Most boaters give little thought to the simple, and little understood hose clamp. Our boats are filled with these simple devices that we hardly notice until one reaches out and attacks us as we are working on other things, or worse it fails and causes a leak. The often over looked hose clamp, in many cases is the only thing keeping our boats afloat.
As a marine surveyor I have always been surprised at just how many bad and broken hose clamps I find while doing inspections. Sometimes it is understandable given some difficult and hard to reach locations of some hoses and clamps. However, many of the bad clamps I see are often easy to spot and fairly easy to replace. Clearly most owners do not spend much time thinking about these small but critical bits of equipment.
Hose clamps can come in many types and sizes, understanding the different types, helps to know if the right clamp is used in the right application. Most boaters are familiar with the basic screw, or worm gear type clamp, but this is not the only type that may be found aboard. T-bolt clamps and spring clamps, are also found aboard our boats.
By far the most common clamp found abaord boats is the worm gear type. These are general purpose clamps that come in a wide range of sizes from one half inch to more than 12 inches. The two main styles found are the slotted, or perforated strap which are the most common. These have the familiar slotted straps forming threads for the adjusting screw. Similar are the non-perforated strap type which, although not as common, is the superior type. These still have the worm screw for adjusting but the strap is solid with raised threads for the adjusting screw.
The problem with the perforated strap is it leaves little metal at the ends of the slots. This is where most of these clamps fail. The strap will break at the end of the slot causing the strap to loosen or even fall off. The non perforated style does not have this built in weakness and rarely fails from the strap breaking. Another problem with the perforated strap is that it can cut into the hose cover when tightening, this can damage and weaken the hose.
While we are talking about worm gear clamps there are a couple of other styles worth mentioning. Constant tensioning clamps can be found in some heavy-duty applications. These basically have a heavy spring under the screw head. This spring keeps the clamp tensioned under spring pressure once the clamp has been initially tightened. Constant tensioning clamps are normally found in larger diameters of over one and a half inches. They are particularly useful in environments with significant temperature fluctuations, high pressure, or vibrations. You may also run into the quick release style of clamp. These have a hinge or pivot on the screw. This allows the screw to be lifted off the threads of the strap, quickly releasing the clamp. These are useful on hoses or parts that need routine maintenance such as an engine air filter.
Somewhat similar to the worm screw clamps are the T-bolt and banjo bolt clamps. These have a solid strap with a T-bolt rather than a screw to adjust the tightness. This allows the clamp to be tightened with more pressure on the hose. These are most often used with heavy reinforced hose that might otherwise be hard to get tight enough with a worm screw clamp. Exhaust hoses are the most common use of T-bolt clamps aboard a boat. Banjo bolt clamps are very similar to t-bolt however the bolt is bent to follow the curve of the hose, this allows them to be used on smaller diameter hoses. Careful size selection is important as there is not as much travel, or adjustment range as is often found in screw clamps.
Spring clamps are another type of clamp found aboard our boats. Spring clamps are made of a spring metal that squeezes closed on the hose holding even pressure. These are most often found on engine and outboard hoses. They normally have tabs that can be squeezed with pliers to open the clamps. Normally found on smaller diameter and low-pressure hoses, these have to be sized correctly to work well. Many engine manufactures use these as they are inexpensive and quick to install. I normally replace these with screw clamps when needed as finding the correct size replacement can be difficult.
Regardless of the type of clamp proper sizing is important to how well the clamp will work. A large clamp on a small fitting may actually cause a fitting to leak by squeezing the hose unevenly. The clamp needs to provide even pressure around the full circumference of the hose. Once fitted and correctly adjusted there should only be a short part of the strap left exposed. A long section of the strap hanging out unused not only looks bad but can be a hazard to anyone working near the clamp.
No matter the type of clamp, all stainless-steel construction is the material of choice, this includes any threaded part of the clamp such as screws and bolts. Many so-called stainless-steel clamps use carbon or plated steel for the screw. In the marine environment this will result in the screw rusting making the clamp hard or impossible to adjust or remove and can often result in the clamp failing. 316 stainless is better than 304 but harder to find in hose clamps.
With a better understanding of the types of hose clamps commonly found aboard most boats it is time to think about the hose clamps aboard your own boat. As mentioned, it would appear most boat owners pay little attention to their hose clamps. This can be a mistake that at best can cause a inconvenience and at worst potentially sink a boat.
Most boaters will check hose clamps on the engine when doing annual service, but rarely go much further than the engine compartment. It doesn’t take that much more time to expand the inspections to include all of the engine hoses as they run outside of the engine compartment. Checking both ends of a hose will also help verify the hose its self is still in good condition along with the clamps.
Haul out time would be a good time to inspect thru hulls along with the hoses and clamps attached to them. Hoses and their clamps attached to thru hulls are not only critical to keeping the boat afloat but are in a harsh environment being in the bilge and exposed to seawater. A perfect environment for corrosion so these clamps require careful inspection. Pleasure boats are not required to have double clamps on below the waterline hoses. Although not specifically required it is still a good idea and can add some piece of mind. Technically the only hoses requiring double clamps on pleasure boats are exhaust hoses and fuel fill hoses, this is a USCG regulation.
Without doubt the one area I most often find bad hoses and clamps are on drain hoses. Deck drains, locker drains, propane locker drains, and any other type of overboard drain. I think these are the most neglected because they rarely need any attention, as long as they work nobody pays them much notice. Add to that the fact that builders seem to go out of their way to make many of these fittings hard to access, with the result being they get very little if any attention. The good part is once serviced these fittings can go longer without follow up servicing. Every five years or so would be a good service interval for this type of use.
Of course there are many other locations for hose clamps. Water systems and waste systems should also be given a quick visual inspection at regular intervals. As with engine maintenance I try to check clamps when servicing any pumps in the system. Don’t forget to check the hoses and clamps on the bilge pump systems as well as this is another critical use. Bilge pumps are in a very harsh environment where they are exposed to wet and dry cycles on a regular basis. This creates a very corrosive environment. The last thing anyone wants is a hose to fall off a bilge pump when the pump is needed most.
Anywhere a bad or suspect clamp is found it should replaced. I always recommend any perforated clamps be replaced with non-perforated style clamps. Although these are more expensive it will be worth it in the long run as they will not need replacing as often. Try to get a clamp that fits as closely as possible. When installing the new clamp, you want to make sure the bitter end of the strap is pointed in a direction that will not snag anyone working near it. I call it the bitter end as anyone who has gotten caught on one is pretty bitter!
How tight a clamp should depend on what is being clamped. A large hard reinforced exhaust hose will need to be tighter than a soft vinyl drain hose. This can be as much visual as by feel. You do not want to over tighten and crush the hose or the fitting the hose is on. You can be a little tighter on a metal fitting than on a plastic or fiberglass fitting. Keep in mind over tightening can actually cause a hose to leak by pushing it out of round.
Of course, before an old clamp can be replaced it has to be removed, this is not always as easy as one would hope. Rusted or corroded screws can be impossible to turn, or even break when trying to turn. Trying to force the screw or twist the clamp can damage the hose and fitting. I have found the easiest way to remove a stuck clamp is to cut the strap with a dermal tool and small cut off wheel. For perforated clamps the strap can be easily cut at the ends of a slot. Other types may need the whole strap cut. Care needs to be used not to cut or damage the hose when doing this. Try to look for a weak point in the clamp and cut there. In some cases, cutting the screw housing off to release the clamp can avoid damaging the hose. Take your time and be careful not to get the clamp too hot while cutting.
When installing clamps particularly on new hoses it is often a good idea to go back later and recheck the tightness. Hoses will compress over a period of time causing the clamp to become loose. I will often check clamp tightness anytime I am working in a area near the clamps. I am often surprised at how loose some have become. Even when the clamp looks to be in good shape it would not hurt to check the adjustment, you may be surprised at how many loose clamps you encounter. This is also a good way to verify the adjusting screw is still in good condition.
It is a good habit to get into to check hose clamps when doing any work on your boats systems. It is often not hard to just do a quick visual inspection, following the hose to check the clamps along the path. I keep a box of mixed clamps aboard not only for emergency use but also for replacing bad clamps when I come across them. Try to make the time to inspect hoses and clamps in areas no often checked such as locker drain hoses. It usually does not take much time to check and replace bad hose clamps and doing so will give you peace of mind in the long run.
By Capt. Wayne Canning
