Sorry Boring Anode Question

[MarieK]

My Prop nut anodes are not lasting an entire season so I want to help them out with shaft anodes. So a few questions if the forum would be so kind as to answer

I see a lot of mobos without shaft anodes - are they hassle?

How close to P bracket should I fit shaft anodes?
As they wear down will they become loose on the shaft?

 

[jrudge]

http://www.ybw.com/forums/showthread.php?334993-Prop-shaft-anode

 

[kashurst]

before you stick shaft anodes on - try a galvanic isolator first, makes a big difference.

 

[MarieK]

Thanks J - believe it or not I did do a search first but that post did not appear!

So that will be a no to the shaft anodes then!

Already have a Galvanic isolator but I should inspect that its correctly wired up as it doesnt seem to be doing mucH!

 

[thinwater]

Remember that a galvanic isolator does NOT address galvanic corrosion due to dissimilar metals on your boat. It is to protect you from specific stray current issues on other boats. A shaft anode serves a completely different purpose, though it can be consumed by stray current.

 

[Bandit]

Prop nut anodes provide little mass or surface area for protection of prop and shaft and anything else it may be connected to.

Shaft brushes are good but must be regularly checked to see if they are giving protection ie continuity and connected to an anode on the hull in sight of the props and sterngear.

Connections across couplings and gearboxes must be electrically proven.

Firstly fit a Galvanic isolator anyway if not already fitted, then with the boat out of the water work out what is connected to which anodes all strern gear, props & shaft, P brackets, Rudders, Trim tabs ( also each part of the trim tab to the other if not fit a bonding wire) and skin fittings.

Your boat probably was fitted with brass skin fittings and valves depending on its age? Brass skin fittings if you have a cathodic problem or a ground leak on your 240v system will degrade very quickly. Brass skin fittings and valves should inspected regularly and replaced at 5 years with DZR.

Personally I find shaft brushes, shaft anodes with a Jubilee clip above and below on the shaft to stop it slipping down with the tail trailing when running ahead and skin fittings bonded works for me and i work on annual inspections of all fittings and valves plus a continuity test.

Look for any pinkness of props or prop nuts, a sign of poor protection.

 

[omega2]

Have you got proper anodes bolted on the bottom of the hull? if not get some fitted, then bond them to the engine earth bell housing is a good place, then connect the r&d coupling across from gearbox to shaft.
www.clementsmarine.co.uk talk to Paul Williams