Ouch no guages. You will need to invest in a hand held ohm/volt meter if you don't already have one. You will be able to check the voltage output with it and will save you tons of money and time with the boat.
Some examples from my mistakes: My first boat I owned the tach would not work and the battery always needed charged. I bought the top of the line $200+ 1 hour rapid charger back years ago. Finally bought the repair manual and replaced the rectifier $50 (easy installation) which fixed both my tach and my charging problem. Then my $200 rapid charger was wasted money. Next my boat lost power and would stall while going down the lake. Instead of me buying a $60 volt/ohm meter to check the parts, I started replacing parts.. $800 later I realized my stator ($250) was going out. Then one day I was flying down the lake and it went to a complete halt. Another $900 later realized it was the power pack ($250). Could have saved $1200 investing in a $60 ohm/volt meter
My latest screw up.. I took a grinder to my brand new tach because the mounting screws was to long. Now it reads 0 or 7000. I am about to waste a bunch of money again if I don't invest in a repair manual soon.