There usually one or more solenoids involved in starting circuits.
Clicking suggest that at least one of those is getting power. You need
to multimeter and a helper. Start at the starter and check back. On
chevys there is usually a small wire at the starter than pulls the
solenoid. There may be a second solenoid further upstream form that.
Or if it's a ford the solenoid may be separate from the starter. A
service manual with a wiring diagram would help. Onething that is
common on older boats is bad connections due to corrosion. You can't
look at a connection and tell if it is bad or not. You have to take it
apart and wire brush it to make sure it is connecting well.

Drew wrote:
I have a 1987 fourwinns I/O merc cruiser. I'm having problems
starting the boat. I have replaced the battery. When I try the key
all that happens is I heard a small click form the engine. I check my
battery connection and my fuses (none where blown), but if I keep
trying checjking all connections it will eventually start. Is this a a
loose fuse problem or starter?

Drew

Thanks, keep boating