What Bolts to Use (Metal Interaction) ?

[Dulcesuenos]

Hello, the helm was a little loose on our Cat, it is a Edson pedestal The pedestal seems to be painted aluminum, not sure.\, there is also a aluminum bracket under it to hold the helm cables in place. The bolts used are large aluminum bolts. One has corroded in half. The other two are corroded so bad they will break. The 4th turns ok. I plan on installing aluminum plate below the pedestal. I am not sure what bolts to use, aluminum (hard to find didnt last anyhow but 17 years) Stainless steel or zinc plated steel?

[DeepFrz]

I would use stainless with an insulating sleeve and insulating washers.

[capngeo]

Originally Posted by DeepFrz

I would use stainless with an insulating sleeve and insulating washers.

+1... which is still in service on my 26 year old CAL28 with an Edson

[KenH]

Try Titanium bolts, little spendy but as long as the application is not for a moving part (bolts are hard "brittle"). the Titanium should last in saltwater.

[Kettlewell]

Stainless will be fine. Look at what spar makers use to attach all sorts of things to your mast. It is ideal if you can put an insulating sleeve in, but not really necessary IMHO.

[Dulcesuenos]

Good points all of these! Thanks

[AnchorageGuy]

If any of the aluminum is threaded to accept the fasteners, sleeves won't help. Use a good coating of Tef-Gel on the threads to eliminate corrosion. Chuck

[capngeo]

Agreed! Tef-Gel is some good stuff!

[avb3]

Originally Posted by DeepFrz

I would use stainless with an insulating sleeve and insulating washers.

This may be an obvious question to most, but what the heck is an insulating sleeve and washer? Does one buy them that way, does one jury rig them that way or???

Thanks for any input.

[DeepFrz]

Plastic, nylon, fiberglass, anything that is strong and non conductive.

[CGB GAREY]

Deepfrz is right. Stainless is probably your best bet. Get yourself a squiz at a 'galvanic series chart' (tells the potential of any metal you're dealing with). The idea is to use metals close to each other on the chart... if you can. The pedestal will be cast aluminum but as long as you can isolate the pedestal and backing plate from the s/s you're OK. Plastic, fiber... anything that eliminates contact between fastener and the aluminum at any point will do.

[sabray]

My yacht specialties is bolted down with stainless. I Had the whole thing out three years ago. The bolts were fine. I used new ones with lancet nothing appeared to have been on the old ones. I did the same with all the upper bolts like the ones that hold the binnacle and the inserts between the control plates. These on mine were a beast to take out. A few broke and I had to retap. Good to do this something you may need to get to and having seized bolts would be very bad. Of the 4 bolts at the base of my pedestal I replaced one with an eye bolt it's pervert for the safety harness or bungy tying the wheel off.or ..... Life raft lanyard

[capttman]

Here is the metal chat from noble to least noble may help ya

• Graphite
• Palladium
• Platinum
• Gold
• Silver
• Titanium
• Stainless steel 316 (passive)
• Stainless Steel 304 (passive)
• Silicon bronze
• Stainless Steel 316 (active)
• Monel 400
• Phosphor bronze
• Admiralty brass
• Cupronickel
• Molybdenum
• Red brass
• Brass plating
• Yellow brass
• Naval brass 464
• Uranium 8% Mo
• Niobium 1% Zr
• Tungsten
• Stainless Steel 304 (active)
• Tantalum
• Chromium plating
• Nickel (passive)
• Copper
• Nickel (active)
• Cast iron
• Steel
• Lead
• Tin
• Indium
• Aluminum
• Uranium (pure)
• Cadmium
• Beryllium
• Zinc plating (see galvanization)
• Magnesium

[Kapena]

Waterwayguy has it correct. A stainless bolt but you need tefgel or anti-seize compound. Ask any motorcycle shop about this.

Basically you won't be able to remove the stainless bolt (if it bolts into the aluminum), after just a short while, without the tefgel or any other anti-seize compound. Your helm isn't under water so you don't need much concern about noble metals.

[Dulcesuenos]

The bolts are just going through the aluminum pedestal base, The base will be sitiing on a 3/16" aluminum plate, for support, then through the floor, (guess its about 1"of nidacore and glass) then through another 3/16" plate under the entire floor area for exta strength. I am thinking stainless bolts. and use the tef gel. The above plate and pedestal are painted with polyurethane. And I had planned on useing 4200 or 5200 on the bolt heads to prevent moisture.
would galvanized bolts or zinc coated be a bad idea?