At 08:28 PM 7/27/98 -0700, Nicholas Kluznick wrote: Paul's words: >> ...I do not consider currents at >> all, since all speed measurements are relative to the water anyway.... Nick's words: >2 to 4 knot currents are every day things in the San Francisco Bay, Delta >and rivers. 6 to 12 knots in some parts of the Pacific Northwest: >Desolation Sound, the San Juans, Princes Louisa Inlet.... A few extra >knots sometimes come in handy. Picture yourself under the Golden Gate >Bridge fighting a 4 kn ebb and you look back and see a rare Pacific squall >heading your way, now might you not consider ground speed to be much more >significant than water speed? These problems are not unique to the West coast. We see much the same thing in Florida, though almost never more than five or six knots. You are right, that you will want as much speed as practical in these conditions. I would figure out the maximum "practical" speed for my boat, and then buy enough iron to attain it. There will be times when I need or want it, current or no current. That is why I ignore current when figuring speed and power requirements. A few years ago, scallops were big business out of Port Canaveral. The folks going after them had "real" trawlers. By that I mean that they had a TT ratio of one or greater, in accordance with Beebe's latest revised book. They were typically 70-80 feet on the water line, with nominal D/L ratios in the 350 neighborhood, though they were sometimes loaded up to the 600 ball park. All the ones I ever had an opportunity to become familiar with had between 1000 and 3000 hp, though I have heard second and third hand that some where running much more than that. In general, the owners did not believe that it was possible to put too much power onto them; and they did not think anything at all about burning a thousand gallons of fuel per day or more. These boats were typically at sea 21 hours per day, and in port for three. Each one had a standing appointment to off load their catch the same time each day. To miss an appointment may mean that they would have to dump their catch overboard; but I do not remember any of them ever having to do that--except inadvertently by means of the occasional capsizing. Now comes the part where I tie this story back to our current subject: They would typically had to commute as long as five to eight hours each way to their fishing grounds, so they wanted as much speed as possible for running to and from; so they would run balls out all the way out, and all the way back. Even with all this power, it was rare that any of them could exceed an S/L of 1.5. I do know believe any of them could exceed 1.6. Now you know why I am so impressed that you can get 1.6 with so little power, even given your relatively light displacement. >>.......Many folks on this list have much better >> semi-displacement boats than you do,....... > >I prefer to say that few people on this list have a better displacement >boat than I do. You have already read my second post on that, so you know that I agree with you. >Her deep fore foot, the long flat run aft, the wine glass >hull, the round chine, all add up to an easily driven hull that affords >great economy and better than expected top end speed, for a displacement >boat. At 05:10 PM 7/28/98 -0700, Nicholas added to this discussion: >Paul, I enjoyed your note about your observations and expectations for the >K39. I would just like to say that the underwater hull at the transom is >not all that flat. I guess that "flat," like beauty, is in the eyes of the beholder. :-) >> ......You are dragging a small amount of flat transom below the water >>line. It...... >> >> .....As you said earlier, you to have a "wine glass" tail, but it is a >>rather fat wine glass. The features of a semi-displacement boat are >>not very.......... >As viewed from the stern, it has a about a 3:1 slope, or about an 18 degree >rise. Just thought you would like to know. That is about what I had estimated from the very excellent pictures that Mike Ford sent to me, but when you are aft looking forward, you are looking at the dead rise angle. That is not very relevant to our current discussion. Lots of semi-displacement boats and planing boats have a similar dead rise. I've got 30 degrees of dead rise myself, and could very well have a planning hull. I only call it a displacement hull because those are the speeds at which I plan to operate it. Wil and others have cited the PC, the D/L, and the A/B ratios for this boat to prove that it is a full displacement boat. The fact of the matter is that none of these and no combination of them serve that purpose. It is just that we have become accustomed to seeing these parameters within certain ranges for conventional full displacement boats. If you come up with something outside of the convention, then none of these ratios can give you a true indication of whether the boat is full or semi-displacement. What actually defines a semi-displacement hull compared to a full displacement one is the quarter beam buttock angle. This is the angle of the aft run of your hull bottom, when measured from plane of the water line and viewed from the side. You have told me that you have a long flat run aft. This is also what I see in these pictures, and it indicates a very shallow quarter beam buttock angle; though I am not able to make good measurements from these pictures. Perhaps you can tell me what this angle is? I'm guessing that it is about 6-8 degrees, in which case you are on the transitional line between semi and full displacement. Neither one of us would really be wrong for calling it one or the other. >I'm sure Mike would have told you himself but he has been mighty busy these >days getting his new boat ready for sea trials. I wish him well, and look forward to hearing from him after the sea trials. He may very will have valuable information to add to this discussion at that time. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ :: Paul and Cindy Kruse :: KJV Joh 14:27 Peace I leave with you, 165 South Kenneth Court :: my peace I give unto you: Merritt Island, FL 32952 :: not as the world giveth, give I unto you. E-mail: plkruse@iu.net :: Let not your heart be troubled, 407-453-6206 :: neither let it be afraid. :: +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++