The amount of positive flotation is calculated using the weight of a cubic foot of water, sea water weighs 64 lbs. per cubic foot and fresh water 62.5 lbs. To calculate flotation requirements the loaded displacement of a boat in lbs. is divided by 64 or 62.5 depending on the type of water the boat is used in. Areas for flotation foam should be chosen throughout the hull to ensure balanced flotation.
Once the amount of flotation is determined, the areas to be filled with urethane foam must be prepared by cleaning and removing any debris. A small amount of foam should be mixed as a test to determine the amount and rate of expansion, as large amounts of expansion can displace members in an enclosed area.
Urethane foam is a fast drying material and should be mixed using a power drill and paint mixing attachment. Hand mixing should not be attempted as the mixture will not be properly mixed before it begins to set.
As the foam expands and dries in a short period of time all areas should be prepared and safety equipment should be worn throughout the installation. Small amounts of urethane foam should be mixed and poured into the chosen spaces to ensure damage is not caused as the foam expands.
When the foam is poured into enclosed areas one inch ventilation holes should be placed throughout the foam installation to prevent damage to the hull. The foam should be poured within one minute of being mixed.
