anodized bolts?

[rbh]

still have a month and a little worth of boating left to do, but then its time to pull the motors (twin 260s)and pull the legs and redo the transom seals, and clean and paint bilge area.
one thing that I have noticed is some of the bolts on the inside of the transom have very rusted heads, and who knows how bad the rest is?
question is do they make a anodized grade #5 , #8 bolt, and because the leg transom plate and the bolts are disimaliar (sp) metals, should you coat them with any thing?
thanks
rob

 

[rbh]

Re: anodized bolts?

any one want to take a stab at this one.
thanks
rob

 

[proxyx]

Re: anodized bolts?

not sure, but shouldn't they be stainless?

 

[wca_tim]

Re: anodized bolts?

aluminum just isn't as strong as steel - not nearly as strong. - especially on a per unit cross sectional area, volume, bolt size, tc... basis. to say that the strongest grades of aluminum are as strong as some grades of steel is based on weight. that is the aluminum would have ot be three times as thcik as the steel. however, since aluminum weights about 1/3 as much as steel... they're about the same strength for a given weight.

no way there are aluminum bolts that will match a grade 5, 8, etc... steel bolt in strength.

anodizing, especially if you're talking hard anodizing / hard coating, covers the surface of aluminum with an extremely hard coating that won't conduct electricity but doesn't add much strength to a bolt.

that's what you see stainless used for most fasteners that require a significant amount of mechanical strength...

 

[gadget73]

Re: anodized bolts?

Stainless is not always the best material for a given situation though. It tends to gall the threads, which can be just as bad as a rusted bolt. Depending what its threading into, you have to be careful about mixing metals like that. Honestly, you might be best off just replacing the bolts with the same material as original, and giving them a good coat of paint to help ward off rust problems.