strengthening of deck in way of opening

Dear sir,,

a tug is to be designed with a towing hook and its breaking strength of the towline rope is 100t, so i have given enough strengthening over the hook area for main deck, but the problem is an opening is commind very closer to that area for removal of engines. so here i have to prove that the forces and moments comming at towing hook are within limits keeping in mind there is an opening comming on deck. so how can i prove that even that opening is there the structure is well enough that can take care of all the forces and moments comming in way.

 

The general analysis of the problem is very simple and, as you say, it must be shown that the cover, with the opening for removal of engines, is capable of withstanding the stresses to which it is subjected. That said, one only needs to know the details of the aperture, its position with respect to the hook, the hook structure, the structure of the rest of the cover, the connection thereof with the sides. Without it, tell you how to fix the problem is not possible. You're asking precisely calculate everything that makes the tug is a different from the other ship.
Maybe if you provide some detail, you'll find someone who can help.

 

It depends on whether you use the hatch as a structural member or not. That depends on whether the rules allow it too. A bolted panel can be part of the structure.