CRABS

I got a cheap water dtctr and yeas I find alot of stuff in the water but its not deep. 2-3"only.

Most my finds are between 4' to 6'. Snorkl or dive tanks a must at the deeper side.
Or just take a deep breath

One of the best ways for a newbie to learn is to hunt with someone or someones that has hunted before. Don't worry about looking silly, there's very very few seasoned hunters that can't remember when they started and how they felt.

Hunting with others does a number of things.
You can see and learn other styles.
Bad habits are harder to get ingrained.
Competition is motivation.

A good example of a water proof box is in Andy Sabisch The Minelab Explorer Etrac Handbook page 127 but" OMG" buy trhe machine materials and machining time or cost ...just buy a machine for use in water a few popular ones out there unless you are partial to your super machine ...hope its sealed