Hi Repsol and welcome to Scale Models. Nice to see another R/C boat modeller amongst the ranks!
If your hull is balsa, as your title would indicate, then I would definately recommend getting some strength into it. If you don't the slightest knock will result in a hole and a lot of tears!!
I would buy a tin of fibre glass resin, Halfords do a small tin with a hardener, mix it up and paint it on. The first coat will soak straight into the balsa but the second coat should stay on top of it. Rub down between coats and wipe over with a thinners afterwards to clean any traces of wax off it. Then a couple of light coats of Halfords primer, followed by a very light dusting of matt black. When you rub the matt black away any imperfections in the surface will stand out and you can apply a bit of filler before rubbing down. Then another coat of primer before two or three top coats of Halfords acrylic car paint of your choice.
No I don't work for Halfords but you get get everything you need under one roof! If you haven't got a Halfords any car paint vendor will do.
You will then end up with a hard durable surface that will take the odd knock and scrape without risk of loss.