Water Cooled Stuffing Box

[ndutton]

My general feeling on the subject is the same as bullet proof vests. Sure, they're uncomfortable, bulky and hot and for the vast majority of the time serve no useful function but when that once in a lifetime incident occurs you're glad you have it.

Counting on air in the upper section of the hose to prevent a siphon is risky. Water passing downhill through the hose - if of sufficient volume to fill the cross section - can draw enough vacuum to pull water in behind it and the siphon is started. This is not in every case, there are a variety of conditions that must be present but still there's a chance. That's the charm and bane of siphons, the ability of liquids to naturally run uphill in a portion of the system and never stop on their own once they're started.

As you know, that's what anti siphons do - break the vacuum caused by the scenario described above. Are you prepared to crawl behind the engine every time you shut down to close the shaft valve too?

[JOHN COOKSON]

Originally Posted by hanleyclifford

For syphoning to take place there must be continuous liquid in a line which opens up below the water line. I would entertain comments/criticism on this "line" of thinking.

Hanley - I'm not sure I understand your plumbing but I do have this to offer for your consideration:
As a warm engine located below the "pool" of water cools it could possibly create enough of a vacuum to to start a siphon even with a bubble(s) in the line.

TRUE GRIT

[hanleyclifford]

Winter has a way of making us second guess ourselves and so when Neil made the comment about cleaning up the inside of the packing gland shaft after threading in the close nipple for the water injection I realized what a small clearance existed to the shaft and thus how little water I was going to inject into that log. So...scrap all the above. This is the new (water) dispensation as I see it. A few bugs still need to be worked out, like - how worried should I be about the hole that had to be drilled into the deadwood to bring in the (now) 1/4" nipple? Should I fill with epoxy (thus creating a tough repair for the next guy?) or be content with a wood, mechanical collar on the deadwood?

[ndutton]

The tight clearance you observed is all the more reason this cutlass 'irrigation' system is a positive. While considering the flow you'll have when it's done, think about what it has been in the past with only simple immersion.

I see the fact you're thinking about it and analyzing your installation as a great thing.

edit:
Y'know, Buck Algonquin already manufactures a product ready made for this application:
http://catalog.buckalgonquin.com/vie...ing-spud-type?

[hanleyclifford]

Neil - I did look thru the Buck Algonquin catalogue and that unit you referenced is a beauty but they don't get down to my size (1" shaft").

[Ball Racing]

Can you run a stern bearing like this?
That what I have, get tons of water.
http://catalog.buckalgonquin.com/vie...s-oval-flange?

[Scuppers]

FWIW...have you seen this?
http://www.pbase.com/mainecruising/p...ft_seal&page=2
From Maine Sail.

[ndutton]

Hanley,
It makes no difference where the water is injected as long as it's somewhere between the cutlass and the flax packing. Buck Algonquin's version has it actually on the stuffing box assembly which should be well outside the deadwood.

Scuppers,
The hose on the PSS style dripless seal looks identical but serves a different purpose. It does not connect to a pressurized water source and therefore does not aid in cutlass cooling or lubrication; it's a vent to burp a potential air pocket at the seal.

[joe_db]

WARNING:
I used to sell stuffing boxes with water injection. They offer more than one way to flood your engine, depending on how you run the hoses. Don't ask how I know

I currently have a PSS carbon shaft seal and it has been fantastic. I had the seal replaced 2 years ago and it had been in service since about 1988. Mine does not have this, but the new ones have VENT hoses. This is not water injection, this allows trapped air to escape upwards. PSS suggests switching to positive pressure water injection at speeds over 12 knots.

[hanleyclifford]

After studying this I can see that there are indeed several ways to run the cooling line. I believe it does matter where the water is injected. The bronze tube that holds the packing gland is very tight to the shaft and allows for little flow whereas injecting further aft into the schedule 80 PVC tube, which is 1 1/4" ID, allows more flow for a given pressure and affords a preferential flow aft to the cutless.

[67c&ccorv]

Hanley...I think you may need a solenoid activated shut off valve?

Just sayin'!

[hanleyclifford]

Originally Posted by 67c&ccorv

Hanley...I think you may need a solenoid activated shut off valve?

Just sayin'!

I am intrigued by the idea but I'm so OCD the valves would just be a redundancy.

[hanleyclifford]

This illustrates the difference between injecting right at the packing gland versus moving aft into the plastic tube itself. With 1 1/4" ID the tube allows 1/8" clearance all around for the 1" shaft whereas the bronze pipe holding the packing and lock nuts barely allows 1/32".

[ndutton]

Originally Posted by joe_db

WARNING:
I used to sell stuffing boxes with water injection. They offer more than one way to flood your engine, depending on how you run the hoses.

Absolutely agree, mentioned it 10 days ago on the wandering Exhaust Valve thread:
http://www.moyermarineforum.com/foru...2&postcount=65

[hanleyclifford]

Originally Posted by joe_db

WARNING:
I used to sell stuffing boxes with water injection. They offer more than one way to flood your engine, depending on how you run the hoses. Don't ask how I know

I currently have a PSS carbon shaft seal and it has been fantastic. I had the seal replaced 2 years ago and it had been in service since about 1988. Mine does not have this, but the new ones have VENT hoses. This is not water injection, this allows trapped air to escape upwards. PSS suggests switching to positive pressure water injection at speeds over 12 knots.

Point is well taken; the injection is another hole in the boat and will generate it's own protocols which must be strictly followed, very much like the engine raw water thru hull.

[ndutton]

I was thinking, instead of assuming the flow in the current configuration will be insufficient why not hook up a hose and perform a bench test? Well, an outdoor bench test.
Where's the risk? Either your concerns will be confirmed or you'll be pleasantly surprised. Remember, this is intended to only improve the previous cutlass flow (immersion) that has worked fine for decades, not replace it entirely.

[sastanley]

Neil, in the NorthEast, the words, "outdoor" "test" "hose" & "water", don't work so well together this time of year...

[ndutton]

Sorry, I'm a product of my environment. 85° in Los Angeles today, a record. Got in my truck right at dusk for the drive home, 73°.

Test it in the bath tub??

[hanleyclifford]

New shaft log now installed with water injection nipple running thru deadwood over sternpost. Nipple epoxied in tight but with heat shrink tubing around nipple in case removal is required. Fitting above is shut off valve sans handle.

[ndutton]

Recommend an antisiphon between the pictured injection and the pressurized water source.

[hanleyclifford]

Does anyone know the overall length of the anti syphon valve in the MM on-line catalogue?