The correct gear ratio for a rinker 242?

Onexl85

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Hello all,
i have a 2002 rinker 242 with a 5.0 pushing a alpha gen 2 1.81, I’ve had lots of trouble planing and holding plane under 3800 rpms. My question is, is 1.81 the correct ratio?
 

Bondo

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Ayuh,...... What prop are you runnin',..??..??

What's the rpms at Wot,..??..??
 

harringtondav

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Just an anecdote...I had a friend with the same engine in 24' Crownline cuddy. He was a bit short of power. He had the same complaints. He'd pitch his prop up to improve plane top speed, but then he could hardly get on a plane.

I'm guessing you've got the correct ratio drive. Per Bondo, your prop pitch is the key.
 

alldodge

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I think your ratio is correct but a prop isn't going to fix the overall performance. A lower pitch prop will help get it up quicker, but you'll have low top end and it can over rev.

Your boat is 5400 dry and the 5.0 just doesn't have enough to get the boat moving. My 232 is 4800 dry with a 454/B1 and does real well. Another with the same boat 5.7/B3 has trouble getting up
 

Scott06

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What prop are you running now? I had good success with an under powered bow rider switching to a 4 blade. I got better ability to hold a plane at lower speed and rpm. In every respect except top end (which is so little % of use) the 4 blade performed better. This was with a Michigan votex which for $125 is cheap, there's others out there from Mercury, solas, turning point etc but I'd think you'd see similar results. Best if you can find a prop shop or dealer who will let you try before you buy

None of this will be a magic bullet vs bigger engine but I'd think you'd be happy with the results.
 

harringtondav

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I've got a Stiletto 4 blade SS. I don't have a power problem, but it performs as mentioned above. It didn't break the bank to purchase it.
 

Onexl85

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Currently running a quicksilver nemesis 4 blade 14x19p, with two people on board, 3900 rpm to hold plane.
 

Scott Danforth

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Currently running a quicksilver nemesis 4 blade 14x19p, with two people on board, 3900 rpm to hold plane.

too much prop. (no where near enough motor)

a 5.0 with a 1.62 drive spinning a 15 x 19 is pitched right in a 3000# boat

a 5.0 with a 1.81 drive pushing a 5500# + boat will need about a 15 x 17p 3 blade
 

alldodge

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Currently running a quicksilver nemesis 4 blade 14x19p, with two people on board, 3900 rpm to hold plane.

Agree with Bondo, need your WOT rpm and could also use what GPS speed

A 4x19 is like a 3x21, how long does it take to come up on plane?
 

alldodge

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Wot is right at 4800, gps speed is 22

Dang, that's 53% prop slip.
Half of the power of the motor is wasted

I'm amazed the boat can stay on plane under 20mph

I would like to see the hull to drive pic
 

alldodge

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Try this, get the drive flat and even with the bottom of the hull, then go WOT and see what your RPM and speed is. Don't raise or lower the drive to get more speed. I'm trying to figure out of there is setup problem
 

QBhoy

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Something way wrong here I’d say. I’d think a 19” wouldn’t be too far off the mark with that set up. No way you should be at 22mph and a whopping 4800 rpm.
Do you think it’s genuinky at those rpm ? Is it a carb or mpi ? Just wondering for the Rev range and limiter it would have.
Is your hub kit ok in the prop ?
 

Scott06

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Definitely verify the tach, either it is off, or you have a bunch of water in the foam, or bottom is dirty??

I found the spitfire /nemesis prop to slip a bunch but nit that much. I got the same wot rpm with a 23" spitfire as a 21" vensura, not much bite on a heavier boat.
 
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