Antifoul around rudder

[Konan the Bavarian]

I am preparing to slip my new-to-me 2006 b37cr and I have been wondering why the hull area around the aluminium rudder tube is not a different (copper free) antifoul paint, like the area around the sail drive. Can anyone please enlighten me?

Steven
S/V Konan the Bavarian

[Symphony]

You can mask off an area around the lower bearing housing and use trilux there - but most people don't bother, Same with the top of the rudder near the shaft. Not much evidence that there is a corrosion problem through using ordinary antifouling.

[JEN-et-ROSS]

Our B38 is similar. We use Trilux on the Saildrive, but I just wrap some masking tape round the space between the bottom bearing housing and the top of the rudder in case any antifouling gets in, than remove it when I've finished.
  Last year I had cause to remove the rudder, so I was able to examine the aluminium of the rudder stock, there was no pitting on the stock or tube.
  So I guess you needn't worry, though it's well worth checking that the stock is electrically isolated if it's aluminium.
 

[Yngmar]

I've stumbled across these very comprehensive and sensible instructions for rudder antifouling whilst shopping for a new bottom bushing for mine (which should arrive any day now): ftp://ftp.jefa.com/rudder/maintenance/Rudder_blade_anti_fouling_instructions.pdf

[Konan the Bavarian]

Thank you all, for the information.
Boat is out of the water, and now the fun begins.
Steven
SV Konan

[Konan the Bavarian]

Thank you Yngmar for that link.

I have spoken to a local shipwright yesterday, and he commented that he has seen a growing number of boats showing signs of electrolysis around the alloy rubber tube, and he now strongly encourages the area around the rudder tube be treated similarly to the sail drive. ....and this is what Jefa has recommended.

It would seem to me for not much more additional effort, following the instructions would help minimise any potential problems.

Steven
SV Konan

[sailersal]

I have always used the alternative, except when i had the work undertaken by two yards, and they did not do it. I noticed some corrosion, and have gone back to my original strategy, and believe it is the safest option for little effort. Also worth remembering that corrosion rates from any differential will vary with location, salinity, water contamination or temperature and stray marina currents, so i suppose it comes back to personal assessment of risk.

Have fun scrubbing !

[Konan the Bavarian]

After a week on the hard, all work on the boat has been successfully completed.
The keel has been grit blasted & encapsulated in a series of epoxies, before 3x coats of antifoal.

Just thought I would share my recent experience with electrolysis on lower aluminium rudder bearing housing.
Whilst the boat was out of the water, I too the opportunity to remove all existing antifoal from around the lower aluminium rudder bearing housing, prepared area & painted with Trilux. The was quite a bit of corrosion on the housing, not enough to be a problem, but I forgot to take a photo at the time.

Next time out the water, I will replace the aluminium housing with a stainless steel bearing housing.

[Konan the Bavarian]

and here is a close up of the corrosion.

[Sweet As]

Corrosion of the aluminium rudder housing was a serious issue in our 2004 Bav36.  The corroding housing was placing pressure on the bearing to such an extent that it started to impact ease of rudder movement. We replaced with a stainless housing.