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Old 04-06-2018, 17:54   #1
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How to clamp a hose below waterline when there is not enough room for two clamps?

I have a pair of Yanmar 3GM30F engines on my catamaran. The water pump (which is this Yanmar 128397-42500 Engine Cooling Pump Bronze ) does not have enough room to accept two hose clamps on the input and outputs. I have tried two, thinking the second one is ridding on top of the ridge of the nipple, but really I think the second one is around only hose. I have been using clamps of high quality like these (https://www.defender.com/product.jsp...artId=14711916) but some nights it keeps me up not having two hose clamps on any connection below the water line. Any ideas?
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Old 04-06-2018, 18:09   #2
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

I believe that the ABYC only mandates dual clamps on exhaust systems???
I am personally not as concerned with a single “good” clamp holding a hose on.
My personal preference is for AWAB 316 stainless clamps tightened with a 1/4” drive ratchet.
You can cause real damage trying to cram too many clamps where they do not belong.
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Old 04-06-2018, 18:13   #3
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

Once again, courtesy of Compass Marine...

https://marinehowto.com/proper-insta...e-hose-clamps/
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Old 04-06-2018, 18:14   #4
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

Consider these hose clamps.....

https://www.defender.com/product.jsp...584&id=3030025
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Old 04-06-2018, 18:15   #5
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

Also consider using the clamptite system
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Old 04-06-2018, 19:49   #6
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

The Clamptite is a great tool, and it belongs on every boat for emergency damage control if nothing else.

BUT>>>>

It is NOT suitable for clamping hoses below the waterline. A hose clamp you can inspect, and tighten. You can loosen it and twist it around to inspect the back side, and put it back.

A clamp made of bent wire is prone to undetected failure. Fine for non-critical things, but if the failure of the clamp leaves a 1 inch hole to the ocean, you DO NOT want to use it.

How often do you replace the formed wire clamp? when it breaks? Too late!
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Old 05-06-2018, 00:25   #7
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

Quote:
Originally Posted by Seymore View Post
I agree with Seymore, T-bolt hose clamps are the way to go for anything below the waterline.
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Old 05-06-2018, 06:21   #8
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

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I thought about the t-clamp hoses but the smallest clamp listed there is too big for the exit hose from the salt water pump which is a special Yanmar hose, Yanmar calls it a 'pipe'.

Trident marine does not make a smaller clamp (http://tridentmarine.com/wp-content/...tion-Sheet.pdf)

The smallest Trident t-clamp is rated at 1.28" min. The 5/8" hose on the input has an OD of 1". Will the t-clamp work? Probably not.

The EXIT hose of the pump is a Yanmar special hose that has an even smaller OD than typical hose. For the aba hose line it uses #8 which is rated at 5/8"-1". The smallest Trident t-clamp hose will definitely be too big.

So I guess I use the aba hose clamps unless I can find a smaller t-clamp hose than Trident makes.

Is that as safe as it gets?
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Old 05-06-2018, 07:30   #9
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How to clamp a hose below waterline when there is not enough room for two clamps?

The T bolt clamps are usually used when there is a lot of thermal expansion, like on exhaust stubs in turbine engines etc.
It seems most clamps fail by the SS band itself breaking, and if this is correct, it may not be much more safe than a solid band regular clamp, sorry forget the name, but one brand does not have slots cut into the the band for the screw.
I have a couple of under the waterline fittings with only one clamp, air conditioner pumps for example, the nipple length won’t support two clamps, but as I have always had to cut those hoses off when I replace them they are so tight even after the clamp is removed, I reside myself to the belief that regular inspection is the best policy, as I don’t see the hose coming off on it’s own even with the clamp failed.
A hose should never be subjected to any pulling force that could pull it off, if it is from being too short, you need to lengthen the hose of course.
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Old 05-06-2018, 07:59   #10
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

Quote:
Originally Posted by a64pilot View Post
as I have always had to cut those hoses off when I replace them they are so tight even after the clamp is removed.
That is my experience with every hose I've ever removed from a fitting on a boat. Seems like within a couple of days of installing the hose it becomes permanently attached to the fitting. Usually they will come off with a little application of the heat gun but older hoses do seem to need a knife. Does seem to make the clamp redundant but I not so much I'll start pulling them off.


Quote:
Originally Posted by a64pilot View Post
sorry forget the name, but one brand does not have slots cut into the the band for the screw.
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.

Anytime I work on a hose I go with a new AWAB clamp. Slowly replacing all the old style.
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Old 05-06-2018, 08:26   #11
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

Every boat I've seen has nipples that wont take 2 clamps somewhere. Just have good hose and good clamp. I've seen many surveys that request 2 clamps be installed in places but the bonehead surveyor doesn't have enough sense to see there is no room.

To me the AWAB clamps are a worse risk than a normal clamp. They slip readily. Just try tightening one too tight sometime! A good PROPERLY SIZED clamp doesn't cut the hose.
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Old 05-06-2018, 08:26   #12
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

Two things at work here - first, double clamping is intended to provide redundancy, not because you need the extra clamped surface area; second, the need for redundancy is because SS clamps are NOT known for their reliability over time in a seawater environment.


So - in this situation where a non-replacable hose barb is too short, I would get the highest-grade clamp I could (AWAB or the like) and make a point of inspecting it regularly (to include removing the clamp{but NOT the hose!}).


In my experience, AWAB clamps won't show corrosion even after years of saltwater exposure - if you see any, replace immediately! For critical applications, I think they are worth the expense of acquiring the necessary metric nutdriver


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Old 05-06-2018, 08:30   #13
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

Quote:
Originally Posted by Seymore View Post

There it is. T-clamps are the way to go.
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Old 05-06-2018, 08:39   #14
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

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Originally Posted by S/V Alchemy View Post
There it is. T-clamps are the way to go.
They dont work well on small hoses. Great on big hoses.
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Old 05-06-2018, 08:58   #15
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Re: How to clamp a hose below waterline when there is not enough room for two clamps?

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