How much flotation do I need?
This depends on the material used to construct the dock, intended use of the dock, and desired height off of the water. Our team can help to sort out the solutions to the issues impacting your dock project. Give us a call for assistance, but if you want to work through a general dock scenario – we offer the following:
For a general dock with the use of a few people, we aim for about 30 lbs. per square foot to calculate flotation for a dock using a wood frame and wood decking. A marina expecting more than a few people needs about 40 lbs. per square foot. Rarely will you get the exact poundage, but you should strive to obtain as close to these benchmarks as possible.
Once you have the flotation needed for the design phase, you then choose the floats you want to use. We offer many options, but, generally speaking, the 12” and 16” deep floats tend to make a more stable dock. For our example, we will be building an 8’ x 20’ dock section. The amount of square feet of dock is first determined by multiplying 8’ x 20’ = 160 square feet. We then calculate 30 pounds of flotation per square feet and multiply 30 x 160 = 4800 pounds of flotation needed to satisfy the design criteria.
The next step is to determine the size float you would like to use. For this example, we will use a 4’ x 8’ x 12” float. This float has a supporting weight of 1680 lbs. per float. Three of these floats will provide 5040 lbs. of flotation. If we divide the total flotation by the square footage of the dock (5040 divided by 160) we find that our choice of float delivers 31.5 lbs. of flotation per square foot. When using these large floats, that 1.5 lbs. per square foot difference is almost as close as you can obtain and would be acceptable.
