Now - im not a fisherman at all - but.
If all you want to catch is a few mackrel for the odd beach BBQ - this is what works for me.
A handline with a nice heavy 10 or 12 oz trolling weight then 10m of line with a swivel to a spoon spinner.
Chuck it in and tow it along at about 3 to 5 knotts (tickover on most outboards)
Not very professional looking but mackrel just jump on it - you can pretty much throw it in and pull it straight out with a mackrel on the end everytime (man them fish are dumb).
Other advantages are it cost less than £10, very small (ie stash it under the seat so its always there), Doesnt need any bait.
Disadvantage - doesnt look very cool like real fishing gear would, cant catch anything other than mackrel (well i havnt anyway).
If what you meant by "sea fishing" was a bit more serious than this - please disregard this post and wait for a proper fishing enthusiast to answer you.
What ever you do have fun