Sinking Boat: Calculations & Results

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SUMMARY

The discussion centers on the calculations related to a sinking boat with specific dimensions: a length of 50 m, a width of 10 m, and a height of 5 m. A circular hole with a diameter of 20 mm allows water to enter, and the initial height of the boat above water is 3.5 m. Key calculations include the velocity of water entering the hole, determined to be approximately 5.425 m/s, and the time for the boat to sink, calculated at around 285.95 hours. The discussion also emphasizes that the difference in water levels inside and outside the boat remains constant at 1.5 m until the boat is fully submerged.

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  • #61
I don't see how a pressure notably below ambient downstream pressure could be maintained in the stream. Such a pressure difference sucks in water from the outside. That is happening, of course, but I would expect that to form a somewhat stable vortex without large pressure differences.
 
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  • #62
mfb said:
I don't see how a pressure notably below ambient downstream pressure could be maintained in the stream. Such a pressure difference sucks in water from the outside. That is happening, of course, but I would expect that to form a somewhat stable vortex without large pressure differences.
I had trouble finding anything on this that is not behind a paywall. Finally found https://books.google.com.au/books?i...zAG#v=onepage&q=flow submerged sluice&f=false. See eqn 5.24
 
  • #63
I cannot access the previous page in the preview, which makes the formula unclear.
 
  • #64
mfb said:
I cannot access the previous page in the preview, which makes the formula unclear.
It has a diagram with H1 as the depth in front of the sluice, H2 as the general depth downstream of the sluice, and H3 as the depth just after the sluice. The surface water is lower just after the sluice than further downstream, so H3 < H2, as per the formula. The height difference used for the flow rate is H1-H3.
 
  • #65
Interesting, opening the PDF again I can now see the previous page, but not the page I saw before.

It discusses a notable effect as long as "a" (the height of the opening) is relevant compared to H2. For a negligible hole size, and assuming we can adapt this to the vertical case, all the a/H terms vanish.
 
  • #66
mfb said:
Interesting, opening the PDF again I can now see the previous page, but not the page I saw before.

It discusses a notable effect as long as "a" (the height of the opening) is relevant compared to H2. For a negligible hole size, and assuming we can adapt this to the vertical case, all the a/H terms vanish.
Ok.
 

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