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Model profile · for Great Loop buyers
Sea Ray 420 Aft Cabin
What the published record establishes about this model, what owners report,
and the questions worth asking while a boat is still a listing. This page is about the
MODEL — a specific hull always gets its own homework.
A heavy planing-hull aft-cabin cruiser that Loops well only when diesel-powered. Air draft and draft both want measuring rather than assuming; fuel economy and engine access are the watch-items.
The Sea Ray 420 Aft Cabin is a roomy, ~20,000 lb (loaded ~30,000 lb) planing-hull motoryacht that was offered with both gas (7.4L MerCruiser) and Caterpillar 3116/3126 diesel power over its run. For the Great Loop the diesel boats are strongly preferred; gas versions are widely considered underpowered and thirsty. Air draft (~15'6" per a brochure) and draft (~3'1") are favorable, but the planing hull burns heavily at any speed and true economy comes only at slow displacement speeds. Known model-specific issues include aft-cabin kick-out panel leaks, generator-dependent 110v/220v systems, and very difficult in-hull engine removal.
How to read this: 🟢 Fact = confirmed against a document, spec sheet,
or owner. Everything else — Claim, Pattern, Question, Context — is not yet
verified: things to check, not settled truth. Sources are linked where published.
Builder and support
CONTEXT
Sea Ray discontinued its sport-yacht/yacht lines (which included large aft-cabin cruisers) effective June 26, 2018, to focus on boats up to 40 feet.
Sea Ray is a going concern, owned by Brunswick Corp (NYSE: BC), still designing and building boats in 2026 (new SLX debuted at CES Jan 2026). BUT the 420 Aft Cabin belongs to the LARGE-YACHT/CRUISER category Sea Ray permanently exited in mid-2018 — no new boats like it are made, and it's an older diesel/sterndrive cruiser. The brand runs a live factory support channel (24/7 phone line, dealer netw
src:
Brunswick/Sea Ray press & CES coverage (Boating, StockTitan, GlobeNewswire, Jan 5–7 2026); Brunswick Q4 2025 results reporting (ad-hoc-news, Apr 1 2026); searay.com official Owners/Contact/Resources p
Range & Fuel
CONTEXT
Cat diesel burn has a sweet spot around 2200 rpm
Per the forum Cat specialist (per engine): 350hp 3116 ~11.3 gph @2400 rpm; 385hp 3126 ~11.7 gph @2400; 420hp 3126 ~13.0 gph @2400. All show a sweet spot near 2200 rpm at ~9.0/9.1/10.0 gph respectively. Double these for the boat.
src:
Club Sea Ray (Cat specialist 'FrankW')
CONTEXT
Real-world diesel burn: heavy at cruise, much better dead-slow
A 420 AC owner with Cat 3116s (350 gal) reports ~22 gph at 17 kt cruise for ~250 nm range; slowing to ~8 kt drops burn to ~3.5 gph for ~750 nm. A comparable 410/3126 sips a little over 2 gph at ~7.5 kt approaching 3 mpg.
src:
The Hull Truth; Club Sea Ray
CONTEXT
Planing hull: slowing down helps less than expected mid-range
As a planing hull, running at 10-12 kt burns nearly as much as being on plane. Best economy is either well up on plane or well below hull speed (~7-8 kt), not in between. A tester noted it 'burned a lot of fuel at any speed' compared to true trawler hulls.
src:
Trawler Forum
Air draft & Draft
CLAIM
Low air draft and shallow draft are favorable for the Loop
Brochure/listing figures suggest a modest air draft (a listing cited ~15'6") and a shallow draft (~3'1"). The boat carries a radar arch/antennas that add height. Confirm what can be lowered. The buyer must measure the actual air draft (with arch and antennas) on the specific hull rather than trusting the brochure.
src:
A classified listing for a 2000 420 AC
Your move: Measure the real air draft with the arch and all antennas in place and identify what can be lowered.
Systems
CLAIM
Refrigeration and A/C are shore-power/generator dependent
Fridge and freezer are 110v and A/C units are 220v, so at anchor the generator must run to keep refrigeration going, and dockside you need a 50A 220V hookup. One owner budgeted the generator at ~3/4 gph running 2-3 hours a day. A meaningful Loop consideration for anchoring and shore-power planning.
src:
Club Sea Ray (420AC owner threads)
CLAIM
Aft-cabin kick-out hatch/panel leaks are a recurring complaint
The aft cabin kick-out hatch/panel is a known, model-specific leak point. Multiple owners report persistent leaking even after gasket replacement, and evidence of prior owner caulking attempts.
src:
Club Sea Ray (420AC thread)
CLAIM
Underwater exhaust pipes are vulnerable
An owner knocked off an underwater exhaust pipe in open water and only discovered it when aft bilge pumps kept cycling. Worth inspecting these fittings.
src:
Club Sea Ray (2001 420AC owner)
Reading the boat
QUESTION
Does the bilge take on water only after running, suggesting deck-seam or shaft-seal leaks?
Owners report hard-to-trace bilge water intrusion. If the bilge fills only after running, water may be entering through a failed deck-seam seal or running gear. Check whether bilge intrusion correlates with use.
src:
Club Sea Ray
Your move: Ask the owner/broker whether the bilge takes on water underway vs. at rest, and inspect deck seams and seals.
Engines
The engines research — factory options, tested performance,
and the engine-specific questions our members' dossiers carry — is part of the
full profile inside the product. It travels with every dossier and survey brief
built on this model.
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