I/O (Sterndrive) Conversion to Outboards

[tpenfield]

Maybe use a wire cup brush in the angle grinder to get in the crevices

I'll try that . . . The main stringer is nothing but corduroy . . .

I did go back (just now) and hit some of the low spots.

This is what I'm trying deal with . . . Plenty thick on the outside, not so much on the inside.
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I did not want to grind too much more.

There is some of the corduroy in the background . . .

 

[tpenfield]

Epoxy over poly is fine. Poly and vinyl shouldn't go over epoxy. Gel can't go over epoxy either. There are bond coats that you can allegedly use on epoxy to put gel over it but I've never tried.

Due to the nature of the chemistry of epoxy, the other resins will not form much more than a light mechanical bond. Epoxy and it's chemistry will still form a really good mechanical bond over prepped poly/vinyl.

Without going too far into the rabbit hole of the chemistry.... poly and vinyl work really well in a chemical bond but don't form the best mechanical bonds. Epoxy forms a fantastic chemical bond and coincidentally also works really well in mechanical bonds. If you take a peak at the chemical work ups of each reaction, it makes more sense but only if you get chemistry... that's when you also learn that vinylester is like a hybrid of sorts of both poly and epoxy and is why it is popular in place of one or the other.

Since I'll be scarf joining and gelcoating, I chose to stay away from epoxy.

 

[tpenfield]

The wire cup wheel was a bust . . . it just can't get into the groves to any extent.

Since it is cold(er) and damp this AM, I started the grinding on the outside on the transom. Much better and goes fairly quick with the 'corded' angle grinder.
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The gelcoat on this boat is fairly thick . . . I'd say 0.045"

 

[Pmt133]

Maybe soften the ridges with MEK? You'd be in the wee bit aggressive camp of chemicals though.

 

[Lpgc]

The wire cup wheel was a bust . . . it just can't get into the groves to any extent.

How about a narrow wire wheel, radial type instead of cup type, run it along the length of the 'corduroy' grooves?

 

[tpenfield]

I'll just do the best I can on the inside. The outside (where it really counts) is going well though . . .
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I bought 20 flap disks (40 grit), and there are not many left. I've got some 60, 80, and 120 grit as well, but 40 grit is for the grinding.

 

[tpenfield]

I am out of 40 grit disks, which was fine for today, as I can only do so much grinding in a day.
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I'll be getting more 40 grit, because the underside of the swim deck needs some grinding . . . not the hole area, but where I want the contact points.