How to clamp a hose below waterline when there is not enough room for two clamps?

[a64pilot]

Originally Posted by skipmac

Are you thinking about the AWAB clamps? The slots are pressed into the band, not cut and they don't penetrate to the inside of the band so a smooth surface against the hose.

Yes, the AWAB, not to keep from cutting into the hose, cause I doubt that would make a proper Marine hose fail.
I think the cut slots are stress risers, built in failure points if you will, regular clamps seem to often break right at one of those slots

[01kiwijohn]

I have the same issue, with my one Yanmar/ Johnson pump.
I use good quality clamp and inspect it frequently, replacing it every time I re-kit the pump. Rest easy.

[jseth]

RickyEM - This is something I’ve thought a lot about, too. I used to double-clamp everything but, like you, stopped doing that on stubby fittings. I have also had good experience with the Scandvik/ABA clamps. I echo a64pilot and 01kiwijohn about inspection and add that I think an effective inspection requires that the screw be backed off a few turns then re-torqued. I found a broken clamp that way that otherwise looked and felt fine because the band was stuck to the hose.

Since we’re down to one clamp we should treat it right. I try to torque the screw properly. The spec is here, if this is your clamp:
https://www.scandvik.com/index.cfm?m...&productID=297

There are purpose-built T-handle tools for torquing hose clamps, but since the hex heads come in 9/32 and 5/16 I just keep a 1/4”-drive click-wrench and use a socket. Most torque values presume a lubricated thread. For clamps I like to use Boeshield T-9 which also offers some long-term corrosion protection. Waterproof grease works, too.

Finally - and I don’t know if this is a good idea or not - some people coat the male fitting with 3M 4200 before installing the hose. I can attest that when applied to a clean, dry fitting, at least in the larger sizes, getting the hose off later is an ordeal. Which might be exactly what you want.

This goes beyond the scope of your question, but keeping the seacock closed when the engine is not in use is an option. That confers the additional benefit of exercising the seacock so it doesn’t freeze up from lack of use.

[jmschmidt]

Let's face it, with engines not running both inlet and outlet hoses, if tight fitting, will probably stay on without clamps. With an engine running the suction alone will keep the inlet hose on. Not a good practice, for sure, but indicative of the redundancy.

[john61ct]

If regularly replaced as part of scheduled checklist maintenance

Using the Clamptite system,

what would be the recommended wire / gauge to use, with better longevity than stainless in salt water?

[Ken Z]

I know of your problem as it is my problem. I use the best ss clamps I can get and check it constantly. I only use a screwdriver and not a wrench . Deforming the strap grooves usually is the first point of weakness and the screw usually gives out as the second. My advice is to moniter for wetness around the junction, maybe take a 1/16 turn if loose and relax. A drip in time doesnt blow my mind.

[stormalong]

Another common mistake using clamps is to overtighten them. There is no need to crush the hose. They only need to be tight enough to hold the hose on the hose barb.



Also realize that the water pressure is minimal. A through hull three feet down from the waterline is only at 1.5 pounds per square inch. Consider that your pressure water system is 20 to 40 psi.



Once a year go around and test the tightness.



As others have said the hose will be so hard to get off that the hose clamp will become redundant.

[Suijin]

I use only Scanvik clamps...they last longer than others and being indented/pressed instead of cutout I’ve never had one fail at the perforations

I inspect all my sub-waterline clamps every few months. Takes half an hour.

[model 10]

Just about every aircraft piston engine has an intake hose for each cylinder. Many are just about the same size as 1.5" sanitation hose. Even on turbo charged engines we used silicone grease and a single clamp.
On my boat the clamp band fails under the screw. I've started using Tefgel on the threads.

[Scout 30]

Originally Posted by Seymore

Consider these hose clamps.....

https://www.defender.com/product.jsp...584&id=3030025

I think these are best used when it's possible to install 2 clamps because 1 clamp does not give 360 degree coverage. If only 1 hose clamp can be installed I would follow the advice of Compass Marine.

https://www.jamestowndistributors.co...SAAEgKNQPD_BwE

[Kiwi.]

Stormalong is correct, when the motor is not running. We're talking about 1 to 2 psi here when the motor is not running, when it is running we're probably talking 0 psi or, with a big motor, negative pressure; so nothing to do with clamping pressure, water pressure etc. We're only talking about total pipe failure or accidental pull off.
I prefer to put a good dose of Vaseline on the fitting and use an ordinary stainless (inexpensive) single clamp with a very good quality cable tie (maybe 50 cents) before the clamp. In my experience the cable tie has always been in perfect condition (no sun or UV) even when the clamp has been rusted and had to be cut off. Cheap solutions replaced every year are the best. Double clamping with identical clamps is firstly silly (1psi versus 40psi in your car's cooling system and when did that last burst!), and secondly all about leaving something without inspection for years. (Don't do that.) With a bit of Vaseline, cable tie and cheap clamp, I get no leaks and the ability to easily pull the pipe off every haul-out and have a look at the inside of the pipe which is the only thing that matters because: Failures at motor intakes (apart from blockages) are mainly due to the electrolytic corroding of the wire reinforcing inside the pipe which then allows the pipe to collapse (because we are talking about vacuums here not pressures) which then closes the pipe off and overheats the engine. This problem is quite obvious if somebody looks inside the pipe regularly (hence the Vaseline.)

[GordMay]

Originally Posted by sva3

Also see "Constant Torque" clamps. Not the same as a T-Bolt clamp.

These clamps are particularly useful where you have temperature variations (expand/contract).
To deal with hose "cold flow", re-tighten clamp a couple of days after installing.

[RickyEM]

Thanks for this discussion. I noticed several of you recommended using nut drivers when tightening a clamp. As opposed, I assume, to a screw driver. Why is this? Is it to torque the clamps? Another reason? Just wondering not disagreeing...

[Hartleyg]

Ricky,


A nutdriver (or socket wrench) will:
a. Not slip off at an inopportune moment (and these hose clamps are ALWAYS in a nasty spot )
b. Won't potentially break the tightening screw or chinger up the end.
c. Are much easier to align for best (most even) tightening performance


Hartley
S/V Atsa

[jamhass]

A nut driver is easier to use and keep on the screw, especially in tight, constricted, and/or blind places.

My plumber has the coolest nut driver he uses on hose clamps. It is a torque-limiting driver. Works just like a torque wrench, avoiding over-torquing the clamp. No larger than a regular nut driver.