After a 27-foot criuser was raised after it sank at its dock (Claim #0200825), investigators could couldn't figure out where the water had come from. All the seacocks were closed; there had been no heavy rains recently; and the boat's bilge pumps were operating, though the battery was dead from trying to keep up. Eventually, the surveyor spotted an outdrive shift bellows that appeared to be loose. The hose clamp that was supposed to hold it in place was still there and appeared to be serviceable. It wasn't until the surveyor started to remove the clamp that he noticed it was completely rusted in half on the side opposite of the screw (inset).
Our Marine Insurance claim files have a lot of problems caused by hose clamps that failed: exhaust leaks, gas spills, and boats that sank. Don't take hose clamps for granted — the safe operation of your boat depends on them.
Hose Clamp TipsUse Good Ones: Clamps should be made completely of 316 stainless steel by a reputable company. Some clamps have screws that are made of cheap steel and rust easily — and break. Running a magnet over a clamp can tell you if there is any non-stainless steel, but unfortunately can't always tell you if there is any lower-quality stainless used in the manufacture. Companies such as Ideal, Tridon, and AWAB are known for making suitable clamps if they are marine grade and not for automotive use. AWAB clamps use smooth non-perforated bands, which prevents the inevitable corrosion in the slotted-type clamps. The rounded solid bands also prevent your clamps from acting like a cheese slicer on your hoses.
Install 'em Right: An informal survey of boat owners here at BoatUS headquarters on how tight hose clamps should be caused a lot of head scratching. How do you know if your clamps are tight enough without being overtightened? Clamp manufacturers have tables with torque specifications, but how many boaters have an inch/pound torque wrench in their pocket protector? Craig Senovich, an engineer at Tridon, did an informal test for Seaworthy to find out how much torque an average person could muster on a hose clamp. Craig gathered a few co-workers, and using a sophisticated measuring device, invited everyone to crank their hardest on a hose clamp using a nut driver (similar to a screwdriver, but less likely to slip). The average person could produce about 37 inch/pounds (interestingly, using gloves nearly doubled that figure). That number happens to be very close to the specifications for a clamp in the 5/8- to 1 1/2-inch range. Craig then put a 6-inch ratchet on the clamp. Though he easily could have kept turning, he stopped at 381 inch/pounds so he wouldn't damage the testing equipment. Lesson: Use a screw or nut driver and don't be afraid to hand-tighten unless you're built like a linebacker — then you'll need to use a proper torque wrench.
Look at 'em: Assume the clamp inspection position and check all your clamps periodically. You may be surprised, like one member in Florida, to find pieces of clamp come off in your hands, so give 'em a little pull — better to fail now than when it's unexpected. Any corrosion is likely to be on the bottom of the clamp where water collects. This is often the hardest place to look, but a small inspection mirror and a flashlight can make the job easier. Any corrosion, kinks, or other damage means their life is over — replace them.
Seaworthy Magazine 10/2003