Please welcome Eyoyo Underwater Fishing Cameras.https://amzn.to/3siEgXn
Yep, 3"-4" for a portable and minimum of 6" for the permanent. If you put a perm. on 3"-4" it creates a bow in the ice around it and if it warms up at all the water on top of the ice funnels into it and deteriorates so fast it will be unsafe to get to it to save it. I saw this happen last year to a friend that jumped the gun.
Im big into spearing jus wondering wht u guys thought of how much ice do you wait for to spear