Need prop help for a new tri-toon

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ToonGuy
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Need prop help for a new tri-toon

#1 Post by ToonGuy » Mon May 16, 2011 3:22 pm

New to me, so I don't have any base line to start from. What prop would you reccomend for this boat:

24' Tri Toon, 25" tubes, six-6" full length lifting strakes, motor set back 18" + 6" jack plate (24" total, 5" up & down), motor (for now) will be a 1984 Johnson 140.

Motor came from a little 17' speed boat so I will need to replace the prop I'm sure right away. Stainless is not out of the question, just depends on what I can find. Suggestions?
Just one boat...after another, after another :-)

Bmac
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Re: Need prop help for a new tri-toon

#2 Post by Bmac » Mon May 16, 2011 4:30 pm

Does that 140 have the 13 or 15 spline lower unit?

The 13 spline (small V-4) lower unit has a gear ratio of 2.00

Some 140's had the larger lower unit with a 15 spline shaft which can use V-6 props. The 15 spline unit ratio is 2.25 to turn larger dia. props.

If your best guess of top end is about 30 mph you'd be looking at a 13 pitch (v-4 13 spline) prop,or a 15 pitch (v-6 15 spline) prop
'' 27 mph 11 pitch (v-4) / 13 pitch (v-6)
'' 35 mph 15 pitch (v-4) / 17 pitch (v-6)

This a ball-parking, but a place to start......

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rrhodes
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Re: Need prop help for a new tri-toon

#3 Post by rrhodes » Mon May 16, 2011 7:10 pm

Without any base numbers I am going to guess a 15p prop. Make sure you order from someone that offers a prop exchange program so if you are too far off you can swap them out.
Rick
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Woody
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Re: Need prop help for a new tri-toon

#4 Post by Woody » Mon May 16, 2011 7:42 pm

I would agree with Rick. A 15 works well on my Tri toon with a 135. I think it would be a good place to start.
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ToonGuy
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Re: Need prop help for a new tri-toon

#5 Post by ToonGuy » Tue May 17, 2011 4:44 am

Hmmm....I'll have to check the splines today. How does the the diameter play in? My buddy has a 15p (13-spline) but it's a 12.25. I have seen others as big as 13.5? Thanks for the input! :nana
Just one boat...after another, after another :-)

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The_Hellbilly
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Re: Need prop help for a new tri-toon

#6 Post by The_Hellbilly » Tue May 17, 2011 11:27 am

Woody wrote:I would agree with Rick. A 15 works well on my Tri toon with a 135. I think it would be a good place to start.
+1 I'm running a stock 17 on mine, but gonna try a SS 15 after I fix/replace my tach
Counting all the a$$holes in the room Well I'm definitely not alone

2005 Voyager 22ft Tritoon
2004 Honda 135hp
Strakes, underskinned, aluminum deck, etc.
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Woody
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Re: Need prop help for a new tri-toon

#7 Post by Woody » Tue May 17, 2011 12:15 pm

The_Hellbilly wrote:
Woody wrote:+1 I'm running a stock 17 on mine, but gonna try a SS 15 after I fix/replace my tach

So, do you know what kind of RPM's you're turning with the 17 ?
2014 Benny (Until I find a replacement for my totaled JC Tritoon)


Usually somewhere on the TN River

Bmac
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Re: Need prop help for a new tri-toon

#8 Post by Bmac » Tue May 17, 2011 4:27 pm

ToonGuy wrote:Hmmm....I'll have to check the splines today. How does the the diameter play in? My buddy has a 15p (13-spline) but it's a 12.25. I have seen others as big as 13.5? Thanks for the input! :nana
Good question,

In short it effects the slip ratio in the equation. If pitch is true,a 12.5" dia. will turn more rpms than a 14" dia. prop of the same pitch. So, you can to a point factor that in at around 100-150 rpms per 1/4" change in diameter.

Here's a fun tool to play with when testing props,or ball parking a starting place. http://go-fast.com/Prop_Slip_Calculator.htm Find your gear ratio and start plugging in numbers.

Keep in mind that not everybody measures pitch the same. Especially with today's progressive pitch profiles. One company's 15 pitch may be anothers 16. But with known props a guy can dial it in.

JonCBrand
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Re: Need prop help for a new tri-toon

#9 Post by JonCBrand » Wed May 18, 2011 5:51 am

I running a 14.5" x 17 pitch 4 blade on my V6

Post some pics of your boat!!
Last edited by JonCBrand on Wed May 18, 2011 6:40 am, edited 1 time in total.
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The_Hellbilly
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Re: Need prop help for a new tri-toon

#10 Post by The_Hellbilly » Wed May 18, 2011 6:13 am

Woody wrote:
So, do you know what kind of RPM's you're turning with the 17 ?
Just a hair less than 6k. FWIW: my toon with the current furniture setup is REALLY heavy. I currently run in the mid 30's light, 30-32mph loaded down, and ran in the high 20's with a log full of water. (all gps verified) I'm hoping the right prop and maybe a setback will get me to 40mph. My biggest issue is that my motor is right at the azz-end of my toon, intstead of set back 12-24 inches as is the current trend.
Counting all the a$$holes in the room Well I'm definitely not alone

2005 Voyager 22ft Tritoon
2004 Honda 135hp
Strakes, underskinned, aluminum deck, etc.
Towed by: '11 Chevy Z71 Crewcab

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Woody
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Re: Need prop help for a new tri-toon

#11 Post by Woody » Wed May 18, 2011 9:07 am

[quote="The_Hellbilly My biggest issue is that my motor is right at the azz-end of my toon, intstead of set back 12-24 inches as is the current trend.[/quote]


Me too. I would like to change that someday. I don't have strakes either, but will eventually add them also.
2014 Benny (Until I find a replacement for my totaled JC Tritoon)


Usually somewhere on the TN River

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ToonGuy
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Re: Need prop help for a new tri-toon

#12 Post by ToonGuy » Fri May 20, 2011 4:50 am

I hae the 13 spline unit. So I'm thinking a middle of the road dia. 15p to start with. I do NO water sports, the boat is just used to cruise (mostly to the sand bar and back :drink4 ). I'm usually lightly loaded (4-5 people, and my tank is only 19 gal. max). Whatcha think?
Just one boat...after another, after another :-)

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The_Hellbilly
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Re: Need prop help for a new tri-toon

#13 Post by The_Hellbilly » Fri May 20, 2011 7:53 am

FWIW: That's where I plan on starting
Counting all the a$$holes in the room Well I'm definitely not alone

2005 Voyager 22ft Tritoon
2004 Honda 135hp
Strakes, underskinned, aluminum deck, etc.
Towed by: '11 Chevy Z71 Crewcab

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ToonGuy
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Re: Need prop help for a new tri-toon

#14 Post by ToonGuy » Fri May 20, 2011 8:59 am

Well, I'm picking up a 12.25x15 new OEM aluminum for $70, I think it's a good starting point.
Just one boat...after another, after another :-)

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Shopguy
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Re: Need prop help for a new tri-toon

#15 Post by Shopguy » Fri May 20, 2011 9:07 am

Isn't 12.25 a little small? Just goin on what I hear but "on a toon go as big as you can get and then pitch for rpm. Just throwing that in there for conversation.... :)
Shopguy

23' Tritoon with a 150F Yamaha
Strakes and skins

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