Cooling system routing, Oil Cooler sequence.
 

Just want to make sure I'm thinking correctly here:

Water pickup -> Strainer -> Oil Cooler -> into front of block - > exit top of manifold -> into exhaust -> Exit boat.

Just want to make sure oil cooler is first in line. I assume you don't want heated water from block into oil cooler but also not positive you want heated water from cooler into engine.

The BTU's transferred from the oil cooler are minimal compared to the engine so the temp rise will be minimal as well. My system is plumbed the same and I have more difficulty keeping the oil cool than I do the motor. The engine also holds a greater volume of water so it can hold more BTU's than the oil cooler can.

Power steering cooler?

My oil and power steering cooler are one unit. If you have 2 seperate I would put engine oil first.

No power steering cooler. No power steering. Just manual hydraulic.

Ok, here is my plan. The way I see it, I can not run a thermostat in this scenario. Feedback requested!
https://lh3.googleusercontent.com/-E...no/cooling.png

Not much action here! You guys gotta all know this! I am now questioning maybe a tee out of the strainer and feeding the oil coolers and exhaust cooling separate from engines so I can run a thermostat? Then I would need to figure a way to dump the engine water overboard.

Drill and tap the front of the intake with 1/2" pipe run a bypass hose to the top of the thermostat housing. 1/2" hose. Put a thermostat in and drill a couple 1/8" holes around the thermostat.

Thanks Black Baja. Here is what I THINK would happen as a result of your recommendation:

1. A small amount of water would pass through the 1/8" holes in the thermostat.
2. This water would head up through the thermostat housing (some of which would go through the main exit and into the headers and some would go through the bypass line).

So, I understand that the holes would get some water to the exhaust while the thermostat is closed but I don't understand how the bypass at the top of the thermostat would help.

I feel like my issue with a thermostat is that I would not be getting enough coolant through the exhaust. It is very likely I still don't understand the whole thing.

Good thinking but wrong. It works I've done it more than one the 1/2" bypass hose will give your exhaust plenty of water until the thermostat opens. I have completely dry exhaust with two 1"dumps out the side of the boat and it looked like two garden hoses running out the side of the boat. If you do the bypass like I'm telling you u will be fine. Believe me I messed with the water system in my boat for 2 months over the summer because I couldn't stop two cylinders from detonating. I ended up doing a reverse cooling deal to stop the detonation. Whatever you do. Do not buy a water crossover with a bypass on it and bypass the cold water b4 it enters the motor you will have problems whether you know it or not. Bypass the warm water coming out of the motor and you will be fine.