Page 1 of 1

Question regarding how to properly finish a hull

Posted: Tue Jun 21, 2022 8:20 am
by MageDK
I was wondering, once you have a boat what are all the different layers needed to finish the hull and deck, and in what order should they be applied?

I am looking at the 28' Trawler and plan on keeping it in the water here in Miami. So I imagine the hull will need a layer of antifoul paint. What about a UV protection coat?

Re: Question regarding how to properly finish a hull

Posted: Tue Jun 21, 2022 9:19 am
by fallguy1000
Plywood and epoxy are faired and then painted.

Fairing is a process to make the boat sides and bottoms follow a fair line and not have ripples or waves.

Rick Laporte did a great video fairing a tw28. If you want to see it, I will look. Not sure it was any action.

After fairing, usually a mist coat of paint is done and more fairing to get to a perfectly smooth surface without waves.

Then epoxy primers are next. Epoxy primers are ultra high ashesion finishes used on the entire boat. My favorite is Interlux 2000e.

After the primer layers are applied, a sanding is done at least one or several times to get to 180-220 grit finish. Then usually, two part polyurethane paint is applied. It is a very hard paint applied just a bit past the waterline. After the topcoats are done, the boat is masked off to about 2"-5" above the waterline and the topcoat and primercoats are sanded and antifouling applied.

The choice of anti-fouling is usually localized, so in Miami, you'd need to go to a marina that is friendly and find out what people are using. A marina with a yard is best.

Re: Question regarding how to properly finish a hull

Posted: Tue Jun 21, 2022 6:34 pm
by OneWayTraffic
The amount of time you spend finishing a hull will be related to the quality of finish you are after. Regardless, any paint will do it's job of protecting the epoxy from UV. Above the waterline you could use latex house paint or expensive polyurethane. One will be more expensive and durable, but house paint is easy to apply and touch up. If you want to use an expensive two part paint then finish quality is important. A hard glossy paint will highlight every little mistake in fairing.

Re: Question regarding how to properly finish a hull

Posted: Tue Jun 21, 2022 8:40 pm
by TomW1
Fairing is the most important step in the quality of your boat finish, especially above the water line. Below the water line you want a good fairing job with no high or low spots. But above the water line if you don't get a smooth fairing job every high or low spot can be noticed. especially as the quality of the paint goes up. Most people use a high level two part paint these days as it is longer lasting, but higher cost. My suggestion is buy the best paint you can afford, you won't regret it.

Tom

Re: Question regarding how to properly finish a hull

Posted: Wed Jun 22, 2022 3:49 pm
by MageDK
Thanks for the feedback all. It helping me plan out what and how to get everything done.

Re: Question regarding how to properly finish a hull

Posted: Fri Jun 24, 2022 5:38 pm
by bklake
OneWayTraffic wrote: Tue Jun 21, 2022 6:34 pm The amount of time you spend finishing a hull will be related to the quality of finish you are after. Regardless, any paint will do it's job of protecting the epoxy from UV. Above the waterline you could use latex house paint or expensive polyurethane. One will be more expensive and durable, but house paint is easy to apply and touch up. If you want to use an expensive two part paint then finish quality is important. A hard glossy paint will highlight every little mistake in fairing.
As of this morning, I am a dissenter on latex house paint. I am re coating a wood center console I made for my skiff. Most of the epoxy has peeled off on the outside but is holding strong on the parts out of the sun. I used some paint stripper on the exterior where the paint was holding fast. The epoxy under the paint is cloudy and brittle. I think I made this console ten years ago and it has been in the sun every single day since. I used white acrylic exterior house paint.

Not one to give up, I'm going to epoxy coat it this weekend but this time I'm going to put a coat of black primer on first then the white paint. I'll be back in 10 years with an update. I would prefer silver paint used to protect aircraft fabric but the only thing more expensive than boat stuff is airplane stuff.

Re: Question regarding how to properly finish a hull

Posted: Fri Jun 24, 2022 5:46 pm
by Jaysen
bklake wrote: Fri Jun 24, 2022 5:38 pm I think I made this console ten years ago and it has been in the sun every single day since. I used white acrylic exterior house paint.
That stuff won't last 10yr on a house. I can't imagine it should be expected to last that long on a boat. If I was using "not marine specialty" paint I would plan to strip/repaint every 2-3yr just like with varnish.

That said, my crappy prep, crappy applied, and beat-to-crap EMC paint is still sticking and hard to sand off (in the areas that aren't peeling due to dust between layers). I would suggest that no matter what paint you use, you're in for the same cost. It's just a matter of cash flow management

Re: Question regarding how to properly finish a hull

Posted: Fri Jun 24, 2022 9:20 pm
by bklake
It's the same amount of work to properly apply any paint. Cheap paint that doesn't last or good paint that lasts a long time? That is a time vs. money question that only the person involved can answer.

My main observation on my console was that the house paint didn't stop the UV from degrading the epoxy. The paint peeled mostly because the epoxy failed. Underneath and out of the sun still looks fine.

The house paint was supposed to last 20 years. Said so on the can. Maybe I should have paid attention to the asterisk after that claim. Probably 20 ways that 20 year claim wouldn't be valid. Paint can long gone, no way to check.

Re: Question regarding how to properly finish a hull

Posted: Fri Jun 24, 2022 9:42 pm
by fallguy1000
Latex house paint is not even waterproof.

Ask me how I know.

All paints vary in adhesion and hardness and adhesion and hardness is what boat exteriors need.

Most latex house paints aren't even scuff proof, just sayin.

Re: Question regarding how to properly finish a hull

Posted: Fri Jun 24, 2022 10:11 pm
by Jaysen
Rustoleum porch paint refreshed every 2yrs worked to protect a FL14 pretty well. But that stuff is pretty hard.

Re: Question regarding how to properly finish a hull

Posted: Sat Jun 25, 2022 1:41 am
by BarraMan
I think my finishing protocol went something like:
Once finished glassing and fairing:
1) 4 x coats of epoxy sanded with 80 grit after the last coat
2) 2 coats of epoxy primer sanded with 120 grit after the 1st coat and 240 grit after the 2nd
3) 2 coats of 2 pack polyurethane undercoat sanded with 240 grit after the 1st coat and 400 grit after the 2nd
4) 2 coats of 2 pack polyurethane topcoat sanded with 600 grit between coats

Image

Re: Question regarding how to properly finish a hull

Posted: Sat Jun 25, 2022 4:13 am
by OneWayTraffic
Seems I got a few comments on the porch paint. I'm using some on mine, but not for exterior surfaces. Inside of compartments and other places that should not get exposed to sun or much abrasion. Regardless of the paint I think it's a good idea to store a boat under cover and out of the sun.

Re: Question regarding how to properly finish a hull

Posted: Sun Jun 26, 2022 6:33 pm
by TomW1
OneWayTraffic there are various grades of porch paints. I spent over $15 a quart for one that had a high abrasive content and a high gloss. I would not be afraid of using the right porch paint in my lockers.

Tom

Re: Question regarding how to properly finish a hull

Posted: Sun Jun 26, 2022 11:21 pm
by Fuzz
OneWayTraffic wrote: Sat Jun 25, 2022 4:13 am Seems I got a few comments on the porch paint. I'm using some on mine, but not for exterior surfaces. Inside of compartments and other places that should not get exposed to sun or much abrasion. Regardless of the paint I think it's a good idea to store a boat under cover and out of the sun.
So I take it this is not the best way to store a boat :lol:
Image

Re: Question regarding how to properly finish a hull

Posted: Mon Jun 27, 2022 8:37 am
by MageDK
BarraMan wrote: Sat Jun 25, 2022 1:41 am I think my finishing protocol went something like:
Once finished glassing and fairing:
1) 4 x coats of epoxy sanded with 80 grit after the last coat
2) 2 coats of epoxy primer sanded with 120 grit after the 1st coat and 240 grit after the 2nd
3) 2 coats of 2 pack polyurethane undercoat sanded with 240 grit after the 1st coat and 400 grit after the 2nd
4) 2 coats of 2 pack polyurethane topcoat sanded with 600 grit between coats

Image
WOW that finish looks amazing. So far this looks like the best way to go. I am going to be keeping it in the water most of the time and the Sun in South Florida is Brutal. I'm going to try and stick with good quality paint for the interior spaces as well. I don't think interior latex paint is going to cut it.

Re: Question regarding how to properly finish a hull

Posted: Tue Jun 28, 2022 7:10 am
by OneWayTraffic
Fuzz wrote: Sun Jun 26, 2022 11:21 pm
OneWayTraffic wrote: Sat Jun 25, 2022 4:13 am Seems I got a few comments on the porch paint. I'm using some on mine, but not for exterior surfaces. Inside of compartments and other places that should not get exposed to sun or much abrasion. Regardless of the paint I think it's a good idea to store a boat under cover and out of the sun.
So I take it this is not the best way to store a boat :lol:
Image
Out of the sun, and under cover.

Looks good.

We're just off the shortest day here. I managed to get some glassing done outside. With slow hardener. 60F in the shade at the middle of the day. Nicer in the sun. Bit different to Alaska for sure.

Re: Question regarding how to properly finish a hull

Posted: Wed Jul 13, 2022 2:11 pm
by bklake
Update to my update. I ended up stripping all the paint. It would seem that the areas I stripped first were over fairing compound. I didn't remember fairing anything so I assumed it was cloudy epoxy. Turns out the epoxy under the paint was a nice golden tan.

What did fail me was the Home Depot plywood. Just because the glue in it is waterproof doesn't mean the type of wood used is good for wet use. The wood swelled and contracted a lot causing the epoxy to crack and let water in. That is where the failure is. I posted about this console and wood about 10 years ago noting that it sucked up much more epoxy than any okoume I used before. I glassed the console this time using a bunch of scrap cut offs from other projects. The only reason I bothered to save it is because it fits well and it has all the holes cut for my stuff.

Just use okoume or meranti and good epoxy to save yourself a lot of grief in the future.

Re: Question regarding how to properly finish a hull

Posted: Thu Jul 14, 2022 8:58 am
by pee wee
bklake wrote: Wed Jul 13, 2022 2:11 pm Just use okoume or meranti and good epoxy to save yourself a lot of grief in the future.
This should be a sticky!! :D

Re: Question regarding how to properly finish a hull

Posted: Thu Jul 14, 2022 10:59 am
by bklake
Agree. One post, one sentence, closed for comments. :lol: