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Disclaimer: I am not a spokesperson for the US Coast Guard or ABYC. For an official interpretation of regulations or standards you must contact the US Coast Guard or other organization referenced.. More..... |
I developed an E-course in Capacity and Flotation for Boat Builders, for Professional Boat Builder Magazine. They no longer offer it. In addition to these web pages I am offering it as an e-book. Go to Ike's Store to see more | I also have a perfect companion to the Capacity and Flotation Course. It is an excel spreadsheet that does the calculations to determine the amount of Flotation needed. Easy to use. Go to Ike's Store to see more |
SAFE LOADING AND CAPACITYHow do I determine how many people my boats can carry, how much weight?SAFE LOADING: CAPACITY: 3 CFR 183.21 - 183.43 Applies to Mono-hull boats under 20' The Maximum safe load and the persons capacity that a boat can carry is based on the displacement weight of a boat. What is displacement weight? That is essentially the amount of weight that it would take to sink your boat. There are several ways to find this out.
If you want to do it this way hire a test lab or call the Coast Guard. See the flotation page for information about testing. Slide Show of a boat being tested for Maximum Weight Capacity. 3. Or with smaller boats fill the boat with water using a bucket of a known amount. Fill it until the level of the water in the boat and outside the boat is equal, that is when water starts to flow in and out of the boat. Multiply the number of gallons times 8. That gives you the displacement weight. Inboard and Stern-Drive Boats under 20 feet. Maximum Weight Capacity=(displacement weight-boat weight-4(machinery weight))/5 = W or: Maximum Weight Capacity = (Maximum Displacement - boat weight)/7 = W Maximum Persons Capacity = W; or for boats with W less than 550 use the test method. Add weights along the outboard side of the passenger area . The weight should be at seat height and distributed equally for and aft. Add weights until water is about to come over the gunwale. Stop. Add up the weight. Maximum Persons Capacity = Total of Weights/0.6 Maximum Persons (in people) = (Maximum Persons Weight + 32)/141. Round up or down. A bit of advice. Maximum persons capacity doesn't have to be the maximum amount, it can be less. Smart boat builders down rate the maximum weight and persons capacity to cover liability and all that other heavy junk people carry on to their boat like coolers full of beer, extra gas, the spare fish finder they just have to have, the ski-boards and slalom skis, etc., etc. REMEMBER! The boat operator will exceed whatever you put on the label and then blame you if something goes wrong! Be conservative. Give yourself some room. Outboard Boats under 20 feet rated for greater than 2 HP. Maximum Weight Capacity = W- boat weight /5 Maximum Persons Capacity = Maximum Weight Capacity - Col 9 Table 4 Outboard boats under 20 feet, 2 HP or less. Maximum Weight Capacity = (W- boat weight) x 3/10 Maximum Persons Capacity = (Maximum Weight Capacity - 30) x 0.90 Maximum Persons (in people) = (Maximum Persons Weight + 32)/141 Round up or down. Manually propelled boats. Maximum Weight Capacity = (W- boat weight) x 3/10 Maximum Persons Capacity = Maximum Weight Capacity x 0.90 Maximum Persons (in people) = (Maximum Persons Weight + 32)/141 Round up or down. The same warning applies to Inboard boats. Be conservative. Error on the side of safety. copyright https://newboatbuilders.com 2010 All Rights Reserved Revised 03/062019
Revised 01/13/2011 © newboatbuilders.com 2011 All rights reserved |