Even with the big tips on a dump gun . Still have to thin?
Pretty sure you are going to have to thin.
I will tell you what I Can. I'm having to learn my way too.
I have done painting.., years ago, but not gel.
And I researched(a LOT) and read and talked to several buddies that paint and to others that do gel.
But I am also not going to sugar coat this as in you may not like everything I say.
You said you have hplv...
What I bought was HVLP and I have 4.8mm & purchased extra 3.5mm just in case... And pretty sure I will have to thin.(with those gigantic tips)
1st. off you might as well figure on a Lot of sanding and polishing even if you have a perfect spray.. Thats just Gelcoat. it doesn't spray anything like paint. you can just forget a smooth slick finish with gel out of the gun without shooting in a mold. And you are not doing a mold.
Again sanding, A Lot.., then polishing or clear coat over.
You have to spray it thick enough not only to cure but allow for all the sanding to get it smooth.
Every gun sprays different, everybody sprays different, even most gels will spray different from brand to brand, and things change too from what you thin with and how much you thin. THEN.. you have temperature and humidity like others have already said. Not to mention if you start spraying outside in the shade and then the sun hits it directly. and if the sun hits it you probably won't outrun that.
And you should be running some sort of air dryer if you haven't heard or know that already.
Another thing, are you running waxed or unwaxed. And you have to spray and get it thick enough to cure properly and getting the mekp ratio is another key and adding enough to overcome whatever additives you add and again Temp.
There is a lot to this and getting things to halfway turn out takes effort and a little luck helps.
And if you don't have at least 5Hp compressor, you may have air problems to boot. not enough air flow, And thats a whole different cascade of problems. Compounded with you trying to learn you'r way.
I will be running (2) twin tank compressors totaling 13.5Hp with an additional tank. just for reference, I don't want air problems. Air is 1 thing I CAN maintain control of.
1 Thing I can tell you for sure.. you need to flush gun with acetone between coats, If it ever starts kicking off in gun you probably can throw Another gun in the trash.
That has been repeated to me several times.. by many sources.
I plan to practice with at least 1/2 gallon, no way I am starting on my boat with just blindly trying to get it right by chance.
And if you think gel is expensive, and you bought cheapest thing you could find you have that as an added possible problem too.
You could always hire it done if it's too expensive.
If you continue on your boat, you are probably going to have a nice big mess.
With all the seemingly bad things I said. its just blunt truth.
I hope you find something different to practice on.
Get your gun dialed in..
Get to where you can make a good consistent pattern and blend.,. thats on flat and in corners and around edges.
Then your confidence should tell you if you'r ready for the boat.
best of luck.