Prop shaft wear

[feebs]

Hi,

I have 1800 hour SD 50's which I have owned for last 2 years & clocked up 200 of these hours. On a recent haul out, I decide to have prop shaft seals replaced as preventative maintenance plus I wasn't sure of their history.

Now my mechanic has said that grooving is too far gone - either replace shaft or put on a speedie sleeve as minimum.

My question, is this normal wear for an SD50 with this many hours & will new seals make a water tight seal? Are these grooves beyond an acceptable limit?



Thanks for any input

?

[Captsteve53]

Hi there, I must say your shaft dosent look to bad from the pictures (always hard to tell though) here is the typical Maritime class rule for some but not all organizations as 3% of the shaft diameter for not more than 10% of the shaft as follows:

It is allowed to reduce the rule diameter by 3 % (corresponding to a decrease in torsion strength of 10 %) by machining or grinding. Therefore if crack depth deeper than 1.5 % or shaft diameter (shaft being rule size) the shaft shall be rejected. Repairs of corroded or cracked shafts within limits given above shall be smoothly ground out to reduce stress concentrations to a minimum. The hollows should be filled with propriety metal filler if in way of sealing rings etc.

Looking at yours(from the pictures alone) I WOULD SAY by moving the seal/seal face by a few millimeters will present a new clean shaft area for the seal to run on, i would not in my opinion be turning down and fitting any kind of wear ring for that minimal area, the question here is not about shaft strength but about future premature wear of your new seal if fitted in the same exact position,

I have done numerous re fits such as this and just adjusted the new seal in the housing so it dosent locate in the exact same place,and to note unless your vessel is under any of the class rules then suitable wear or not is left to the owner/yard to agree on, I am a registered marine surveyor but you must understand these opinions are just that(out side third party opinions) as i am not an appointed surveyor regarding your vessel,

Cheers Steve

[Captsteve53]

Sorry forgot the last part of the question,

Normal wear? i have seen better (not even a mark) and worse for the similar hours so some what hard to judge if normal?,

Sealing: I would give you better than 95% the new seals will do just fine, how ever they may not last quite as long depending on the profile of the grooves, as long as the grooves have no sharp or knife edges then all should be good,
Im sure if had not thought to check you would have had many more seasons of use even from the original seals

Cheers Steve