Prop Shaft seal

[Skipper599]

On the subject of Prop Shafts as many of us can attest to, the Stuffing Box is often in a very awkward and sometimes almost impossible spot to perform maintenance adjustments.

That being said, I'm wondering what everyone's collective thoughts and comments are with regard to Dripless Shaft Seals?

There are as we know, a variety of these devices on the market. Just wondering if any of you have had first hand experience with them, pos/neg experiences.

Which one might you recommend as being the "best one" to buy? and, can any of them be truly called "trouble free"? (one can only hope).

[Duncan]

I have a PSS Dripless Shaft Seal, installed by the previous owner, and I haven't checked it in three years.

I think that can be the problem, versus a normal stuffing box that forces you to adjust it and keep an eye on it as part of the regular routine.

Having just read the instructions for my PSS for the first time, I will from now on:
1) move the carbon seal back once every three months and let a little water in the boat.
2) inspect the vent hose and the part of the bellows that I can see (the top and sides) on an annual basis
3) replace the bellows every six years

So, I haven't had any problems and I haven't heard of others having problems, but nothing below the waterline should be neglected. I guess the issue with these is that one needs to have the discipline to check on them regularly, even though they don't cry out for attention the way a dripping stuffing box does.

[Tim]

I think anything that encourages neglect is probably ultimately a less good idea.

If your access to the stuffing box is inadequate, perhaps look at ways of improving it, whatever choice of packing gland you make.

I prefer old-fashioned stuffing boxes to the dripless type myself. New graphite-impregnated packing materials mean that the "drip" portion is minimized to the point of being a non-issue (it's really a non-issue with any properly maintained traditional stuffing box), and I like the idea that I can repack the thing with materials easily found on board if the emergency need should arise. That's only my own thought and preference on the issue, of course.

[Maine Sail]

I have had dripless or PSS seals on many boats as well as traditional stuffing boxes. I worked on a 55 foot sport fisher that had over 5k hours on two PSS seals with zero issues. My buddy Jerry owns a 100+ foot "yacht" (how the other half lives) and it has two huge 16 cyl Cats and two PSS shaft seals. Boat has perhaps 70k nm on her and not a single issue. The one on our own boat went for 2782 hours before I replaced the bellows. I shipped the bellows to PSS and they tested it within like new specs at 6 years old and 2782 hours. Lots of reputable builders such as Sabre, Valiant, Hinckley, Little Harbor, Pacific Seacraft, Swan and the USCG use them too.

Both types work and as Tim said with new packings, such as Johnson Duramax Ultra X, Gore GFO or Western Pacific Trading GTU the traditional boxes can be made to drip very, very minimally. I am replacing a cracked stuffing box hose this week so both system require periodic maintenance of the hose but traditional hoses do and can last longer between replacements. This boat is a 1987, just 23 years old, and the hose is in quite poor shape.

Our boat has a v-drive and is near impossible to re-pack, see or get to. Any sling from a traditional box winds up slinging up under the engine where it causes rust and eats things such as oil pans, so the PSS, for me, is what I prefer on this particular boat. I literally put my finger through the oil pan on one boat that had a v-drive and traditional box, due to rust. Ever since that point I vowed to never use one on a v-drive where the box was under the engine again. If I had a standard drive, and good access, a traditional box would be fine with one of the newer packings. The PSS is bone dry but the new packings still need some water for lubrication.

Properly maintained both systems are very reliable.