Glide in a rowboatgreenspun.com : LUSENET : Open-water rowing : One Thread
Okay, most of my boating is done on a small to medium size lake and here's what I am trying to achieve. I'd like to take a few strokes on the oars(6 to 8 maybe) and then coast for awhile. And then repeat as needed. I'm not in any really big hurry to get anywhere. In order to be able to do this, I will either build or buy another boat this summer. Hull shape and weight are the two factors I haven't decided on yet. Because they are the ones that will determine how well the boat will do what I want. Okay, let's say the boat is 15ft long with a beam of 40in. and weight of 45lbs. Underwater shape is similar to that of a dory. V-shaped, but flat on the very bottom, about 6-8in wide bottom plank. This boat wouldn't have a lot of rocker either. Now, I would expect this boat to track very well BUT, would the relatively light weight cause it to slow down sooner? Especially on a windy day? And, what if I loaded it down more with, say, 60-80lbs of additional weight? Then, would it coast better? If it would, then maybe I would be better off with a heavier boat to begin with. Now, let's say the same size boat(15'x40''x45lbs)BUT, with a slightly rounded(almost flat) bottom. This boat(I would assume) would have(maybe) more wetted surface and less glide? BUT, if it weighed, say, 100lbs instead of 45, would the extra weight give it glide comparable to the earlier boat(dory shaped) at 45lbs? SO, which is the BIGGEST contributing factor to achieving glide in the boat, weight or hull configuration? Andre? David? Anyone? (Wish I had the money for a SKUA so I wouldn't need to ask these questions) Thanks, Guys. Ron
-- Ron Roberts (firstname.lastname@example.org), March 19, 2002
Glide is a function of efficient hull shape and weight. A relatively heavy Whitehall is a nice gliding boat. My wherry does not glide very well as it only weighs 90 lbs. A big heavy work skiff will not glide very well because of its boxy shape. Build yourself a nice rowing boat but make it a little heavy. Design it so most of the extra weight is in the bottam and you will also have the advantage of more stability. I doubt that any boat under 200 lbs will give you the kind of glide that you describe. Hope this helps.
-- Jon Aborn (JonEAborn@aol.com), March 19, 2002.
It's said that there is no such thing as a perfect boat. Having tried and designed about as many rowing craft as anyone, I believe that to be true. About the closest thing that one can find to a perfect rowboat is one that puts, and keeps, you in such a frame of mind that you rarely find yourself wishing you were in some other boat. That craft for me is what I call an un-Xtreme boat. A century ago J.H.Rushton, Fletcher Joyner and others regularly built such craft. They called them "Pleasure Rowboats". These boats were long, low-sided, round-bottomed, fairly narrow, open boats. They were as seaworthy as workboats, just not as heavy or burdensome. Though usually rowed from fixed seats they could keep easy company with many of todays recreational shells, especially in rough water. Typically these craft were 14'-18' long, weighed between 60-120 lbs and had beams between 3-4 feet. You could row these clean-lined boats all day long without tiring. They track well without being stiff. Rowing these elegant craft at 90% of hull speed requires just enough effort to feel like it's doing your body good but not so much as to feel like work. You cannot duplicate the "magic carpet" performance these types craft exhibit in plywood. This may not be the answer you are looking for but, there are no short cuts to Nirvana.
-- Andre de Bardelaben (email@example.com), March 20, 2002.
In my earlier submission I neglected to deal with certain factors that were mentioned by others regarding the matter of glide. I have seen little evidence that weight is an important factor affecting glide. An excellent example is the 60 lbs. Adirondack Guideboat. Few boats can match its glide. If it should be determined that a boat needs more weight ballast can always be added, whereas a heavy boat is always heavy and nearly always has more wetted surface (friction) than a ligher boat of similar shape. The most important aspect affecting a boat's glide are long smooth waterlines. The smoothest lines and least wettest surface can be designed into round bottomed boats. Round bottomed craft will also tend to be lighter for a given size. In fact, every aspect of boat performance can be maximized, speed, stability and seaworthiness, by adopting the more sophisticated rounded hull form. A high degree of speed and seaworthiness can be achieved in various hard forms, be they dories, V-bottoms or multi-chines, but the compromises will be much more noticable. The motions of all boats, in the roll plane (side to side), tend to be as abrupt as the angles in their sections. Again, seamless, buttery performance is the reward of spending the necessary time in the shop and at the drawing board.
-- Andre de Bardelaben (firstname.lastname@example.org), March 21, 2002.