Another prop question

[sdeyoung99]

Hi, Great forum here. I'm just looking for a little advise. I just bought a 1996 220WA Angler with a 1996 150 Mercury outboard (V6 2.0L). Max RPM's is 5600 and WOT is about 200 lower. According to Michigan props I should have a 14.5 X 17 prop, which is what I have. The aluminum prop is pretty tore up, so I figure thats why I'm a little low on the WOT. I don't have trim tabs but I do have the dolfin trim set up on the motor. What I'd like to get is more speed from my WOT, so before I but a prop any suggestions would be great....Thanks

 

[Dhadley]

Re: Another prop question

Welcome!!<br /><br />Lets see if we understand this correctly -- your target rpm is 5600 but you only get 5400 -- right?<br /><br />If thats right, the first thing that comes to mind is why do you only want 5600? seems a bit low. But thats up to you.<br /><br />Anyway a 17 seems a bit big for a 2 liter on that big (heavy) of a boat. But if we can get a 17 to get you the right rpm's, thats good.<br /><br />Generally if a prop is tore up it will produce more rpm, not less. Although the speed should be down because its less efficient. A tore up prop = more slip.<br /><br />I'd also bet the motor is too low for the fin to do any good. If the motor is real low, it will actually hurt your performance.<br /><br />Are you palnning on getting the aluminum prop rebuilt? I might suggest that be done. Then we can test again to get a good baseline. If you buy a ss prop then the aluminum prop will be a good spare.

 

[sdeyoung99]

Re: Another prop question

Wow quick reply...thanks.<br /><br />Next to the serial# it says max rpm's 5600. The motor is 25" shaft so I couldn't tell you if its too low, It dosen't seem to be. All compression is good, new plugs, just decarbed. Possibly an old Tach gauge. all other gauges have been replace except that one. I'm just wondering if i should stay with the recommended prop or could I change sizes to pick up a little more speed. The boat and motor were a package from Angler, but i do realize it could be almost under powered...

 

[Dhadley]

Re: Another prop question

Well, we're guessing you mean the motor only turns 5400, right? Thats pretty low and it may develop stuck rings pretty quickly. Keep an eye on that.<br /><br />By "mounted too low" we are talking about the relationship between the anti-ventalation plate (flat plate directly above the prop) and the bottom of the hull when they are parallel. Is the AV plate below the bottom or even or up an inch?

 

[sdeyoung99]

Re: Another prop question

"Anyway a 17 seems a bit big for a 2 liter on that big (heavy) of a boat. But if we can get a 17 to get you the right rpm's, thats good"<br /><br /><br />I was think so myself. I was looking at going with a 14.5 X 15 to get my RPM's up...What do you think?

 

[Silvertip]

Re: Another prop question

Wahoo -- don't spend money on a prop until you make it clear what you are experiencing. Make sure the AV plate is as Dhadley suggests. And also clarify if you really are getting only 5400 at WOT. If the engine height is right, I'd try removing the fin to see if performance picks up. If you still need a couple hundred RPM, the 15 pitch prop sounds like a good choice.

 

[Dhadley]

Re: Another prop question

Changing to a lower pitch prop is always your last resort. Lets look at set up first, we have to start from square 1.<br /><br />We still havent verified if 5400 is truly your top rpm...

 

[sdeyoung99]

Re: Another prop question

Thanks...I will get my prop rebuilt, check my AV plate and give it a run to see what my true WOT rpms are....