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Model guide · Trawlers

Used Mainship trawler buying guide: the classic 34 and the 390 and 400

Updated 7 October 2026 · 3 min read

People enjoying a sunny day on a boat in Lake Vättern, Sweden.
Photo: Efrem Efre / Pexels

Mainship built two very different kinds of trawler-style boats that buyers search for today: the classic Mainship 34 of 1978 to 1988, one of the cheapest ways into a trawler-style boat, and the Mainship 390 and 400 Trawler of the late 1990s to 2008, a newer, roomier boat popular with Great Loop cruisers. Don't confuse the classic 34 with the later Mainship 34 Trawler of the mid-2000s, which is a different and much more expensive boat.

At a glance

Classic Mainship 34 Mainship 390 / 400 Trawler
Years 1978 to 1988 (34, 34 II, 34 III) Late 1990s to 2008
Length 34 ft 39 to 40 ft
Hull Semi-displacement, draft under 3 ft Semi-displacement
Power Single 160-hp Perkins diesel Diesel inboard
Best for Budget river and coastal cruising Loop and coastal cruising with space

The classic Mainship 34

The original 34 was built from 1978 to 1982, followed by the 34 II and 34 III through 1988, on a semi-displacement hull with a single 160-hp Perkins diesel.1 One owner reported cruising at 10 knots on about 4 gallons an hour, and about 2 gallons an hour at trawler speeds. With a draft under three feet, she's at home on rivers, the Intracoastal Waterway and the Great Loop.

The honest trade-off: the owner Soundings spoke with said she's "not fond of quarter-following seas,"1 which is what you'd expect from a flat, shallow, economical hull.

What to check on a classic 34

Soundings points to four things on these boats: the holding tank, previous owners' electrical work, soft spots under stanchions and rails, and built-up layers of bottom paint.1 Add:

  • The Perkins diesel: service records, an oil sample, the cooling system, exhaust elbow and engine mounts
  • Fuel tanks and the fuel system: age, condition and filters
  • Window and deck hardware leaks into the cabinetry

These are 40-year-old systems. Buy the best one you can find, not the cheapest, and budget for a first-year catch-up. See the true cost of owning a boat.

The Mainship 390 and 400 Trawler

The 390 and its successor, the 400, brought the trawler look to a newer generation: a semi-displacement hull that can cruise faster than a classic trawler, a single-level main deck with a big salon, and a large flybridge. They're popular with couples who want space without the maintenance of an old Taiwan trawler.

What to check on a 390 or 400

  • Engine and running gear: service records, hours, an oil sample, the shaft seal, cutless bearing and alignment
  • Flybridge and deck leaks: look below the flybridge and around windows for staining
  • Generator, air conditioning and the other systems a newer boat carries more of; test each under load on the sea trial
  • Bow thruster: many have one; test it
  • Bottom and blisters at the survey haul-out

At this age, the price difference between boats is mostly the condition of the engine and systems. Pay for records.

Questions to ask the seller

  • How many hours on the engine, and when was it last serviced? Any oil analysis?
  • When was the holding tank last replaced? (classic 34)
  • Who did the electrical work, and is it labeled?
  • When was the bottom last taken down and repainted?
  • Where has the flybridge or cabin leaked?

Common questions

Is a Mainship 34 a good first trawler?

For budget river and coastal cruising, a well-kept classic 34 can be a lot of boat for the money. Expect 40-year-old systems and budget accordingly.

What's the difference between the Mainship 34 and the Mainship 34 Trawler?

The classic Mainship 34 was built from 1978 to 1988. The Mainship 34 Trawler of the mid-2000s is a different, newer and much more expensive boat.

Is the Mainship 400 good for the Great Loop?

It's a popular Loop boat because of its space and semi-displacement speed. Check its air draft and fuel range against the route's limits before you buy.

Sources

  1. Soundings: Used boat, Mainship 34

HullVet guides are written by the HullVet team with AI help, from the research behind The Honest Boat Buyer's Kit, and facts are linked to their sources. They're general education, not a marine survey or legal, tax or financial advice. Rules and prices vary by state and change over time, so check what matters for your boat.