Rusted-out Drain Plug!!!

[snowman48047]

Re: Rusted-out Drain Plug!!!

If its rusty and falling apart it should have been replaced long ago. You don't say if the plug was new in the spring or 5 years old. For $5, replace it every spring and keep a backup on board. I have 2 boats with the T handle and they both stay in the water (fresh) all season with no issues. Mine install from the inside. Untill this year I had never heard of them being installed from the outside. Makes sense on an I/O but mine are O/B.

 

[Lyle29464]

Re: Rusted-out Drain Plug!!!

I have to disagree with you, Ron; thru-hull fittings should NOT be bonded, if they are isolated from all other metal components.
?Do not bond any thru-hulls or other immersed metal that can be electrically isolated. Specifically, keep your metal keel/ballast, your metal rudder shaft, your engine/prop, and all thru-hulls electrically isolated, from each other, and from the engine.?
http://www.westmarine.com/webapp/wc...catalogId=10001&page=Marine-Grounding-Systems

Damn I hate to agree with Ron. But I have to. #1. yes if your in a hot marina your boat might fair out better with no bonding. But. You will never pass survey and get insurance or financing. #2. It is not possible to isolate your prop and shaft. The shaft is bolted to the coupler and the gears. If you dont think the gear is a path to ground try welding on the shaft. The rudder may be hooked to the stearing cable. The wet fiberglass will offer some path to ground to everything . If you spread the stray current over all metal you will not notice the damage as much as you will when it is confined to one or two areas.

PS what is a drain plug? I dont have any.

 

[Brentathon]

Re: Rusted-out Drain Plug!!!

For my I/O, the prop, shaft, rudder, keel, etc. is not relevant....but, I continue to see an increase in publications that specifically state that you DO NOT have to electrically bond isolated bronze fittings that are below waterline (i.e. like thru-hull fittings). I have 2 on my boat; a seacock for my head intake, and a seacock for my macerator pump....both seem absolutely fine, and are kept in salt water 7 mo/year since 1991. I wish the rest of my boat's fittings held-up as well as these 2 bronze fittings......

HOWEVER.......what type of fasteners do you guys use to attach your bronze garboard? Stainless steel screws? That's dissimilar metals right there...different scenario. Also, I REALLY HATE stainless steel screws used below waterline....I've had funky corrosion on my swim platform screws; likely from the "low-O2" condition, as well as localized galvanic corrosion; that's why I bonded all my stainless steel swim platform posts/screws to the rest of the drivetrain.

 

[Chris1956]

Re: Rusted-out Drain Plug!!!

Silicone Bronze screws work real well in salt water, as do silicone bronze fittings in general.

 

[sasto]

Re: Rusted-out Drain Plug!!!

Every boat built around here, 5 sportfish manufacturers of 60 to 80footers has a bonding system. Our 35 year old boat has a bonding system. Every boat I ever ran had one. These boats are in the water year around This news about not bonding is new to me.

A bonding system is not just running a ground wire to each underwater fitting. A true bonding system will have a sacrificial metal (zinc) located underwater to which the other noble metals are bonded to. In no way have I ever seen this system fail unless the zinc wears out. I can't get insurance on on a boat without a bonding system. My neighbor recently failed an inspection on his 56footer only because of his bonding. Thru hulls eaten up and a visible halo around the fitting alerted the inspector. His bonding system was removed by PO.

Whether it works or not, I'm no scientist, I don't know. I do know I replace an eaten up zinc every year. I know my 35 year old bronze underwater fittings are as good as the day they were new. I know I will continue this practice because it works for me....and the hundreds around me. I also know I can find anything on the internet, on any subject, and get opposite results.

 

[rwidman]

Re: Rusted-out Drain Plug!!!

Bonding underwater metals is the industry standard practice. Yes, it's possible to theorize that this is not the best practice in some cases, but it is still how most manufacturers design and build their boats and it's still what a surveyor will look for.

BTW: We install sacrificial anodes ("zincs", although for fresh water, magnesium is preferred) on our boats so when the inevitable corrosion does occur, it's the anodes that are dissolved, not our expensive thru hulls, props, or drives.

Perhaps that's part of the OP's problem - no anodes.

 

[Brentathon]

Re: Rusted-out Drain Plug!!!

Other than my bronze thru-hull fittings, the drain plug, and the metal sleeve of the drain plug hole (thru the transom at the keel), everything else is bonded with zincs. I even bonded my SS swim platform support posts, as I was getting recurring corrosion on the screws into the transom......also, un-protected SS below waterline is not good.....and I can show you TONS of boats with SS swim platform posts that are below waterline and not zinc-protected.
Just because a manufacturer bonds or doesn't bond; doesn't necessarily mean that it's done correctly........similar to just because someone posts something on a forum...etc. etc.

 

[Chris1956]

Re: Rusted-out Drain Plug!!!

Do you have zincs on those trim cylinders? They need wires to connect them to the rest of the OD as they are insulated by rubber.

How about zincs on the trim tabs? That is a good idea as well.