This subject is often discussed here on CF, and in the end, it really depends on how YOU like to learn things.
The experience that you have gained o n your trailer sailor is adequate in terms of sailing skills to make the jump to the larger boat... lots of folks have made such a jump. But in terms of dealing with all the other facets of larger boat husbandry, well, you have a lot to learn! And learning
on the smaller vessel will be less expensive, and the lessons will be readily transferred to the bigger one later.
In my case, I went from a Catalina
22 trailer boat to a 30 foot S&S keel boat. That boat taught me so much... we raced her seriously, did coastal cruising in California
(meaning 300-400 mile passages coastwise) and eventually a SF-Hawaii round trip. After that cruise
, I felt that I was ready for a larger boat to do long term cruising
, and I had enough personal knowledge that I felt oK about buying
an older IOR one-tonner, even though everyone said it was unsuitable as a cruising platform. Ann and I lived aboard her for 17 years and cruised over 86,000 miles...
So, my personal advice is to buy your 30 footer, one that is old enough to not depreciate too much from simple aging, and don't try to "improve" her with expensive modifications. Do learn all about maintenance
, about all the systems on board, about coastal cruising (and you have so many wonderful coastal destinations in NZ), about wx and how it affects you when there is no trailer to jump back on when it gets crappy out... all the stuff that will serve you well when eventually you jump off for the tropics. Then sell and move up. Don't expect to recoup all the money
that you willl have spent on the 30 footer... that's unlikely! But consider the lost
funds as tuition expenses, and the price
for lots of fun that you will have had... and the cost for being able to wisely buy your next boat.
Worked for us... hope that you can enjoy the same successes.