Pontoon Boat & Deck Boat Forum

Hello guys,

I'm looking into getting a new toon. I plan to keep it docked the whole season. So I got some sac zinc questions:

1) there's a bracket at the end of 1 log, to which I think most ppl put their zinc plate. Does that bracket need to be bare metal? I imagine I don't want it to be bottom painted right?

2) what fastener should I use to bolt the zinc to the toon? Stainless steel? does it matter?

3) what about the other log? would the cross joist be enough to keep both logs protected? or would I need another zinc, or some kind of wire to connect the 2 logs together? if so what kind of wire?

Thanks in advance.

More is better. I have one on each outboard log one on each side of the motor on the center log + the 4 that come built into the motor. I am in fresh water and never had any problems with caroshion until we got a slip on a pier that had power on it, the stay current from the author boats started to cause it so i added the exstra zinks. as part of my refit i added a 110 shore power system and that really caused it, looks like kernels of pop corn so I added a galvanic isolator and problem solved. you don't want any paint or clear coating between boat and zink and use good stainless screws to attach with

thanks! Only problem is I'm not sure if the other log has a bracket to fasten the zink to. I'll have to double check...

I am not sure but I thought that little bracket on the left log is the mount for the speedo and depth finder?

then where would be a proper place to attach a zinc? Anybody knows? I'd like to put one on each log if possible.

If that bracket on the back of your logs is free, or has space, then mount it there. I don't see why you can't put it there, since it would be the most logical place to drill a few holes and mount one. I just needs to be under water, and attached to the log. So even if you had to mount it on the top of that bracket, which would be away from the transducer of a depth finder or spedo, then you would still be protecting that log.

I may be way off here,,,, so if your in the know,,,, then correct me,,,,
I believe the anodes are for areas where there are TWO DIFFERENT metals in contact with each other.
That is what causes electrolysis (corrosion) and the anodes are sacrificial so as to save the important parts (your boat).
You find different types of metal in the engine and outdrive. Aluminum and Stainless steel for example. When they are in contact with each other and under water, will corroded. Your logs are not in contact with another type of metal so there should not be electrolysis happening there. What your seeing (the little white popcorn stuff) is more likely an element or mineral in the water that is reacting to your logs. Not sure an anode will fix that.

Bill1031 wrote:I am not sure but I thought that little bracket on the left log is the mount for the speedo and depth finder?

yes,,, for the most part that is true. I have seen them used to mount a small dia pipe for a water pick-up for an on-board water system. Use it for what you need it for

I hang one of these magnesium fishes in the water at the stern of my boat,our boat sits in a fresh water slip year round, they also come in Zinc. http://www.westmarine.com/buy/martyr--c ... P000485144, the alligator clamp clamps on my engine mount bolt, the alligator clamp is attached to a cable on the grouper anode. here's one for $52.00 http://www.amazon.com/Martyr-Magnesium- ... uper+anode

I also think you do not want real zinc to be used for your sacrificial anodes in fresh water. I think actual zinc is only effective in salt water, and has no effect at all in fresh water, so make sure you buy what is appropriate for where you boat. Robster mentioned magnesium, and that may be what the fresh water sacrificial anodes are made of (I don't remember for sure). There is a material that works in fresh water, but will not work in salt water, and that may be magnesium. Some of the anodes are actually made from aluminum, but it is a type/grade/class/whatever of aluminum that will give up faster/easier than what you are trying to protect, thereby serving its sacrificial purpose. No matter what it is made of, you may see them called "zinks", but make sure the actual material is right for your use.

Unless the boat is parked in a marina year-round I assume there is nothing to gain for the sacrificial zink/magnesium?

I thought this web page was very informative. http://www.boatus.com/boattech/casey/sa ... -zincs.asp
Seems to touch on just about everything. (dislike the math part)

drogonx, your post reminded me where I had read about the different materials being used, which is the same article that stated that actual zinc in not effective in fresh water and should be used in salt water only. Here is the Boat US article: http://www.boatus.com/magazine/2012/dec ... rosion.asp

JBO wrote:Unless the boat is parked in a marina year-round I assume there is nothing to gain for the sacrificial zink/magnesium?

electrolysis is always working when the boat is in the water. So if you have no zinks,,, then SOMETHING is going to get damaged,,,, every day and every hour it's in the water,,,
it's your boat , do what feels right for you, but my boat has them and I do not leave her in all year,,,

Yep that's why we use the Magnesium grouper in fresh water, in the freeze months when we keep our motor trimmed down into the water that's when we switch from out our stainless prop to the aluminum. Our stainless prop did cause some corrosion around the lower unit on our Yamaha 150. In the non-freeze months I keep our motor trimmed out of the water.