Fqs

While I'm questioning conventional wisdom, my limited knowledge of hydrodynamics leads me to question whether Froude's work really says that sticking your arm out in front of you greatly reduces wave drag. My recollection of Froude was that for a given displacement a narrower hull resulted in lower drag, I am not at all sure that you can make a boat faster by attaching a flag pole to the bow under the waterline, which is the rough equivalent to sticking your arm out while stroking on your side. If this worked I would expect to see such underwater protrusions in high performance sailing yachts. I think cross section normal to the direction of motion is the critical factor and long thin hull has a smaller cross section for a given displacement than a shorter hull. The width of the waterline would also be a factor as the bow wave would be acting on a smaller area even for an equivalent cross section (deeper is better than wider). I'm not saying that extending your arm out is not the right thing to do, just that the explanation of why seems questionable to me, in the same way that all that talk about foils never made sense. Extending the arm might help balance or body position or roll or be beneficial in some other biomechanical fashion. Any hydrodynamic experts care to fill us in?

While I'm questioning conventional wisdom, my limited knowledge of hydrodynamics leads me to question whether Froude's work really says that sticking your arm out in front of you greatly reduces wave drag. My recollection of Froude was that for a given displacement a narrower hull resulted in lower drag, I am not at all sure that you can make a boat faster by attaching a flag pole to the bow under the waterline, which is the rough equivalent to sticking your arm out while stroking on your side. If this worked I would expect to see such underwater protrusions in high performance sailing yachts. I think cross section normal to the direction of motion is the critical factor and long thin hull has a smaller cross section for a given displacement than a shorter hull. The width of the waterline would also be a factor as the bow wave would be acting on a smaller area even for an equivalent cross section (deeper is better than wider). I'm not saying that extending your arm out is not the right thing to do, just that the explanation of why seems questionable to me, in the same way that all that talk about foils never made sense. Extending the arm might help balance or body position or roll or be beneficial in some other biomechanical fashion. Any hydrodynamic experts care to fill us in?