question: "Squat effect" (shallow water effect)

Kapitan · 01-31-10, 05:52 PM

Ive been reading about the squat effect basically when a vessel enters a shallow at speed an area of low pressure is created underneath the hull and makes the ship sink lower than expected.
other than making the ship sit lower in the water it adversly effects the handling of the vessel as well, and this squat effect was the cause of the capsize of the heral of free enterprise in zeebrugge in 1987.
Reading into it more and more i can only think this effect isnt modeled in game?

Does anyone have anyother information about shallow water "squat" effect ?

and anyone know if its modeled in game?

Pisces · 02-01-10, 12:38 PM

Sounds like typical Bernoulli principle, pressure in a medium drops as it flows faster through a conduit.

http://home.earthlink.net/~mmc1919/venturi.html

I doubt if it has been moddeled. I have cruised often enough with just 1 feet under keel, but depth didn't change when the seabed dropped.

Dr.Sid · 02-01-10, 03:54 PM

I don't remember anything like that too. Good to know anyway. Same applies for subs close to surface (they are pulled up), and most probably also close to flat bottom.

Kapitan · 02-04-10, 04:33 PM

well i didnt think it would be modeled but it does make for a very intresting read and ships have sunk and scrapped bottom because of it too.

Bubblehead Nuke · 02-04-10, 09:12 PM

Knowing how hard planesmen work to hold PD, I would have to say no. Just going to the ships control panel where you can see plane angles shows that they are pretty much static. They show plane angle change to get to the depth and then don't move much till you change depth later.

In RL, the planes are moving to compensate for the change in surface suction. They are doing small and sometimes LARGE angle changes. It is stressful for the boat handling crew to maintain PD in anything other than light seas.

The suction dynamic varies with sea state above you, the currents around you, and the dynamics of the hull in this constantly changing enviroment.

To honest, to simulate this would require HUGE amount of compuational power. We are talking fluid dynamics here. I would just say that the planesmen are competent in this aspect of ship handling and not worry about it.

SeaQueen · 02-12-10, 07:56 AM

Quote:

Originally Posted by Bubblehead Nuke

To honest, to simulate this would require HUGE amount of compuational power. We are talking fluid dynamics here. I would just say that the planesmen are competent in this aspect of ship handling and not worry about it.

Have you seen the online submarine handling simulator at John's Hopkin's University / APL? It's pretty neat, I thought. I always wondered why they didn't do something more like that with DW.

Bubblehead Nuke · 02-12-10, 08:41 PM

Quote:

Originally Posted by SeaQueen

Have you seen the online submarine handling simulator at John's Hopkin's University / APL? It's pretty neat, I thought. I always wondered why they didn't do something more like that with DW.

Do you have a link?

01-31-10, 05:52 PM	#1
Kapitan Sub Test Pilot Join Date: Mar 2005 Location: UK + Canada Posts: 7,130 Downloads: 77 Uploads: 7	question: "Squat effect" (shallow water effect) Ive been reading about the squat effect basically when a vessel enters a shallow at speed an area of low pressure is created underneath the hull and makes the ship sink lower than expected. other than making the ship sit lower in the water it adversly effects the handling of the vessel as well, and this squat effect was the cause of the capsize of the heral of free enterprise in zeebrugge in 1987. Reading into it more and more i can only think this effect isnt modeled in game? Does anyone have anyother information about shallow water "squat" effect ? and anyone know if its modeled in game? __________________ DONT FORGET if you like a post to nominate it by using the blue diamond Find out about Museum Ships here: https://www.museumships.us/ Flickr for all my pictures: https://www.flickr.com/photos/131313936@N03/ Navy general board articles: https://www.navygeneralboard.com/author/aegis/

02-01-10, 12:38 PM	#2
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,904 Downloads: 304 Uploads: 0	Sounds like typical Bernoulli principle, pressure in a medium drops as it flows faster through a conduit. http://home.earthlink.net/~mmc1919/venturi.html I doubt if it has been moddeled. I have cruised often enough with just 1 feet under keel, but depth didn't change when the seabed dropped. __________________ My site downloads: https://ricojansen.nl/downloads

02-01-10, 03:54 PM	#3
Dr.Sid The Old Man Join Date: May 2005 Location: Czech Republic Posts: 1,458 Downloads: 6 Uploads: 0	I don't remember anything like that too. Good to know anyway. Same applies for subs close to surface (they are pulled up), and most probably also close to flat bottom. __________________ ComSubSim forum at CADC

02-04-10, 04:33 PM	#4
Kapitan Sub Test Pilot Join Date: Mar 2005 Location: UK + Canada Posts: 7,130 Downloads: 77 Uploads: 7	well i didnt think it would be modeled but it does make for a very intresting read and ships have sunk and scrapped bottom because of it too. __________________ DONT FORGET if you like a post to nominate it by using the blue diamond Find out about Museum Ships here: https://www.museumships.us/ Flickr for all my pictures: https://www.flickr.com/photos/131313936@N03/ Navy general board articles: https://www.navygeneralboard.com/author/aegis/

02-04-10, 09:12 PM	#5
Bubblehead Nuke XO Join Date: Feb 2006 Posts: 435 Downloads: 5 Uploads: 0	Knowing how hard planesmen work to hold PD, I would have to say no. Just going to the ships control panel where you can see plane angles shows that they are pretty much static. They show plane angle change to get to the depth and then don't move much till you change depth later. In RL, the planes are moving to compensate for the change in surface suction. They are doing small and sometimes LARGE angle changes. It is stressful for the boat handling crew to maintain PD in anything other than light seas. The suction dynamic varies with sea state above you, the currents around you, and the dynamics of the hull in this constantly changing enviroment. To honest, to simulate this would require HUGE amount of compuational power. We are talking fluid dynamics here. I would just say that the planesmen are competent in this aspect of ship handling and not worry about it.