marina says i need a different prop

[rowdy85]

I just bought a 95 23' centra lazer with a 300hp 7.4 mercruiser and a bravo 1 outdrive. well i had a mechanic do a tune up, reseal the outdrive, and check it out and he said everything is good to go. So last weekend i take it to raystown and i cant get the boat on plane. it only pushes water till 2500 rpm and thats it. the engine runs awesome in neutral. i can hold it at 4500 rpm in neutral and it sounds great. In gear it almost feels like im trying to pull out in 4th gear in a car. The mechanic is telling me the boat has the wrong prop on it. It has a 3 blade stainless mirage quicksilver a41 23p. so my question is does this sound like the wrong prop. or is something else wrong? The boat weighs approximately 3850 pounds empty plus 3 people and 60 gallons of gas.

 

[lrlima]

Re: marina says i need a different prop

dont know if thats the right prop, but i wouldnt hold 4500 RPMs in nuetral. Also, an engine performs much differently under load. my guess is either engine performance issues or maybe the prop has a spun hub in it.

 

[junior1113]

Re: marina says i need a different prop

does engine rev in forward or is it just reving up to 2500. if motor pushes water to 2500 then revs higher with no more speed you need prop rehubbed. if it only revs to 2500 in gear motor issue.

 

[rowdy85]

Re: marina says i need a different prop

dont know if thats the right prop, but i wouldnt hold 4500 RPMs in nuetral. Also, an engine performs much differently under load. my guess is either engine performance issues or maybe the prop has a spun hub in it.

I didnt hold it there long just a moment. I was more revving it to see in it was breaking up or bogging out

 

[rowdy85]

Re: marina says i need a different prop

does engine rev in forward or is it just reving up to 2500. if motor pushes water to 2500 then revs higher with no more speed you need prop rehubbed. if it only revs to 2500 in gear motor issue.

nope in forward gear the highest rpm is 2500ish with the boat nosed up pushing water

 

[Dhadley]

Re: marina says i need a different prop

Since you just bought it we'll assume it ran good on the test run. If so then it might be worth it to ask the seller if he changed props after the test run. If it's the same prop - the exact same one, not one "just like it" - then you might question the mechanic as to what he did in the "tune up".

We'll further assume you are trying to plane out with the drive trimmed all the way in (down). Right?

 

[rowdy85]

Re: marina says i need a different prop

Since you just bought it we'll assume it ran good on the test run. If so then it might be worth it to ask the seller if he changed props after the test run. If it's the same prop - the exact same one, not one "just like it" - then you might question the mechanic as to what he did in the "tune up".

We'll further assume you are trying to plane out with the drive trimmed all the way in (down). Right?

I know im going to get flamed for this but no test run lol!! I bought this boat cheap knowing it needed its outdrive resealed. i only payed $3000 for the boat and trailer so i took a gamble i just hope its not a losing one now!!

The mechanic says it has good compression in all cylinders and the engine is sound so thats why i took the gamble!

 

[junior1113]

Re: marina says i need a different prop

dont believe this is a prop issue. that 300hp should turn any prop more than 2500rpms.

 

[Dhadley]

Re: marina says i need a different prop

We'll further assume you are trying to plane out with the drive trimmed all the way in (down). Right?

???

 

[ufm82]

Re: marina says i need a different prop

Agreed on the hp thing- it should be able to turn the prop easily and even cavitate it. The comment about engines sounding great unloaded and then being dogs on the water is also true. Even if he was trimmed way up the engine should easily be able to break the prop loose I would think. Wondering about engine performance and timing/fuel issue. His boat isn't a whole lot heavier than mine and at 150 hp I can run 50mph- he should be able to hit nice speeds with the big block. Something seriously amiss.
With no additional rpm the hub isn't spun. Have you tried "pedaling" the throttle? That is, get her plowing, pull the throttle back to let the bow drop and then hammer it again? It isn't the right way to do it but it may show you something about engine performance.

 

[Kainon]

Re: marina says i need a different prop

does the fuel tank have Fresh Fuel in it ? take a sample of the fuel from the tank, and compare to some fresh fuel.

 

[Tail_Gunner]

Re: marina says i need a different prop

???

We'll further assume you are trying to plane out with the drive trimmed all the way in (down). Right?

This is one you need to answer before going futher..

And does the boat have trim tabs...Thats a deep v heavy and hard to get out of the hole..

 

[rowdy85]

Re: marina says i need a different prop

We'll further assume you are trying to plane out with the drive trimmed all the way in (down). Right?

This is one you need to answer before going futher..

And does the boat have trim tabs...Thats a deep v heavy and hard to get out of the hole..

yeah it was trimmed all the way down. looks like the ignition module is bad. So I'm trying to find a new one.