Mercury classic 50 prop question

guntruck

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Joined
Jul 17, 2012
Messages
6
So I just bought a 14.5' Wahoo with a Merc classic 50 that runs beautifully. It has a 12P prop that was damaged so my buddy gave me a SS 13P and I took it out for a cruise. Me (280lbs, GF 130, and friend 200) full of 8 gallons of fuel and boat that weighs 675lbs. It planed but it took a while and my friend had to get on the bow then it gradually got up on plane, it was a big slug though. So I threw an aluminum 11P on today and took it out, just me and my gf and 3/4 fuel, surprisingly it just kept on plowing until she moved up towards the bow then it hopped right up on plane. It ran pretty good and sounded good and kept on plane no problem. My buddy said the 12P was perfect but he was mainly solo and much lighter than me,and he claims to have had 5 people in the boat and it took a while but got on plane no problem. My question is given the weight of the boat does it sound about right that the 11P is the way to go? Not sure of RPM's but from the sound of it it sounds somewhere in the neighborhood of 5200RPM? Any thoughts would be appreciated.

Thanks in advance. ;)
 

jimmbo

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May 24, 2004
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12,944
Re: Mercury classic 50 prop question

Welcome to iboats
This belongs in the prop section, but...

"sounds somewhere in the neighborhood of 5200RPM" Hmm, tachometer ears. Seriously we would need to know the rpm, from a tach, before anyone can give GOOD advice regarding a choice of prop. Does the engine have power trim? if not, what hole is the tilt pin in? From what it sounds like all the props you tried have too much pitch, provided the engine is in good shape mechanically and in tuned.
 

guntruck

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Jul 17, 2012
Messages
6
Re: Mercury classic 50 prop question

Welcome to iboats
This belongs in the prop section, but...

"sounds somewhere in the neighborhood of 5200RPM" Hmm, tachometer ears. Seriously we would need to know the rpm, from a tach, before anyone can give GOOD advice regarding a choice of prop. Does the engine have power trim? if not, what hole is the tilt pin in? From what it sounds like all the props you tried have too much pitch, provided the engine is in good shape mechanically and in tuned.


Just noticed about the forum maybe a mod can move it..........No power trim and the pin is the second to last hole. THe tach ear thing Im with ya, its a best guess............been around engines all my life and rebuilt many a 2 stroke just not marine :( .............anyway I am going to get a tach just wanted to get some thoughts on similiar set ups and what others are running.


Thanks
 

jimmbo

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May 24, 2004
Messages
12,944
Re: Mercury classic 50 prop question

when you say second to last hole, which are you counting as the last hole? The one closest to the transom or the one furthest away? Generally most consider the one closest to the transom as the first hole.
The basics are your engine has an WOT rpm range of 5000 to 5500, and should be propped to run in the upper end of the range, usually with a light load. However if the average load is considerably higher than a light load then it should be propped with less pitch and a watchful eye on the tach to prevent over revving with a light load.
 

guntruck

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Joined
Jul 17, 2012
Messages
6
Re: Mercury classic 50 prop question

when you say second to last hole, which are you counting as the last hole? The one closest to the transom or the one furthest away? Generally most consider the one closest to the transom as the first hole.
The basics are your engine has an WOT rpm range of 5000 to 5500, and should be propped to run in the upper end of the range, usually with a light load. However if the average load is considerably higher than a light load then it should be propped with less pitch and a watchful eye on the tach to prevent over revving with a light load.


That is correct sir, 2nd hole closest to the transom. I appreciate your feedback, I am installing a tach today so I can get an accurate # on the RPM's. A friend of mine also recommended doel fins on the outboard said it will help it plane quicker and be better out of the hole. I think the prop is good the 12P may even be good, its the heavy boat my 280lb self sitting on top of an 8 gallon fuel tank behind the console towards the rear is whats making it struggle to get on plane.
 

steelespike

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Apr 26, 2002
Messages
19,069
Re: Mercury classic 50 prop question

My 1965 Merc 500 on a 57 18ft Crestliner utility total weight about 900 runs an 11" pitch it has also had a 12" at times.
Boat has been in storage for years now but the previous owner was a knowledgeable boater former racer from the 50s.
He had the equipment and experience to set it up right.I think he went to the 11 inch because he was carrying more weight
and it did better than the 12".I do think your 13 may be too much unless very light load.
You also may want to see if the Wahoo has absorbed water over the years. Usually comes from poor storage boat standing for long periods with water in it.
 

guntruck

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Joined
Jul 17, 2012
Messages
6
Re: Mercury classic 50 prop question

My 1965 Merc 500 on a 57 18ft Crestliner utility total weight about 900 runs an 11" pitch it has also had a 12" at times.
Boat has been in storage for years now but the previous owner was a knowledgeable boater former racer from the 50s.
He had the equipment and experience to set it up right.I think he went to the 11 inch because he was carrying more weight
and it did better than the 12".I do think your 13 may be too much unless very light load.
You also may want to see if the Wahoo has absorbed water over the years. Usually comes from poor storage boat standing for long periods with water in it.

Steele you got a good point about the water absorption.....Any ideas on the best way to check that and or eliminate it/dry it out?
 
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