Any ideas how to paint my submarine like this box art?

I am assuming you mean the spots and light refraction from the water?  I would approach this like a grid drawing and literally draw a grid on the model on the box.  Then lightly draw it on your primed plastic.  From there, using a pencil, make the square on the model look like an outline of the square on the box.  Then apply paint using blue and grey mixed at varying ratios with some white added for lighter spots, and black for darker.  

I am of course completely spitballing, but I think it would work.

Groot

White chalk possibly,but I dunno

Had another random thought, I remember seeing a model sub with a clear water surface mounted above it.  I thin it was a thin piece of acrylic carved with a rotary tool and polished.  In any event, it looked like a slightly choppy water's surface and was suspended by a missile exiting the sub and the plume with it.  The model was not enclosed inside any kind of resin or acrylic, just had the sheet above it.  Using something like that and some tinting and lighting shining through it you could probably achieve the same effect, possibly with a box around the model with one open (viewing) side.  Let me know if I'm not explaining well and I'll try to draw a diagram or something.

Groot

Cool idea!   I've seen a few subs painted that way and nobody really offered an easy solution to creating the paint job.  It was usually the result of experienced airbrush work.  If I had to pull one off, and I'm NOT a talented airbrush artist, I'd look at underwater reflections and try to dissect them into layers and try to find a way to simulate them using different masking techniques.

To replicate the pic above I might try to find some type of material that, when pulled/stretched looked like the light reflections in the photo and use it as a mask over a light base coat through which I'd spray the sub color.

Another option might be to take some flexible caulk/silicone and make a wavy surface like the above on some type of flexible material, paint the sub as usual, clear it and use the caulk surface like a rubber stamp to apply white oil paint to the model then use a brush to feather out some of the reflections.

Please note: These are just ideas.  I've never done any of these.  No warranty is expressed or implied.

Good luck!

Given the amount of surface texture/stuff on sub kits, I might be tempted to find an image like the one above and print a decal from it.

This would probably mean having to do a 'fade" paint job on the hull, going from full dark on the sides, then lighter on top.

Just now, I'm dithering over whether a person would want a flat finish over that, or a glossy one, to look "wet."

I would think flat since most military subs are non reflective and even underwater light does not reflect off of dull surfaces the way it does glossy ones.  Didn't think about a decal... might be an aftermarket idea there.   Kinda like the wood decals for WW1 aircraft.

Kaysee, google "seaquest sub model".  It's one of the most common sub models that people do this kind of finish on. It might give you some ideas.

If you've ever been in the open ocean underwater, at a bottom depth of more than about 20-30 feet, there's really not much to see. I consider that painting to be fanciful in the extreme. Look at these guys diving on the AirAsia jet at 90 feet which is sunk at a small fraction of the length of that submarine.

They are fumbling around with artificial lighting and getting pretty murky images, in summer time tropical waters.

wow Groot, this idea sounds good but so costly ^_^

The first one sounds good but hard ^___^ but i do like it

hmm.....probably your idea might get the job done, thanks Raual!

CapnMac82

 .....to find an image like the one above and print a decal from it.

i hope some manufacturing company dude reads this and makes my day ;)

Thanks Mac!

CN Spots

Please note: These are just ideas.  I've never done any of these.  No warranty is expressed or implied.

haha........wth?  Those are GREAT ideas!  You can be sure my gratitude is explicitly expressed here

Innovative Model Supply has a product called Model Skinz, adhesive backed vinyl graphics.  They have a few water sheets: MG 3812 water features; MG 3618 water; and MG 3831 light blue water.