Mainship 400 Trawler
Mainship's third-generation trawler · single Cat, Cummins or Yanmar (315–385 hp), or twin Yanmar 240s · semi-displacement
Every height ever reported for this boat clears the Loop's lowest bridge with feet to spare. We still list the air draft as the first thing to measure, because not one of those figures is verified. No professional review states a bridge clearance for the Mainship 400, and listing figures scatter from 12'8" to 16'4". The folding radar mast was a factory option, so hulls differ. Ten minutes with a tape settles the number before the deposit, and the same tape tells you whether the lower optional routes, like downtown Chicago's 17' run, are open to you. Everything else clears on published figures with room to spare, and the tested burn is honest trawler economy.
Mainship 400 Trawler
41'4" LOA, five single-engine choices or twin Yanmars, full keel with the singles. This dossier.Predecessor 390
A different boat with its own record, including swim-platform and following-sea questions that may or may not carry over. Ask; don't assume.The gates
What a Loop boat has to clear
| Gate | The number | Why it binds |
|---|---|---|
| Air draft | Under 19'6" | The Illinois River bridge at mile 300.6. AGLCA calls it the lowest unavoidable fixed bridge on the Loop. There is no alternate route. Miss it and you cannot complete the Loop. |
| Water draft | Under 5' preferred | Trent-Severn carries a controlled depth of 6', and over 5' needs a signed waiver. The Rideau is maintained at 5'. The tightest published figure on the whole route is the New Jersey ICW at under 3', which AGLCA pairs with local knowledge, and otherwise advises running outside in the ocean. Then the rivers and the Gulf ICW, where shoaling moves faster than the charts do. |
| Range | Plan 250+ nm | AGLCA names the long leg: Alton, IL to Paducah, KY. That's about 250 miles on their Inland Rivers page, ~240 in their FAQ. It shifts as marinas open and close, so verify current fuel stops. |
Only one of these is a wall. Over 5' of draft means a Trent-Severn waiver. That's a form, not a barrier, and AGLCA says outright that many boats drawing more than 5' have finished the Loop. Short range means carrying deck fuel, which AGLCA suggests itself. The Chicago River's 17' has the Cal-Sag Canal around it. The 19'6" bridge has nothing around it. That is the number to measure twice.
Scorecard
Gate by gate
| Criterion | Status | The read |
|---|---|---|
| Air draft | VERIFY | No professional review publishes a bridge clearance for this model, listing figures scatter (12'8" and 16'4" mast-down have both appeared), and the folding radar mast was a factory option, so hulls genuinely differ. Nothing here suggests she can't clear 19'6"; it means the number has to come off a tape, not a listing. |
| Water draft | PASS | 3'8" published, well under the skinny-water line. Confirm loaded, but there's plenty of room. |
| Range | PASS | 300 gal at the tested ~8 gph and 9 knots is roughly 340 nm. That covers the 250-mile leg with margin. Test-day figures on the 385 Cat single; plan on measured burn for the hull in front of you. |
| Diesel | PASS | All diesel: five single choices (Cat, Cummins, Yanmar) or twin Yanmar 240s. Which one this hull carries is the first identity question below. |
Risk 01
The air draft nobody publishes
The one number that can end a Loop, and on this model it has no published basis. Measure it first.
Your move: measure to the highest fixed point · confirm whether this hull has the folding mast · never inherit another hull's number.
We're also fixing this gap for good: the Measured Heights Project is a free public registry of owner-taped air drafts, by model. If a 400 owner has taped theirs, it's there.
Risk 02
Which engine is actually in it?
Your move: name the exact engine · pull its service records · ask what she burned per hour, and at about what rpm (the trade sizes engine life by fuel burned, so the answer converts the hour meter into how the hours were spent) · have the engine surveyor measure blowby and give you the number.
Risk 03
Tanks and systems, where they live
Your move: eyes on the tank surfaces and fittings · run the generator at its own hatch · confirm the engine room's all-around access claim on this hull.
Risk 04
Read the boat right
How to read this
Every claim wears its confidence
No owner-verified facts on this model yet. Those get added as real owners confirm them, with a name and a date. This is the research-grade starting point, tagged honestly. An inference doesn't become a fact through confident phrasing; it becomes one when someone who owns the boat answers.
Beyond this dossier
What membership adds
Go deeper
This page is one boat's dossier. The model itself has a full public profile, with every claim sourced and tiered: the Mainship 400 Trawler in the model library →
Paste in her listing and the workup builds from it. Your first boat is free.
Work up your first boat free →You still need a survey. We just keep you from wasting one on a boat that was never going to fit.