Proper Installation Of Double Hose Clamps

001MaleAdapterTooShort

Male Adapter Too Short

Quite often when working on boats I notice or see odd fitting hoses. It doesn’t take much to figure out why once you start paying attention. Many, if not most generic non-marine male hose adapters are not built, designed or ever intended for marine applications where the use of two hose clamps, for below waterline applications, is preferred for safety.

When the male adapter is too short, tightening down a second hose clamp can actually distort the hose, create a potential for it to rip or tear and it can actually work against the hose adapter by trying to “pinch” the hose off the end.

If the first clamp were to fail, as they can and do, the second clamp could potentially have enough pressure on it to aid the hose in coming off the hose adapter.

This nylon hose adapter is far to short to accept two hose clamps. Always measure the exposed barb surface before installing two hose clamps.

Correct Length Male Adapters

These are marine bronze male adapters, one made by Apollo/Conbraco and one made by Groco. Note the length of the hose adapter portion. There is plenty of space to fit two hose clamps and this is exactly what you will want.

It should go without saying that hose adapters, for below waterline use, need to be marine bronze, Marelon or otherwise UL or ABYC complaint. Materials used need to also be galvanically compatible (A UL requirement for below water fittings). They should not be made from yellow brass or PVC. While home center yellow brass may be fine for the domestic plumbing aboard, or even some fuel fittings, it is not suitable for use below the waterline.

Always make sure your hose adapters will fit two hose clamps..

002CorrectLengthMaleAdapters

003Measure

Measure

When it doubt measure what you have..

Compare

Now compare your measurement with the actual male adapters length. This one is fine but is cutting it very close. It’s really bordering on too short despite being made of marine bronze. This bronze male adapter was made by Perko and Perko pretty much dropped the ball on this one.

004Compare

005IncorrectlyClamped

Incorrectly Clamped

Double hose clamps won’t do any good, and can actually be detrimental, if they are not clamping anything but air.

Please be sure your hose clamps are clamping what they are intended to clamp.

Low Quality Perforated Clamps

The other half of this equation is to always use good quality 100% Stainless steel hose clamps. Here at Compass Marine we use only AWAB or ABA brand non-perforated hose clamps.

These days there are far too many substandard perforated hose clamps on the market just waiting to sink your boat. Even clamps marked as “all stainless” are often not “all stainless” or the stainless or no-name imported mystery metal is anything but all stainless. With off shore sourcing & heavy price competition it has become hard to know what constitutes a good quality perforated clamp vs. the plethora of junk that may compromise the above water stature of your boat.

This is one of those suspect clamps I referenced above. It was marked, as you probably guessed, “all stainless“.  I suspect it might be “stainless” if you stored it in the Tupperware container, with a bag of Damp Rid, and stuck in the the Mojave dessert with 12% relative humidity. On a boat, in the actual ocean, it certainly was not “stainless” at all.

We used to keep a bucket of failed perforated hose clamps to show customers, this was just one of them. The issue of low quality hose clamps has become so bad that we will no longer install perforated hose clamps for below water applications. Do yourself a favor and request AWAB or ABA branded non-perforated hose clamps for your below waterline applications.

006LowQualityPerforatedClamps

007AWABNonPerfVSPerfClamp

AWAB Non-Perforated vs. Perforated Clamp

Our clamps of choice these days are made by ABA or AWAB of 100% 316 SS. The clamp pictured on top is an AWAB brand clamp. The quality is excellent & we have never once been able to strip one or seen one fail. We can’t say the same for perforated hose clamps. For below waterline hoses, 1/2″ ID and larger, they are an excellent choice.

There are also plenty of knock offs to the ABA or AWAB clamps but they are not all created the same. The ABA or AWAB quality is consistent and has proven to us, time and again, the value in in using them.

Typical Perforated Clamp Failure Mode

This is just one of many perforated clamp failures we’ve come across, and one reason I no longer trust my own vessel, or customers vessels, to them. This clamp was a single clamp, not one of two as it really should have been. It was installed on a galley sink drain. The hose was weeping because the single clamp had “slipped” and let go. If that hose had fallen off the male adapter, the boat would have sunk. One of our guys caught this just in-time.

To recap, please make sure the hose adapter is long enough, use two clamps for below waterline applications and consider using a higher quality non-perforated clamp such as those made by ABA or AWAB.

008TypicalPerforatedClampFailureMode

009PerforatedClampFails

Perforated Hose Clamps = FAIL!

Just in case you needed more reason to STOP USING perforated hose clamps here are some complete failures we’ve found on-board some of the boats we work on.

All of these perforated clamp failures were from BELOW WATER fittings and three of them were the ONLY CLAMP……! Ouch! Yes, leaks were happening.

Good luck & happy boating!

Let’s Keep This Site Running!

Like what you saw or read? Would you like to see more articles like this? Is so feel free to donate, support the site and keep it growing. I am trying my hardest to keep this information FREE. If you liked it, learned from it or I saved you some money feel free to make a small donation, that’s all I ask.

Click the DONATE button below if you would like to make a donation.

Donate To Marine How To!