18 MA Prop

[Nag Juice]

What props are you guys running with the F150? I'm running a OFX4 x 17 currently and I'm not super impressed. 4K is 28-30 mph. Top end is 47-48mph. 

[Marshfly]

That OFX4 is a high diameter prop for a 150. I'd look for something closer to 14.25" diameter with 4 blades or 14.5" with 3. I bet your holeshot is slower than you think it should be too. 

[Nag Juice]

Yeah I knew the difference between a 4 stroke and 2 stroke would be noticeable but I didn't think it would feel like a 150 vs a F115. 

[Marshfly]

I see you had a 2stroke 150 before in your signature. That prop was probably marginal on that. The OFX4 is designed for bay boats running 250-300hp. It's just too much blade area for 150hp. Try one of the smaller diameter props from Powertech and that motor will feel much more similar to your old one. I know the F150 on my 2016 HPX-V feels like driving a Corvette, but then, I have a 14.5" diameter 3 blade. If it's a new F150 and not the original one, it puts out 160hp so it should rip. I'd think you could turn up a 19 or 21" pitch as well with the slightly higher slip from a smaller prop. 

 

Also, did you verify that when the new engine was mounted that they mounted it at the correct height on the transom. Too low will cause exactly what you are experiencing.

[wthree3]

Running a 21p Yamaha Pro 3 blade which is a smaller diameter and vented. Spins up nicely on the F150. Good all around prop and probably one of the faster props. Mid to high 50s, 5800 to 6000 RPM. depending on the load, water conditions, temperature. Engine mounted in the lowest position. Going to guess that the newer MAs are a little lighter than the older ones, but not sure.

[Nag Juice]

Thanks. The OXF4 is too much meat for that motor. Mine is also mounted on the lowest position. Sounds like a 21 3 blade is the number. What's the diameter of yours?

[wthree3]

As a point of reference, I called Marcus a few years ago and told him I was running a 21p Yamaha Pro and the numbers I was getting. His suggestion for equivalent PT pitches were a 20P OFX 3 or a 18P OFX 4. Never tried them so I don't know if they are really comparable. I do know the OFX series are big diameters and difficult for a four stroke to spin up.

Turbo Ultima 4 might also be a good option.

 

[Nag Juice]

I spoke to him yesterday and he recommended a OFX3 19. The goal is to get it running like my last one. 5K @ 50mph or better...

[hurricane]

I don't have an 4s, but just some info from my 2s 150. I"ve tried a OFX3 21 and it was too tall, I also have a OFX3 19 and its too small. So in that prop I need a 20.

Currently I run an OFS3 19 and it is a good all around prop. I think the OFX will run a bit better, but the OFS gets it done. Will run up to 53-55 mph load varies, and has a fair hole shot even with a good load. I would like to try a small diameter prop, like a Turbo.

Like to hear some numbers when you get it dialed in. If I ever repower, F150 will most likely be the way I go. But I like the idea of the SHO 175......

[poleposition]

I had a late model MA18.5 with the F150.  Marcus and I became best friends with as much as we spoke on the phone.  I can tell you that in my experience and in working with him, the OFX319 was the best option.  The boat with that motor and prop is a low 50s boat (like 51-52 in perfect conditions).  I also ran an SCD420 (semi-cleaver) which will give a little more speed, but the trade-off is lost grip in turns...it would ventilate when running creeks.  The SCD was "liveable", but not great.  I also tried the Turbo Ultima, but moved quickly back to the OFX3...can't remember exactly why as too many tears have passed.  

 

In the end, it is my belief that the F150 is NOT a great match for the MA18.5; a boat that was initially designed for midrange v-4 power.  In my case, the boat always required a "touch of tab" to keep the porpoise gremlins away.  a function of weight to length ratio.  Also, if you fill the MA18.5 well and sit two anglers on the bench, the hole-shot is sluggish at best with the F150.  If it were me, I'd re-power with another two stroke which all have better torque curves to help the hole shot.  I know most people dislike the 2s, but they have a place in a shorter boat that carries much of it's weight aft.  When I moved from my MA to my current 18'9 flats boat I went with a PROxs175.  While I recognize it is not a meaningful comparison, the hole-shot on the 18'9 with a 2 stroke was in a different universe.

[Mitz]

on the 02 18.5 w 175 hpdi 1/2 tank, just me, normal gear, troll batts in front compartment, jackplate, powerpole, house batt. i ran the turbo 2+2OT 22 pitch good for 5.2/5.3k, turbo ultima 21 pitch good for 5.4k, ofx4 19 5.3k. OFX4 insane grip and stern lift but imo give up too much speed. I ever ran a 3 blade since i liked the performance of the turbo props. With the two turbo props you were looking at a max speed of around 56/58.

[poleposition]

What the 18.5 does with a 175HPDi or the HPX18 does with the F150 is not of **much** help in finding the best prop for the 18.5 with the F150.

[wthree3]

On 9/9/2016 at 8:10 PM, Nag Juice said:

Thanks. The OXF4 is too much meat for that motor. Mine is also mounted on the lowest position. Sounds like a 21 3 blade is the number. What's the diameter of yours?

The PRO series is a 14 1/2"diameter.

[Ksayles44]

I have a Hewes Light Tackle 20 with a 06 F150 and I am using a OFX3 19. I really like the performance with it. I know its not apples to apples but I see full RPMs and gained some mph.