Boat Lift Off-Center Load Calculator

Welcome to the IMM Quality Boat Lifts off-center load calculator.

First, calculate the load at each corner. You will need to enter the amount of shift, based on the boat’s center of gravity (CG), from the lift center. This shift can be in the direction of the bow or stern, as well as in the port or starboard directions.

For this calculator, a shift in the bow direction will be expressed as a positive value. A shift to the stern will be a negative value. Likewise, a shift to the starboard will be expressed as a positive value, while a shift to the port will be a negative value.

IMM Quality Boat Lifts recommends that all boats have their CG loaded over the center of the lift. However, in certain circumstances, the homeowner may desire an off-center loading of their boat. Perhaps they need to move the boat to stay within their property’s water rights, or maybe they want to move the boat closer to the dock to make boarding easier. Whatever the reason, this calculator can be used to determine how far off-center the boat may be moved before the lift becomes overloaded.

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You can find the lift’s maximum capacity rating on the yellow sticker that’s located on the top beam. You can also determine the lift’s capacity by measuring the cradle beams and the height of the top beams. With these values in hand, look at your lift model’s specification sheet and compare the values to determine the capacity.

This refers to the total wet weight of the watercraft. Please read the article for more information, or simply use our calculator.

Please contact your boat manufacturer for help determining the center of gravity. They will be able to provide a lift and/or trailer drawing that indicates your boat’s CG.

Please note that sling marks are not necessarily equally spaced from the boat’s CG. They are often underneath bulkheads or other internal structural support, and don’t necessarily have any relation to the boat’s CG.

Use a tape measure to determine the distance of the cradles from bow to stern (see A, in figure above). Measure to the same face of both cradle beams to ensure an accurate reading.

Use a tape measure to determine the port to starboard distance between the cables on the two ends of the cradle (see B, in figure above).

If you plan to move the CG in the bow and stern direction, enter the amount in inches. Enter a positive number for a shift in the bow direction and a negative number for a shift towards the stern.

If you plan to move the CG in the port and starboard direction, enter the amount in inches. Enter a positive number for a shift in the starboard direction and a negative number for a shift towards the port.


IMM Quality Boat Lifts cannot determine the accuracy of the information that you have input. This includes the weight of the boat, the center of gravity, the measurements, and more. For that reason, IMM Quality makes no claims as to the accuracy, completeness or timeliness of any results produced by our calculators, including fitness for any particular purpose. 

If you use these results for any purpose, the responsibility and risk of that use is entirely with you, the user. These services are provided on an “as-is” and “as available” basis. We expressly disclaim all warranties of any kind, whether express or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose.

By using this calculator, you expressly acknowledge and agree that we will not be held liable for any direct, indirect, incidental, special, consequential, punitive, or exemplary damages, including but not limited to, damages for loss of profits, goodwill, use, data or other intangibles (even if we were advised of the possibility of such damages), resulting from the use of our calculators.

By using this calculator, you agree to indemnify and hold IMM Quality Boat Lifts and their shareholders, subsidiaries, affiliates, directors, officers, employees, and agents, harmless from any claim or demand, including any attorneys’ fees that they (or the other indemnitees) may incur resulting from or arising out of your actions, your access, and use of IMM Quality’s calculators.