Prop for 2000 Johnson 25 HP

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alumacrafty

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Nov 19, 2013
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Location
NW Ia, on the Missouri River
Revealing my total ignorance here.
I want a new prop for my 2000 Johnson 25 HP, Model J25TESSD. You would think that would be enough information for anyone to find a prop online but where ever I look, it lists more questions/options than I can answer.
Is it 13 spline or 14? Is it the commercial motor? Does it have thru exhaust?
I have the original manual and the answers aren't in there either.

And I also would like some opinions and/or expertise . . . is a stainless steel prop worth the money on a 16' jon boat used on the Missouri River? Should I stick with a 10 X 13 or is a change in dia/pitch in order? I'm not unhappy with the performance, but it's the only way I've run it . . . maybe it can be better?

I have a Tiny Tach on order so I can check the RPM this spring.

Help is appreciated.
 
14 spline. i gained approx 2 - 3 mph when i switched from aluminum to stainless of the same pitch. really need to get rpm before recommending a prop
 
Okay, tell me about yours. Do you have a 25 HP? What did you put the stainless prop on? What boat?
I have a 16-ft. Alumacraft rivieted jon with little weight. I try to minimize extra "stuff" in my boat and I'm pretty light weight myself so the Johnson moves me along pretty well and I usually fish alone. My son weighs about 260 so it's noticeable when he gets in the boat but we still move okay.
More tips are welcome.
 
Yes to the Tiny Tach. Great tool. Forget the fancy option version. I have tried other tools. Checking a prop needs two things. Tach and GPS.
I believe your engine has a maximum RPM of 5500. This is your target. The Acceptable Full-Throttle Range is 4500-5500RPM. Consult your specific manual to be sure. The engine must run in this range at full throttle. If it can't run fast enough it is being overloaded and may ping and overheat. If it is running too fast, it is being over revved and can tear itself apart if severe. Either condition reduces performance and can destroy the engine...sooner or later. Some of these engines have a range 5200-5800 so I don't mind running them a little on the high side. If you see 56-5700 don't panic. Some models have a rev limiter in the ignition module set at 5800 or 6100. If you hear the engine skipping at full speed, it is likely bouncing off the rev limiter. Now you NEED a prop with more pitch, slow the engine down a little.
Unload the boat completely and trim the boat for maximum speed. Run the boat at wide-open throttle and note the RPM and speed. Your engine should run in the factory specified RPM range...at or near the top of the range. If the engine is over revving you will need to increase pitch to reduce the RPM. If your engine is running too low an RPM then you will need a prop with a lower pitch so it can rev up a little higher. If it is over-revving 'a little' , it might be fine with the boat loaded normally. Careful buying too much pitch. If you are wrong you're stuck with it.
You do this with an empty boat, and aim for the top of the RPM range. That way, as you load the boat with persons/gear, the RPM will drop off but still be in the acceptable range. If you load the boat severely, the RPM may drop below the lower end of your RPM range. Your spare prop should be one size smaller to allow it's use during a heavily loaded day out. Rule of thumb...you can use a prop one size too small. You can never use a prop that's too big. Make purchases carefully.
I like stainless props. They have thinner, stronger, sharper blades. They are more efficient when performance is critical. For every day use, especially in unknown waters, aluminum is a more practical choice. It will give if you hit a solid object. It is repairable at lower cost. The loss of performance, for these engines, is hardly noticeable without a GPS. An aluminum prop is less likely to become the property of the local thief.
Your GPS is nice because you can see small changes in top speed for various conditions. These are flat or choppy seas, with or against the wind, all-important trim angle, and even slight differences in identical props.
I spend lots of time setting up boats with a Tiny Tach and a GPS. It seems though that I always guess wrong on the initial set-up. Your 16ft boat should make pretty good use of the 13pitch standard OMC prop. Some engines are stronger than expected and can use a 15pitch. A 30hp engine set up with a big carb on a good lightweight hull can occasionally make use of the factory 17pitch stainless 'cupped' prop. Condition of your prop is critical. A banged up, distorted prop is useless. Two of my personal boats are Alumacrafts. They work well.
 
i don't have the exact answers to your question but being new i had the same questions for my prop. the prop on my boat is pretty beat up so i asked three of the doctors at work that run bay and off shore boats about props. all three told me to contact Mike Hood prop repair and see if they could fix my prop for a lot less than buying a new one. https://www.mikehoodprops.com/about.htm maybe you have a prop repair shop in your area that can help you. the doc's told me with my smaller motor that i might ask about cupping the prop. i am fixing to order a tach also so i haven't done anything with the prop yet and i want to finish the wood work/mods inside and load with gear to see how things are running before i change the prop.
 
[url=https://tinboats.net/forum/viewtopic.php?p=339989#p339989 said:
alumacrafty » 43 minutes ago[/url]"]Okay, tell me about yours. Do you have a 25 HP? What did you put the stainless prop on? What boat?
I have a 16-ft. Alumacraft rivieted jon with little weight. I try to minimize extra "stuff" in my boat and I'm pretty light weight myself so the Johnson moves me along pretty well and I usually fish alone. My son weighs about 260 so it's noticeable when he gets in the boat but we still move okay.
More tips are welcome.

i have a 2001 35 hp 3 cylinder on a 2013 alumacraft 1648 mv. decked out, 2 batteries, 24 v trolling motor up front. gas tank, lawn mower battery to start the motor and tilt trim. i turn a 15" stainless at 5800 rpm for 33 mph. holeshot is throw you back instant. with an aluminum in same pitch i was getting 29.5 and a lot of slip.

i had a merc 25 on my boat and with aluminum prop i was getting 26 mph. switched to stainless in same pitch and got 28.

my boat weighed down with everything but people is approx 700lbs.
 
Thanks guys. I didn't mention that I also intend to buy a GPS/depth finder later in the spring (in addition to the Tiny Tach).
Also, I found one prop dealer online, https://www.propmd.com/contacts/index/[/color]
that has a "pitch exchange program" where you can buy, try out, and exchange various pitched-props for the cost of shipping. That seems more than fair to me.
I'm never in a real hurry when I'm on the water and not sure why I'm getting obsessed with this prop thing but it's -12 degrees here in Iowa and dreaming about catfishing on the river helps get me through these cold days.
 

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