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Mainship 43 Sedan Trawler

The published record on this model and what owners report, with the questions worth asking while a boat is still a listing. This page covers the model. Every boat still needs its own homework.

A comfortable semi-displacement sedan trawler whose risk profile hinges almost entirely on which engine it was built with. The 440hp Yanmar is the one to scrutinize.

The Mainship 43 (part of the Mainship 430 series, built roughly 1999–2006/07) is a semi-displacement sedan trawler that will cruise economically at hull speed yet has enough power to plane. It was offered with several distinct powerplants over the run (Cat 3126, Yanmar 370hp, Yanmar 440hp, and rarely Cummins 8.3L), so many of its known issues are engine-configuration-specific. The single most important thing a buyer can establish is exactly which engine and layout their candidate hull carries. It is a capable Loop boat, but air draft and engine access are the two items that repeatedly surface in owner discussion.

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How to read the tags on this page. CLAIMstated by one source, not yet confirmed QUESTIONopen, and settled by looking at the boat itself CONTEXTbackground on how this model is built or used Sources are linked where published.

Engine access

CLAIM
Engine room is tight for major work Owners report the engine space is cramped: roughly 29" of horizontal clearance against 28" engine mounts, and because the engine isn't centered the door opening makes removal awkward. A recurring Mainship complaint is that some basic maintenance or part replacement can require cutting hatches. This is a hull/layout property, not an engine trait. src: Trawler Forum, "Need advise on engine removal from Mainship 430" and "2003 Mainship 430" threads
Your move: During survey, have the surveyor confirm access to filters, heat exchangers, aftercoolers, and pumps without removing structure; factor labor difficulty into service-cost estimates.

Reading the boat

QUESTION
If Cummins 8.3L powered, what's the service and repower history? Some later/rarer 43s were fitted with twin Cummins 8.3L (buyers report ~480hp a side, around a 2006 model). Substantial owner failure reports specific to Cummins-powered 430s were not found. This is 'not documented,' not 'proven trouble-free.' A Cummins in what is often a Yanmar/Cat boat also raises the question of whether it's a repower. src: Trawler Forum, "Mainship 430 aft" thread
Your move: If Cummins-powered, ask whether this was factory or a repower, and get the full service history and any repower documentation in writing.

Air draft

CLAIM
Air draft varies widely with mast, arch, antennas and canvas Owner-measured air drafts on this model range widely depending on equipment. Some measured under 19', others near 20' after adding gear, and many 430s in the field have no hinged/lowering mast. Radar posts, satellite antennas, convertible tops and enclosures all change the figure. This spread is exactly why the model needs individual measurement: two identically named boats can differ by more than a foot, which affects access to lower-clearance Loop routes. src: Trawler Forum, "Air draft of a 430?" thread; YachtWorld, "Mainship 43 Trawler"
Your move: Measure your specific boat's air draft at a known load state, and identify exactly what (mast, antennas, arch, canvas) can be removed or lowered and how much each saves.
CONTEXT
Load and water density shift the measured height Owners note a boat sits lower in fresh water than salt and lower when lightly loaded, so air draft should be assessed near the load state you'll actually run. One owner deliberately measured with a half-load of fuel before a low-clearance canal. src: Trawler Forum, "Air draft of a 430?" thread

Range & fuel burn

CONTEXT
Expect economical burn at hull speed with the 370hp Yanmars Owner reports with twin 370hp Yanmars: roughly 8.5 knots at 1600 rpm burning just under 4 gph total, and about 9 knots near hull speed at 1800 rpm averaging ~5 gph including generator/heater. The 440hp boats pushed harder plane and burn far more. Owners advise keeping cruising rpm at 2,800 or less, burning ~20–25 gph for both engines at that rpm. Slow-cruise range is comfortable; planing range is short. src: Trawler Forum, owner fuel-burn reports

Engines

The engines research is part of the full profile inside the product. It covers factory options, tested performance and the engine-specific questions in our members' dossiers, and it travels with every dossier and survey brief built on this model.

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Spotted something wrong or have first-hand knowledge of this model? Email support@caniloop.net. Corrections are how a profile earns its Facts, and we credit them however you choose. This profile reflects sources opened and verified by a person. It's buyer homework, and it makes no judgment on any particular hull.