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VS-MasterAngler

How many RPM's??

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How many rpm's are you guys getting WOT on an 18.5MA with a Yamaha 150 vmax ox66?

I just got my 18.5 and dropped it in the water this morning to put it on the boat lift and on my way to the lift I had her wide open pushing a consistent 5100rpm @47mph... Thought I red about some of you guys with a 150 hitting about 54/55mph.

 Boat has a 3 blade Powertech prop but cant really make out what the specs are on the side of the prop.  See attached picture, maybe you guys could help. 

By the way Fort Myers Marine did a great job, as always... putting on the power pole and servicing the engine, Chuck and 3 other guys including their Yamaha mechanic actually came out to compliment the boat and how great of condition it is in! Made me feel pretty good about the purchase!

I plan on taking the new-to me boat out for a full day tomorrow so I'll definitely take a bunch of pics and post them!

Sorry about the pic being sideways.

20171107_171507.jpg

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Hey VS, first of all congrats on the new boat, you will love her!  

As for your speed and RPM, you are definitely not getting what you should from her.  I am under propped but was getting 54 at 5900 RPM.  I believe that is over the recommended max RPM on the OX66 so I dont go over 5500 and will probably adjust my prop to get lower RPM and more speed.  

 

Get some pics posted up in the owners photos thread!  

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I just went from a Power Tech OFX4/17 to a Yamaha 14.5/21

the PT would spin up to 5800-6k and 48-49mph

the Yamaha will spin 58-5900 and 52-53mph

you need a smaller diameter prop. The PT might be 15.25 and takes a bit to spin up. The 14.5 has a better hole shot and top end

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12 hours ago, Nag Juice said:

I just went from a Power Tech OFX4/17 to a Yamaha 14.5/21

the PT would spin up to 5800-6k and 48-49mph

the Yamaha will spin 58-5900 and 52-53mph

you need a smaller diameter prop. The PT might be 15.25 and takes a bit to spin up. The 14.5 has a better hole shot and top end

Thank you this is what I'm looking for! where did you find a Yamaha Pro Series 14.5/21... I looked for a while last night online and couldn't find any:(

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42 minutes ago, VS-MasterAngler said:

Thank you this is what I'm looking for! where did you find a Yamaha Pro Series 14.5/21... I looked for a while last night online and couldn't find any:(

I traded a buddy in town. I don't have a pro series just a Reliance with the right pitch and diameter. I did just buy a Apollo 14 3/4 x 21 I haven't used yet. It's newer and can't imagine 1/4" being too big a deal. That said, the pro series props are for the most part consistently back ordered. If you find one, grab it.

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8 hours ago, VS-MasterAngler said:

What do you guys think about the Solas HR Titan 3 prop 14.5/21pitch?    MFG# 3551-145-21

 

     

I would look for a Tempest Plus or a Yamaha Pro Series.  I can spin a 20p Yamaha Pro to 5800 @ 55mph and That's a 21MA with a little 2.6L ProV 175.  Your 18MA should spin a 21 no problem. 

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35 minutes ago, Lap it Up said:

I would look for a Tempest Plus or a Yamaha Pro Series.  I can spin a 20p Yamaha Pro to 5800 @ 55mph and That's a 21MA with a little 2.6L ProV 175.  Your 18MA should spin a 21 no problem. 

Lap it Up , I didn't think Yamaha made a Pro Series in a 20 pitch  . 

 

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9 hours ago, VS-MasterAngler said:

What do you guys think about the Solas HR Titan 3 prop 14.5/21pitch?    MFG# 3551-145-21

 

     

I have not tested a HR Titan 3.  The description looks impressive in their brochures and videos and the lower price is attractive.  However, I bought a Solas Rubex NS3 and ran it on my boat.  The performance was not impressive, compared to Yamaha and Merc props of similar size and pitch, and the quality of the finish work (stainless casting) fell short of Yamaha and Merc props as well.

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2 hours ago, dabear said:

Lap it Up , I didn't think Yamaha made a Pro Series in a 20 pitch  . 

 

Correct,  I had it turned down at Barracuda Props in Miami.  It used to be a 14.5 X 21

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On ‎11‎/‎23‎/‎2017 at 12:13 PM, VS-MasterAngler said:

just got my 18.5 and dropped it in the water this morning to put it on the boat lift and on my way to the lift I had her wide open pushing a consistent 5100rpm @47mph

I don't understand, he is hitting 5100 RPM's with a 19 pitch prop and you are saying he needs to go 'up' in pitch? Why not go down so his rpm's will increase closer to 5500 RPM's which should be his max running light?

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Seems to me like back in the day when that combination was brand new it was a 52 MPH boat. Dale when you had your 18.5 with a 150 yama 2 stroke all brand new what prop,speed and RPM was that thing seeing ?

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The carbed 150s had lower gear ratios than the four strokes. The carbed motors can spin bigger diameter props with lower pitch whereas the four strokes with taller gears need more pitch and less diameter. Ofx3 15.25 x19 vs pro series 14.5 x 21. 

I had a pretty lengthy conversation with Marcus at Power Tech about this. He's not a fan of the taller gears in the four strokes. In fact, he complimented Suzuki on their gears.

My first 18MA with a carbed 150 Yamaha was a rocket and would Top out in the 50-52 range. My F150 is a slug out of the hole, but I'll see 51-53 consistently. 

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17 minutes ago, Nag Juice said:

The carbed 150s had lower gear ratios than the four strokes. The carbed motors can spin bigger diameter props with lower pitch whereas the four strokes with taller gears need more pitch and less diameter. Ofx3 15.25 x19 vs pro series 14.5 x 21. 

I had a pretty lengthy conversation with Marcus at Power Tech about this. He's not a fan of the taller gears in the four strokes. In fact, he complimented Suzuki on their gears.

My first 18MA with a carbed 150 Yamaha was a rocket and would Top out in the 50-52 range. My F150 is a slug out of the hole, but I'll see 51-53 consistently. 

Good point on the different gear ratios.  That's probably why the X7 alloy Merc Enertia and Fury are so popular on the newer V6 4-strokes.  They are smaller diameter props with large blade area and pitch.  For the smaller skiffs like the Redfisher and HPXs, it would be great to get an accurate performance comparison between the 4S Mercury 115 Pro XS Standard gearcase (2.07:1) and Command Thrust gearcase (2.38:1).  Haven't seen a performance test bulletin yet, that was done correctly - matching boats, matching WOT RPMs, with the best prop installed for each gearcase.

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Going from a two stroke to a four stroke I had to adapt and get educated on it. I knew it made a difference but to put it another way, a Prius can still hit 55 without 4:11s...

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2 hours ago, Nag Juice said:

The carbed 150s had lower gear ratios than the four strokes. The carbed motors can spin bigger diameter props with lower pitch whereas the four strokes with taller gears need more pitch and less diameter. Ofx3 15.25 x19 vs pro series 14.5 x 21. 

I had a pretty lengthy conversation with Marcus at Power Tech about this. He's not a fan of the taller gears in the four strokes. In fact, he complimented Suzuki on their gears.

My first 18MA with a carbed 150 Yamaha was a rocket and would Top out in the 50-52 range. My F150 is a slug out of the hole, but I'll see 51-53 consistently. 

Your issue is torque. Two less cylinders and a lot of moving parts in that 4 stroke.  

OP has a 2.6L on a 18.5.  Trim, trim trim and hammer it to the glass. Itll swing a 21. 

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13 hours ago, dabear said:

Seems to me like back in the day when that combination was brand new it was a 52 MPH boat. Dale when you had your 18.5 with a 150 yamaha 2 stroke all brand new what prop,speed and RPM was that thing seeing ?

Joe, you are correct, I looked in my folder (yes, some of us still keep paper folders) and I had a 2003 18.5 MA and a 150 VMAX. It had a powertech PTC 19 pitch 4 blade and ran 52 @ 5750 rpms running by myself.

I have notes like very tab sensitive and for best holeshot- 1/4 tabs and ease the throttle down , don't stab it from a start. also likes lots of trim (which is what Kevin says above)

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On 11/23/2017 at 12:13 PM, VS-MasterAngler said:

I just got my 18.5 and dropped it in the water this morning to put it on the boat lift and on my way to the lift I had her wide open pushing a consistent 5100rpm @47mph... Thought I red about some of you guys with a 150 hitting about 54/55mph.

 Boat has a 3 blade Powertech prop but cant really make out what the specs are on the side of the prop.  See attached picture, maybe you guys could help. 

VS, your Powertech prop is a PTC3 19 pitch which has a 14.25" diameter.  Like Lurem said, increasing the size and pitch of your prop would not get you the extra RPM you need for best performance.  Assuming your motor has been checked out as ok by a Yamaha mechanic, and your PTC3 prop is in good condition, and you are running with the motor at the correct height on the transom - trimmed up for more bow lift and speed...  the only way to stay with a 19+ pitch prop and get more RPM is to run a prop with a diameter less than 14.25".  Just a suggestion - the Mercury Enertia 3-blade is highly rated and comes in sizes: (14 x 19p) and (13.75 x 20p) and (13.8 x 21p).

**Edited to add transom height and high trim after what Lurem posted!

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22 hours ago, lurem said:

I don't understand, he is hitting 5100 RPM's with a 19 pitch prop and you are saying he needs to go 'up' in pitch? Why not go down so his rpm's will increase closer to 5500 RPM's which should be his max running light?

agreed, confused too. He should be going less pitch to increase the 5100 RPMs.

Now if switching to an entirely different prop with smaller diameter and/or less blades... then you actually could go up in pitch and also raise rpms...but that's guesswork.

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Ok Guys,  I was on the boat all day and something odd happened this morning while heading over to get bait. I was running up on plane and getting the same numbers I mentioned in my earlier posts,  WOT 5100rpm @47 mph (trimmed and aired out) then I got 5200rpm for a little bit... But the crazy part happened when  I was backing off the throttle coming up to the bridge,  at about 30mph it felt kinda like the boat jumped forward and released or something. Idk know what it was but I decided to hold off on getting bait and ran the boat WOT and immediately got up to 5700rpm and 54mph with just me and about a half tank of gas!! I was easily able to get those numbers the rest of the day.  

Not really sure If a fuel filter or something was clogged and became clear... But I'm extremely happy!

Oh and the morning top water Snook bite was pretty solid (caught the very tail end of the incoming tide) with 3 landed and about 6 blowups. Once the tide turned around I went to the causeway and filled the well up with perfect size Whitebait with a few Threadfins mixed in and caught 5 or 6 more Snook before heading back to the dock.

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