Need a few more details...what is the month/year. What type of boat are you in?
Keep in mind, if you are by chance in a S boat, things will be more difficult.
S boats are noisy in this sim to begin with and believe were made even more so with the original TMO mod. I never tweaked the engines or anything, just the damage model and max depth, they were tanks and could dive far too deep before. For upcoming version I'm including a revamped enemy sound/sonar sensors to be more in line with player running s boats. Sim is built around fleetboats. Still testing but goal is to keep the challenge but permit player to have realistic experience in S boats, not diving far beyond 150 feet, etc
First, don't give up the ship. Not being critical, but you're doing something wrong that is getting you detected. Even if they have radar, unless you're sailing broadside directly to their beam for long period of time, should should not detect you in most cases. They can, but usually will not. I routinely attack convoys with radar equipped escorts on the surface at night and about 3000-3500 yds range from the ESCORT, depending on profile to the beam. Make sure your periscopes and SD antenna was DOWN while submerged. The IJN surface search radar's min height was altered to get more realistic long range performance, i.e. not spotted a sub 12 miles away like its a BB because subs were difficult to detect on radar esp at long ranges. Basically, the beam is set to where it just skims over the periscope shears, i mean by inches probably or 1 ft lol so with masts raised, it will detect them. I found this out in hours of testing when modifying the radar years back.
Visually, 10000 yards is 4.94 nautical miles, if you're that close on the surface in daylight, you should be spotted, need ot keep a minimum of six miles from enemy vessels in daylight and that is pushing it, I keep 8-10. If pulling ahead for attack, need to dive 8-10 miles ahead and provide time to close to attack position. That is realistic as Japanese had excellent optics and well trained lookouts and while a sub is difficult to spot compared to other ships, on a clear sunny day, they are doing to spot you. Of course there are many factors such as your profile to them i.e. angle on bow, fog, light etc.
Submerged...
I am getting the impression you're too close making too much noise.
Try this...
If you are surfaced and ahead of attack, make sure are 8-10 mile ahead.
Soon as you head your boats engines switch from diesel to electric motors when submerged, order 1/3 speed and soon as see the "Rig for Silent Running" button become clickable, rig for silent running. This will cut you boats noises down during the approach. Not most realistic thing but way devs designed sensors to work, its necessary to make a approach and get close for attack. After torpedo impact, I secure silent running until or if escorts locate me and rig again.
Pay attention the RPM's on the tachometer in at the helm station in conning tower or control room. Speed is not concern so much as RPM , when rigged for silent running at 1/3 speed most boats do around 80 RPM. Anything less than 100 youre solid in silent running situation. With silent running enabled, it cuts down other noises your boat projects aside from the engine noises.
Often, you may need to make a high speed submerged run to close the range for a shot. Skippers in real life often found themselves having to do this. This will test your plotting skills for sure. If need to do this, 150 ft is a bit too shallow for making such noise. Go to 250 ft minimum, if moving at full or flank speed, go for 300-350, if seas are really calm, def want to be at 350. Listen for thermal layer, being below a thermal layer is important, most thermal layers are below 150 ft I have found.
SH 4 simulates this as it has three sets of engines for subs....two are visible to us, diesels and electrics used in normal operations. A third are "silent engines" or "creep engines". When silent running is active, these simulate the electric motors but are quieter than normal engines, more difficult for AI to hear. When take damage not as quiet and in TMO they can be destroyed. They are linked to electric motors so if those are damaged or destroyer boat will be extra noisy. Boat also has a noise signature aside from its motors, it simulates pump noises etc. When on silent running, these noises are greatly reduced.
Evasion
"homing DC's" they are not, I promise. Type 95's are easier to evade because their sink rate is slower, Type 2 has a high sink rate so can reach depth faster and pack more of a punch but promise can be evaded.
So you have just completed attack, escorts are closing. Order 20 degrees rudder to appropriate direction to closest escort, so your angle on the bow is narrow as possible, this will give his sonar beam less of a target and make it more difficult for him to accurately track you. Order depth, say 200-250 ft. or if find a thermal layer, level off about 5-10 feet below it, unless really shallow. Once turned into him with near zero AOB as possible, list keep moving. When hes close about to pass above, go to ahead standard. As he passes above, listen carefully for his last ping. Once e has stopped pinging, order ahead flank and if at 250, order 300 feet. Listen for the splashes of depth charges
, once hear splashes make sure your dive angle is minimal, don't want your stern sticking up at the depth you were where most of the charges will be exploding, remember the length of the boat.
Now once pattern of charges have exploded and think thats it, order all stop and ten degrees rudder starboard or left. This will make you quiet for a moment, allow momentum of the boat running at flank speed to carry you along and into the turn, then go back to 1/3 speed after 1-2 minutes.
Escort comes in for another run, repeat the procedure, changing direction and depth. Over time, this will confuse the AI and prevent consistent contact. AI is on a timer once it is attacking a sub (not sure what it is exactly, hardcoded) and gives up after x amount of time without solid contact.
Say you're 100 ft beyond test depth and its not safe to go too much deeper, trying going back to 300 for a couple runs, then back to 350 etc. Again, changing it up. Once in a while, when appropriate, go all back emergency as escort roars above to drop charges. You will be heading in opposite direction you were when he last pinged and most charges will exploded ahead of you. go to back 1/3 for a few minutes until next DC attack, then ahead flake and change directions. Again, over time, this will confuse the enemy.
Damage model was changed in the update so you're boat could take a beating, as subs often really did, but even a really close charge can take you out in a instant or cause mortal damage, which is why have to get out from under the patterns. The ominous "magic" depth charge TMO was notorious with is very rare now. Usually only happens when youre way beyond test depth and the safety factor, where the extra pressure effects of underwater explosions are exacerbated and can cause hull failure. Example...
in testing I found a Balao with test depth of 400 ft can take a close charge and not suffer hull collapse at 500-550 feet. But at 600+ feet, same type of charge, exact same distance, so same hit points, will cause heavier damage, even hull damage and at that depth, even losing a little hull integrity can cause hull collapse. Tolerances vary with the class of boat you have. I consider every fleet boat to have a safety zone of 100 feet below their test depth.
Also, you could try the depth charge disturbance mod ( I will post a link here shortly) I released a few weeks back. This is a revamp of TheDarkWraith's
excellent mod customized for TMO Update. I don't use it because to me it makes AI counter attacks too easy and duration if generally shorter (not always, depends) but its there and was something real life subs use to get away, the moments are depth charge attack when enemy's sound gear was essentially useless due to water disturbances caused by underwater explosions.
Hope this helps, don't give up though, you can do this. TMO drove me nuts when I first started using it as well, it is more difficult than other mods, which was its point, to force player to use proper tactics, decision making, etc for a challenging yet rewarding experience. At times, esp due to the damage model it was too easy to get killed, which is why I've worked to modify things for a improved experience. Let me know if have any questions.