Not all "trawlers" are passage makers. The marine nomenclature used by mariners, boaters, yacht brokers, and marine architects or surveyors can be confusing, because not everybody has the same knowledge base. The definition of "trawler" to a salesperson or trawler express yacht builder can be very different than the same word used by a naval architect or a surveyor. A trawler is a full displacement boat and by definition cannot go much faster than its hull speed which is measured b
y the square root of its waterline times 1.34. For a 50-foot boat, that calculates to just over 9 knots, and if it can go much faster than that, it's not a trawler. But, if you go on YachtWorld and search for "trawler," more than 50% of the listings that come up are not trawlers.
The word "trawler" originated with the fishing boats that trawled the oceans for days or even weeks at a time, long enough to be able to bring back sufficient fish to make the trip worthwhile. For them to succeed on these outings, they needed to be able to have engines that could run for many days only on the fuel in their tanks; there are few gas stations out at sea. They also needed to be able to hunker down if the weather deteriorated, because the fishing grounds could be hundreds or miles from any port. In essence, these two necessities created the design for trawlers; long legs, which necessitated big fuel tanks and small engines, a big bow to protect the seamen from oncoming waves when the going got rough, and some sort of stabilizers to stop rolling in beam seas.
Don't be fooled by boats that look like trawlers, or call themselves trawlers, that are not trawlers. They are usually semi-displacement boats which can go as much as two to three times their hull speeds because they don't have round bottoms. They also usually have bigger engines. There are many, many examples, and to list just a few well-known brands: Beneteau Swift Trawlers (exemplary oxymoron), Grand Banks (one-way ticket to the Grand Banks), most DeFevers, Azimut Magellanos (Magellan's circumnavigation would have ended in the Azores), Ocean Alexanders, Island Gypsy, most Marlows and Flemings, etc. My rule of thumb to determine if it's a passage-maker is to look at the horsepower of its engine(s). A passage-maker doesn't need more than 50 horsepower for every 10 feet of LWL (length over water line) unless it's length is greater than 70-80 feet. And the bigger the fuel tank(s), the better. I like to see at least 1000 gallons for smaller passage-makers and 2000 gallons for those around 60 feet. The other reason for big fuel tanks is that they can serve as ballast (which helps with stability in rough seas), especially if the tank is down in the keel.
Trawlers are also equipped with some sort of active or passive stabilization. Because of their round bottoms, without stabilization and in a beam sea, they will roll, and roll, and continue rolling until everyone aboard looks and acts like little Martians with food poisoning. A sailboat also has a round bottom but doesn't roll (too much) because the sail(s) prevent the boat from rolling back windward in a beam reach. But, since (most) trawlers don't have sails, they need another form of stabilization. There are three forms of stabilization available: para-vanes (flopper-stoppers), fins, and gyros. All three have their advantages and disadvantages. I only mention stabilization because a passage-maker without some sort of stabilization is probably NOT a passage-maker.
If you find a boat that qualifies as a passage-maker with a full displacement hull, appropriately sized engine(s) and fuel tanks, and with some sort of a stabilization system, you now need to look at a plethora of other details that will make your passage uneventful. My recommendation would be to read "Voyaging Under Power" by Captain Robert Beebe. This classic written more than 40 years ago imparts passage-making wisdom still valid today. Although our technology has improved, especially with navigation, the bare necessities for passage-making required in the last century are still valid today.