Deep Sea Seal

(These Notes from the Ops Notes 2012)

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Plastimo Website:

 

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Replacing the Plastimo

Shaft Seal:

 

1. Remove prop shaft and prop anodes

2. Clean prop shaft on its full exposed length.

3. Straighten the prop tab washer and remove prop nut

4. Remove retaining grub screw from rope cutter.

5. Withdraw prop and rope cutter together using hub extractor. (Noting which way around the rope cutter is fitted.)

6. Remove the 4 flange bolts attaching the inner end of the prop shaft to the gear box.

7. Release the 3 grub screws from around the perimeter of the steel ring on the seal.

8. Entirely remove the prop shaft into cabin.   This can be done easily if the prop is lubricated with washing up liquid. Hold the stainless ring during this removal process.

9. Probably by now you will have noticed that the stern tube is not aligned with the shaft, the misalignment is about 4mm in 35mm of length.  Lucky we have a bellows to compensate.

10. Loosen the 2 jubilee clips attaching the bellows to the stern tube and carefully remove the rest of the seal.

11. If on examination the graphite ring shows little wear, uneven or otherwise, carefully clean.

12. If on examination the bellows appear to be in good condition, carefully clean before inserting the graphite ring.

13. Always replace the o-rings on the steel ring. The rings are 30mm I/d 3mm section.

14. Replace the reassembled graphite ring and bellows onto the stern tube.

15. Feed shaft back through the gearbox and replace the stainless ring taking care not to damage the graphite disc.

16. Feed the shaft through to steel ring, this will need the washing up liquid again.

17. Tighten the flange bolts attaching prop shaft to gearbox.

18. Align the steel ring with the grub screw indents on the shaft. This can just about be done by sight. Replace the 3 grub screws using thread tight.

19. Line up the grub screw hole in the rope cutter with the indent on the shaft, and introduce the rope cutter to the shaft. Omit the keyway and follow the cutter with the prop.

20. Attach the prop nut and compress on the cutter with the prop but maintain a 5mm gap with drill bits between the cutter and the rear boss of the prop. Fit the rope cutter grub screw.

21. Remove the prop with the hub extractor, replace the keyway, refit the prop, tab washer and nut and fully tighten the nut. Bend over the tab washer.

22. Refit anode

23. When in the water and before starting the engine burp the seal by compressing the seal bellows. A little water will emerge.

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Sizes:  Graphite ring 70mm O/D x 33mm I/D x 32m long      

‘O’ rings: 30mm I/D x 3mm.

Stainless ring: 70mm I/d x 30mm O/D x 20mm with 3 x M5 countersunk screws.

Total length: 130mm leaving approx 42mm clearance to gearbox.        

Stern Tube Spigot: 60mm x 30mm long.

Propellor Vetus Three Blade: LH 11” x 17” pitch.

Nut, Key, Tab & Anode Set – Vetus code SN30set 30mm shaft.     

Aft anode and tab renewed Apr 2011.

Cuttlass bearing. Vetus RL3045 30mm shaft. S=45mm L=120mm. Bronze. Renewed 2007.

 

Cathodic Protection:

Negatively wired system to all metal skin fittings, propeller shaft and anodes.

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