Prop for top speed |
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ibiz ![]() Groupie ![]() Joined: June-18-2012 Location: Kansas Status: Offline Points: 50 |
![]() ![]() ![]() ![]() ![]() Posted: May-23-2023 at 9:01am |
Hi,
Two props came with my 2000 Sport Nautique 1. 12.5 x 15.5 2. 13 x 16 See photos. Which one would give me the most top speed? Thanks Jerry
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Jonny Quest ![]() Grand Poobah ![]() ![]() Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2937 |
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Not an easy question nor answer. Props that are cast and not CNC machined typically won't perform as well. The OJ prop in the picture is not a CNC prop. The OEM prop for your boat was most likely the 13X16 Cupped OJ.
The prop's diameter is boat specific. Not too big so that the blades pass too close to the hull, and not too small so that the prop sacrifices efficiency. The pitch should allow the engine to just achieve the engine manufacturer recommended maximum operating RPM at wide-open-throttle (WOT). External impacts on WOT engine RPMs are things like altitude, people / weight in boat, etc. The cup will also impact propeller performance. The cup is the "bend" on the prop's trailing edge. The idea behind the cup is to change the effective pitch by adding camber to the prop blade shape. So, a prop with less pitch and a bigger cup may allow the engine to spin up faster at slow speeds without sacrificing too much speed at WOT. Keep in mind that not all "cups" are created equal. Cups will vary in effective pitch. One rule-of-thumb for cups is: "When using a cupped propeller, the design pitch value should be reduced by 1-2 inches compared to the non- cupped propeller." So...not an easy answer. Also, a repaired prop often (not always) does not perform as well as an original (non-repaired) prop. Give 'em both a try and see how the boat performs. CCF member TRBenj often frequents the site and has a lot of good info on props. He can likely give you more useful information. JQ
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2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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ibiz ![]() Groupie ![]() Joined: June-18-2012 Location: Kansas Status: Offline Points: 50 |
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The 13 x 16 is the one we have had on the boat. It gives more than enough of pullout of the water for skiers. At the top end it appears that we are at max RPM or can be slightly higher.
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KENO ![]() Grand Poobah ![]() Joined: June-06-2004 Location: United States Status: Offline Points: 11015 |
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JQ gave you the only answer you really need, due to all kinds of variables ...........try both props on the boat. ![]() From your description and no picture, .your other prop is unknown to anybody It could be a newer design Acme 422 as a guess, but a prop swap will tell you everything you're trying to find out
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ibiz ![]() Groupie ![]() Joined: June-18-2012 Location: Kansas Status: Offline Points: 50 |
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![]() the other prop pic is now showing.
You are exactly correct the other prop is a 422. Jerry
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KENO ![]() Grand Poobah ![]() Joined: June-06-2004 Location: United States Status: Offline Points: 11015 |
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I'm psychotic or psychedelic or something like that.
![]() Still the same answer...........try both 11 out of 10 people would say to put the 422 on for a try/comparison
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ibiz ![]() Groupie ![]() Joined: June-18-2012 Location: Kansas Status: Offline Points: 50 |
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So I tested both props yesterday at 4200 rpm (max recommended continuous speed) and at 4800 the maximum RPM (redline).
Interestingly the speed from both props were essentially identical, 38 mph and 41 mph at the two RPM levels respectively. The 422 prop appeared to allow RPMs to go into the 5200 range (briefly) where the other prop got to just 5000 RPMs briefly. So I won't be using the 422 prop as I want to help insure that red line is not accidently exceeded. It is still too cold to get in the water to test with a deepwater slalom start but there didn't seem to be any difference getting up to 32 mph between either prop. Thanks all for the feedback and suggestions. Jerry
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Gary S ![]() Grand Poobah ![]() ![]() Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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38 and 41 essentially identical? Some would kill for 3mph
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MrMcD ![]() Grand Poobah ![]() ![]() Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3733 |
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I may be silly but when my boat is running great and hits 5,200 RPM I celebrate knowing it is in fine tune. No worry at all that 5,200 will hurt it. I never keep it at high RPM for any period of time but it is nice to know it can do it.
Even adults when out with friends sometimes have fun racing each other. 1 or 2 MPH can let you win sometimes? Maybe I am just a 65 year old teanager out there having fun? Since both props ran the same speed at 4,800 I am assuming it goes faster with the 422?
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KENO ![]() Grand Poobah ![]() Joined: June-06-2004 Location: United States Status: Offline Points: 11015 |
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Umm.............go read what he said again 4000 rpm they each went 38 4800 rpm they each went 41 |
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fanofccfan ![]() Platinum Member ![]() ![]() Joined: December-13-2009 Location: North Bend NE Status: Offline Points: 1769 |
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Too cold for water test on the slalom? I am north a state and there have been quite a few water tests up here!
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2004 196 LE Ski 1969 Marauder 19 1978 Ski
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