Bow thruster props

Post by **Denis** » Thu Mar 01, 2007 1:09 pm

Thanks Jack, I'll check into that zinc. Denis

Post by **Veebyes2** » Fri Mar 02, 2007 7:26 am

Denis, you may have the same thruster that I have on my 1996 A32. If so the zinc fits on the bottom of the oil drain plug. It is one expensive little beast. The cheap alternative is to use half of a small rudder/trim tab zinc.

Post by **StockHR** » Fri Mar 02, 2007 8:24 am

Dennis, I thought that green wire was all I had on my Vetus thruster also until I had a problem and had to remove the prop. Behind the prop the mechanic point to the "zinc" and remarked that it should be replaced this spring. So you might have a zinc located on the lower unit. In the instruction manual it shows a seperately mounted zinc plate located in the tunnel attached to the green wire. I have the manual for the BSCHR12A model if I can be of any help let me know. Mike

Post by **Denis** » Fri Mar 02, 2007 9:10 am

Mike & Veebyes2, thanks for your replys and help. All I can say is Vetus must have quite a number of different types of thrusters with all kinds of minor differences. I have looked several times and there is no oil drain plug and I have the prop. removed right now and there is no obvious place for a zinc to go. Behind the prop is a rubber collar (that needs to be replaced) and that is about all. I keep thinking that maybe a zinc slides behind the prop in some way but there is no room. I keep looking for some galvanic damage to be occurring but there is none. It's all a mystery to me but I certainly don't want any surprises. Thanks Denis

Post by **Mariner** » Mon Mar 05, 2007 2:12 pm

It shouldn't be necessary to install a zinc on your bow thruster as it should be connected to the boat's bonding system, that protects all metal below the waterline.

Post by **JackK** » Mon Mar 05, 2007 3:07 pm

Mariner wrote:It shouldn't be necessary to install a zinc on your bow thruster as it should be connected to the boat's bonding system, that protects all metal below the waterline.

I don't agree. Major components are way too expensive to ignore one more point of protection. Engine zincs being the major biggie that comes to mind. Would you skip replacing them too? I wouldn't.

Jack
_____________________
2003 28 TE Dogonit

Post by **Mariner** » Mon Mar 05, 2007 5:06 pm

Jack,

I wouldn't, for two reasons:

1. They're already there, engineered into the design, and easy to replace.
2. They are specifically designed to protect parts of the engine that are particularly vulnerable to corrosion due to their high relative nobility.

A bronze thruster housing, on the other hand, has relatively low nobility and, if bonded, is sufficiently protected from corrosion by the boat's hull mounted zincs. If you're worried about the thruster housing, then you should also be placing zincs on all your through-hull fittings, because they are equally at risk.

My point is simply that, if the thruster doesn't have a provision for a zinc, and it is properly bonded, it's not necessary to worry about finding a way to put a zinc on it. It's already sufficiently protected.

Post by **JackK** » Mon Mar 05, 2007 7:29 pm

I would agree if it did not have a provision for a zinc. However, I located a zinc specifically for the 23 kgf thruster. That tells me it is designed in and should be replaced.

I have also read somewhere that you can "Over-Zinc" a boat causing more harm than good. I tried to locate the article but didn't find it first glance.

Jack
________________
2003 28 TE Dogonit

Post by **DougSea** » Tue Mar 06, 2007 12:25 am

JackK wrote:I would agree if it did not have a provision for a zinc. However, I located a zinc specifically for the 23 kgf thruster. That tells me it is designed in and should be replaced.

I have also read somewhere that you can "Over-Zinc" a boat causing more harm than good. I tried to locate the article but didn't find it first glance.

Jack
________________
2003 28 TE Dogonit

Write up of "proper" protection, has info on over-protecting:

http://www.boatzincs.com/corrosion-quiz.html

Post by **Denis** » Tue Mar 06, 2007 7:10 pm

I finally found the manual for my Vetus bow thruster. A picture in the manual shows a zinc attached inside the tunnel with a wire going from the top of the zinc mounting screw to the gear housing. I do not have that zinc inside my tunnel but it is bonded to the zinc block on the transom.
I thought I was losing my mind, Im glad I found that book.

Post by **DougSea** » Tue Mar 06, 2007 7:56 pm

Denis wrote:I finally found the manual for my Vetus bow thruster. A picture in the manual shows a zinc attached inside the tunnel with a wire going from the top of the zinc mounting screw to the gear housing. I do not have that zinc inside my tunnel but it is bonded to the zinc block on the transom.
I thought I was losing my mind, Im glad I found that book.

Does your thruster also have a shaft mounted zinc? My manual has the same picture you describe above but also references a zinc behind the prop - however it has no picture or part number showing a thruster mounted zinc. I'll have to pull the prop this weekend, assuming the temperature is above 10 degrees!

I've got the 23kgf version in my 1997. I'm also wondering if the 'new' prop, which is listed as fitting the 25kgf fits the 23.

Post by **Denis** » Tue Mar 06, 2007 10:12 pm

My picture does not show a zinc behind the prop, just an O-ring, a V-ring and a drive pin. My prop is mounted with a nylon washer and a screw. I was at Defender today and the Vetus rep. was there. I asked if the new six bladed prop will fit my 23 and he said it would not, so that is just about that.

jcollins · Post by **jcollins** » Sun Apr 01, 2007 11:20 am

JackK wrote:Ok - I couldn't resist. I ordered the prop this afternoon. I already had mine removed so it seems like a good time to try. Defender said they sold the last one today and that it would take a week or so for it to come in.

My thruster is loud as well. If it cuts down the noise by even 25% it would be worth it to me.
______________________
2003 28 TE Dogonit

Have you installed the new prop yet?

Post by **JackK** » Sun Apr 01, 2007 11:24 am

John -
I haven't installed the prop yet. I went down to paint the bottom and found a small piece of fiberglass had delaminated from the bottom of the tunnel. It's less than 1/2" long so the plan is to grind it off with a dremel and re-glass so no more lifting occurs.

That should be done by next weekend. Then I'll install the prop and finish the bottom painting inside the tunnel. Then it's splash time. I will post results once she hits the water.

Jack
__________________
2003 28 TE Dogonit

Post by **Pitou** » Mon Apr 02, 2007 3:30 pm

Richard & JackK

Ok you guys got me. I'm in!

Yesterday I ordered the new 6 blade prop for my bow thruster along with a new anode from Defender. Can't wait !!!

While following this thread I saw and spoke to the Vetus Rep at the Maine Boat Builders Show and he also said how much quieter things will be along with 10% less power used. Those thrusters sure do draw some juice.

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Bow thruster props

Thruster Zinc