Marin,
You have defended your position concerning the name “trawler” eloquently. However, I think you have a fixation on the use of the boat rather than a description of the type of boat. If a fishing trawler is converted to a yacht is it no longer a trawler? Its configuration is the same but its purpose has changed.
Boats tend to be named for their purposes. It's the most intelligent way to define them since boats can have an almost infinite number of shapes, configurations and characteristics.
So you get battleship, patrol torpedo boat, destroyer (shortened from submarine destroyer), seiner, troller, bulk carrier, tanker, trawler, yacht, cabin cruiser, runabout, minesweeper, etc.
The vessel itself tends to be secondary. For example, in our harbor there is a Grand Banks 42 Europa (I'm pretty sure it's a GB42 but I've not been close to it so it could be a GB46.). It looks exactly like every other GB42 Europa on the planet.
But..... for whatever reason, the owner has installed a full-scale salmon trolling rig on the boat. Trolling poles and supports, gurdies, a hull extension on the back I assume to hold the fish, and a commercial license number on side. I've posted photos of it in the past.
So what is it?
Well, it's set up for salmon trolling and the guy apparently uses it for that purpose so that makes it a troller. Is it a Grand Banks, too? Of course it is. That's the make of the boat. Is it a cabin cruiser? Sure, that's what it was designed and built to be and the owner could still use it for that despite all the trolling gear towering over his head. Is it a trawler? No, it's a troller and very obviously so.
Trawling is first and foremost a method of fishing. Just as trolling is or seining or gillnetting or long-lining are. As long as the gear can be installed on a boat, that boat can be used for that purpose. So if we stick a drum and line guides on the aft deck of our Grand Banks and decide to go off long-lining for halibut, the lack of a license notwithstanding, when we are engaged in that type of fishing our boat is a long-liner. Was it designed and built to be a long-liner? No. That's why we don't call it a long-liner now even though we could conceivably use it for one if we put long-line gear on it.
I used to do aerial fish spotting for a group of local fisherman in Hawaii. The boat they used was a big, clunky rectangular aluminum thing about 30 feet long with a tower on the bow and an outboard on the stern. If anything, it was a John-boat on steroids.
Their method of fishing was to motor out near the school of fish I had spotted earlier in the day and then shut off the motor and start rowing. A kid went into the water with one end of the net and the rest of the guys rowed the boat around the school under my direction from the plane I was flying about 500 feet above them.
When the net was all the way around the school they pulled on the purse lines, bagged the net, and hauled it aboard. The net was a purse seine and while they were using that rude and crude boat in this manner it was a purse seiner. Not much resemblance to the snazzy Alaska limit seiners in the boatyard in our harbor right now, but the function was exactly the same.
So it is with a trawler. It's a boat that uses trawl gear to catch fish. It can be commercial, it can be private, it can be outboard powered, it can be diesel powered, it can be slow or fast, it can be whatever configuration of boat one wants it to be. The only requirement per the correct definition is that it is used to deploy, tow, and retrieve a trawl net of which there are a number of varieties and configurations.
A boat that is NOT equipped with trawl gear is not a trawler. "Trawler" does not define the shape of a boat. It does not define its hull type. It does not define its weight. It does not define its length or beam. It does not define its deadrise. It does not define its sheer. It does not define its power. It does not define its speed. It does not define its living quarters. It does not define how many heads it has on board. It does not define what its pilothouse looks like.
So what the hell does it define about a boat? Turns out it consistently defines only one thing--- the boat is used to carry, deploy, tow, and retrieve one or more trawl nets.
It's a staggeringly simple concept which is why it's so amazing that some people don't get it.
So to your question.... what to call a boat that was built to be a trawler but isn't one anymore? Well, if one was really unyielding it shouldn't be called a trawler anymore because it's not engaged in that activity. But I'm not that unyielding. I would consider a boat that was built to be a trawler and actually
was one before being turned into a cruising boat to be deserving of the name trawler even if it isn't serving that purpose anymore. I wouldn't call it a trawler myself, but would use the term "converted trawler" when trying to describe it.
Our good boating friends have a lobsterboat. Do they use it for lobstering? No. But it's hull was built to be a commercial lobsterboat by a company that builds commercial lobsterboats in New England. It just so happens that this particular hull was bought by a fellow who shipped it out here and put more of a cruiser house on it. So my friend calls it a custom lobsterboat and that seems fair to me.
But a boat that was designed to be a recreational boat from the outset with no thought to using it for any of the commercial-style fishing methods is not a fishing boat and so shouldn't be called one. I haven't heard any of the Bayliner or CHB or GB or Mainship owners in our marina referring to their boats as seiners or longliners or trollers (with the exception I assume of the fellow that owns the GB I described earlier). So what makes them trawlers but not longliners?
The reality is that they are neither.
:lol: 
