Think I need new props

[Scubadoo]

Interesting thread. I have been told my props only have a season or two left in them, taking them to around five years, is this normal or an indication of a problem. D6 stern drives.

I think pictures are needed, it is all down to how well you maintain your props and of course anode protection. If they just have the usual black Volvo paint which flakes off and exposes the bare metal, the salt water will corrode leaving at first pitting and then failure. I am on my 3rd set in 15years, the last set was replaced due to fishing rope, so I guess you are doing okay.

 

[rubberduck]

I think pictures are needed, it is all down to how well you maintain your props and of course anode protection. If they just have the usual black Volvo paint which flakes off and exposes the bare metal, the salt water will corrode leaving at first pitting and then failure. I am on my 3rd set in 15 years, the last set was replaced due to fishing rope, so I guess you are doing okay.

We caught some rope up the thames last year & that is the side affected, so perhaps that has something to do with it. Props were okay at previous lift.

 

[SC500]

Just to give an update on the issue, i have now had the connectivity of wiring of parts to anodes checked to see whether she is generating the problems or whether they are from an outside source.
Quick reminder. RH Prop showing extensive surface corrosion and needs replacing. RH Rudder, LH Prop and Rudder in good condion.
Taking meter reading between anodes and gave the following results.
RHS Connectivity between Prop, Rudder, External Shaft, Shaft to coupling, coupling to Gearbox and engine block was good. (strange with RH Prop issue).
LHS Connectivity Rudder okey, but there was a problem with the driveline as the signal between the prop and shaft was an issue! There was connectity from prop to shaft to coupling and through the coupling but the signal was breaking down where the shaft enters the gearbox. if the shaft was rotated a little the connectivity was good, rotate a few more degrees and the signal was lost, in affect isolating the LH Prop and shaft from the circuitry, but this side was okey! There appered to random connection dependent upon where the shaft stopped. I assume this is due to connectivitybetween coupling/shaft and gearbox being through the bearing. I have started the engines through the winter on a monthly basis, but this does not seem to have helped the situation. Am no expert but was advised that when all parts are conected the entire boat is nuetralised, but if one section brakes down then one part becomes an Anode, the other a Cathode and corrosion starts. Cant work out how the connectivity issue was with the LH drive line with the RH Prop be affected. However am now fitting McDuff Electro Eliminator brushes to both shafts to over come the gearbox issue, and will be fitting a Galvanic Isolator as well as advised by you guys, so hopefully all will be well.
Did check all terminals to the anodes and found many were suffering from age corrosion even though providing good connectivity, I moved one wire up and down to check for tightness and the terminal snapped, so decided to renew all terminals as well.
As VP suggested, In future when replacing anodes, a meter will be put over them, and suggest you guys do the same when the oppotunity arises, otherwise it turns a little expensive.
Contacted Clements for a replacement prop and the cost was around £1050 + vat but they could not ensure it would be matched to LH. They do offer a bespoke service whereby you send your prop, they scan it and make an exact copy for £90 extra. Problem is they quote 4-6 week turnround.
Am advised existing prop is certainly okey for another season as corrosion is more cosmetic but it will be replaced, therefore she will probrably go back in as is and then sort the prop out end of season unless I can source a direct replacement. Princess have not responded to my email yet but as mentioned previosly, if anyone knows the whereabouts of a replacement it would bve appreciated. Prop size: RH 23" x 31" to fit a 2" shaft.
Will be interested to read your views of how the anticorrossion system works, and thanks for the good advice.

 

[Bandit]

You need to know the taper of the shaft , the width of the prop bore at the wide end , length of boss, taper will be expressed as 1in 16 or 1 in 20 etc.

Also keyway size and length are specific.

You could spend say £600 on a secondhand prop and find it wont fit due to either of the above or that the modification of the secondhand prop costs you more. Bear in mind machine shop labour at say £50 an hour plus travel time.

In your position I would consider taking the prop to Clements for measuring and scanning if they can, order a new prop , get the old prop back on for the season and change next year, I dont think Clements are that far from you?

 

[LionsDen]

You can always swap the props over when you have your mid season lift done - just a thought :encouragement:

 

[SC500]

As mentioned, visible damage was a good warning that it could have been worse. Prop has been inspected at it still has a nice ring to it when struck, therefore in the meantime we are going to skim the surface especially on the drive side to minimise any cavitation issues due to corroded surface. Clements is only an hours drive away and they can scan part pretty quickly. When I do receive the new part I will switch the prop, mis season if possible.

 

[LionsDen]

I think pictures are needed, it is all down to how well you maintain your props and of course anode protection. If they just have the usual black Volvo paint which flakes off and exposes the bare metal, the salt water will corrode leaving at first pitting and then failure. I am on my 3rd set in 15years, the last set was replaced due to fishing rope, so I guess you are doing okay.

Hi Scubadoo - The pros in question are on shafts btw - hence no Volvo black paint is required - Princess 430 is a lovely boat - I looked at buying one about 15 years ago with cherry wood interior....