Advice on portable gelcoat spray system

I do a lot of small gel repairs on fiberglass boats in boatyards and marinas and have been using the Preval Spray to do them which works okay for small areas. However, sometimes I have a larger repair area and would like to find or create a mobile spray system but have no experience with what I would need or if it's feasible.

My thoughts were to have a small air compressor with a gun system. I would hope that the finish comes out better than the Preval as well. However not sure if a small portable 6-15 gal compressor is powerful enough to work a spray gun effectively. Thank you in advance for your feedback.

 

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You want to reach out to member @ondarvr or see if he responds now. He is an expert on such.

 

I have used the small Harbor Freight gravity fed spray guns for years. They can be thrown away instead of cleaned.

 

It sort of depends on how much you want to spend, super cheap, cheap, or more.

You can get adequate performance from even the lowest cost stuff, and it will typically be reliable enough. Take one step up in price and you get a significant improvement in quality.

The harbor freight cheapie used to be my favorite, it worked OK and you could drill the tip out from the stock 1.4 to 2.5 if needed, and for gel coat it is.

The newer version of that gun can be tricky to use, I bought several before I knew they had changed the design. On these new models if you take the nozzle out it won't seal correctly when you put it back in and it won't spray. It also makes it difficult to drill the tip out. I don't know if there's a work around for this yet, but there might be on YouTube.

These could still be a good choice if the 1.4 tip works for what you do, and instead of talking it apart you just flush it well. Or at the sale price of less than $10, throwing it away is an option.



The super cheap small air compressors work OK too, there are a bunch out there for $50-$100, and while not great they do work.

What I use now is the $38 off Amazon with either a 2 or 2.5 tip, for gel coat the 2.5 would be better.

I use that with a Harbor Freight Fortress air compressor. It's extremely light and quiet.

For small repairs you don't need a large compressor, but this model is light and going bigger than the smallest one is better. Especially if you plan to do larger repairs.

If you plan to spray an entire boat, the bigger the compressor the better.

 

I use a modified airbrush. Like this one.

 

Yes, a small portable compressor can work with a spray gun for gelcoat, but it must meet the gun’s CFM and PSI requirements. HVLP or gravity-feed guns are best for smooth finishes, though small compressors may need breaks on larger areas. Using a proper spray gun will generally give a better finish than a Preval.

 

Had to do a remote job that required a small plane ride in, ended up buying a new compact dewalt compressor. It was the highest cfm rated 120v compressor we could find. Its got an extension cord as big as your thumb, definitely pulled hard on the generator we used to push it. Set it up with a portable tank that was 15 or so gallons, the combo seemed to keep up with a 2.5 mm nozzle on a repair that ended up being about 130 square feet. Certainly worked better than our prior attempt at daisy chain of some little pancake compressors. Was compressor D55146 for a part number.

Still had to go slow and methodical, with a helper mixing smaller batches. Turned out pretty good for a commercial boat, didnt take a ton of sanding to make it look "good enough".

 

HVLP gun and a pair of scuba cylinders with the appropriate regulator.

 

I am not sure what flow you could get from a first stage regulator. Assuming 10 CFM at 140 PSI for a small spray gun, a standard 80 cubic feet tank would get at most 7 minutes of work. Even a small job would require a huge bank of tanks. A gas operated compressor is more convenient.