[Mithrandir]

Dear all,
I write this post to announce that it seems that I finally managed to solve a bug critical for the S-18 class submarine in SH4.
The fact that nobody before me have noticed this terrible bug (I searched a lot the forum but without any result) is clearly an indication that very few people use this old submarine class, so I think that my discovery will be of very low importance... Anyway it can be very useful for those people, like me, that still use it.
All started some time ago when, during a terrible surface combat between my S-18 and a Japanese destroyer, my Engine room was flooded and the diesel engines were damaged (not destroyed). I managed, in some way, to sink the destroyer and I started repairing my sub.
Diesel engines were repaired, the water pumped-out and the submarine was again shining new (except the hull that was damaged to a certain extent, of course!).
So I tried to return to base and... nothing, the sub was sitting in the water like a duck. All repaired but no propulsion power.
Furthermore, when I tried to submerge the sub sunk like a stone as when you have a compartment fully flooded, but all the water was pumped-out!!!
This situation was later experienced several times and all the times with the same result: need to reload a previous save.
I decided that it was necessary to find a solution...
Using S3ditor I discovered that the S-18 (the only sub with this bug) was also the only sub with a type 29 zone in the "subname.zon" file.
After reading a post on the forum on the zones in "subname.zon" file, I noticed that the effect of this zone is to stop propulsion in case of complete flooding of the parent.
This zone seems also not prone to repair and to water pumping, so is this zone that causes the bug.
I decided to remove the node of this zone from the zon file and I tested it in several combats (offering the stern to the enemy guns to let them hit the engine room): the sub behaviour in case of engine room damage and complete flooding was now perfect. The diesel engines can be damaged, repaired and destroyed and the sub, once repaired behaves normally for what concerns propulsion power and submerging.
More surprisingly: reloading one of the saved games with the sub struct in the ocean with no propulsion power after the engine room flooding, the problem disappeared and, after repairs it returned to sail perfectly!
Personally I think that the presence of zone 29 in the s18 class (only in the s18 class) is an error made when Ubisoft corrected a similar bug in all the other subs in one of their official patch.
May I ask if there is someone of you that still use the s-18 interested in testing this solution?
Bye,
Mith