Large hydraulic yard trailer info
It's winter storage time in northern climes and I thought it might be informative to point out the good, the bad and the ugly amongst large hydraulic yard trailers.
There are two basic designs....keel lift, and pad lift. The first two photos depict a keel lift design. The second two show a pad lift design(sorry, no photos with a boat aboard, and absolutely not mine).
With the keel lift configuration the boat is lifted from the haul-out well with a travel lift, and then moved forward over the waiting trailer. Large wooden blocks are positioned on three or four lateral slats in the trailer frame, such that the keel sits on those wooden blocks when the boat is lowered. When most of the weight of the boat is on the trailer, the crew activates four hydraulic arms with pads to stabilized the hull. A very small amount of the weight is taken by the hydraulic arms/pads. The wheels on the trailer are extended downward during this evolution, and then raised (lowering the trailer frame and boat) for the actual trip to the storage building. When the boat is in position in the building, the wheels are again extended thereby lifting the trailer frame with the boat. Blocks are positioned under the boat keel (between the slats). Finally, the trailer is lowered by retracting the wheel carriage, and boat keel is resting on the final keel blocking for the winter. Jack stands are inserted along the sides of the hull and the trailer is pulled away. The integrity of the boat's hull structure is respected at every stage of the evolution.
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The second design type uses a pad lift arrangement with no support for the keel. The trailers I've seen have manual jackscrews for the pads. Careless and rushed crews rarely take the time to fine tune the screw jacks at the four corners and in my 15 years of observation, never even bother with snugging up midspan pads. The result for larger, heavier boats is huge compression, deflection, and twisting loads on hull skin and structure. Pad trailers might be OK with lighter, smaller boats but they are causing hidden damage on large, heavy hulls. I have seen 50' plus boats on a nominally 35 foot trailer. If your yard is using a pad lift trailer, odds are very high that they are damaging your boat. Cored hulls are at serious risk. Beware, and don't assume the yard is looking after your property.
It's winter storage time in northern climes and I thought it might be informative to point out the good, the bad and the ugly amongst large hydraulic yard trailers.
There are two basic designs....keel lift, and pad lift. The first two photos depict a keel lift design. The second two show a pad lift design(sorry, no photos with a boat aboard, and absolutely not mine).
With the keel lift configuration the boat is lifted from the haul-out well with a travel lift, and then moved forward over the waiting trailer. Large wooden blocks are positioned on three or four lateral slats in the trailer frame, such that the keel sits on those wooden blocks when the boat is lowered. When most of the weight of the boat is on the trailer, the crew activates four hydraulic arms with pads to stabilized the hull. A very small amount of the weight is taken by the hydraulic arms/pads. The wheels on the trailer are extended downward during this evolution, and then raised (lowering the trailer frame and boat) for the actual trip to the storage building. When the boat is in position in the building, the wheels are again extended thereby lifting the trailer frame with the boat. Blocks are positioned under the boat keel (between the slats). Finally, the trailer is lowered by retracting the wheel carriage, and boat keel is resting on the final keel blocking for the winter. Jack stands are inserted along the sides of the hull and the trailer is pulled away. The integrity of the boat's hull structure is respected at every stage of the evolution.
[/QUOTE][/QUOTE]The second design type uses a pad lift arrangement with no support for the keel. The trailers I've seen have manual jackscrews for the pads. Careless and rushed crews rarely take the time to fine tune the screw jacks at the four corners and in my 15 years of observation, never even bother with snugging up midspan pads. The result for larger, heavier boats is huge compression, deflection, and twisting loads on hull skin and structure. Pad trailers might be OK with lighter, smaller boats but they are causing hidden damage on large, heavy hulls. I have seen 50' plus boats on a nominally 35 foot trailer. If your yard is using a pad lift trailer, odds are very high that they are damaging your boat. Cored hulls are at serious risk. Beware, and don't assume the yard is looking after your property.
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