Power limitations on a 150 Mariner outboard?

EDIT: misleading thread title - meant to put Mariner, as that's what it is EDIT: Fixed that

Hello all,

I'm about to take the dive on a neat 17' Hydrostream Viking with a 1987 150HP Mariner outboard. I'm planning on putting a decent little sound system in it - Sony head unit and a single 4-channel amp pushing two Polk 6.5" front channels with the other two channels bridged for one 8" Polk sub. I'm also going to replace the old stock battery with an Optima Blue Top.

My question is, will the boat's electrical system handle this setup? (factoring in also running a VHF radio - which can be cut for a handheld unit - and lights, etc) I don't know much about the charging and power systems on these old outboards. The amp spec says it will pull a max of 33amps of power.

Thanks!

Re: Power limitations on a 150 Merc outboard?

Re: Power limitations on a 150 Merc outboard?

What you need depends on how long you sit in one spot with the electronics operating. 1987 is definitely not old considering there thousands of outboards from the sixties still moving boats with gusto. I'm guessing that your outboard has a 20 - 25 amp charging system. What that means is when the engine is running wide open it will output 20 - 25 amps to the electrical system. If you sat in one spot for say 2 hours with a 10 amp steady current draw from the battery, you would use 20 amps of power. That then means you would need to run the boat wide open for one hour minimum to replace that amount of current. Anything less than that you would be losing ground -- so to speak. Anytime one adds a high power amp to a boat it generally means to avoid being stuck with a dead or discharged starting battery, you add a second Marine Deep Cycle battery via a dual battery switch or automatic charge relay as well as a single or dual output on-board charger. Both of these topics are discussed to death in this forum and have ample instructions and diagrams to illustrate the why and how this is done. Use the "Search" feature to find those posts. Use search terms like "Dual Battery Swtich" or "Dual Batteries" or similar terms. Or just scroll down the list of topics. There have been a couple just in the last few days.

Re: Power limitations on a 150 Merc outboard?

Re: Power limitations on a 150 Merc outboard?

Not trying to sound too old or anything, but you're willing to forgo a fixed VHF radio for a hand held as long as you can have your AF/FM/CD with amp & speakers? Please make sure that the necessary safety equipment is in place prior to spending too much time making sure the tunes are cranked up.