Watertight compartments can create enough buoyancy to keep a holed boat afloat.
Divers’ lifting bags, or inflation units specially made by RIB re-tubing companies, can hold up small boats.
C. A boat is safer with through-hulls situated in watertight lockers.
D. Through-bulkhead spigots enable better pipe runs.
E. Small boats need some buoyancy high up in the hull to keep them stable while you bale them out.
F. Blocks of buoyant foam pushed into the top of the mast can prevent a capsized boat from turning over completely.
G. Polystyrene foam blocks are easily shaped and great for adding buoyancy to a boat. Some people cover them in plastic film to contain polystyrene crumbs.
H. Plastic bottles and wine-box bladders can be a cheap way to create buoyancy.
I. Even a small dinghy needs quite a bit of buoyancy when swamped. The online U.S. Coast Guard Safety Standards for Backyard Boat Builders describes what is needed.
J. Two-part polyurethane foam can be poured into voids to create flotation chambers. However, read the instructions carefully to avoid hurting yourself or the boat, and be aware that some foams can degrade after many years and will then need to be removed.
K. For that reason an open-topped compartment—lined with a release agent—that can be later sealed with a lid is a good option.
L. Buoyancy bags need to be strapped in securely as they can exert quite a force on the surrounding structure. Remember, one cubic foot of air creates 60lb of buoyancy.
M. Some people store a few of the “big boat’s” fenders inside the tender to act as buoyancy.
N. Several types of inflatable sponson tubes have been added to hard tenders. The fold-up fabric Nautiraid tender also has inlatable top panels that increase buoyancy and stiffness
Dick Everitt has sailed thousands of miles in various parts of the world. He has been an illustrator, journalist and engineer for more than 40 years. Illustrations by Dickeveritt.com