4.3 litre Mercruiser question--90 Amp fuse on Starter Solenoid

[nipper]

Hey guys, especially Thefermenator, I believe my electrical problem is likely the 90A fuse on the starter solenoid. Owner's manual states "A 90 amp fuse is located on the large post of the starter solenoid. This fuse is designed to protect the engine wiring harness if an electrical overload occurs." In addition, OM states "A 15 amp accessory fuse is located on the rear of the engine. This fuse protects the accessory circuits." Any help which y'all can provide to find these fuses would be appreciated.

And next logical question would be what might be causing such a large amperage fuse to blow? I DO NOT want this to happen again.