what is best a u shape float tube or a round float tube in salt water

For salt, a round tube is best, because they are more stable. You don't need an expensive tube, 85 ar 90 dollars tops. Check out Cabellas ar something.

Word. Actually, my next float tube will be the caddis proline, which is like $130, but I use it a lot and use it for more than saltwater, so for a beginning "entry level" float tube, all you need is something to get you used to the concept. Once you wear that one out, you can step up if you want to.
-Brian

dude
go bargin basement round tube all the way.
My lews cruiser tube has lasted me 6 or 7 years and it cost 100 bucks.
U boats get murdered in the waves. Just ask Jamon, he flipped his uboat twice down off Ventura

Don't know about them round tubes, but I had a u-tube for a spare. I sold it because it felt really unstable. But, I'm 270lbs and it was too small. Plus, I'm used to my Navigator II. That I do like. As for getting it out in waves. Well, I guess I'm just smart enough to launch in coves where there isn't any waves. Doh!
I actually do choose areas to launch that are protected. Where I tube (in Laguna Beach) it is pretty easy to find a protected cove. Rob and Brian are the guys to talk to about "real" surf launchs.

Amish Ed

I also like the round tubes. I have not used anything else but know people who have and most of them have round tubes now. I used the Caddis "High Sierra" or "Deluxe" for years and it was great. I now use the Proline II and love it.