Scott, Re hull speed...
Hull speed is more theory than true practice. Using one formula might provide more accurate results in a particular case, but be way off in another. Basic formula is (from memory, which I know is often wrong) is something like 1.3 X square root of LWL. This does not take into consideration wetted surface, displacement, or shape. Certainly a long barge with the same LWL, wetted surface, and displacement would not be expected to have the same characteristics as a sailboat. I come up with about 6.5 knots for the hull speed of my H320, which is about what I get under power according to my GPS. I do go a little faster under sail, which pleases me greatly. I don’t think my 320 is the only boat that does that. Something that might have something to do with the change in speed under sail and power is that the stern squats down under power quite a bit, and changes the pattern of the second bow wave which effects speed. Under sail the boat is much more balanced and goes faster. I guess you can just pick any formula you like, but real world is where its at. I guess the point I was trying to make more than anything else was that I was happy with the performance of my boat, both under sail & power. Kind of an agree to disagree with you about the engine choice. Steve
Hull speed is more theory than true practice. Using one formula might provide more accurate results in a particular case, but be way off in another. Basic formula is (from memory, which I know is often wrong) is something like 1.3 X square root of LWL. This does not take into consideration wetted surface, displacement, or shape. Certainly a long barge with the same LWL, wetted surface, and displacement would not be expected to have the same characteristics as a sailboat. I come up with about 6.5 knots for the hull speed of my H320, which is about what I get under power according to my GPS. I do go a little faster under sail, which pleases me greatly. I don’t think my 320 is the only boat that does that. Something that might have something to do with the change in speed under sail and power is that the stern squats down under power quite a bit, and changes the pattern of the second bow wave which effects speed. Under sail the boat is much more balanced and goes faster. I guess you can just pick any formula you like, but real world is where its at. I guess the point I was trying to make more than anything else was that I was happy with the performance of my boat, both under sail & power. Kind of an agree to disagree with you about the engine choice. Steve