thruster zinc

[trailertrawlerkismet]

With our R27 sitting on its trailer I've been performing spring time boat chores. One of the maintenance items needing done was to replace the bow thruster zinc. Easy enough to unscrew the bolt but then I found the zinc had adhered itself to the thruster shaft and did not want to budge. After repeated attempts trying to work it off with pliers and lightly tapping on it I gave up. Walking by my work bench I noticed a spray can of WD40 and a light bulb went off in my mind......I preceded to spray the zinc area aggressively and let it sit overnight. The next morning it came off easily. Has anyone else experienced the bow thruster zinc hard to get off and or why this happens?

 

[baz]

Jim: My diver replaces my thruster zincs with our boat in the water and he's not reported this issue to me yet. :roll: However, he did say that DO NOT let the thruster zincs get eaten away beyond 75% as the remaining zinc will not be sufficient to protect the metals in the thruster. What can happen is not only does the holding bolt get eaten away but the threads in the thruster that the holding bolt engages will start to get eaten away as well. If this condition occurs the holding bolt cannot do its job and an expensive thruster repair will result.

Of course my diver cannot use WD40... :lol: However, I will ask him if he's ever seen this issue on my boat or other boats he services.

I assume you thoroughly cleaned off the WD40 before attaching a new thruster zinc... otherwise the WD40 might negatively impact the effectiveness of the zinc as an oily film would be present between the zinc and the shaft.

 

[trailertrawlerkismet]

Good call on cleaning the WD40 off, yes I will. Interesting enough, after 1 1/2 years of usage the bow truster zinc was well over 50% remaining.

Jim

 

[baz]

Jim: Was that "... 1 1/2 years of usage ..." water usage or a combination of dry land and water use. :lol: If dry+water just how much time was your boat in the water (fresh and salt ?). ? Thanks.

 

[trailertrawlerkismet]

To be precise our boat is 21 months old. Of the 21 months the boat has been in salt water 70%, fresh 30%. Of the 21 months the boat has experienced 12 months of being in the water, with the balance on the trailer in our drive, in transit to the next fun adventure or in storage.

 

[baz]

Hmmm... 50% zinc remaining after 12 months in the water is pretty good. 🙂

What about the stern thruster zincs ?????

 

[HRowland]

I have had to use pliers to get the anode to release. Never much of an issue. After about 7 months in salt water each year they have about 40-50% remaining.

The thruster anodes are actually an aluminum alloy (Al-Zn-In) now. Imtra-Sidepower changed the anode metal from zinc in 2010. See http://www.boatzincs.com/imtra.pdf.

Per Q&A on the BoatZincs web site:

Q: I was under the impression that one was not to mix aluminum and zinc anodes on a boat. If aluminum is only available for my Imtra thruster should I switch the others to aluminum?

A: Imtra Side-Power thrusters are engineered to have their underwater metals electrically isolated from the rest of the boat. This means that there is no electrical path available for the thruster (or its anodes) to interact with any other underwater metals (or anodes) either on or adjacent to your boat. You can, and should, continue to use zinc anodes elsewhere on your boat while upgrading your Imtra Side-Power thruster to these new, technically superior aluminum anodes.

Howard

 

[Automaticman865]

Figured I register at this point where I just had the same problem on my cutwater 28. Once you get the bolt out just a simple plumbers basin wrench will get in there and give you the leverage to twist the zinc out.

 

[baz]

Howard... thanks for posting that Side Power advisory about using Alu anodes for the thrusters. I will be checking with my diver to see what he's been using for my thrusters. I like the idea that the Alu anodes last longer per the Advisory note. 🙂 Mind you the Alu anodes are more expensive than the Zinc ones from what I can tell.

 

[baz]

My diver responded saying they have been using Alu anodes for my thrusters for some time now and said they're only made in aluminum now. 🙂

 

[trailertrawlerkismet]

I just received my spare thruster anode order from Boatzinc.com and it is aluminum with part # SM31180A Side Power