Im looking at buying a boat with inboard Mercury engine.

Ive been told this isn't a good option in Thai waters and that a Yamaha or Suzuki outboard is better.

Can anyone confirm this from experience?

Off topic nonsense removed

Directly, I have no answer, but can probably suggest a useful direction to look.

Which manufacturer has the closest service center to your location?

Do any of the manufacturers produce the engine locally?

Is the model you are looking at still in common use?

Outboard a lot easier.

You said Mercury. I've never heard of a Mercury inboard but maybe they make them. I've had a couple of Mercury inboard-outboards that worked great. The disadvantage is that they are heavier than an outboard and the outboard of about 2/3 the power will seem to have the same power unless pulling something.

There are two reasons the outboard seems more powerful. One is that it simply weighs less giving less weight to push, and the other is that the outboard if 2 cycle will wind up faster.

The outboard is cheaper to buy new, and to work on.

Mine had Mercury out drives (lower units) and Chevy V8 engines. The engines were branded Mercury but they were, except for the cooling system which didn't have a radiator but rather circulated water through the lower unit, all Chevy. I can tell you that the inboards were heavy and needed a lot of power to bring the boat up into a plane. Once up onto a plane the extra power wasn't needed and the engines were throttled back unless the boat was pulling something such as a couple of water skiers.

The 4 cycle Chevy inboard burned about 1/2 the amount of fuel per hour as the outboards. Outboards are fuel hogs if 2 cycle.

Basically I'd want to decide how much torque I needed, how much I was going to travel in water - in other words what the application is. In most cases the outboard is cheaper and simpler except for fuel. Fuel is a big deal if you run it for extended periods.