# Soft Water behind ships, sink when you hit **URL:** \ **Category:** Factual Questions\ **Created:** [April 28, 2013, 6:55pm UTC](https://boards.straightdope.com/t/soft-water-behind-ships-sink-when-you-hit/656930 "2013-04-28T18:55:34Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Apocrypha8](https://avatars.discourse-cdn.com/v4/letter/a/e8c25b/32.png) [@Apocrypha8](https://boards.straightdope.com/u/Apocrypha8)\ **Post date:** [April 28, 2013, 6:55pm UTC](https://boards.straightdope.com/t/soft-water-behind-ships-sink-when-you-hit/656930/1 "2013-04-28T18:55:34Z")
Is this a myth or not? I’ve been on a lot of cruises as a kid, and my dad told me that the white foam/water behind the ship is mostly air so if you jumped and hit it, you would sink. ---
**Author:** ![smiling\_bandit](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@smiling\_bandit](https://boards.straightdope.com/u/smiling_bandit)\ **Post date:** [April 28, 2013, 8:01pm UTC](https://boards.straightdope.com/t/soft-water-behind-ships-sink-when-you-hit/656930/2 "2013-04-28T20:01:54Z")
> [@Apocrypha8](#): > > Is this a myth or not? I’ve been on a lot of cruises as a kid, and my dad told me that the white foam/water behind the ship is mostly air so if you jumped and hit it, you would sink. It would depend on just how much spray it was kicking up, but you wouldn’t sink _far_. Foam won’t support your weight, true, but even a very big cruise ship doesn’t have that much spray coming out. The white indicates it’s being churned, but that falls off extremely quickly; the white itself is only the oxygen going to the surface - which means it’s a thin and very temporary layer on top. I’d say this is a myth, more or less. ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [April 28, 2013, 8:08pm UTC](https://boards.straightdope.com/t/soft-water-behind-ships-sink-when-you-hit/656930/3 "2013-04-28T20:08:49Z")
IIRC MythBusters found the upward current caused by the rising bubbles made it harder to sink. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [April 29, 2013, 5:09am UTC](https://boards.straightdope.com/t/soft-water-behind-ships-sink-when-you-hit/656930/4 "2013-04-29T05:09:24Z")
The water in the wake of a ship is mostly water with small air bubbbles in it. The air comes from cavitation of the screws. I would expect cruise ship screws to be turning may be 120 RPM on a full ahead bell. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [April 29, 2013, 5:53am UTC](https://boards.straightdope.com/t/soft-water-behind-ships-sink-when-you-hit/656930/5 "2013-04-29T05:53:42Z")
> [@Snnipe\_70E](#): > > The water in the wake of a ship is mostly water with small air bubbbles in it. The air comes from cavitation of the screws. I would expect cruise ship screws to be turning may be 120 RPM on a full ahead bell. As the screws are under water, they only create vacuum if they enter cavitation.. The cavitation zone does not make contact with the surface - if it did you’d hear distinctive loud noises of the air rushing into the cavity. The bubbles come from the turbulence. When the turbulence hits the surface , it pushes up, and the splashing makes bubbles. There’s some bubbles from the splashing occurring at the bow and on the sides, but mostly its from the turbulence. See > **[a-a-r-s.org](http://www.a-a-r-s.org/acrs/proceeding/ACRS1999/Papers/ENV99-3.htm)** > > This domain may be for sale!