Sorry not to be a sweary laddish lad but in the interests of objective facts, the EPIRB's on Estonia do appear to have been the auto-type. These are activated when submerged in water by at least 4m, often before.
In his post in Nov 2021 Captain_Swoop claimed that Kannad did not make automatic Cospas-Sarsat certified EPIRBS until 1997. I am afraid this appears to be incorrect.
http://www.internationalskeptics.com/forums/showthread.php?p=13654136#post13654136
Posted by: Captain_Swoop
On: 12th November 2021 11:42 PM
He claims that the SOLAS regulations for Cospas-Sarsat certified EPIRBS did not come into force until as a result of the Estonia accident. But in fact it came into force after the Herald of Free Enterprise inquiry, as follows:
There is ample official evidence that Estonia had automatically activated beacons which were primed to activate when submerged in water (of course, they can also be activated manually if desired).
29.9.
1994 2:00
https://www.hs.fi/kotimaa/art-2000003370653.html
Also:
25.1.
1995 https://www.hs.fi/kotimaa/art-2000003373270.html
and
Thus it becomes clear that the Swedish and Finnish passenger ferries were using automatically activated EPIRB's long before 1997. This can be readily ascertained in that they are primed to activate when
submerged in water, or at least one of them is.