Electrolysis, finding a Propeller for a Princess 435 and lining up the dual rudders

[60F]

The propeller

I've had a problem with poor continuity on a Princess 435 which has resulted in the propeller becoming unrepairable (aka scrap) according to Hamble Propellers - who came heavily recommended. They are able to make a replacement, but it could take around 5 weeks. I am trying Princess-parts, but wonder if anyone has any ideas where I might be able to source a new propeller quickly (right handed, 23x28, 3 blade, cupped trailing edge, 1 3/4 inch shaft, 5 1/4 boss length, 7/16 key) as I'd like to get her back in the water next week if possible!

Continuity

We have checked out all the wiring, replaced the cable from the engine to the stern tube box and replaced the anodes, but not found an obvious problem. As I understand it the cables bolted to the stern tube box are only connected to each other (and link the engine, fuel tank and anode) and there is nothing inside the stern tube box connecting them to the propeller shaft. Accordingly, it seems that the electrical continuity between the propeller and the engine is only provided through the propeller shaft and via the gears in the gearbox. It seems very strange that we have good continuity on the port engine but not on the starboard one but it has been explained that this might be due to the gears not fully meshing (which would seem odd) or dirty oil (possibly even odder as I did not think oil was a good conductor of electricity but would presumably be better if it had metal bits in – does that mean I should actually be more worried about the other gearbox where it would appear there is good continuity?). I have ordered some MG Duff EE1 bushes for each shaft, the idea being that the bushes rest against the shaft and are connected to the engine thereby ensuring good continuity. In theory this should solve the problem. However, I would love to hear from anyone who has experience of these problems who may have greater insight - as I'd hate to ruin another expensive propeller. The rudders and P brackets both sides are unaffected and do have good continuity.

Handling and the offset rudder

I've not been particularly impressed by the handling of the Princess over the year that I have owned her and whilst inspecting the props and assorted rudders and brackets think I may have discovered the reason (well perhaps just one of them, as I’ve also discovered that the trim tabs are permanently down – but that is another thread for anyone who is interested). With the port rudder dead ahead, the starboard rudder appears very visibly (perhaps 10 degrees or so) to starboard. I recall on the survey there was a point on the port rudder needing tightening and entrusted the work to someone - I think they might just have forgotten to make sure they were parallel first. Again, I would appreciate any advice from anyone with insight into such matters, but I assume all I need to do is loosen the bolt securing (probably the port rudder as that was the side that had the problem before) aligning the rudders by measuring the distance between the leading and trailing edges of both rudders and then tightening. How hard could it be? To add to the confusion, whilst the flying bridge rudder indicator shows straight ahead, the one down below shows about 10 - 15 degrees starboard rudder. Does anyone know how these work, and in particular how they can be adjusted? I assume that there must be a sensor somewhere.

 

[volvopaul]

Hi as your boats shafts have R and D type couplings there should be a boning wire or even 2 from the bolts to the gearbox coupling across to the nut on the shaft coupling, thats how you get continuity across from the prop shaft to the anode via the engine, thats how it was designed, where as fairline have always been a fan of shaft brushes, which dont work that well either when the mild steel springs rust away rendering it useless, so id be checking out the couplings, not an easy task on a 435.

Funny thing is over the years ive been in this business ive heard about more 435s with this problem than I can remember, one of which sat on the river Ouse not very long and ended up with virtually no prop left at all.

As its aft cabin and engine room tight it usually an overlooked item on the servicing that ends up this way.

As for the prop sorry I cant help but im sure there would be one out there somewhere, if you local to the Hamble try the chandlery barge opposite RK Marine on Blundell lane Bursledon, there are many props there. Out of interest Hamble props made all the props for Fairline at one time, they did mine.

 

[oldgit]

but wonder if anyone has any ideas where I might be able to source a new propeller quickly (right handed, 23x28, 3 blade, cupped trailing edge, 1 3/4 inch shaft, 5 1/4 boss length, 7/16 key) as I'd like to get her back in the water next week if possible!


Vetus ? http://www.abcpm.co.uk/vetus/sterngear/

 

[sarabande]

long shot , but try here ?

http://www.woods-group.co.uk/props.htm

 

[Firefly625]

or give these guys a call, very very helpful and the cheapest props in the UK (as far as I believe....)

http://www.falpropellers.co.uk/newpropellers.php

 

[runner911]

Give these people a try. Based at Newton Abbot in Devon. Always very helpful.

http://www.coengineering.co.uk/

 

[coreng]

Continuity

Hello,

You can check anything you like and add any devices you want, the only way to know if your propellers are not going away is checking their electric potential afloat through the shafts. This tells you if your protection is working properly. If electrolysis occurs despite protection measures are over -500 mV / potential 0 given by an immersed reference electrode. Very simple, quite largely unknown in pleasure boats.

 

[JaySTee]

When dead ahead I believe it is correct for the rudders to toe in slightly help keep the boat in a straight line and not wondering/weaving. The two helm indicators are often slightly out probably due to the resistance difference in the different length of cables to lower and fly helm. You can adjust the sender on the steering tray to get the best reading you can on both, and try cleaning all the connections up. At the end of the day it is only and indicator for use when slow manovering.

Edit: just read your post again and it sounds like your rudders are actually toeing out which doesn't sound right! The rudder arms should only be able locate on the rudder stocks in one place/angle and the rudder alignment angle is normally set by the length bar that joins the two which should have been set at the factory. Is the bar adjustable? Maybe the rudders are on the wrong sides As I said above they should toe in slightly...

 

[omega2]

www.clementsmarine.co.uk they make them for your boat. Paul Williams is your man.

 

[sgoodwin71]

Give these people a try. Based at Newton Abbot in Devon. Always very helpful.

http://www.coengineering.co.uk/

i believe that c & o may have this props in stock.

 

[60F]

Thanks for all your help, I've sent various emails out tonight and hopefully someone will have a propeller or can make one quickly.

Volvopaul, you are right about the (single) wire from the gearbox to (one of the bolts on) the shaft coupling, but how would I check out the shaft coupling itself - presumably I need a marine engineer? I suppose there is a some sort of internal contact between the shaft coupling and the shaft that is not easily serviced and that there is not a simple solution like running a cable between all of the bolts on the shaft coupling. I understand your cautionary note about the shaft brushes, but assume if these are maintained and I periodically check for continuity between the gearbox and the interior part of the shaft I might have a workaround solution?

JaySTee - I confirm that the rudders would actually toe out at the stern. She is currently at Port Solent so I will have a closer look this weekend at the potential adjustments (and wander round with my tape measure and have a good look at other boats out of the water). I just assumed that it would be inefficient for the rudders to be anything less than square on and assumed that outward wash from the props would stabilise her.

 

[volvopaul]

Thanks for all your help, I've sent various emails out tonight and hopefully someone will have a propeller or can make one quickly.

Volvopaul, you are right about the (single) wire from the gearbox to (one of the bolts on) the shaft coupling, but how would I check out the shaft coupling itself - presumably I need a marine engineer? I suppose there is a some sort of internal contact between the shaft coupling and the shaft that is not easily serviced and that there is not a simple solution like running a cable between all of the bolts on the shaft coupling. I understand your cautionary note about the shaft brushes, but assume if these are maintained and I periodically check for continuity between the gearbox and the interior part of the shaft I might have a workaround solution?

JaySTee - I confirm that the rudders would actually toe out at the stern. She is currently at Port Solent so I will have a closer look this weekend at the potential adjustments (and wander round with my tape measure and have a good look at other boats out of the water). I just assumed that it would be inefficient for the rudders to be anything less than square on and assumed that outward wash from the props would stabilise her.

Hi I think I have worked on your boat, did I fit you a water hose last year from the exhaust elbow to the g/box cooler, job came via Clive Hook?

Im in PS on Friday so will have a look at your boat.

The wire doesnt come from the g/box casing but from the g/box output shaft bolt then across the plastic coupling to the bolt on the propshaft coupling.

Presume yours is the one with copperbot?

 

[60F]

I only bought her last March, but haven't had any work done (other than the coppercoat that you have noticed, some minor mechanicals - and a lot of polishing!). I think she was ashore at Hamble Point and, prior to that, Northney before then for some time - but you may have worked on her then. She was previously called Northern Star II. There is another similar boat in PS - Ultimate I think.

Sadly I am stuck in London until the weekend, it would have been interesting to meet up.

 

[volvopaul]

Yes it is ultimate ive worked on, although I have had a look around your boat before a year or so back.

Maybe see you sometime.

 

[60F]

Just like to think Omega 2 and Clements Marine. After my initial thread on 4 April, Clements Marine managed to get an identical new prop back to me by 21 April, which meant the boat was launched on 27 April ready for the long weekend. Brilliant service and recommended to anyone else who needs a prop in a hurry and at a good price.