Ive been reading the book "The Underwater War 1939-1945" by Commander Richard Compton-Hall MBE, RN (Ret'd) 1st published in 1982. I bought it from a second hand book shop.
It mentions the following:-

In 1939 HMS Triton and HMS Oxley encountered each other off Oprestad with the result that Oxley was sunk.
4/5/1943 U-439 and U-659 collided while pursuing a convoy and both sunk.
Jan 1945 HNMS Dolfijn was fired on by an RAF Mosquito ending the war for her.
11/11/1942 HMS Unbeaton sunk by RAF aircraft.
HMS Unison fired on by a "friendly" ship while travelling in convoy.
29/5/1958 USS Stickleback rammed and sunk by USS Silversteen

"Submarines of World War Two" by Erminio Bagnasco published 1972 lists the following as sunk by "friendly" forces

Germany
Type VII U-235 Baltic 1945

French Perle Atlantic 1944

Great Britain
O Class HMS Oxley N Sea 1939
U Class HMS Umpire N Sea 1941
U Class HMS Unbeaton Atlantic 1942

Italian 600 class Topazio Mediterranian 1943
Italian Perla Class Gemma Med 1940

USA
R 19 (as P514) Atlantic 1942
S 25 (as Polish jastrzab)Atlantic 1942
Sargo Class Seawolf Pacific 1944

The list above shows the subs final fate and does not take into account the number of "friendly" fire incidents which did not result in a sinking.
All in all Germany did pretty well in respect to "friendly" fire. The Brits had more aircraft (fewer subs), the Germans more U-boats, so it was not surprising that the RAF mistook submarines, most of the subs that they saw would be U-boats.
"Friendly" fire incidents perhaps should be modelled if SH5 includes British subs but is not as much an issue for U-boats.

I will bet you the testicle of your choice that not only will a friendly fire option not be in SH5, but won't be in any future SH game either. And it'll be the right decision every time.

In December 1941, the U-557 was mistaken for a British submarine and was rammed and sunk by the Italian patrol boat Orion near Crete.

http://en.wikipedia.org/wiki/Unterseeboot_557

Pretty rare event overall though.

(Ahem)

(/Ahem)

From a gameplay standpoint, I would skip the friendly fire aspect. As a player, you expect that your enemies would be Allied units and not your own. To be attacked by an Axis unit would break the unspoken contract between game designers and players that says "this is your target over here and this is your buddy over here". While I understand that this may have happened (rarely) in real life, I think this is a case where gameplay needs to win out over realism.

I vote for realism option. :up:

I don't see why we can't repeat entries from others in this wishlist. It gives the Sh5 devs, or who else Neal is keeping incognito from us, an idea of HOW BAD we want it.

The SH4 system where off-duty crewmen stay in their compartment has to go. This leads to problems where the entire bridge complement ends up being killed or injured during a depth charge attack, because the game still sees them as being up on the bridge.

Simply put, the game needs to put all off-duty crewmen in a crew quarters compartment - one fore and one aft.

I agree with most of the points made already. so I won't repeat them. I have some more ideas though.
1) Tides. I think it'd be nice for work in shore if you had to consider the tide state before trying to cross shallow water.
2) A round world. First time I tried crossing the Atlantic in a type IX I noticed that SH3 world appears to be flat. I plotted a grand circle course and it was longer than a straight line. :P
3) More serious battery damage effects. In SH3 battery damage is an inconveniance. IRL it was potentially deadly as sea water in the batteries made them emit chlorine gas into the boat! Having to deal with gas leaks could make things quite a bit more interesting.
4) Fires actually damage ships/aircraft. I've had burning aircraft circling my boat for up to 30 minutes or more, is this realistic? Not very. Also if you started a big enough fire on a ship like a tanker, even if it didn't sink the fire would destroy it. One time in bad weather an Elco MTB found my boat and forced me to dive. The Elco had a HUGE fire burning aft the whole time but the AI completely ignored it!. It finally left, doing 20 knots, STILL burning, over an hour later.

I'll jump to the conclusion: UBI, cmon guyz, make the game more moddable and please don't release it with bugs. First build a modding application to build the game, document every piece of it, and then ship that application with the game itself to allow these gifted players to mod it for 20 years to come :salute:. Even a 9 year old must be able to use it.

I've seen so many good ideas here that I don't think i have anything else to add. I will some day write a huge letter to Ubisoft (thank god i'm romanian) to share with them my wishes. The thing is, during these years we all gathered that feeling of "what it could/should be like". We can almost taste it, it's so close. Silent Hunter is probably the best simulator of any genre because you're not just doing things with your keyboard, it almost feels like u're there. SH5 really deserves to go to the extreme, the pinnacle of simulation, no matter how long it takes to make it. Build the ultimate sim and even 10 years later people will still buy it. For example I'm still looking for the 744 Precision Simulator which doesn't even have 3d graphics. There are many layers in a simulator and SH has almost touched the hardest thing to achieve in a game: emotion. Let me give you just one idea, tell me what you think about it:
- On the highest difficulty setting the game saves itself automatically, like a MMORPG does. Most of us don't use Save/Load, but it's still there, tempting us and giving us false hope. Take it away from us and laugh at us how we cry after dying in late 1944 from a plane attack after 30 mins of siting on the sea floor with water puring in the command room.

directX10 for SH5
 

The people at UBI need to sit down and play Call of Duty4. They should have a game where you can go from one compartment from one end of the boat to the other. They need to make the enviroment inside the boat and outside to a higher quality. We should not have to mod the whole game just to get it up to a decent standard. Make it directx 10 or nothing. The stock torpedoes are a joke, So are the fast moving clouds and the quick repair of systems and the order of importance. C'mon guys putting fixing the radar when the main pump and bulkheads are damaged is wrong.:hmmm:

You are on to something there.
Accurate depths of the sea would be a good thing to have.
In SH3 for instance the Norwegian fiords which are very very deep in real life are only roughly 25 odd meters deep in game.

More accurate maps in general. More ports, where they should be (St Nazaire especially in SH3 is highly inaccurate, the U boat pens were much further up the estury near to the dry docks).
Independant telegraph controls, so you can steer with the props on multi-screw boats.
Oh, and Mine laying subs please. Or at least TMB torpedo tube launched mines as an option for regular boats.

Make it possible to add air support to a convoy/task force. It should be dependant on range from base and aircraft type/availability though or the presence of a CV/CVE/MAC. High value groups should also get dedicated air-support automatically when in range of airfields.

Funny you should mention that. I just ran into a HK group in the middle of the Atlantic with a Bogue escort in the middle of it. It launched a couple of fighters when the group picked me up on radar. I think the basics for this are there, it just may need to be refined.

I agree with your dedicated air support statement though.

Carriers will launch....but not in front of you.

If your out in the middle of nowhere and suddenly come across for example, a swordfish, you can guarantee there is an Illustrious somewhere in your vicinity.