Leaking at shaft

If your shaft packing has some room for adjustment then tighten the packing. It's the big brass nut with a locknut in your bilge where the shaft comes through. Loosen the locknut and tighten the packing nut until you get a drip of water about every 10 seconds. Then tighten the locknut and run the boat for awhile. Shut down engine and check to see that drip rate is acceptable and that stuffing box isn't getting too hot.

If your packing doesn't have any room for adjustment it will need to be replaced. Skidim.com is a good place to get the materials should you ened to go that route.