Before it touches water

Sterndrives hide winter damage better than outboards — a cracked block or split bellows may not announce itself until the boat is floating. Work this list on the trailer or stands first.

Engine

• Verify winterization actually happened: look for drain evidence, ask for records. If unknown, inspect for freeze cracks along the block sides and manifold ends before starting — a cracked block pumps water into the oil or bilge.
• Oil level and condition (milky = water; find out where from before cranking).
• Belts, hoses (squeeze test — crunchy or mushy hoses get replaced), clamps doubled below the waterline.
• New fuel filter/water separator; inspect fuel lines and the tank vent.
• Battery load-tested, terminals clean and tight.

Drive and transom

• Bellows inspection at full trim travel (see the bellows article) — this is the sink-risk item.
• Drive oil condition if not changed at layup; milky means pressure test now.
• Anodes past half = replace. Continuity-check bonding where fitted.
• Prop off: fishing line check at the seal, grease splines, inspect hub.
• Grease gimbal/u-joint fittings where present; listen for gimbal chirp on the first run.
• Trim cycles smoothly full range and holds position overnight.

Safety systems

• Bilge pump: lift the float, verify it runs and actually pumps overboard; check the discharge hose isn't cracked.
• Blower runs and ducting is intact — gasoline sterndrive engine boxes accumulate explosive vapor; the blower matters.
• Fire extinguisher in date; horn, nav lights, lanyard kill test.

First start and sea trial

1. Muffs or in-water with someone watching the bilge for the first ten minutes — literally watching.
2. Run to temperature: verify thermostat opens, no alarm, charging voltage normal.
3. Sniff test after warm-up: raw fuel smell = shut down and find it.
4. Sea trial: shifts crisp, no gimbal chirp on turns, temp stable at cruise, WOT rpm within the range in the service manual.

Common mistakes

• First launch without a bilge watch
• Skipping the blower test on gas engines
• Assuming last fall's "winterized" sticker means it was drained — verify

When to walk away

Water in the oil before first start is a stop — do not crank it. Diagnose (block crack, manifold leak, resting water intrusion) and re-quote.