Do I need oil temp gages?
 

My entire history of boating has been stock setups. This is the first year that I will be running modified engines. BBC's 500 hp. I did buy new oil coolers that are supposed to be good up to 700hp. They are not thermostatically controlled. I kept the stock oil pans. My builder said that at my hp level they would be fine. I plan on using the 160 degree thermostat for water. I am running the standard belt driven sea pump and brand new BBC standard (marine) circulating pumps. Should I also now start monitoring the oil temps? I see a lot of posts on here that refer to oil temps and how they modify their boating based on those numbers.
My next question is about 02 sensors. I was thinking about running fuel injection so when I ordered my new risers I had them weld in the 02 bungs. I have decided to go with carbs and was going to just plug them up. I was looking through the misc. new posts and pics and noticed that someone running carburetor's also had 02 sensors installed. Do some of you guys also run gages at the dash for AFR? FYI, my new engines have been dyno'd and set up so not sure its necessary to monitor? Looking forward to your comments.

Yes yes and yes.
Extremely cheap insurance.
I`ve never ran a boat without AFR gauges. Dyno AFRs were lways completely diferent than in boat.
Oil temp yes, the more info you have the better.

Agree to all, example of oil being roasted and didn't know
160 degree stat and temps never went above 180 running hard, but oil was getting black fast. Installed oil temp gauge and it was over 330*F. Larger cooler and hoses all good now

Oil temp is one of the most important gauges that should be on your dash.

I replied to your pm about the O2 sensors.

Carburetors… If you’ve got a good tune from your dyno sessions then they’re a nice to have. They allow will help you dial them in just that much more and they’re good for alerting you to trouble (though with a carb you usually get warnings from run-ability first).

Forced induction and basic fuel injection is where these really become important. In these cases you’re using the afrs to spot situations that would contribute to a burn down.

Keep in mind too that this information can be overwhelming and you could start chasing problems that aren’t really there. You should compare your readings with looking at plug condition and so on.

So I'm ordering new gages this week. Where does the oil temp sensor get installed? There is a spot in the oil pan (stock mercruiser pan) that seems a little too high but maybe that what's for? I did see in a different post that had installed his there. I don't know if it was a stock pan or not. Thanks again for your comments. I certainly want my investment to last.

I have Gen VI blocks and take the reading from the oil cooler port right next to the filter pad.

In this application, I'm not sure there's a difference but I am running GEN V blocks. I am still using the stock oil filter relocation mount that locates the filter up by the exhaust risers and it has unused bungs because you can attach the hoses in either direction. Can the sensor be installed there? I believe the goal is to monitor the oil temp at a location that will show how hot the oil gets not how cool you can make it? I did buy the Hardin Marine billet piece to attach to the block itself. Had an issue with the stock unit leaking.

My oil temp sensors are on the remote oil filter housing. Came from Fountain that way I believe. Definitely want oil temp sensors on modified engs.

Water pressure gauge is a good idea too. Saved my bacon once when a water hose popped off.

Thanks for all of the comments and input. I will be loading my dash up with gages before this upcoming season.