A Good Idea or Not?

Ralph Johnstone · Jan 2, 2014

We'll Give You All the Conflict You Want .................

Soaring eagle said:
I've talked to a few boat yards and have some conflicting reports.

.................. when it comes to shaft sealing.

And BTW, welcome to the site and a Happy New Year ! to you and yours

.

If you go to the search menu above and look for such topics as seals, mechanical seals, packing, packing gland, stuffing, stuffing box etc. you'll find a veritable library on the subject.

Now IMHO the best choice, with your starting new in that area, would be a packing gland for the following reasons:

They are cheaper.
I believe the PPS drip less seal manufacturer requires that the rubber bellows be replaced every 8 years. May be subject to correction by others.
Maintaining the mechanical seal requires the shaft be pulled. A gland only requires periodic packing which can easily be done in the water.
With a brand new shaft and proper care, the packing gland (with proper packing) can be run dry, without leaking. I've done it for over 1,800 hrs. in 14 years. Other do the same.
Proper packing can be run for several years without changing. I usually replace every three years and it just doesn't need it. I last did mine in Dec. 2011 and I'm looking to make it last five years until renewing.
If (rarely, but it can happen) the mechanical seal fails, it's catastrophic. A packing gland will only leak.

You be the judge.

Meriachee · Jan 2, 2014

We had a fair amount of corrosion on our original shaft, so we replaced the shaft, coupler, cutlass bearing and installed a PSS at the same time. I'd never go back. The seal on the PSS threw a little graphite when it first settled in, and thereafter has been clean and dry, and never required adjustment of any kind.

I would highly recommend it.

Cheers
Gary

hvbaker · Jan 2, 2014

I would go with the dripless seal as I did and just love it.

TLW · Jan 2, 2014

I agree with Meriachee to the letter.

Regarding Ralph's assessment: (a rare occasion when I disagree with Ralph)

If one is pulling the shaft anyway, as in the case above, there is very little cost difference.

replacing the boot on a packing gland also requires pulling the shaft, or at least removing the coupling-not a fun job in place. Might as well do it all at once, as Soaring Eagle plans, eliminate drips, and be done with it.

a traditional packing gland with no drip is probably scoring the shaft.

One should be aware of the differences in using the P.S.S. seal in a powerboat application and a sailboat application.

BTW: excellent price on PSS Seal at Defender

I also did the whole job last Summer: replaced bronze shaft with Stainless steel, new coupling, new PSS seal, new cutlass bearing - cheaper in long run to do it all at once.

Meriachee · Jan 2, 2014

And one more item; being the paranoid type (something about a potential hole below the waterline) we got the shaft clamp. The little set screws are a little small, the clamp is an inch thick, with nice thick bolts. Changing the whole works at once with a "faced" shaft from CD was probably a little more money, but the closest boatyard beyond my garage is 800 miles, so knowing the parts would fit right the first time was worth it. The whole job can be done in a day, except that CD requires an exact shaft length measurement, and that's hard to do without removing it. The factory brass shaft slices really easily with a 4" cutoff wheel and if you remove the old one that way, you don't have to deal with the coupler being "welded" to the shaft. If you cut it off that way, be sure to add the thickness of the cut to the shaft length.

jimmcgee · Jan 3, 2014

There's another benefit to the PSS seal - less boat smell.

If you're in salt water the bilge can start to smell funky when the boat is closed up for a while. This can be an issue with your significant other, especially when clothes and bedding stored on board start to smell like old boat. A dry bilge makes a big difference with boat smell.

If you're going with a new shaft consider a split coupling. It will make removing the shaft for service much easier. The retaining ring is a safety item. Check with Defender. When I looked up PSS on their site the photo of the PSS seal now shows the retaining ring so it may be included.

I've had ours in for a couple of years and I would never go back. The only concerns I've ever heard about them are from people who don't have one.

Meriachee · Jan 3, 2014

I guess you learn something everyday! I would have put a split coupler on, had I known they existed. That removes all the concern overt he eventual bellows change in a few years......

Meriachee · Jan 4, 2014

All cattle excrement. There is nothing that supports any part of the shaft between the coupler and the cutlass bearing. Seals it, yes, supports it, not at all.

hvbaker · Jan 4, 2014

Meriachee said:
All cattle excrement. There is nothing that supports any part of the shaft between the coupler and the cutlass bearing. Seals it, yes, supports it, not at all.

I was concerned that chafing could be a problem, but as Mariachee says it is not an issue at all.

dziedzicmj · Jan 6, 2014

Just to add my $0.02, I did the wholesale change last spring, as well. And I am quite happy I did.

A few things to keep in mind:
- Catalina Direct sells a great combo (shaft and coupling). Spend the extra $40 for the matching job.
- triple check the size of your coupling; I had a problem that they sent the wrong size.
- if you are on the hard for winter, start the ordering process early. CD delays cost me at least four weeks of the season.
- PSS does not come with the extra retention ring (at least did not last year). But order it together to save the shipping costs. A good place in Canada for PSS product is Marine Outfitters in Hamilton, but you may find them at better prices close to your home.
- make sure that you have the right compression on the bellows; when mine was installed (by a local contractor), the compression was off (not enough). If the compression is not right the seal would leak.
- Check carefully, where you water level is. When you look from inside (engine bay) it is surprisingly high. You may want to start with a long transparent tube for the breathing tube (it would show the water level). General consensus is that that a plastic tube is not a good choice for under water line applications.
- some report (compare Maine Sail) that almost regardless how high your breathing tube ends it would burp some water on occasion; usually due to some dynamic pressure caused by the reverse thrust. Some interesting contraptions have been installed to prevent this.
- I changed the cutlass bearing at the same time. I strongly recommend doing it.