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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!

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

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 :-)

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?

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

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

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

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

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 ...

One thing more

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

Thank a lot!