Regarding Initial Design of AHTS

[JRMacGregor]

Happy New Year to you also !

Your dimensions and BP are quite modest - not at the high end of performance.

Your ship is quite similar to a family of AHTS with BP 65 to 80 tonnes which was built by Keppel Singmarine in Singapore.

They had dimensions LOA 60m, LBP 58.7m, B 16m, D 5.5m or 6m, T 4.2 to 5.5m. Main engines 2 x 2000KW.

If you go to the Keppel website I think you can find datasheets for these ships with outline GA showing the internal arrangement.

In addition to ballast or drillwater (about 800m3) fuel oil (500m3), potable water (c. 300m3) they had storage for liquid mud 230m3 and dry bulk powder (4 tanks) 170m3.
If you cannot find them on Keppel website search for names like HADI XI, Pacific 8, Pacific Copper etc.

Good luck with your project.

[shettythunderz]

Sir how do we decide or calculate the power based on bollard pull? How much does the bollard pull affect on power compared to the power calculated on speed??

[JRMacGregor]

You can calculate the power required for the bollard pull by checking the thrust produced by the propellers (of known diameter) when operating at zero ship speed with known pitch at a known RPM. BP-delta diagrams are a useful tool for this work. That is the subject of propeller design - should be part of your course.

There is a rough rule of thumb saying 100 hp per tonne of BP. So for 80t BP you would need 8000 hp total or 4000 hp per prop, which is 3000kW per shaft.

To check the power needed for free running speed is standard naval architecture resistance and propulsion work. You need to calculate the hull resistance, and then the efficiency of a propeller which can convert shaft power into propulsive power.

You will have a controllable pitch propeller so that the pitch can be adjusted for a decent efficiency when free running.

Whether or not the BP or speed will determine the required power varies from project to project.

[shettythunderz]

sir in stability check how to calculate the stability of ship during anchor handling. General stability has been checked but for AHTS we also need to check the anchor handling stability, so how to proceed with it??