print dive site review | contribute site info / photo
Diving Stoney Cove, England Inland Dive Site
Dive Site: Blowout Preventer (BOP)
Depth: 18 to 20 metres (60 feet)
Rating: See Stoney Cove overview
Location: From the Bus Stop entry take a 280 degree bearing and expect a 5 minute slow swim down a steep sloping rock wall. If entering from the main slipway increase your bearing to 290 degrees and expect a 5 - 8 minute swim. The BOP can also make interesting viewing if you are returning from a deeper dive in the 36 metre area. From the deep Hydro Box you can ensure you pass the BOP by taking an 80 degree bearing or if you've been to the deep Mini then return on a 20 degree bearing. Once at the BOP it's a 155 degree bearing to the bus, or a 105 degree bearing to the Viscount Cockpit which is just south of the Bus Stop exit point. Close to the BOP are the Tower and 20 metre Hydro Box which can usually be seen from the BOP and are on a 270 degree west bearing a few metres away.
History & Description: A Blowout Preventer (BOP) is essentially a large valve located at the top of a drilling well. This allows the control of the pressure of fluids within the drilling well. This pressure is normally hydrostatic pressure or the pressure exerted by a column of water from the formation depth to sea level. We've all seen the oil wells on TV spewing out oil when the drilling crew strike it lucky. A BOP allows the crew to close a valve and gain control whilst then employing other measures, such as increasing mud density, until it becomes possible to open the BOP. There are many different shapes and sizes and the one located in Stoney Cove is of medium size and probably had a medium pressure rating. Some BOP's attach directly to drill pipe casings at the top of the well, while others can seal an open well-bore. An annular blowout preventer has a large rubber sheath which is squeezed onto either erect piping or straight into an open hole. This means it can deal with a variety of different shaped and sized holes. There's also a ram blowout preventer which is in two half's and can be quickly forced together to seal troublesome holes. These sometimes have a circular cut out so that seals can be made even while the pipe is still in the hole!
Rik Vercoe, BSAC Advanced Instructor
Do you have any comments on this dive site?
print dive site review | contribute site info / photo | top
Do you run a dive operation in this area?
Click here to find out more about being listed on this
page in dive site directory.