What do you mean "open sea"
If you have a good VHF radio
to receive weather
forecasts and the good sense to listen to them sailing 100 miles (20 some hours) off shore will give you plenty of time to retreat to shore in case of bad weather
- If - the shore offers safe harbors that do not close out 18 hours before the storm. Most any 30 footer will work
in that situation.
I've made a number of trips from the NW coast of the continental US to the Western Coast of mainland Mexico
and have met lots of people with cheap
24 - 30 foot boat that had no problems.
At this time friends are doing the Baja
Bash (Cabo to San Diego) in a Catalina 36
I had friends sail non-stop from Cabo to the SW tip of Vancouver
Island - (way west Canada) in a light cheap
32 footer - 42 days non-stop.
I knew two couples who sailed all over the Sea of Cortez
in a McGregor 26 but were really careful about timing.
Another couple I cruised with from San Diego
thru the Sea of Cortez
to Zihuatenejo Mexico
(way south) were in a Mariner 32. We went thru a number of snotty 35 knot
blows and their boat did fine.
I just had a new acquaintance over for a beer
this afternoon on our boat in San Diego
. He had never been on a sailboat in his life - flew to San Francisco
and bought a beat up old Newport
30 - spent two months fixing it up and sailed it to San Diego (Monterrey to Pt Conception and around to Santa Barbara can be as challenging as most any water
out side the high latitudes) and is now living aboard
here in San Diego. He said the trip down was "interesting" but he survived and is now planning to continue south to Mexico.
So - it is darn near impossible to give you an answer without knowing where you are going to sail, your sailing attitude, your feeling about risk, and how much money
you want to spend.
Another choice of a stout go any where 30 footer is an Alberg 30
. I sailed one all over Puget Sound
and the Salish Sea and was very impressed with it.
I sailed a lot with a couple on a Ranger
33 - very stout and fast. I use to race
them in the early '70s is some rough weather and always liked them.
Continuing on the Yankee theme suggested above - I raced a lot on a Yankee 28 and was very impressed with how it was built and it was quick.
You really need to sail those old IOR boats before you buy one. They were designed to beat rules and had some quirks of handling. Some people didn't mind their squirrelieness - others hated it. (I do know the R-33 was not an IOR boat but most Rangers (29, 32, 38) were as were all the Yankees I knew.) I loved all of them but we raced with big experienced crews... and still broached and death rolled on occasion.
My closest sailing friends left Seattle
in 1999 in a 1967 Columbia
and have sailed to Bermuda
twice and have been in the Mediterranean
Sea for five years and 5,000 miles. After two rough trips from Florida
they decided their old Columbia
should be shipped to the Med (this is after sailing 10,000 miles from Seattle
to Cartegenea to Bermuda)
So a really old Columbia could be a cheap choice and if you have the wisdom, of my retired USCG officer friend, if could be a safe choice.
Their are literally infinite possibilities.