Steel Hull - What 2 part epoxy primer in US?

[Asa Hammond]

Hello, I have posted before about the 42 foot steel hulled sailboat I am refitting / restoring/ rebuilding. I would like to get the community recommendations on 2 part epoxy primer and paint systems people recommend for a steel vessel available in the US (California). Should I use something different for the interior vs the exterior? Above vs below the waterline?
I will be painting during the upcoming summer months, 70-100F degree heat. I am sandblasting the hull first. It is possible I could spray, but also could just brush/roll it on.

Any and all bombproof solutions you have used would be appreciated.

Thank you!

Asa

 

[comfisherman]

As a young man I think I blasted the inside and out of about a half a dozen big commercial steel fishing boats and the prescription was always two coats of 302 topped with two more coats of 235 and then whatever top coat over the top usually worked with that. That's what we primed above and below the water lines fish holds lazarettes and engine rooms. Always blasted before and coated rather quickly with the 302 first coat.

 

[fallguy]

Com has far more experience.

I like working with Interlux 2000e on fiberglass.

Curious if he knows how it compares..

 

[comfisherman]

I like 2000e for a general 2 part. Have only used maybe one or two kits. For the $ 235 is one of my favorite things, it's not uv stable but it's tough stuff. Way up nort I've used it for sacrificial deck coating on boats where no one was willing to re gel or use a lesser top coat.

We would blast then acetone wash the dust then roll a coat if 302 on, that coat was followed by spray coats of 302 and after that 2 to 4 coats of a 235 or equivalent.

Keep in mind these are 50-100 foot commerfisl fishing boats where weld seams aren't faired and post blast I found base adhesion was better rolled than sprayed. On a fairer hull I'd still manually make sure full permeating coat on seems but probably spray the rest. 302 takes some heavy duty equipment, we had a commercial airless that would push it but only just and needed some thinning temperature dependant.

 

[jehardiman]

Most of my work was with military vessels. Standard was MIL-24441 150 ("Chrome" Green but not chrome now) primer, then 151 (Haze Grey) or 152 (White) base coat, then another 152 (White) or 153 (Dark Grey)/156 (Red)/160 (Black) topcoat. Lasts about 10-15 years external and takes pressure washing, but make sure you paint the exposed edges twice as that's where it wears as it stays fairly soft. You can paint anti-fouling/ ablative/ or teflon over it.

 

[rangebowdrie]

I've not used the 302, but I'll second the use of the PPG Amercoat 235 for a primer over what you choose as a "pre-primer".
Shortly going to be doing my deck and cabin, (fiberglass,) and the 235 works for that also.

 

[comfisherman]

Yeah it's a pretty solid go between product. I've abused the heck out of it on commercial boat decks, quite frankly nothing holds up forever and the 235 does great per dollar.

 

[Barry]

http://pacificsouthwest.net/wp-content/uploads/2017/08/302H_PDS_AI.pdf

It would appears that the recommendation is for a 302 Dimecote primer followed by the 235 amercoat. As per the attached sheet
A couple of important items:
1) Amercoat has the equations to determine how thick the coating has to go on WET, Wet film thickness, to realize the Dry film thickness value. The important facet of the primer is that it
has to cover the peaks of the particular level of the sand blasting was done to. This is to ensure that the peaks are completely covered by the minimum film thickness
2) You can purchase a wet thickness tool for about $10 to ensure that as you are applying the paint, you can check the thickness as you go and if spraying can go back and add a bit where
necessary during the process
Link and some information---https://carbit.com/predict-thickness-paint/
Note that this needs to be done on a pretty flat area of the boat as aggressive curves within the 4 inches of the tool could impact the accuracy of the reading
3) There will be an MDS sheet that will offer information about the VOC's. A "free air" system ie clean air pumped to a respirator is the best but if you decide to do it yourself, then it is
a wise choice to purchase a respirator with the APPLICABLE filters to take out whatever solvent/flashing vapors will be. All to often people will purchase either a pure particulate
filter or a standard carbon filter. Adding a thinner almost always adds to the dangerous fumes coming out of the coating during painting. An airless sprayer reduces vapor production and is
recommended
Link attached- https://multimedia.3m.com/mws/media/639110O/3m-respirator-selection-guide.pdf

There was some information that they do not recommend rolling the 235 unless it is brush "tipped" to remove bubbles

 

[Asa Hammond]

Thank you for all the great info! The boat currently has Amron 235, I am not sure what primer it is over. Are there any concerns with the zinc in 302? I have heard various forms of grumbling about it, but I like that its holding up well on fishing fleets. My boat is a bit more of a ship than a yacht I think in terms of aesthetic( no ss brightwork glittering about, mainly galvanized steel, or painted steel, or bronze), so a bombproof workboat recipe would make me happy. I am now considering how much to sandblast as a bunch of the interior looks good and has 235 on it. Some areas need help and I could blast and then 302 + 235 them. Or is 302 overkill for the interior?

 

[comfisherman]

We started doing it on everything about 15 years ago. The 302 is caustic stuff, and it's not easy to apply but gave us good results. A full face mask organic would be my minimum. Just a mask and your eyes will burn for days. I've sucked it up and gone full Sar, but understand that's not practical for diy guys.

I'll be perfectly blunt, good blast matters more to me than what it's coated with. Having worked on and owned numerous steel vessels the blasting with a rapid dust removal followed quickly with coating works, could probably us rustoleum or Wal mart Rattle cans on the proper surface prep beats even the best coating without good surface prep.

To me as long as prep is good and application is within paint spec parameters, it should work.

302 tips and tricks are use it fresh, from a supplier with new stock, it's very dense and needs a lot of mixing, biggest batch is best results. I've seen it be finicky mixing smaller touch up batches. It also doesn't self level into welds without manual pressure. We always used a light nap roller over heavy on seams to make sure it got in there. Joke is, if you Prime all day and don't have sore wrists it wasn't applied right. Obviously this is subjective as the surface of a 75 foot steel vessel is a bit more work than a pleasure boat. While not a issue in normal America, it's 2 in the evening in June and my truck says it's 53f outside. So we always wrapped our buckets in heating blankets so it flows through the airless. I've coated down to freezing on some boats, did one of my old boats in 2012 in the cold and saw it the other day hauled and the paint is holding up well considering 10 years and the cold snap we painted in.

 

[jehardiman]

I'll be perfectly blunt, good blast matters more to me than what it's coated with. Having worked on and owned numerous steel vessels the blasting with a rapid dust removal followed quickly with coating works, could probably us rustoleum or Wal mart Rattle cans on the proper surface prep beats even the best coating without good surface prep.

To me as long as prep is good and application is within paint spec parameters, it should work.

+1

 

[jmwoodring]

Can you recommend any shipyards in AK or on the west coast for blasting/priming/coating of larger steel vessels? Or DIY friendly yards where you can do work yourself?

 

[comfisherman]

How big a boat?

 

[jmwoodring]

The vessel I'm interested in is about 80' LOA and 91 Net tons. A high end shipyard that specializes in super-yachts recently spit-balled around 100k for sandblasting and new coatings for the hull and topsides. I imagine they would do a professional job, but I would be interested to get some more quotes and think about other options. I'd be happy with a work-boat finish that I rolled on myself, provided I was confident the coatings would hold up. I'm not a professional painter, though I have rolled and tipped a number of hulls over the years with good results.

 

[comfisherman]

Homer Seward and Kodiak have lifts in south central capable of that work. Seward requires pretty expensive premiums for work, at least in my case the increase in my normal premiums offset the cost of just doing the work in Homer.

I'm not sure you could beat 100k with the big boat haul out in Kodiak. The city couldn't handle management of it so has a private public partnership with a local shipright. They do good work but at eye watering prices.

Homer is capable of doing the haul and have started having big boats blasted there. They are incredibly diy friendly, but they are heavily tidal dependant and it makes a big line for doing work on the bigger platforms. If you're planning on doing winter work it's kind of tough cuz it flat out fills up this time of year.

100k isn't out of line. 81 ft for a full exterior blast is not horrible. Probably looking at 10k in blast shield walls, haven't bought blast media in a while but would guess it's gonna be 5-10k in media. Primer and paint is gonna be another 10k. Then you have haul out and storage costs plus equipment rental. So a full blast and paint is probably realistic about half a yard.