Ok ill try to include as much info as I can, im new to boats. My boat is an alumacraft 1442 flat bottom riveted jon, I have a 1980 evinrude 15 hp in good condition, but needs a prop. The boat is 230 lbs, so wieght is between 930 lbs max and probably 550 minimum for boat, motor, gear and people, I use the boat around 5000-7000 feet above sea level. It currently has a badly worn and chinked 9.5x10 prop, and with a total weight of 570 about, the best speed I got was 16-17 mph, bumping up to 18 once or twice on my gps, and with about 680 and with wieght shifted around for best speed we got up to 13 mph, and with a max load, we were down to about 6-7 mph, and I dont have a tachometer (need to get one) What I would like is a good estimation on size/pitch/3 or 4 blade, as to have a good prop mostly for higher speeds, and being able to reach the best top speed with the heavier loads. I dont go out much alone, so generally it will be in the mid to upper load levels, with seldom use in the lower end. I REALLY appreciate any information, this is a fun project my father and I are going in on. thanks again
TinBoats.net
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Need recomendation for prop on evinrude 15 please!
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I am running the same prop on a 15hp evinrude on a alumacraft 1436. I can hit 27 mph with just me and about 23 mph with two people. Sounds like your prop is slipping. Pull it of and look at the rubber piece in the center. See if it is torn up or melted. Hard to get the right prop without a tach. You set the prop to the max rpm the motor will run.
Ok, ill take a look at that. Ya the 1436 is a little lighter than the 1442 ncs, but only 50 lbs (180 vs 230) so there shouldnt be much difference...accept what elevation are you at? I have heard this high elevation takes a substancial amount of power from watercraft but I may be way wrong lol. thanks again for any help
Ya...so will just a generic tach work or does it have to be an outboard specific one? I would think just a normal one would work...so would you say I should get a tach before I buy a prop and test what I have? Will I get a conclusive test if my prop is slipping?
This is the tach I use. https://www.trailtech.net/digital-gauges/tto/723-a00. The prop will have a rubber hub in the center. If you hit something with your prop the prop will spin on your hub. Keeps from tearing up the lower unit. If the prop has spun the hub. You will know it by looking at it. You will need to find WOT rpm for your motor. Let's say it is 5500 rpm. You do not want to go over that #. Run down the lake wide open. Read what the tach says at wide open. Let's say it reads 6100 rpm. You will need to raise the pitch of your prop. If it is lower than 5500 rpm you will need to lower the pitch of the prop. 5500 rpm might not be right for your motor you will need to find that out.
Ringo Steele
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Also remember the pre 1985(?) or so motors are flywheel rated at 15 HP, where the newer ones are prop rated. I have a 1974 15 HP, and I get about 17 mph with 2 persons and gear aboard (700ish lbs). My hull is about 300 lbs, 15.5' x 50" floor. I'm running the standard 9.5x10 prop. I don't have a tach yet either, but maybe this will give you some comparative information.
Ok, hopefully I can get a tach tomorrow from napa or carquest, and take it out and see what im running. So I looked and my particular motor has a WOT range of 5500-6500 rpm, so what I wanna aim for is between 6000-6500 rpms on an empty load, right? So that way when im loaded I dont drop too far below my rpm range? just tryin to figure out what im goin for when I take it out.
