Flotation

Example of Level Flotation Calculations

Step 2: Determine the flotation material needed to support the swamped propulsion equipment (Fp)

Formula:

Fp = S ÷ B

Where

S = The swamped weight of the maximum horsepower capacity engine for which the boat is rated on the capacity label, plus the submerged weight of the battery. All are found in Table 4, columns 2 and 4 (See Appendix A)

B = The buoyancy of the flotation material in pounds per cubic foot.

NOTE:
The Coast Guard has been given authority to randomly check boats for compliance with the flotation requirements. When this check is conducted, simulated outboard engine weights are used rather than an actual outboard engine. The weight used during this check is obtained from the outboard engine weight table included in Subpart H (Flotation) of the CFR (see Table 4). Due to changing technology, outboard engines heavier than those listed in Table 4 are available. This is particularly true in the case of 4 stroke engines. The reader is encouraged to refer to ABYC Standard S-30, Outboard Engines and Related Equipment Weights, for the latest outboard engine weight table.

Distribute this material symmetrically within 36 inches (30 inches for boats of less than 15 feet in length) of the outside of the transom top at the motor-mounting area or around the propulsion system if engines are not stern mounted.

In small boats, sometimes it is difficult to pack the flotation material in the compartments prescribed here. Use the space on the deck aft, but stay within the 36-inch area (30 for boats under 15 ft.).

FIGURE 5.4 - Flotation Material for Propulsion System

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