Perhaps the truth of the matter can be found on the Israel Navy's T Boat site. As an ex member of the last crew of HMS/m Truncheon which became INS/m Dolphin on 9th Jan 1968 I have followed the Dakar affair since 1968.
The stretched T Conversions propulsion line went Diesel Engine, engine clutch, forward Main Motor, motor clutch, aft Main Motor, stern clutch shaft and propellor. This was of course both port and starboard engines. The engine clutch could not be removed until the engine had been stopped.
It was normal practice to run in direct drive i.e. all clutches engaged when on surface passage shut off for diving. This increased marginally the surface speed and allowed the batteries to be topped up and kept that way.
Some CO's to improve their snorting performance would snort in Direct Drive. If the boat dipped and the engine had to be stopped then the motors were not usable until this had been done.
If a D/E starts to dive out of control it was an accepted maneuver to go full astern to pull her up. I think a USN D/E Captain discoved the phenom.
It would appear Dakar was in direct drive when she dipped and being in direct drive in an effort to make the fastest passage possible she was unable to pull out of her dive. At some point her hull imploded from fin to stern and the last few feet of the stern which streamlined the aft end of the pressure hull snapped off. This where the article claims the aft of the boat was separated from the from by the weapon. It was not and no sign of a weapon hit was found.
I remember all of this so vividly Nutty. There's been a few conspiracy theories over the years about INS DAKAR. one being the'' large chacon of spares welded on the casing tipped her over when she dived.'' Load of shite of course same as the ''Yanks sunk her in revenge ''I recall all the rumours at the time.It was 4 days after our own handover that mrs. dinger and I got married,I went to spare crew the day after the handover and was on the jetty when Dakar sailed along with Dolphin.The inboard boat on one of the pics is Tiptoe I think I had the pleasure of 6 weeks on her shortly after when their cookey boy went to Hasler for drying out.Great days shipmate. thanks for the linky's