Saildrive Prop Shaft Repair

[gruffa]

Thanks Jochen.
When I got the shaft out in our haulout, luckily there was only the faintest wear at one point so I've just cleaned it up and put the new seals in.

I'll attach photos here of the seawater side seal and the shaft.
The seawater seal smelt a little burnt and even looked it too!
No wonder we were getting a bit of water in.
I don't know what could have caused the seal to end up like that.
I've also no idea of when, or ever, the seals have been replaced before (three previous owners).

[Brickwede]

Hello Gruffa,
I've never seen anything like it either. Was there something coiled on the driveshaft, fishing line or thin rope?
Did you find the one metal hose spring in the burned sealing ring?
Water is of course a poorer lubricant than oil or grease. Nevertheless, the radial sealing rings are described as "conditionally suitable" for seawater.
According to the technical specification, black or brown radial sealing rings are suitable for the speed of our sail drives (approx. 3600 rpm). Black sealing rings are only available with steel hose springs and they rust. Brown sealing rings (type FKM) always have a V2A hose spring and on special request V4A. V2A is not seawater resistant in the long run, but that's no problem for 5 years. The sealing ring is more likely to leak than the hose spring made of V2A will rust away.
I read on the internet that you can equip the black sealing rings with an O-ring instead of the hose spring. I think that's absolute nonsense. None of us knows the correct contact pressure of a hose spring. I would never replace that with an O-ring. If I could only get black radial seals I would take the black seals to the nearest major civilization and then get the correct radial seals. They don't rust away in weeks but only in a few months.
Or an even better idea. I have spare sealing rings with me. According to the data sheet, they can be stored for at least 8 years, with silicone oil in an airtight bag welded longer. The main thing is that no light and oxygen can get to the sealing rings.
Then, for emergencies, the stainless hose spring was saved from the last repair and then put on a black sealing ring if you only get a black sealing ring. Then everything is ok until the next maintenance.

Is the radial sealing ring black or brown? This is not clearly visible in the photo. Also look for the hose spring or an O-ring.
I could well imagine that the radial sealing ring was equipped with an O-ring that was too tight instead of a hose spring. This overheated the sealing surface and burned the sealing ring.

The previous owner could also have done a dry run on land to check something on the propeller. But then so long that the sealing ring is destroyed? The machine also needs to be cooled. I think unlikely.

Please keep us informed here in the forum.

Regards Jochen

[skipperpete]

Hi Jochen, thanks for sharing your knowledge and experience with Saildrive shaft seals and in particular , Speedi sleeves. I,m interested to see how the tungsten carbide works out, and how you apply it.

[Brickwede]

Hello Skipperpete,
look here:SD40 / SD50 Saildrive Antriebsachse Refit - Hochseekatamaran Gerda Martha

It is written in German but you can activate an automatic translation in your browser.

Best regards
Jochen

[Brickwede]

Hello Gruffa,
Do you have the pictures in a higher resolution?
After cleanung the shaft, how deep and wide is the groove?
Do you have a closer picture of the burned seal and shaft?

Best regards
Jochen