Swim Platform Rust Stain Issues

[IOLANI]

My gut feeling after looking at it some more is that the 2 SS replacement brackets are what's rusting and causing the issue. I believe the bolts are already high grade 316 which is why none of the others are bleeding rust. I think the rust is forming on top of the flat part of the bracket and the bolt is simply acting as a conduit for the iron particles to creep through the bolt hole to the top of the platform. I can almost guarantee you put those same bolts in a bronze bracket the rust will cease to exist. Replace the bolts with new 316 bolts and the same thing will happen, the rust will return.

All that rust on the bottom of the platform didn't come from that 1/2" bolt.

I could be wrong, but I don't think so.

 

[tkbsurf]

Hi, I installed a new swim platform on my 55C back in July. The fasteners are all 316 with Awlgrip painted on the portion passing thru to the platform. Then starboard between the brackets and the platform as well as the transom. Then large alum backing plates were fabricated on the inside of transom. Allbonded to the ship bonding system.

The brackets were then painted same as the running gear before it hit the water.

 

[IOLANI]

Looks great. Unfortunately I think the anchor plates for my mounting hardware are imbedded within the transom. Looks to be no through hull hardware and even if there was it's not possible to access it. That is going to make running the bonding wires a challenge.
Perhaps I can drill one through hole in a location I can access and then daisy chain them together under the platform.

 

[metama]

Thanks for the suggestions. The platform is well above the water and even if I raised it 1-2 inches the water would still lap at it with the passing boat wakes we see.

I'll be making repairs to mine but just curious where you saw that platform for sale...Facebook...Ebay ?

Word of mouth. The paint guy who hangs around Holiday Harbor and the owners friend who has the 50 sports fish both had one last summer).

 

[bostonhatteras]

The alloy is called stain LESS, and not stainfree, for a reason. Wet stainless in the absence of air will rust. Its a fact. If you want to eliminate the rust you have to eliminate the wetting of the stainless or keep it oxygenated, both are tough to do. Blasted to white metal and epoxy coated (barrier coat) is certainly an option. Monel bolts as another option wont stain like stainless as they are mainly nickel. Coat the hidden parts of the stainless with a corrosion preventer such as tef gel. btw 316 ss bolts are marked as such in one fashion or another. washers usually literally stamped 316 nuts have a dot pressed in sometimes. the manufacturer wants to let you know what it is since it costs far more than 304

 

[IOLANI]

The alloy is called stain LESS, and not stainfree, for a reason. Wet stainless in the absence of air will rust. Its a fact. If you want to eliminate the rust you have to eliminate the wetting of the stainless or keep it oxygenated, both are tough to do. Blasted to white metal and epoxy coated (barrier coat) is certainly an option. Monel bolts as another option wont stain like stainless as they are mainly nickel. Coat the hidden parts of the stainless with a corrosion preventer such as tef gel. btw 316 ss bolts are marked as such in one fashion or another. washers usually literally stamped 316 nuts have a dot pressed in sometimes. the manufacturer wants to let you know what it is since it costs far more than 304

Thanks for the input. Again...NONE of the SS bolts are rusting except the ones that are in the replacement brackets. The bolts in the original bronze brackets are fine even after many years of service. The brackets are the culprit...they are likely 304.