>Wil, how did you equate 1500 # to 1800 rpm with a Lehman 135? That sounds >like a ver interesting calculation. I am getting a Deere 4039DFM 80 hp >engine with my Krogen 39. How can I equate pounds of pull on the anchor >chain to rpm for that engine and that boat? The way to estimate the maximum thrust is to use the table in the archives from my anchoring series. You enter the table with the shaft horse power and propeller diameter. You get the thrust. You can take the engine bhp from the engine, speed curve which will come with your engine. If you don't get one, the manufacturer can provide one. The shaft horse power will be less than the brake horsepower. Use 90% and you will be in the ball park. All we can hope to do without making tests is to get in the ball park anyway. The table is based on the formula : T = 62.72 * (SHP * D/12)^0.67 T = pounds of thrust. SHP = Shaft Horse Power. D = diameter of propeller in inches. Formula taken from "Propeller Handbook" by Dave Gerr and published by International Marine Publishing Co. The ^0.67 means raised to the 0.67 power. Gerr's book should be required reading for every boater. Good luck. CaptnWil Wil Andrews 40 Pier Pointe New Bern NC 28562 (252) 636-3601 captnwil@coastalnet.com