Under 12 volts

What prompted you to put in the new alternator and battery? Have you checked any of the wiring and connections? Do you know if the new alternator is ok? What year is the boat?
I have found that bad corroded connections make a big difference.

Check your voltage at the battery with a digital multimeter. Running should be 13.5 to 14.5 volts. Not running - at least 12.6 when fully charged. Also, what type battery did you install? You can check your electrical connections with the same multimeter. Maximum voltage drop across any connection should be no more than .2 volts. Let us know what you find or if you need more help.

M3, I think the ground is a black wire.

32, check out our ref section as there is a wiring diagram of the dash for 88-89 in case you don't have one. Connections may "look" ok but nuttys suggestion of using a multimeter is really the only way to check voltage drop. I cleaned up all my Tique wiring and gained something like 1.6 volts. Can't remember exactly but when you are only dealing with a nominal 12 volts almost any gain is sizable. Have you checked the output of the alternator other than just looking at the dash volt meter?

Keith,
I replaced the ignition switch right at the end of last summer because sometimes when I turned the key nothing and other times start right up. Have not had that problem since but only ran it a couple of times with new switch. I guess I need to get the volt meter out and start checking. Last night in driveway the dash was reading about 12. Is somewhere between 13 and 14 normal? Where exactly do I check with the volt meter?

32General, as nuttyskier2002 said, 13.5 v to 14.5 v while running. With key on, and not running, 12 v.

-Keith