Freshly hired by the owner, the captain was just joining the yacht as it was getting hauled out for some maintenance work. He maneuvered the boat in position under the Travelift, shut everything down, and watched as divers placed the straps. He was a bit surprised by their placement, but he figured that the yard knew what it was doing. He wasn’t familiar with this shipyard but the owner assured him they had lifted the boat before and had all the specs and information.
So it was hoisted, moved into position, and blocked. Then the captain began a careful inspection. Sure enough, there was some hull deformation where two of the straps had been placed. What a way to start a new job!
The act of lifting a boat out of the water always carries a high level of risk. The Internet is full of videos of hoists gone wrong, including a spectacularly bad one of sling failure mid-air while unloading what looks to be a 40-meter tri-deck from a cargo ship. Slings can fail and the boat can be dropped due to improper care and maintenance or when the yard does not assemble the sling buckles correctly.
In the preparation phase, the more information the better: obviously the vessel’s particulars, but in addition, any kind of maintenance history, hoist history, refits, especially any areas of concern.
Less YouTube-worthy, but not particularly rare, are the results of incorrect weight distribution in the slings and bad strap placement, which can lead to global or local structural failures. Not getting the balance of weight correct in the slings can overload and crack the hull. Local damage can occur when straps are not placed on frames, which on an aluminum boat can cause the shell plating to deflect. On composite boats with foam core construction, damage is often seen at the chine.
Recently, Tyler Jenkins, a marine engineer with DLBA Naval Architects in Virginia Beach, Virginia, hosted a webinar for captains on the key precautions to take when lifting a yacht. His firm is able to assist in producing and verifying hoisting and blocking plans in order to avoid these worst-case scenarios.
In the preparation phase, Jenkins says the more information the better: obviously the vessel’s particulars, but in addition, “any kind of maintenance history, hoist history, refits, especially any areas of concern. We have had a lot of projects in the past where maybe the boat was involved in a collision, and there wasn’t any visible damage. But if you’re able to provide that information, that is somewhere that we can give a closer look and make sure there’s not something below the surface that’s going to cause us any issues. In that case, especially, pictures are absolutely helpful... (also) engineering drawings, of course, with as much detail as possible that show longitudinal and transverse structure, because obviously, we’ll use that to help us determine where we want to put those straps, and then also use that for the blocking arrangement.”
The weight distribution is key, stresses Jenkins. Make sure to provide the general arrangement with placement of engines, gensets, gyrostabilizers, tenders, etc. “Anything major like that which is left out is just more margin for error,” he says. Likewise, if something significant like a tender is shown on the GA but is offloaded for the lift, make sure to communicate this. “The most important thing here is to account for anything that is or is not present on the boat.” Engineers use all this information to perform global and local structure checks to come up with a plan for lifting points, strap placement, and blocking.
Not getting the balance of weight correct in the slings can overload and crack the hull. Local damage can occur when straps are not placed on frames, which on an aluminum boat can cause the shell plating to deflect.
Pre-lift, Jenkins suggests reducing weight where it is practical to minimize the load on the lift and vessel. Easy weight-loss finds are in fuel, water, tenders, and toys. And if the global structure check shows too much deformation at the bow, for example, DLBA would request the anchors and chain be removed.
On the day of the lift, weather conditions should be good with no high winds. “As a general rule of thumb, we say five knots (max),” Jenkins says. The area where the yacht is going to be blocked should be staged so the yacht is not left hanging — literally. Straps need to be placed on frames and bulkheads. “This minimizes the risk of damaging hull plating and allows the transverse frame to take the bulk of the load,” says Jenkins. When a Travelift has a pair of straps in one sling, don’t straddle the frame; one strap needs to be actually on the frame so the load goes into it and doesn’t bend the plate up around it.
Straps also should not cover any hull appendages like lights, transducers, and thru-holes, which makes it a bit trickier. “It can be easy (for the divers) to just slide it farther aft or forward to make things easier; definitely monitor this as closely as possible,” Jenkins says. “We’ve seen it happen many times. It could be unintentional, of course, everyone’s human. So we’ve got to keep each other in check.” He recommends marking the hull side or bottom so it’s easy to confirm the correct placement at a glance.
In addition, “Take care to protect the hull side from things like strap buckles and pinch-points,” he adds. “Plywood, carpeting, and other soft materials can be used for this. Protection blocks should also be used at chines and other ‘sharp’ features.”
Finally, after the boat is safely resting on the blocks (with no air gaps between any of them and the hull), Jenkins advises to carefully inspect all areas that may have been affected during the hoist. For more information, email email@example.com.
This article originally ran in the August 2021 issue of Dockwalk.