Bentirran,

The plastic whistle looks a lot better than the metal one. But if the metal one goes to 100 decibles then it would probably work.
I could not find any standard for whistles from the USCG or SOLAS but the Storm brand whistle says it is between 108-120 decibles and the Storm is supposed to be one of if not the loudest.

I understand what you meant about the military not including a whistle. Most of the original PSKs were E&E kits and had to do more with getting to a friendly country/force than surviving.
A whistle might attract attention when it is unwanted.
I did look into WWII era US Army Air Force survival vests and there may have been a whistle attached to the vest but I am yet to confirm this.


Just a word on the signaling with a flashlight. The SAR folks will not be searching for you at night (I used to do some SAR work in the past and we never worked at night) and someone 20 miles away may be unaware that you are trying to signal.