So why do they put double jubilee clamps on thruhulls? because they are in a corrosion prone area and their failure is rather disturbing.. nothing like a 2″ hole in the bottom of your boat to get your heart racing early in the morning.
For the same reason check these often and at the first sign of corrosion, change them, for good quality Stainless steel ones.
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It’s more important to make sure hose clamps are entirely stainless 316, including the worm gear and its casing. If you’re not 100% sure of this, you should change them now. Don’t wait for visible signs of corrosion.
Embossed straps are better than perforated—less damage to hoses.
It’s not always a good idea to use two clamps. You might be surprised to hear that ABYC standards in the US require double clamps only in two places: wet exhaust hose and fuel deck fills. In other places they are not required and not necessary. Some fittings are of a size and shape that do not readily accommodate double clamps. Adding a second clamp where it doesn’t fit properly can deform the hose or pull the hose away from the fitting. One is usually enough, and two can be worse than one.
Hey Rob,
Good to hear from you and with good advice. You are so right on both counts. We have found not only do you need to ensure they are full stain steel but proper 316L. I didn’t realise until living on a boat that Stainless is not stainless its a range of products and boat life is definitely hard on them.
Also the comment about where to double up, trying to overlap a clamp at the end of a spigot is asking for a failure point and we definitely have some connections that are too short. Not on thruhulls fortunately, but further into the boat, still below the waterline.
Hope you are enjoying my stumbles through the learning process…. people like you with the knowledge have made our travels so much easier.