Original prop size on Oday 34 with Universal 5424

[Jetexas]

Does anyone have the specs for the original prop used on an Oday 34 with the Universal 5424 motor?

Our 1982 Oday 34 came with a 15RH8 3-blade on it and another 15RH8 3-blade under the seat. However, when in gear, I get white smoke, and if I rev the engine above 2000 rpm, it overheats.

I'm trying to figure out if the previous owner over-propped the boat or if I have a low-compression or injector issue.

In normal conditions I can make about 5.5 knots at 2000 rpm with little puffs of smoke. There's no smoke in neutral, only under load (unless I really rev it up high, then I can get lots of white smoke, but I think all engines do that).

Thanks for any help.