High resistance to engine cranking. Yamaha 100 HP 4 stroke.

[FKPhil]

Put the RIB to bed last November, and have come back to it now to find the engine won’t turn over. Massive resistance to cranking the engine (by hand & on starter motor) even with the plugs out.
Anyone any ideas what it might be ?

[codprawn]

Did you squirt wd40 or similar into the plug holes before turning it over?

[JABS]

How did you prepare the engine for storage?

Did you fog the engine?

Squirt oil into the bores? What type of oil?

Was the boat stored inside or outside?

Were the plugs replaced for storage?

Was the engine oil changed before storage?

[Nasher]

I know its obvious, but have you checked to see if its in gear?

Nasher.

[Nos4r2]

What everyone else said-and have you checked the lower unit gearcase for water ingress? It could be a semi seized gearbox.