Boyfriend signed up for the navy, could he possibly switch to the army?

My boyfriend signed for the navy before we started dating, and i dont like that at all. We're both currently seniors in hs school and plan on getting married after graduation. I'm a army brat so im pretty familiar with military lifestyle, but im not to keen on being a navy wife. From what i've heard sailor are almost NEVER home with thier families, and can stay on sea for up to 6 months. WTF?! like seriously? why? My papa was NEVER away from us that long, except for when he went to Iraq and Kuwait. So why do sailors have to be on sea that long? could my bf possibly sign up with the army or air force still?