Spot the... shaft seal!

[Deleted User YDKXO]

Doh! Now I understand... and I can see why the shaft spinning could have trashed the whole rubber housing! :ambivalence:

Exactly. At the time that the seal failed we were offshore and rolling around and I was standing ankle deep in water in the engine bay and panicking. I tightened the emergency clip which stemmed the flow of water a little but didn't stop it altogether so I was still panicking and wanting to get back to a marina with a hoist asap. At the time I didnt realise how the emergency clip worked so my only thought was to get back to our home marina so in fact I gunned it back to the marina 10 miles away at nearly 30kts. How the rubber housing didnt fail I have no idea

Otoh, this DSS thing was fitted on this boat like you see it above, back in 2010 (allegedly, with zero maintenance since then), and both shafts were both bone dry...

My DSS seals were dry for 3yrs I owned the boat until the incident and assuming that the hose clamps hold both rubber housings in place, the system will work fine for years I'm sure. It is simply the fact that the most likely mode of failure is potentially catastrophic that is the problem with them

 

[MapisM]

It is simply the fact that the most likely mode of failure is potentially catastrophic that is the problem with them

Completely agreed.
But as I understand, the most likely failure is a slip of the rotating rubber housing.
In this respect, the additional clamp above is enormously safer than the two clamps on the rubber housing, because no matter how tight the latter can be, they still rely on friction between rubber and steel.
The metallic clamp otoh is something that you would struggle to move even with a hammer, I reckon!

 

[MapisM]

I have also the feared DSSs on my Ferretti. Luckily no issues so far but I'm planning to replace these this winter.

If they still work fine, and you don't need to remove the shafts for other reasons, I would consider fitting some additional metallic clamps as in my pic above - which should be easy peasy, btw.
In my understanding so far of the Achilles' heel of these things, that should make a huge difference.

 

[baylabayla3288]

If they still work fine, and you don't need to remove the shafts for other reasons, I would consider fitting some additional metallic clamps as in my pic above - which should be easy peasy, btw.
In my understanding so far of the Achilles' heel of these things, that should make a huge difference.

Yes that is a good alternative MapisM, But when seing the picture from rich earlier in this thread about the failed rubber I'm leaning towards replacement. After all mine are original meaning 15 years old by now. However they do not leak, they have the elasticy still and thanks to the firmly bolted remote Vdrives there is no axial shaft movement they have to deal with.

I would think that the shafts does not have to be removed, just released and moved a bit.

 

[RobWales]

"After all mine are original meaning 15 years old by now."

An interesting comment that and please excuse the drift from the original thread but I was wondering......
If said seals are filled with water either fresh or sea do they not have a shelf life as per the seals found in common outdrives?
Any outdrive owner is advised to change the seal (ok bellows) on their outdrives at least once every two years!

 

[wizzer]

"After all mine are original meaning 15 years old by now."

An interesting comment that and please excuse the drift from the original thread but I was wondering......
If said seals are filled with water either fresh or sea do they not have a shelf life as per the seals found in common outdrives?
Any outdrive owner is advised to change the seal (ok bellows) on their outdrives at least once every two years!

I will be fitting the new Deep Sea Seals to my Seaward 25 when she is relaunched after her refit. I will be fitting a split shaft collar as described above. I removed the original DSSs from my boat which had been on there since 2005. The boat had hardly been used in that time, but the shaft seals still have their elasticity and look very serviceable, however, it's a matter of preventive maintenance to replace them every few years as recommended by the manufacturer.

 

[wizzer]

If you have some measurements I could turn you one up

The shafts on my boat are 35mm diameter, two of them. I would have preferred a split shaft collar as this would be removable without drawing the shafts. As I have a lathe, I can (and probably will) make a one piece collar from nylon or phenolic which I could tap to take a grub screw. Would you be proposing making a split collar?
Cheers for the offer by the way, appreciated

 

[baylabayla3288]

"After all mine are original meaning 15 years old by now."

An interesting comment that and please excuse the drift from the original thread but I was wondering......
If said seals are filled with water either fresh or sea do they not have a shelf life as per the seals found in common outdrives?
Any outdrive owner is advised to change the seal (ok bellows) on their outdrives at least once every two years!

The DSS manufacturer is recommending to change the rubbes every five years however this is probably needed to cover operating in the worst case environment. They also state that the same seals have been used in commencial craft for more than 10 000 hours before replacing. It seems that aging of the rubber is comming before these wear out. Despite the age of 15 years my Ferretti was standing on the hard for several years before I bought it and it has only 390 hours on the clocks tody.

I have another boat as well that I use for fishing and commuting, a Trophy 2052 from year 2000. It has a Mercruiser with an Alpha one sterndrive and I must admit that I have changed the bellows only once, when it was 10 years old. Even then there was no visible damage on them. I know that Volvo is specifying every second year and it could be that MC is also doing It as well by now. I heard that due to environmental resons the rubber compound used today is different and therefore more frequent replacement is needed. The same goes for impellers.

 

[Bandit]

So DSS say replace every 5 years. (I would remove inspect and replace the seal every 5 to 7 years anyway, its the only thing keeping your boat afloat).

There are several posters here who have had close calls with DSS.

The DSS seal has been overtaken by other superior seals since DSS were brought to market some 30 yeas ago.

You don't see major U.K. Boat builders using DSS any more.

Fit a modern quality seal not DSS.

 

[PetiteFleur]

Here is a possible supplier of split shaft collars - http://www.keysandpins.com/products/shaft-collars

 

[baylabayla3288]

Here is a possible supplier of split shaft collars - http://www.keysandpins.com/products/shaft-collars

Thank you for the link. This is removing one major design problem with the DSS.

The picture above from rich earlier with the ruptured rubber part, could this have been due to the rotating and the fixed parts sticking together? Apparently they can be "glued" together by corrosion after a longer storage.