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Author Topic: Cratus tug?  (Read 2071 times)

geosub1978

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  • Posts: 22
Re: Cratus tug?
« Reply #25 on: July 15, 2023, 06:14:09 »

Goodmorning!

I have just sent you the file Luc! I will check the model tomorrow! Yes, the 180 rotation should be 15sec as response time indeed. However, the handling time of the controlers should be independed from the 15sec time and easily moved. This is how I finaly noticed it in reality.

Many regards

George
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geosub1978

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Re: Cratus tug?
« Reply #26 on: July 16, 2023, 17:19:48 »

This very last model of Fairmount Sherpa is very good indeed! It seems that the increase/decrease rate of bow thruster's RPM needs some acceleration by something like 40-50% but we can live with that! :)

A great thank you!
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LucAtC

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Re: Cratus tug?
« Reply #27 on: July 17, 2023, 20:00:27 »

By "The very last model", did you mean ToisaAnexartiti, from my topic in the Unofficial Ptches of the Community Development ?
Anyway, the 8 s necessary for the thruster to reach full thrust have been reduced to 4.8 s in the attachment, and as the data of the bowthruster of Fairmount Sherpa are well known, as we have her sea trials report, I was able to check at the same time the zero speed maximum rate of turn with 2x735 kW thrusters like mentioned in her pilot card, decreasing with ahead speed, zero "rudder".
In such conditions, the ship pivots somehow too easily, reaching 90° after a little more than one minute, eventually due to the light condition.
Fairmount Sherpa stern thruster was an Aquamaster of 736 kW, 10.5 t thrust, her bow thruster was 825 kW, 12.5 t thrust.
The file should be inserted in the following folder:
X:....\Vstep\ShipSimExtremes\Projects\ShipSimExtremes\Data\Entities\Dynamics

Regards,
Luc
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geosub1978

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Re: Cratus tug?
« Reply #28 on: July 17, 2023, 20:59:16 »

Actually I meant the *.act of  the post July 14, 2023, 23:13:19 in this conversation. I can't find the rest folder of the beloved "Anexartiti" :) :). Sure you posted it there?



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LucAtC

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Re: Cratus tug?
« Reply #29 on: July 17, 2023, 23:27:37 »

In fact, the new topics in this board  don't appear if you just look at the "Latest Post", underneath the home page, probably due to some error in the site, I don't know.
You should lok at the next line "View the most recent posts on the forum.",
Anyway, this is the link to this topic, appearing as a "community development", with a limited number of contributors, sub-board "Unofficial Patches", meaning not followed in the Shipsim.com site :

http://forum.shipsim.com/index.php?topic=31890.0

So, quite sure !
Regards,
Luc
« Last Edit: July 17, 2023, 23:43:23 by LucAtC »
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geosub1978

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  • Posts: 22
Re: Cratus tug?
« Reply #30 on: July 18, 2023, 17:56:31 »

Hello Luc!

"Toisa Anexartiti" is an excellent and realistic model. Only two things:

1. There is an odd heavy roll when pierside.
2. When heading astern and try to turn left (stern first) there is a tendency for rapid turn left which is not compatible with the ordered azi angle. I want to test this further.


I spoke with a friend of mine who can repaint the model but he needs to know how to open the "*.cgr" file. Do you know maybe?

George


 
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LucAtC

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Re: Cratus tug?
« Reply #31 on: July 18, 2023, 21:54:22 »

Hello George,

1. Tested her roll against a quay in Marseille, nothing to be reported, no rolling. Please retry and give me more specific conditions of your test, sea state, harbor, quay? There are eventually some quays left without protection against bouncing.
2. Steering astern is rather hazardous above 3 to 4 kts, while letting the rate of turn be more than 30 or 40°/min, at the risk of an uncontrollable yawing astern. Isn't there a name for that?

The azimuth thrusters are at the very stern of the ship, meaning that the tunnels have almost no effect as her ship pivot point comes closer to the stern, the more the ship has a high block coefficient. The skeg is at her stern as well, where the stern thruster of Fairmount Sherpa was placed. Then, making way astern, the side thrust of the azimuth propellers will also be at the most unfavorable place.

Under 4 kts, the ship remains as controllable as a single screw ship making way astern, but it shouldn't be forgotten that she is anyway easily steered by her two powerful bow thrusters, that's also their main use.

As a side note, I think that such ships should need a second specific steering system, limited to 35 ou 37° both sides, enabling a "normal" steering en route, but I am not sure what the SOLAS rules could be for such an AHTS. Something like I did for the cruise ships in SSExtremes, where it was mandatory. I can eventually do it, but then I need a picture of interior of the bridge to see what I must do to add a new steering console/station.

About the repaint, alas no, I have no compiler or decompiler for the cgr files, but is is not really needed, one can easily see what parts of the models are concerned by the dds pictures, no need to change their names.

Regards,
Luc
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