What Prop, how fast???

[fishn_n_tx]

The boat is a 1760 semi V aluminum hull. The motor is a 71 50 HP Evinrude. Now I have a 13 3/4 x 15 prop. I am thinking this will do well duck hunting with a fully loaded boat. Anybody else run a similar rig as to guess speed? And with just me and a fishing pole in the boat, a 17 or 19 shouldn't have any problems, should it?<br /><br /> Boat is now being built and will be ready in 6 weeks. I have to hang the motor I already have, just curious as to what I might expect for performance.

 

[DJ]

Re: What Prop, how fast???

fishn_n_tx,<br /><br />That engine cannot stand to be lugged. It should be propped to run at 5500-5800 with a LIGHT load.<br /><br />A duck boat is heavy, trust me I know. I think a 15" is probably too steep.<br /><br />Without a tach (at least for testing) you're guessing.<br /><br />Check out the tiny tach-here:<br /><br /> http://www.tinytach.com/origigas.html

 

[Link]

Re: What Prop, how fast???

fishn_n_tx <br /><br />I'm just agreeing with DJ here<br /><br />Sounds like your going to be running a boat simular to mine. Custom built Alum Hull likeDJ said, very heavy! Your 71 50 HP was rated at the power head, not at the prop so it is most likely around 44-45HP. <br />Again like DJ said your going to need a tach to figure out your normal load (weight in the boat) at WOT and your motors Max RPM in this case 5500-5800 RPM (His figures) and chose a prop that puts your motor in this range. 2 cycle marine motors are designed to run at 3/4 to max RPM! Most any prop shops will let you experment with different pitches.. As a matter of fact most prop shops, if you give them the weight of your boat will amaze you with the pitch & dia of prop they sell you. Then it's just fine tunning..<br /><br />Link

 

[longshot]

Re: What Prop, how fast???

I have a 1756 mod V Xpress duckboat. I use it for both duck hunting and fishing. I have a johnson 48 spl. I run a 12 1/4' X 15 prop for fishing (al michigan wheel prop). With me and another 175# guy it will run 33mph. It plains out good with the stuff you take fishing, but needs a different prop for duck hunting. When LOADED for duck hunting with 4 guys and their stuff it takes FOREVER to plain out. I probably need to go to a 13 pitch for duck hunting. I do not have a tack on the motor to give you a WOT rpm. Also the motor does not have tilt and trim. <br /><br />thanks<br />longshot