Flotation - Summary of Level Flotation Performance Requirements & Tests
Each boat subject to compliance with Level Flotation must have sufficient flotation so that after pre-conditioning, the boat will pass the following requirements (Read section 183.220):
1. Flotation Test
2. Stability Test
3. Level Flotation Test
The boat, if selected for testing by the USCG, will be prepared and tested as this Guideline describes, and pre-conditioning the boat is a very important part of the test.
The manufacturer can:
- Perform the tests in-house;
- Hire an independent firm to perform tests and report results; or
- Take advantage of the USCG program, as they will perform these tests free of charge.
Test One: Flotation Test
Performance requirements:
Following the pre-conditioning and loading (see Preconditioning), the boat has to meet requirements a, b and c of CFR 183.225
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FEDERAL LAW
183.225 - Flotation test for persons capacity
Flotation standard. When the conditions prescribed in Sec. 183.220 are met, the boat must float in fresh, calm water as follows:
(a) The angle of heel does not exceed 10 degrees from the horizontal.
(b) Any point on either the forward or aft reference area is above the surface of the water.
(c) The reference depth at the reference area that is opposite the reference area that is above the surface of the water is 6 inches or less.
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FIGURE 5.8 - Flotation Test
FIGURE 5.9 - Reference Area
Test Two: Stability Test
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FEDERAL LAW
183.230 - Stability Test
(a) Flotation standard. When the conditions prescribed in Sec. 183.220 (a), (d) through (h) and paragraphs (b) and (c) of this section are met, the boat must float in fresh, calm water as follows:
(1) The angle of heel does not exceed 30 degrees from the horizontal.
(2) Any point on either the forward or aft reference area is above the surface of the water.
(3) The reference depth at the reference area that is opposite the reference area that is above the surface of the water is 12 inches or less.
(b) Quantity of weight used. Load the boat with a quantity of weight that, when submerged, is equal to the sum of the following:
(1) One-half of the quantity of weight required by Sec. 183.220 (b) (1).
(2) The quantity of weight required by Sec. 183.220 (b) (2).
(c) Placement of quantity of weight: starboard side. Place the weight required by paragraph (b) of this section in the boat so that:
(1) The quantity of weight required by Sec. 183.220 (b) (2) is positioned in accordance with Sec. 183.220 (c); and
(2) One-half the quantity of weight required by Sec. 183.220 (b) (1) is uniformly distributed over a distance along the outboard perimeter of the starboard side of the passenger carrying area that is equal to at least 30 percent of the length of the passenger carrying area so that the center of gravity of the quantity of weight is located within the shaded area illustrated in Figure 12, the center of gravity of the amount of weight placed on the floor of the boat is at least 4 inches above the floor, and the center of gravity of the amount of weight placed on a seat is at least 4 inches above the seat. The location and dimensions of the shaded area are as follows:
(i) The shaded area is centered at the mid-length of the passenger carrying area;
(ii) The length of the shaded area is equal to 70 percent of the length of the passenger carrying area; and
(iii) The breadth of the shaded area is 6 inches from:
(A) For weights placed on the floor, the outboard perimeter of the passenger carrying area; and
(B) For weights placed on a seat, a vertical line inside the passenger carrying area as illustrated in Figure 13.
(d) Placement of quantity of weight: port side. The quantity of weight required by paragraph (b) (1) of this section is placed along the port side of the passenger carrying area in accordance with the conditions prescribed in paragraph (c) (2) of this section.
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Performance Requirements: Following the pre-conditioning and loading (see Preconditioning), the boat must meet the requirements 1, 2 and 3 of section 183.230 (a)
NOTE:
- See Appendix B for 33 CFR Subparts H, Figures 2 – 13.
- The boat must meet the performance requirements when tested with the weights on each side of the boat.
FIGURE 5.10 - Stability Test
FIGURE 5.11 - Loading Area
FIGURE 5.12 - Center of Gravity of Weights
FIGURE 5.13 - Weight Shift for Stability Tests
FIGURE 5.14 - Center of Gravity of Weight on Seats
Test Three: Level Flotation Test (without certain weights)
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FEDERAL LAW
183.235 - Level flotation test without weights for persons capacity
When the conditions prescribed in Sec. 183.220 (a) and (d) through (h) are met, the boat must float in fresh, calm water as follows:
(a) The angle of heel does not exceed 10 degrees from the horizontal.
(b) Any point on either the forward or aft reference area is above the surface of the water.
(c) The reference depth at the reference area that is opposite the reference area that is above the surface of the water is 6 inches or less.
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The flotation attitude requirements for this test are the same as for Test One, but the loading excludes weights for persons capacity as specified in 183.230 (c) (2) (ii) and (c) (2) (iii).
NOTE:
The purpose of this test is to check that the boat, without weights for passengers, will not capsize. The weights may actually help the boat stay level because of a lower center of gravity while, if removed, the boat could overturn if the flotation material buoys up the center of the boat.
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