Galvanic corrosion problem

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nowgrn4
Posts: 245
Joined: 24 Mar 2015, 19:18
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Location: Florida

Galvanic corrosion problem

Post by nowgrn4 »

'00 1652 Weld-Craft that sits in fresh water at my home pretty much 9 months of the year. Having an issue with corrosion around my fish finder transducer. I have bubbling paint and deep etching in the aluminum a few inches around the stainless transducer mount where it bolts below the water line through the transom. Will mounting the transducer to a piece of starboard and 5200 and bolt it to the transom isolate the transducer from the hull and eliminate the corrosion? Fish finder is always turned off. Engine is always tilted up totally out of the water. Battery switch is always on for operation of float switch/bilge pump. Sacrificial Anode needed? Any ideas appreciated.
17' Pro-Line 115HP DI Johnrude Bay rig
1652 Weld-Craft 50HP Johnrude fish camp rig
17' Grumman canoe 3.3HP Johnrude on side mount creek runner

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DaleH
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Joined: 12 Dec 2014, 14:32
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Location: Eastern Mass

Galvanic corrosion problem

Post by DaleH »

Isolate - YES! Add king starboard or hdpe/ldpe cutting board plastic between any SS and tin. Insulate any SS fasteners by covering the bolt body in adhesive-lined heat shrink and then put nylon washers under the bolt head and nuts. Plus add a magnesium anode for freshwater use.

See here: viewtopic.php?f=3&t=36471&p=372383&hili ... ic#p372383

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DaleH
Donor
Posts: 3091
Joined: 12 Dec 2014, 14:32
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Location: Eastern Mass

Galvanic corrosion problem

Post by DaleH »

FYI … all tin MUST BE PRIMED before using any sealant, goop or attaching ANYTHING to the tin hull! Lookie here, for how 3M 5200 can otherwise attack a tin hull:

https://tinboats.net/forum/viewtopic.php?f=3&t=40251

nowgrn4
Posts: 245
Joined: 24 Mar 2015, 19:18
6
Location: Florida

Galvanic corrosion problem

Post by nowgrn4 »

Great info, Thanks! Will do the primer step before I adhere the mount piece with 5200. I'm also gonna run a fused hot directly from the battery to the bilge pump circuit so I can switch the battery switch off when not in use.
17' Pro-Line 115HP DI Johnrude Bay rig
1652 Weld-Craft 50HP Johnrude fish camp rig
17' Grumman canoe 3.3HP Johnrude on side mount creek runner