G3 Gatortuff rear deck pedestal mount

[born2climb]

Took my fishing buddy (84 yeas old) fishing yesterday. Had a good day. I caught  12, he caught 11. But about halfway through the day I noticed the front two screws were backing out of the base of his seat, where it's fastened to the deck. I tightened them back down, but realized they're stripped.  By the end of the day, five of the six were backed out, with one faithful screw holding on. There is no access to the inside of the bench where it's mounted. Has anyone else had dealings with the G3 Gatortuff boats and this issue. I'm wondering how to remedy the situation. Considered going to larger screws, but if they're just threaded into the aluminum deck, they'd strip too. Considered rev-nuts. Thought about mounting the base to a piece of 2x12, and screwing that to the deck, which would spread the pressure out over a larger footprint. Any and all advice appreciated.

[Susky River Rat]

Have you considered using stainless steel rivets? 

[born2climb]

Into the aluminum skin alone? I removed the base today to see what’s under it. The bench is foam-filled, with a 1/2” layer of plywood atop the foam. 

[MN Fisher]

11 hours ago, Susky River Rat said:

Have you considered using stainless steel rivets? 

I'd much prefer riv-nuts and bolt it in place.

[Susky River Rat]

I was under the assumption they were only into the aluminum deck and that there was not wood below it.

 

 

[Scott F]

Riv-nuts will never hold up to the stress of a man rocking on a seat pedestal. Also, using stainless steel connected to aluminum will cause galvanic corrosion and causing another failure. You might have to consider cutting a hole to provide access to the under side where you can put bolts or screws through and get nuts on them. 

[airshot]

38 minutes ago, Scott F said:

Riv-nuts will never hold up to the stress of a man rocking on a seat pedestal. Also, using stainless steel connected to aluminum will cause galvanic corrosion and causing another failure. You might have to consider cutting a hole to provide access to the under side where you can put bolts or screws through and get nuts on them. 

If it were mine, I would seriously consider backup nuts with bolts from an access hole if possible.  However, I have had great success with rivnuts, often folks use ones that are to small for the job.  Also the initial hole to install these submits needs to be snug !  If hole is sloppy the rivnut can easily fail.  I have them on my Side x Side ATV to hold the tree kickers onto the frame.  2" dia x 1/8" wall steel tubing bends and no rivnut failures.  When buying SS fasteners, carry a magnet to test them, if any attraction at all then the fasteners are not pure SS.  When pure SS is used, any corrosion will be so slow you will outlive it by a long shot. My 1983 aluminum boat has real SS screws in there for over 40 years and not one sign of corrosion.  Fake SS can be a real problem....check closely.

[MN Fisher]

4 minutes ago, airshot said:

When buying SS fasteners, carry a magnet to test them, if any attraction at all then the fasteners are not pure SS.

And I would use the Aluminum Rivnuts in this instance...not steel ones. Then as Airshot says...true SS for the bolts.

[Susky River Rat]

1 hour ago, Scott F said:

Also, using stainless steel connected to aluminum will cause galvanic corrosion and causing another failure

If there isn’t electrical current running through it how will this happen? Also aluminum with stainless rivets get used all the time in the fleet truck world. 

[MN Fisher]

5 minutes ago, Susky River Rat said:

If there isn’t electrical current running through it how will this happen?

Galvanic corrosion happens in wet environments when the water is impure (not distilled)...doesn't take electricity running through it.

[Susky River Rat]

@MN Fisher so how is using a stainless bolt going to avoid this when everything else is aluminum? It’s above the waterline. 304 stainless is 304. Doesn’t change if it’s a rivet or bolt. I agree if he has access rivets are not the best. I am just confused that a bolt won’t cause it but, a rivet will.

[MN Fisher]

2 minutes ago, Susky River Rat said:

@MN Fisher so how is using a stainless bolt going to avoid this when everything else is aluminum?

Pure stainless will still cause it (see Airshot's post on identifying pure stainless) - just no where near as fast as 'commercial grade' stainless. They don't sell rivnuts of pure stainless, but they do sell bolts made of it. Aluminum rivnut in aluminum seat with a pure stainless bolt is gonna be about the best if you don't have access to the underside.

1 hour ago, airshot said:

If hole is sloppy the rivnut can easily fail.

Best thing is to make the hole a size where you have to tap the rivnut in before you set it...not pound it in...just a few light taps with a weighted or rubber mallet.

[Susky River Rat]

@MN Fisher what is pure stainless? It’s impossible. There is different grades of stainless but no “pure stainless” 304 and 316L are the two most common grades. There is chromium and nickel in ALL stainless. It’s an alloy. 

[MN Fisher]

4 minutes ago, Susky River Rat said:

There is chromium and nickel in ALL stainless. It’s an alloy. 

And molybdenum too - but you're wanting a low carbon stainless...either 304L or 316L - with 316L having better corrosion resistance...most dive equipment (regulators, etc) is made from 316L for this reason.

[Susky River Rat]

@MN Fisher technically all stainless is low carbon steel it’s the 10.5% or more of chromium  that makes it corrosion resistant. Not all low carbon steel is stainless though. 
 

low to mild carbon steel is usually classified as up to 80k tensile strength. A36 low carbon mild steel being the highest. 

[airshot]

Nickle makes it resist corrosion, the more Nicole the better, a magnet won't be attracted to nickle.  Being an alloy, SS can still corrode with dissimilar metals, but you probably won't live long enough to see it !!

[born2climb]

I decided (before going to too much trouble), to simply replace the six 1/4” screws with 5/16” lag bolts. Seems quite secure.