Thread: Question for PAR

This is a cut away of a PSS water injected stuffing box. Item "9" is the injection barb.

The primary goals of this type of system are, cooling the shaft, lubricating the packing and keeping the contact surfaces of the flange/shaft interface clean.

Where you pick up your water is dependent on a few factors, such as: is the stuffing box pressurized or not and type of cooling system employed on the engine.

A raw water cooled engine (no exchanger, keel cooler, etc.) can use any jacket access (replace plug with a pipe fitting) and this get s a rubber hose down to the stuffing box. On a closed loop cooling system, where you have separate engine and exhaust cooling systems, obviously, you need to get water from the raw water side of the system, maybe a fitting at the front of the manifold, but any where in the raw water system will do, assuming you have sufficient pressure (usually about 5 to 15 PSI). Hose barbed fitting are plumbed into the raw water system and orifice size controls the pressure.

Several companies sell these water injected stuffing boxes or if you have some machining skills you can make one. Look up "water injected stuffing boxes" and a few companies will pop up. Have a look at their PDF's and see if it helps any. This is how I was able to "steal" their engineering (I've probably just admitted to some level of copyright infringment) and make up my own as required.

Thank for the reply PAR,

After googling for stuffing box info I found this website -

Packing Boat Stuffing Boxes


which in part says -

"The older stuffing boxes were simply a compression fitting and sleeve filled with a flax material; they were intended to "leak" a little with the water allowing necessary lubrication. A drip or two a minute is about right. But if want dry bilges, you can make them drip less too. How? By substituting your present flax packing with a new material called GFO Packing, made by Gore-Tex. The new packing has a Teflon impregnation permitting the packing to be constricted to a point where no water will leak from the stuffing box itself. We have used it on the Patricia Ann for two years and have dry bilges."

Have you or anyone else on the forum tried this type of material??

redx

They've used a number of materials for packing over the years, but controlling the leak is only part of the problem. Cooling and contamination are other concerns, which fancy man made packing materials don't really address. High speed craft will twist up a dripless packing material pretty easily, mostly from heat, so it needs to be cooled. You're sucking up raw water anyway, so put it to use cooling and cleaning the stuffing box. On a slow turning engine, you can get by with modern packing materials and no water injection, but if you're spinning the shaft pretty good, you'll water to cool the packing.

Thanks PAR,

I think I'll stick with the old tried and true packing, and probably save some money too.

redx