Underwater lift bags are a means of lifting an object underwater independent of surface support. The lift bag utilizes buoyancy created by displacing sea water with air. Lift bags come in various shapes and size. Once in place the bag is filled with air creating a buoyant sphere that is greater than the weight of the object being moved.
There are two types of lift bags, Parachute, which is open on the bottom and Sphere which is closed. The most commonly used lift bag in the offshore oil industry is the Parachute bag. This type of bag can be rigged to empty its contents in the case of an uncontrolled ascent.
[I]n any lifting activity a good lift plan should be developed and followed. The first step is to evaluate what is being lifted:
Is the lift Dynamic or Static? Dynamic lift is when the object is being lifted off bottom and relocated. Static lift is when the object being lifted straight off bottom and is restrained to the bottom. Even though during a dynamic lift the object is being relocated if at all possible there should always be some type of hold back rigging to prevent uncontrolled ascent of the load and the bag.
Confirm the weight of what is being lifted. Construction drawings should be used if possible. If buried take into consideration mud suction.
Once it is determined what is being lifted then the next step is to develop the lift plan:
Determine the safety factor to be used for rigging, (See Appendix #3 for recommendations)
Calculate the size of the lift bags and rigging. A lift bag that has a buoyancy capacity much larger than the planned lift should be avoided.
Determine center of gravity on the object being lifted
Calculate the number of bags to be used and their spacing. Spacing must be enough to allow the lift bags to completely fill and not interfere with each other.
Determine rigging points
Determine hold back rigging points
Determine where inverter line should be secured.
Determine a lift bag deflation plan.
Once the plan is in place then the divers that are executing the plan are selected:
Confirm the divers are trained to safely carry out the plan
Confirm the divers understand the plan and have input into the plan.
If possible a trial run can be performed in a diving tank to confirm the diver has proper working knowledge and operating experience.
Improper use of lift bags has caused injuries and fatalities in the past! Read the rest of this document to learn more!
Skamania County Dive Rescue contacted Clark County Dive Rescue to see if we wanted to join them on a training mission. So on Dec. 10th, 2017, a couple of CCDRT Divers attended a VERY cold and windy training session in the Columbia River Gorge. Skamania County Dive Rescue was conducting a lift bag training, which was very educational. The CCDRT Divers had a great time and learned a lot from Skamania Dive Team. CCDRT hopes that this relationship between the two counties becomes stronger and more Joint Training happen more often.
While CCDRT does not perform commercial dive salvage and recovery operations, we do perform a public safety service.
Occasionally, valuable or dangerous items are lost in boating accidents. In this case, a boater in a local lake capsized and among other items, a firearm was lost. Fortunately, the boater was fine and no injuries were suffered.
On July 31, 2017, Park Rangers notified Clark County Dive Rescue President Phil Graf and Vice President Jeremy Burnett, by e-mail, requesting the help of recovering items that went into the lake from a capsized boat from the day before. Graf replied back on the date and time of when the Dive Team would be at Battleground lake and requested that the owner of the boat be there as well.
On August 12, 2017, at approx. 9:30am, the owner of the boat met up with the Dive Team at the boat launch of Battleground Lake and showed the team of where he capsized his boat at the north end of the lake. A diver then took a buoy out to the approx. area for a starting point to start the search for the items. Two divers then began the search, at which time an item was found and the buoy was moved to mark that spot. The search continued until 1:30pm and three out of the five items were located and given back to the owner. Reference of where the boat capsized and distance from a point on the shore to the buoy was noted, in case future recovery of the other items is conducted.
Our General Meetings are on the first Thursday of each month from 6 pm to 8 pm at the "Washington State School for the Blind" in the classroom (across from the pool) in the Kennedy Fitness Center, which is located on the north side of the school. (must use East McLoughlin Blvd entrance).
Kennedy Fitness Center - Washington State School for the Blind
2305 E McLoughlin Blvd
Vancouver, WA 98661
This meeting is open to the public and prospective members!
The purpose of this paper is to identify the drag penalties for a number of simple SCUBA configurations. This is achieved through scale model experiments conducted in a wind tunnel. Some comments on the associated energy requirements are made, and from these, the effect on a diver’s bottom time is briefly addressed. The configurations tested include a study of the effect of the equipment configuration and the effect of small changes to the diver incidence.
River diving can place exceptional physical demands on the diver. Thus, river divers should be in good, if not superb, physical condition. Crawling around a river bottom will require upper body strength. Divers should pace themselves and be cognizant of the stamina of the smallest person of the buddy team. Moving against the current can be fatiguing and can rapidly deplete air supply.
CCDRT member train and equip at personal expense. Generous donations from community supporters make a huge difference in our ability to provide public safety services to the county and surrounding communities.
Please consider donating a training course, or a portion of the cost.
We're happy to have new members prospecting with us at the moment, but we're always looking for more folks to come join us. The process to join is very easy!
Last weekend at our regularly scheduled "Second Saturday" exercise,(at Battleground Lake this time) two current members finished up their Full Face Mask certification, while 3 prospective members (including two certified and actively working commercial divers) observed the exercises.
We've just confirmed with Clackamas County Sheriff’s Office that NW SAR Con will not be held in 2017. Due to resource constraints, the program will resume next year, Sep 21-23, 2018.