GT23

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fallguy1000
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Re: GT23

Post by fallguy1000 »

I have never used a vac pump to remove air from manually mixed epoxy. fyi

If you experience bubbling after application; that will be caused by outgassing of the substrate and will decrease with subsequent layers.

epoxy cannot be the final finish
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pee wee
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Re: GT23

Post by pee wee »

fallguy1000 wrote: Sun Feb 11, 2024 2:37 pm epoxy cannot be the final finish
Why not? I know it will degrade in sunlight (UV rays), but the bottom of the boat won't get much light on it. Other builders have said it holds up pretty well unless you turn the boat over to store it, although after a number of years it could turn chalky on the sunny side. I guess it depends.
Hank

TomW1
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Re: GT23

Post by TomW1 »

To get a get a smooth coat with graphite first strain it through a fine kitchen strainer and add to only the epoxy part of the mix no hardener yet. Once thoroughly mixed add the hardener in and mix well in. You should have a glossy shining bottom. For max protection 3-4 coats are ideal. Stir slowly to prevent bubbles. It will be as smooth as neat epoxy and provide the protection you need when beaching. I have seen some so shiny that they made me blind, the key is to put it on, on a warm day. I would never put neat epoxy on the bottom it will only last 3-4 years and when beaching less. Lots of guys have used it and have no complaints.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

drbobopp@gmail.com
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Re: GT23

Post by drbobopp@gmail.com »

You can bet that on my next build I will adjust my use of graphite... too late now. Live and learn. I've got it sanded smooth, and coated with epoxy.
Just need to find an off-ramp, some 'final coat' for her bottom. Was going for the neat epoxy, but now I am awaiting fallguy's reply to peewee's question, as to why epoxy cannot be the final layer on the bottom. If not epoxy, what?

jbo_c
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Re: GT23

Post by jbo_c »

Graphite-epoxy is a common final coat here for boats that won’t be left in the water, as is a good quality top-coat.

Neat epoxy will degrade in sunlight. It’s up to you whether you are concerned with how much it will degrade on the bottom of a trailered boat.

If it will be left in the water more than a few days at a time, a true bottom-paint of your choice is in order.

Given that you’ve already done a graphite-epoxy mix, you could do nothing more, or if you’re unsatisfied with the “quality” of your current final coat, do one more final coat. My stance is that anybody who complains about how the bottom of my boat looks needs to find a new way to get on the water.

Jbo

fallguy1000
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Re: GT23

Post by fallguy1000 »

Epoxy has no UV protection. So, a trailered boat means the sun will chalk out the 'bottom' or hullsides as quick as the sun reflecting on it or hitting it can be...

Once this happens; you have to sand to remove the white chalkiness..before anything new is applied

If you go the following year for a week or two somewhere; that chalky crud is a great place for sea critters to latch onto.

If you are parking the trailer on grass; you can get away with the idea, but I'd put a paint that will tolerate trailer and immersion.

For the hullsides, I'd paint those to 3" above dwl with some type of paint for looks and sun protection.
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fallguy1000
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Re: GT23

Post by fallguy1000 »

Another option is a few neatcoats, sand, and then a graphite coating done right.
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TomW1
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Re: GT23

Post by TomW1 »

Going along with fallguy don't know how many neat coats you have on now but just go ahead and put 3-4 layers of graphite on now. That will protect the bottom from any landings, sand, small gravel, shells, even smooth concrete.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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BarraMan
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Re: GT23

Post by BarraMan »

I faired the bottom of my boat then:

- rolled on 2 or 3 coats of neat epoxy to seal it
- followed by 4 x coats of graphite/epoxy made to Cracker Larry's recipe, sanded with medium grade wet-dry paper between coats (I got a very nice smooth finish and will post a couple of pics tomorrow!)
- then 4 x coats of epoxy primer (sanded back somewhat), 2 x coats of 2 pack polyurethane under coat and 2 x coats of 2 pack polyurethane top coat

I'm not convinced that the epoxy/graphite provides much rub protection. 8O

TomW1
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Re: GT23

Post by TomW1 »

A graphite-epoxy bottom will last forever. Mine was 12 years old when i sold it to another member. It was straight graphite over the primer. If you put it on over neat epoxy rough up the epoxy with 80 or 120 grit sandpaper.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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