Dock Flotation Calculation
It is always important to be comparing “apples to apples” when doing a dock flotation calculation.
Dock Flotation Calculation: The Richardson Advantage
Our pontoon floats run either the entire length or width of your dock or raft. Without any gaps, flotation is consistent giving more stability, strength and buoyancy. A single sixteen foot (12″x 2′ x 16′) float has 32 cubic feet of foam medium. Our larger float (22″ x 2′ x 16′) has 58.7 cubic feet of foam medium.
Dock Flotation Rule of Thumb
Regular dock floats they will support 65 pounds per lineal foot. Considering an 8ft x 16ft dock has three 16ft floats it will support 3 x 16ft x 65lbs = 3,120lbs. The actual dock will weight by itself 10.5 pounds per square foot. Using the same example 8ft x 16ft x 10.5lbs = 1344 pounds. So the net weight an 8ft x16ft dock will support is 3,120 – 1344 = 1776 lbs.
Our Large Pontoon Floats (22′ x 24″ x 16ft will support 130 pounds per lineal foot. Considering an 8ft x 16ft dock has two 16ft floats it will support 2 x 16ft x 135lbs = 4,320lbs. The actual dock will weight by itself 11.5 pounds per square foot. Using the same example 8ft x 16ft x 11.5lbs = 1472 pounds. So the net weight an 8ft x16ft dock will support is 4,320 – 1,472 = 2,848 lbs.
Air Filled vs Foam Filled
An air filled device and a foam filled device have just about the same flotation characteristics sitting dry. Add moisture in the form of condensation or a leak, and everything changes. Water displaces air and if enough gets in it will not support itself. In other words it sinks!
Using foam within the flotation device displaces the water up until the point of saturation. In other words it becomes water-logged.
So – then it becomes an absorption issue of the foam.
Dock Flotation Calculation Absorption Issues
Absorption rates of foam are calculated as a percentage if its total volume exposed to water. In other words, it is not a percentage of the entire float, just what is exposed to the water. So the less flotation you have, the more your float will be under water. You can see, more flotation is better than less. Always look at the flotation data sheet for water absorption percentages.
Pressure Treated Lumber Considerations