Three rules regarding double clamps on all raw water hoses below the water line including all wet exhaust holes.
Rule #1: ALWAYS DOUBLE CLAMP ALL RAW WATER HOSES!
Rule #2: Any questions arise as to whether or not to double clamp raw water hoses below the waterline, refer to rule #1.
Rule #3: if after reading rule number two there remains any question whether or not to double clamp raw water hoses below the waterline, refer to rule #2.
On every boat I’ve ever owned there’s double ss 90 degree rotated from each other on all through hulls near or under the waterline. Also on all hose connections after anti siphon valves on discharge side of outputs.and all connections on raw water intake side. Cheap insurance. This includes discharges (sinks, sump pumps, AC etc.) as well not just raw water intakes as those can sink your boat as well. . We also use a nut driver not a screw driver to tighten them. With a screw driver you can think they’re tight when they’re not. There’s a wide variance in the quality of these clamps so avoid the cheap ones.
With all due respect guys, I would prefer to have a single quality clamp with no perforations than two perforated clamps. Of course I would prefer two quality clamps if there is room. That is ABYC's position.
David
I use AWAB or ABA clamps. They are all 316 S/S and do not have screw slots. They also have rolled egges so they don’t cut into the hoses. Always double clamp unless the hose barb is too short to fit 2 clamps. I have a flexible driver to tighten them, it will bend to get at the clamp screw.
If your surveyor fails to call out missing double clamps then you know you need a different surveyor.
Hose Clamps, Surveyors, and the ABYC
Does the American Boat and Yacht Council require double hose clamps?
By Ed Sherman
I recently received a common question:
I just had a boat surveyed that I am thinking of buying. The surveyor made a big deal out of the fact that the sea cocks on the boat did not have double hose clamps. He cited both USCG regulations and ABYC Standards as requiring double clamps. Is this the straight story?
This is an unfortunate misunderstanding in the industry. The truth is neither the US Coast Guard nor the ABYC require double clamps. In fact, the USCG under title 33, which covers recreational boats, does not even discuss thru-hull fittings, meaning they have absolutely no requirements in this area.
However, boats built in Europe will have double clamps because the ISO Standard that addresses such issues requires them.
As for the ABYC position, I can tell you that its regulation H-27 Standard, Sea Cocks, Thru- Hull Fittings and Drain Plugs, is tried and true. The single clamp requirement has never created any problems in the field—as long as proper, all stainless steel clamps are used. There have been cases where the use of automotive grade stainless band, cadmium plated screw mechanism clamps has caused problems. H-27 is quite specific in requiring clamps made entirely of a stainless steel that is 300 series grade or better.
The thing you need to be concerned with in this case is that the surveyor has made a very basic error, which to my mind opens up the door to questioning his or her overall competency. My advice is to get another surveyor to check out your new boat.
https://www.boats.com/how-to/hose-clamps-surveyors-and-the-abyc/
Putting aside my smart ass comments above, it’s always a very good idea to double clamp hoses. If there’s not enough room to double clamp with half inch hose clamps, use narrower hose clamps and double clamp. don’t go cheap. It’s the most inexpensive insurance one can purchase. More often than not I’ve seen clamps fail. If there’s crevice corrosion, rust ( not stainless), a deteriorating screw, band cracks or any other untold failure mechanism of a clamp, there’s a secondary clamp securing the hose. Remember, while the hose may be tight even when the clamp may have “let go” ,nothing vibrates tight over time.
Here is my collection of old clamps I changed. Tedious work but it gets you to look in areas that aren’t that obvious and to know where all your through hulls and hoses are, their condition and how to get to them.
I use AWAB or ABA clamps. They are all 316 S/S and do not have screw slots. They also have rolled egges so they don’t cut into the hoses. Always double clamp unless the hose barb is too short to fit 2 clamps. I have a flexible driver to tighten them, it will bend to get at the clamp screw.
Here's a hose clamp comparison test.
https://www.practical-sailor.com/systems-propulsion/awab-aba-top-long-term-test
If your surveyor fails to call out missing double clamps then you know you need a different surveyor.
Many raw water hose connections on Escape have double stainless steel hose clamps securing hoses to fittings, but not all of them. Do you guys have double clamps on all raw water connections at or below the waterline?