How do I replace the cutless bearing on a Dehler 34?
My Dehler 34 has noticeable sideways movement at the propeller shaft bearing, and I'm planning to replace it at the next lift-out. Can I order the bearing beforehand, and will the shaft need to come out?
Answer
Replace the cutless bearing with the boat ashore, after checking its dimensions, removing the retaining screws and confirming its extraction route. On a Dehler 34, check the year and actual shaft installation first: the model name alone does not establish the bearing size or whether the shaft must come out.
Check the shaft installation
Establish whether the boat has a conventional propeller shaft running through a stern tube or external bracket. A saildrive has a different arrangement, so this cutless-bearing procedure does not apply.
With the shaft stationary, lift it gently beside the bearing while watching the rubber and outer sleeve. Movement between shaft and rubber suggests bearing wear. Movement of the complete sleeve or bracket needs investigation before fitting another bearing. Inspect for missing rubber, trapped fishing line and uneven wear.
Order by three measured dimensions:
- Inside diameter: the shaft diameter, measured on an unworn section.
- Outside diameter: the bearing sleeve diameter, not the outside of the housing.
- Length: the complete sleeve length, including any portion concealed inside the housing.
Do not assume a bearing described as "25 mm" will fit: that usually identifies only its shaft size. A 25 × 38 × 100 mm bearing and a 25 × 40 × 100 mm bearing require different housings. These dimensions illustrate the difference; neither is a confirmed Dehler 34 specification. Use installation drawings, a previous invoice or measurements before ordering from suppliers such as Vetus or Exalto.
Access and retaining screws
Have the boat securely supported ashore, isolate the engine starting circuit and support the shaft before disconnecting its coupling.
Remove the propeller with the correct puller, recording the order of nuts, locking devices, spacers and key. Follow the dismantling instructions for folding and feathering propellers.
Carefully remove antifouling around the bearing housing and locate every retaining screw. Two grub screws are common, but inspect the complete circumference rather than assuming there are only two. Clean their sockets thoroughly and remove them completely. A partly withdrawn screw can still score or trap the sleeve.
Check the extraction route before disconnecting the shaft. A suitable split bearing extractor can sometimes remove the bearing with the shaft in place, if the housing and access permit. Otherwise, withdraw the shaft far enough to clear the bearing. Check whether the rudder obstructs that movement, and allow for the coupling and shaft seal arrangement.
Extract the bearing sleeve
Inspect both ends for a shoulder, flange or change in bore. The bearing must move towards an unobstructed opening. Do not hammer a tube against it from inside: a concealed shoulder can transfer that force directly into the housing or its attachment.