How to Lift a Boat from the Bottom of a Lake
If you wish to lift a boat from the bottom of a lake, prepare for a painstaking process involving the use of commercial divers, a remotely operated vehicle (ROV) and highly specialized recovery equipment, including a substantial recovery vessel. An observation-class ROV can make the initial assessment of the situation, staying underwater longer than a diver and safely entering dangerous areas where a diver might become entrapped. The divers will make the necessary repairs or attach specialized equipment, working around the clock. With a very high potential for failure, the moment of truth only comes when the lift begins.
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Things You'll Need
- Suitable dive vessel
- ROV and crew
- Commercial dive team and equipment
- Boat repair and patching materials and equipment
- 150 lb. lift bags
- Air compressor
- 40-ton crawler crane
Instructions
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Charter a boat for the salvage operation that's large enough to accommodate a 12-person dive team and equipment for suface-air diving, a large compressor and hoses, and a 10-ton capacity crawler crane. Go to the location of the wreck. Use a remotely operated vehicle--an underwater robot, controlled from the surface -- to establish whether the recovery is possible by gas bag and inflation, the least expensive process; repair and inflation, the moderately expensive process; or a specially constructed lifting frame and straps, the most expensive method. Select the method of recovery based on the information from the ROV survey.
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Plan the dives, advising the divers what your goal is and, in general, what each dive is to accomplish. Discuss the recovery method, whether to repair the vessel sufficiently to fill it with air and float it independently, install gas bags on the vessel and connecting gas hoses to the bags, to fill the bags with surface-supplied gas and raise the vessel along with the bags, or to lay straps beneath the vessel and raise the vessel with a crane.
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When the divers have completed their portion of the project by preparing the vessel for recovery, proceed to pump air into the bags or the hull. If straps were laid under the wreck for a mechanical recovery, have the divers, on their final dive of the recovery effort, connect the straps to the lifting slings lowered from the crane on the surface.
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Raise the vessel slowly, since the water inside the vessel must drain to avoid an unstable lift. Unless the wreck has been lifted from the water by a crane, have the recovery vessel tow the partially submerged vessel to a marina, where trained personnel can fully pump out the recovered vessel.
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Tips & Warnings
This is a job for professionals, not well-intentioned amateurs. Wreck diving and underwater construction are well beyond the scope of the recreational diver's training. Recreational divers who wish to undertake this type of work are encouraged to attend the necessary schools and take the necessary training prior to attempting any underwater recovery.
References
Resources
- Photo Credit bateau naufragé image by Romain Diant from Fotolia.com
