Galvanized Steel Jack Plates

gazza2007au

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Mar 9, 2007
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Hey guys checking in from Australia here, im looking to make a set of jack plates actually i have already made them from galvanized steel structual C 6 inch beam about 1/2 an inch thick

trying to do it on the cheap as a 6 inch jack plate imported from the usa is about $650 if i buy local its over $1000

how would u prep the steel? I am thinking a few coats of epoxy resin than epoxy paint over the top

i have asked on a aussie forum but got limited advice hopping u guys have bigger knowledge on this
 

Chris1956

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Mar 25, 2004
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Jackplates for motors up to 150HP are usually about 3/8" aluminum. Therefore, your 1/2" steel is much stronger than necessary.

If you are using it in freshwater, you have no worries. Galvanized will hold up nicely. If using it in saltwater, and you trailer the boat, again no worries. just keep up on the "cold galvanize" painting of the jackplate.

If leaving the boat in saltwater, I am not sure what to tell you. 2 part Epoxy barrier coats are probably the best, but may not be compatible with galvanized metal. whatever you choose, keep up on the maintenance.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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galvanized steel will be about 3x the weight of the aluminum ones.

however since you started with per-galvanized material, all the cuts, etc are now exposed

cold galvanizing spray (heavy zinc primer) and use it.

or if you want it a different color, light blast, then 2-part primer then color of your choice.
 

gazza2007au

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Mar 9, 2007
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Thanks guys it will be a salt water trailer boat
 

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dingbat

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There is no such thing as cold galvanizing. The term is often used in reference to painting with zinc-rich paint.

Galvanizing by definition means a metallurgical reaction between zinc and iron to create a bond between the zinc and the steel of approximately 3600 psi. There is no such reaction when zinc-rich paints are applied and the bond strength is only several hundred psi.
 

Chris1956

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Cold Galvanizing paint is the name of a paint that is compatible with galvanized steel and provides some zinc-based anti rust properties. It is the best stuff available to touch up hot dipped galvanized steel, at least that I have found. It used to be available in quarts for brush on, which would be convenient for the OP. Not sure if you can find it now.

The local Home Despot also has some latex primer (grey) designed for both aluminum and galvanized metal. It works pretty good and can be brushed on. I am testing in on my galvanized trailer wheels, to see if it stains like the original zinc coating.
 

gazza2007au

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Mar 9, 2007
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We have cold gal paint here in spray and liquid form but its no good the steel still rust
 

robert graham

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Apr 16, 2009
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Heck, with 1/2 inch steel even if you experience some corrosion (which you will, especially in any areas where the zinc galvanizing has been broken), the Jack plates should last for many years....and with a little sanding and painting once in a while should last for decades....
 

Scott Danforth

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short of starting with fresh sheet and having the weldment hot-dip galvanized, your only option is cold galvanizing, then a top coat.
 
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