What kind of bolts for aluminum handles?

[HRG]

Getting close to completion of a new build wooden jon boat. The outside of the hull is fiberglassed using epoxy resin. The boat will be used in salt water.

I bought aluminum duck boat handles, two for the bow and 2 for the transom. The handles will be mounted near the top of the bow plate and transom so they will be well out of the water. But there will be the inevitable splashing of salt water on the handles.

I planned to use 5/16" diameter stainless steel bolts to secure the handles to the boat but now I'm reading that stainless steel can cause dissimilar metal corrosion of the aluminum, especially in salt water.

1. What type metal bolts are used to fasten duck boat handles to commercially sold jon boats?
2. Is the splashing of salt water of minimal concern so don't worry about it?
3. Or are there steps to take to use stainless steel bolts to fasten aluminum hardware?

Thanks.

 

[Texasmark]

Looking at a metals compatibility chart, Aluminum is a Group II metal. Metals in group II are Aluminum alloys, Zinc, Cadmium and Beryllium. With that said, a Cad plated steel screw would be your best bet as long as in the installation you don't disturb the Cad. plating on the bolt......which shouldn't be a problem if you keep the bolt from turning and only use the nut for tension.

Metals in Groups I and III will have galvanic action but to a lesser degree than metals in group IV which includes SS and Copper/alloys. Except for Aluminum, Group I contains the same metals as Group II plus Magnesium alloys.

 

[flashback]

Most all the fasteners on an aluminum sailboat mast are stainless and they hold up fairly well..

 

[Scott Danforth]

I would have gone with stainless grab handles.

However since you have the aluminum. coat the bolts with Permatex aviation sealant when you install them. it will act as a sealant, a corrosion barrier, a galvanic barrier and anti-seize all in one application.

 

[HRG]

Texasmark, flashback and Scott,

Thanks for your research and suggestions. Since flashback mentioned that most fasteners on aluminum masts are stainless steel and they hold up fairly well, maybe stainless steel bolts for my duck boat handles might not be so bad.

Thinking about this before sleeping and this morning, I came up with a plan:

The aluminum duck boat handle has a 3/8" thick base where the bolt goes through. I'm going to coat the portion of the bolts that can contact the aluminum with epoxy and let that cure for at least 3 days. When I install the handles I'll use nylon washers under the bolt heads. I think that will isolate the stainless steel from the aluminum.

This experiment will almost be free since I already have epoxy left over from building the boat, though I will have to buy some nylon washers.

Thanks.

 

[Chris1956]

Silicon bronze was used on boats for a long time. So was chrome plated brass. I would expect either to be strong enough.

 

[HRG]

Silicon bronze was used on boats for a long time. So was chrome plated brass. I would expect either to be strong enough.

Thanks for the info.

 

[Bondo]

Texasmark, flashback and Scott,

Thanks for your research and suggestions. Since flashback mentioned that most fasteners on aluminum masts are stainless steel and they hold up fairly well, maybe stainless steel bolts for my duck boat handles might not be so bad.

Thinking about this before sleeping and this morning, I came up with a plan:

The aluminum duck boat handle has a 3/8" thick base where the bolt goes through. I'm going to coat the portion of the bolts that can contact the aluminum with epoxy and let that cure for at least 3 days. When I install the handles I'll use nylon washers under the bolt heads. I think that will isolate the stainless steel from the aluminum.

This experiment will almost be free since I already have epoxy left over from building the boat, though I will have to buy some nylon washers.

Thanks.

Ayuh,..... Yer waayyy over thinkin' this,.....

Slap it together with ssteel bolts, 'n they'll be there, long after yer gone,....