Thanks, I'll try to remove plugs and then turn the flywheel, i hope the engine is not locked up.
Which way were you turning the prop and what gear was selected? If the conventional gear box, not one setup for counter rotation used with duals, you have to turn the prop CCW (with the shifter in F gear) looking from the rear, plugs out helps as stated. I just stand on a blade to push it down.
On the starter not working need more info.
1998 offshore spells corrosion to me. Corrosion at the battery wire terminals, all of them. You need about 10 volts across the starter terminal and engine block (ground) to get the bendix on the starter shaft to spin up properly, engage the flywheel gear and have enough whoopie for the starter to rotate the engine. With only 12v or so available from a fully charged battery circuit resistance has to be close to nothing. Take all the connections of the red and black cables from the battery apart and clean and shine up removing corrosion, reinstall and tighten. Spraying some red battery terminal protector (WM has it) on the terminals when finished will help to keep them clean.
Next, if you still have your OEM starting solenoid, probably a good idea to get another. Internally the contacts pit due to arcing and the pitting reduces the surface area and keeps it from conducting starting current as well as it should.
Next you need to test your battery to ensure that it can put out 200 amps and still have 11 or so volts across the terminals. As batteries age they sulphate up and develop an internal resistance that inhibits high currents with minimum loss. WM has battery testers too in their auto shop.
Next, the shaft of the starter should be lubed and you should be able to easily rotate the bendix from it's rest position against the starter housing up to where it engages the flywheel. If it doesn't move freely, lube it up.
Go through that and you will probably solve your problem.
