difference between offshore and fresh water

[crane]

Hello this is my first time posting and i am very new to all of this. But i do have one question i can't seem to find the answer to.
i was thinking about purchasing a kit and putting it together but was wondering if an 18 foot boat can be used for offshore fishing. I mean does it have to be a certain depth? (the hull). when i look at the pictures of some of the boats that they sell as kits. the boat sitting in freshwater looks more shallow then the same boat sitting inthe ocean.( the hull looks deeper). I don't know maybe its me but any help would be appreciated thanks.
crane

[Wynand N]

Actually, the same boat will float slightly higher in saltwater than freshwater.
Specific gravity of freshwater = 1000kg per cubic meter and seawater about 1024kg per cube meter

[crane]

Wow! thank you
i knew i wasn't going crazy.
thanks for the quick responce
crane