That was a great whistle test series - the link above is to part IV, but the author posted the five completed parts here:

https://bigpigblog.com/tag/safety-whistles/

[Note: I don't see the part VI "in the woods" test yet, but the author cautions that his preliminary testing indicates different results than in the over-water test.]

In the overwater test, only three of the two dozen whistles tested were heard at 1 mile by the non hearing-damaged subjects. Those three were:

• Storm (heard at 1/2 mile by the hearing-damaged subject)
• Windstorm
• lifejacket whistle (heard at 3/4 mile by the hearing-damaged subject)

The site doesn't give a brand for the lifejacket whistle, but comparing the photos with the Net, I'd say the Sea-Dog Life Jacket Whistle is the best match.

If you have a Boy Scout troop to equip, try searching for "Sea Dog Life Jacket Whistle Display - 40 pack" - the unit price drops below $1.35 including shipping.

I carry the TOPS whistle in my EDC neckpouch, and the STORM in my glovebox.

I did have a lifejacket whistle, and liked it, but my wife liked it better than the others, so it is mine no more.