Looking at a MT Tradewinds 47. Anyone have the max cruising speed on twin Cummins 6BTA 5.9, 250HP each?
Also looking for opinions on engine room space/accessibility.
The max speed would burn a lot of fuel and a max cruising speed is a matter of choice as to how much you want to burn. I would use the following rough rule for a reasonable cruising speed. Take the square root of the waterline and multiply buy 1.3 than subtract one knot. My rough guess without knowing the WL is between 7 and 8K. This would give you a displacement speed cruise at reasonable fuel burn. If you like burning fuel and making large wakes with 500 HP you can go faster the top speed will depend on hull shape and total boat weight props etc. I would guess in the mid teens.
My experience may be a little different than yours as my Cummins 6BT 5.9 (no "A") engines are rated at 210 HP. I prefer to cruise @ 1800 RPM and manage 8.5 to 9 knots burning a total of 10 gals. per hour. If I push them up to 2000 RPM I only gain 1 knot and the burn rate goes up significantly. So, I prefer to enjoy the view a little longer on trips.