Ideal boogie board length/material?

I found a boogie board for real cheap today at a garage sale, so I bought it because it was in good condition. However, its made of this foam material similar to styrofoam, and I'm not sure if it will hold up as a dive float. Its about 3 ft. 8 inch long.

My sister also has one, and its made of a tougher foam material. But its only about 3 feet long.

I just wanted to know your guys' opinions on it. Thanks!

I don't like the brittle styrofoam boards. Costco has good ones for 25 dollars. Use a board that has enough floatation for you, three heavy abs and some gear.