos of the intended ship could also give some idea of what you mean.

About your second question, well, I don't understand, when the camera is used, the keyboard controls should be active, only the walkthrough mode precludes their use, doesn't it?

Regards,
Luc

m/s² ipv m/s ...
« Last Edit: July 10, 2023, 23:24:14 by LucAtC »
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geosub1978

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Re: Cratus tug?
« Reply #7 on: June 28, 2023, 19:31:18 »

Goodevening from Greece!

Actually it is this ship: https://www.shipspotting.com/photos/822648 (Aquamaster system) which is in now in use for the Hellenic Navy. See this:

https://www.youtube.com/watch?v=IdlQ&ab_channel=PireasPiraeus

I don't posess detailed technical data right now but from my sheer experience the rolling of the game model is exrteme in comparison with similar ships I have emarked.  It exists even in calm seas! I can't disagree with your calculations though...

Yes, I was taliking about the keyboard use in walkthrough mode. It is hardcoded I guess? I will test the model an revert!

Many regards!

George
« Last Edit: June 28, 2023, 21:14:52 by geosub1978 »
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LucAtC

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Sherpa as ASD AHTS
« Reply #8 on: June 29, 2023, 15:46:22 »

Hello Greece,
This is Brest speaking... it reminds me the announcements during the Eurovision song contests.
There are few data about this OSV, probably due to her disarmament and the fact that the shipbuilder has been incorporated in some great concern, eventually leaving civilian shipbuilding?
Nevertheless, the hull is of comparable dimensions, as an OSV she is no tug nor has she AHTS capacity.
Anyway, a Sherpa clone, having thus anchor handling equipment, but as an ASD more or less like the OSV Toisa Independent wouldn't be ridiculous at all, still with 70 ton BP thanks to Aquamaster azimuthing thrusters.

Two 2200 kW main propulsion engines, powering thrusters half the weight of the previous version seem to be typical for such 20 years old but still valiant ships, and should satisfy my reluctancy. :)
Now, for the rolling, except for beam and radius of gyration, it is the metacentric height that changes the rolling. It was set at 1.06 m, which gave a 14 s natural rolling period at sea, at the cost of possibly larger roll angles. In the attached version, it is set at 2.26 m, a 9.5 s period of rolling, faster but with smaller angles, depending on the sea.

Yes, you can roll in calm seas, but there are no calm seas, even in harbours. It's a parameter chosen by the game designers, and one that can sometimes be annoying. This is probably due to the fact that the sea level parameters are not allowed too close to zero. It's also the reason why ships drift slowly when left unmoored, the small, relatively regular waves moving the ships slowly.

The attached file modifies the propulsion and decreases the natural roll period, improving the dynamic stability, perhaps also your perception of her movements?

Regards,
Luc
« Last Edit: June 29, 2023, 16:06:33 by LucAtC »
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geosub1978

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Re: Cratus tug?
« Reply #9 on: June 29, 2023, 19:52:46 »

Hello again then!

I tested it and the rolling has been definitely improved. However, the thrust is too low I think...
It is this thruster in reality: US 255-3850/2K8.

Nevermind, you have done excellent work and I will proceed with your previous *.act file! Let's do some berthings!

Thanks a lot!!!

George

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LucAtC

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Re: Cratus tug?
« Reply #10 on: June 30, 2023, 15:56:44 »

Hello George,

Indeed, azimuthing thrusters with 2.80m diameter propellers seem to deliver up to 35 t thrust, driven by 2200 kW engine, probably like the US255 you mention. The previous version was a US285, also a 2.80 m propeller, tweaked to deliver each a maximum of 75t and still enough to give her a 18 kts top speed from 4000 kW engines. The last version was brought down to the realistic 35 t BP, and a top speed 14 kts, like the"Toisa Independent" or other OSVs of comparable dimensions and powering. In view of staying now in the limit of 3000 hp, and to get 35 t BP, I choose to decrease pitch, keeping the same RPM and diameter, while the top speed decreased. Just a choice, of course, I didn't find her propulsion specifications. Now, what are the specifications of the US255-3850/2K8 ?
https://www.kongsberg.com/maritime/products/propulsors-and-propulsion-systems/thrusters/us-azimuthing-thruster/   ...
https://www.kongsberg.com/contentassets/65302d65e4b04e129e23b6a233f89168/22.azimuth-2p_03.09.18.pdf
... is the only reference that I was able to find, almost all my own data are in a defective hard drive, and I am not even certain to have registered these data, at this time easily available on line. Do you have eventually not references about these thrusters?
Anyway, it is a pleasure,

Regards,
Luc
« Last Edit: June 30, 2023, 16:00:46 by LucAtC »
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geosub1978

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Re: Cratus tug?
« Reply #11 on: June 30, 2023, 20:14:38 »

Hi!

I don't have access to the technical specifications right now. I've been told that the propeller diameter is 2,9m., max RPM is 227 and the weight is 30.000kg. It ressembles the 255S I believe.

So, you guess your last attempt should be close to reality then?
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ufolev

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Re: Cratus tug?
« Reply #12 on: July 01, 2023, 12:37:20 »

Hi gentlemen,

May I quote JoMach - the author of the Community patch 1.4:

"FairmountSherpa_CP1.4: 2 pods, azimuthal steering, speed around 16/17 kts.
2 thrusters at the bow, to be independently controlled so the ship can hold her position smoothly if the thrusters work in opposition. The same can be done by opposing pods, kind of dp (lol)."

I made some tests on 1.4 original and the steering can be real fun.
Youtube Video:
https://www.youtube.com/watch?v=DBLgPhn58S8

All Best
ufo :-)
« Last Edit: July 01, 2023, 12:38:56 by ufolev »
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LucAtC

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Re: Cratus tug?
« Reply #13 on: July 01, 2023, 20:01:32 »

Hello ufolev,

Great video, still I must admit some shortcuts when I created the original dynamics. I was hoping to keep the 200 t maximum thrust, but didn't find thrusters of less than 80 t mass each to create a towing capacity as great as that of the Fairmount Sherpa. That is why I selected the US285 with the 2800 mm propeller diameter, a small pitch but a relatively high RPM to get finally a 150 t towing capacity, and a decent lateral list, rolling angle at full side thrust.
I was aware of the design flaw of such heavy propellers at her stern, but as no one complained, perhaps did it go unseen or untested. The same goes for the two bow thrusters, also initially with a way too high thrust, but thanks to George's question, I had the occasion to bring down their thrust to 2x 800kW, some 12 t each at the bow.
Actually, while the RPM of the main propellers is still much too high, thrust and power are of a correct order of magnitude, because I have reduced propeller efficiency and pitch accordingly. So, although I could bring down their value when I get the specifications, I guess it would only mean small changes in Sherpa's  behaviour.

And also an opportunity for you, Ufolev, to test and perhaps demonstrate your impressive skills in a new video.

Best regards,
Luc

1. I'll be probably absent for some days, my PC was struck by a ransom virus, all docs of my game PC are now agvv files...
2. Original of CP1.4, of course, I concocted the true to Fairmount Sherpa much earlier
« Last Edit: July 01, 2023, 20:04:47 by LucAtC »
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geosub1978

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Re: Cratus tug?
« Reply #14 on: July 02, 2023, 16:54:40 »

Ι really believe that the last model has excellent rotation! Maybe the speed-up and the speed-down are a little bit slow but I don't have much experience on that ship so I am very satisfyed in the gameplay!


URGENT! Is it possible to adjust the controls from left-right to right-left and point the thrust increase to the stern when shifting the bridge view to the stern? This would be very helpful because it ressembles reality!
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ufolev

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Re: Cratus tug?
« Reply #15 on: July 02, 2023, 22:00:46 »

Hello geosub1978

Ship Simulator Extremes gives you two keyboard options for every one action
like  the change of the engine revolutions per minute or azipod rotation

On FORE conning position I use:
For the left hand:
The button A to rotate azipods to left and the button D to rotate azipods to right
The button W to increase RPMs and the button S to decrease RPMs
For the right hand:
The button Left Arrow to rotate azipods to left and the right arrow button  to rotate azipods to left
The button Up arrow to increase RPMs and the button Down arrow  to decrease RPMs

On AFT Conning Position I use:
For the left hand:
The button Left Arrow to rotate azipods to left and the right arrow button  to rotate azipods to left
The button Up arrow to increase RPMs and the button Down arrow  to decrease RPMs
For the right hand:
The button 4 numpad to rotate azipods to left and the button 6 numpad to rotate azipods to right
The button 8 numpad to increase RPMs and the button 5 numpad to decrease RPMs

Look this video how it is looks like:
https://www.youtube.com/watch?v=jUHInsO-peA&t=3s

And there are some examples from the game practice:
https://www.youtube.com/watch?v=fkSfB7_Kg3g
https://www.youtube.com/watch?v=hhDkEWtARyc&t=8s
https://www.youtube.com/watch?v=7JrOTwSbv98
https://www.youtube.com/watch?v=j_nPc9cp9Bo

Regards
ufo :-)


« Last Edit: July 02, 2023, 22:26:59 by ufolev »
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geosub1978

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Re: Cratus tug?
« Reply #16 on: July 09, 2023, 13:04:15 »

May I ask something?

I wonder if the effect of each azipod is modeled side depended. I mean... by  turning the port pod to "30 outside" does this have the same effect with the right pod turned "30 inside" or is it combined with the additional dynamics based on the side in relation to the longitutional axis?

Thank you

George
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LucAtC

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Re: Cratus tug?
« Reply #17 on: July 09, 2023, 16:43:38 »

Hello geosub1978,

Perhaps looks the following like some too basic, generic answer, but it is exactly like that, without going deeper into details ?
The ship is represented by a 3D rigid body, (dimensions, mass, mass moments of inertia, center of mass), almost independently from her graphical representation.
The movements are defined, computed by the physics engine, taking inertia and "external" forces into account, in position and orientation relative to the body.
Gravity and buoyancy are the main external forces, taking the sea, waves into account, and are computed by the PhysX engine.
The water resistances opposing the ship movements are computed according to hydromechanical laws, resulting in opposing forces and moments. They are computed and applied by specific processes. The inertia, i.e. displacement and moments of inertia are modified by so called added masses.
Other forces are created by appendages, rudders and thrusters, taking orientation and speed vectors into account, applied to their position relative to the hull.
So, the same settings of the thrust vector for a port or starboard pod have different resultant forces and moments on the body.
Does this correctly answer your question?

Regards,
Luc
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geosub1978

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Re: Cratus tug?
« Reply #18 on: July 09, 2023, 20:25:24 »

Yes, of course! Actualy this was the core of my question. I guess the wind effect is applied with same accuracy as well? Haven't tried it yet.

Thanks LucAtc!
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LucAtC

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Re: Cratus tug?
« Reply #19 on: July 10, 2023, 10:26:05 »

Hello geosub1978,

Sorry to disappoint you, there are sadly no wind effects, and no tidal streams, no currents. It was disregarded, to our great diappointment as we, moderators, knew that at least wind effects would have been easily inserted, while it was thought out and developed at the same time as for Nautis, for which we were beta testers too.
Ze boss was eventually right about that, it would have been too tempting for some to use SSE as a replacement for Nautis at this time. I doubted it, because simulators without knowledgeable instructors are meaningless, all the quality comes from their expertise.
If you see abandoned player ships moving slowly, it is due to residual sea effects, as small waves cannot be suppressed even in harbours, to avoid zero values in possible denominators. The preset minimum value should perhaps have been smaller than the final choice. But then, who abandons an unmoored ship?

Regards,
Luc
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ufolev

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Re: Cratus tug?
« Reply #20 on: July 10, 2023, 20:49:35 »

Hi Luc and George.,
3 years before to step on the bridge of the ASD tug I had
several ASD tug manuals, ship simulator extremes , many YouTube ASD tug videos and
the book of the captain Jeff Slesinger "ASD Tug: Thrust and Azimuth Learning to drive a Z drive"
With this "experience " on age 53 I made a
transition from a tug company with conventional tugs only to other with ASD tugs
And driving the real asd tug was easier than driving a ASD tug on simulator

Best regards
Stefan
« Last Edit: July 10, 2023, 21:03:44 by ufolev »
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geosub1978

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Re: Cratus tug?
« Reply #21 on: July 11, 2023, 10:57:29 »

Ahh! I plan shifting into Nautis when I will be able to buy an adequate pc machine!!!

Toisa's azi is 2200kw each and 735kw each bowthruster.

By the way...is it possible to add anchoring sweeveling to a non-player ship (eg stationary or AI) or any other kind of drift? This is for berthings on anchored ships.

Yes, I agree with uflolev that.sometimes reality is easier  but itis always the sense of danger that always makes you nervous haha!!!
« Last Edit: July 11, 2023, 11:00:05 by geosub1978 »
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LucAtC

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Re: Cratus tug?
« Reply #22 on: July 11, 2023, 15:16:27 »

No, I don't think so, unless AI ships could be forced to follow a small diameter circular path but I am not at all proficient in the mission editor peculiarities.
Are you sure that anchored ships wouldn't pivot when slow ahead with some rudder ?
Also, some ships had a hidden stern thruster that I didn't erase, existing, powered but without controls, except keyboard ones. I used the thruster to check pure yawing, but it is long ago, and have forgotten if it was deleted or not.
Would mooring to a moving, pivoting ship not be even or more interesting, I think that was a goal in some missions ? You could also be do that in freeroam, after having created an environment that contains the ships with which you want to try your skills.
And stopped player ships don't move faster than an anchored one, I think.

I still think that I have made her azimuth thrusters pivoting too fast, that 6 to 8 seconds for 180° would be closer to the specifications than 4 s.  Who knows?

Regards,
Luc
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geosub1978

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Re: Cratus tug?
« Reply #23 on: July 12, 2023, 12:32:14 »

Hello! I just sent you a PM but I am not sure if it was sent because I can't see it in the sent box... The time to rotate an azipod by 180deg is as high as "15" "fifteen" seconds until it reaches its final position! The hand stick itself rotates acording to the force applied by the user freely.

 I will check the mission editor and revert!

 If you adjust the time is it possible to set max a 225 rpm range for up to 14 kts and bow to 1600rpm then?

Best Regards

George
« Last Edit: July 12, 2023, 14:42:36 by geosub1978 »
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LucAtC

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Re: Cratus tug?
« Reply #24 on: July 14, 2023, 23:13:19 »

Hello geosub1978,

Attached, the version with the steering time set at 15 s for 180°, or 2 RPM, this time rather slow for handling, manoeuvring and normal for steering. The azimuth thrusters have kept the same 35 t max at 225 RPM, and the 2 thrusters have kept their 12 t thrust each. Her maximum speed reaches 14 kts.

Regards,
Luc
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