Help w/set up

[Payday]

I have a 18' Mr Pike with a 150 Optimax. The motor was mounted one hole up upon delivery, during initial test it was losing bite. Could not trim up at all or it would cavitate. The RPM's were not registered as the tach was miscalibrated (another story).

The dealer recommended and lowered the motor one hole, to flat on transom. Overall, it handles well but the hole shot is not as good as it was previously.

Max RPM is 5k, it should be 5250-5750. Current prop is a 21 Pitch Tempest plus.

What is the correct pitch prop for this set up? Would dropping to a 19P gain 500 RPM's? What about hole shot? or Top end?

If you have a comparable rig, what prop are you running?

Besides changing props what are my options?

[VMS]

I ran into this same problem with my rig when I tried to go up from a 17 pitch to a 19 pitch. I could not trim out without ventilating the prop and I'd lose bite.

When I dropped back down to a 17 pitch, I was back up to my normal RPMs (5400 from 4800 on the 19 pitch) and handling was really good.

If the motor is down on the transom and you are getting only 5000, I think you might be a bit over-propped, and that is why you could not trim up... if you drop 2 inches in pitch, you should gain your RPMs back, and you may be able to move that motor back up, if not even higher.

Also...you may want to try a pro series prop on there as well in both pitches. Many times, finding the right prop will get your rig to do many things it could not do with the current one.

Steve

[PerchJerker]

Everything Steve said is right on.

Dropping the pitch and raising the motor will get your rpms back. Dropping the pitch will help your holeshot. Dropping the pitch will hurt your top end.

I agree that you are over-propped. Maybe a Tempest is too aggressive for your rig???

Did they put the right size motor on your boat for the transom height? Usually you can raise motors up, usually you don't have to drop them down???? I'd ask the question just to be sure.

I have a 175 Opti on a heavier boat than yours, with the motor as high as it goes I turn 5650 rpms with a 21 P Tempest.

[Payday]

This morning the dealer repropped with a 19P. He said I should see better hole shot, aprox. 5500 rpm, and better top end. I won't know until this weekend if it was the correct move or not. I'll post my results on Monday.

Thanks PJ & Steve!

[Payday]

When I was out on Saturday I was able to get 5200-5300 RPM and a top end of 48.6mph. I was able to trim fully with no blow out or large rooster tail.

What should I expect by moving up 1 hole?

[Fishing Junky]

What should I expect by moving up 1 hole?

Quicker holeshot and another 100 rpms or so. I'd give it a whirl.

[Payday]

I was actually hoping that I would be able to get 50+ and 5600-5800 RPM.

So if I subscribe to the 100 rpm/hole, I'd need to go up 5 holes to get my max RPM

Since I was loosing grip with the 21p up one hole; will I be in the same situation with the 19p?

Anybody have this motor boat combo?

[Valv]

18ft MrPike is a big boat, I would be happy with the performance you have now, I don't think you'll gain much more.

[Payday]

I'm not so concerned with gaining speed as I am in gaining RPM.

I realize that a 18 Mr Pike is, by some, a big boat BUT that does not mean that the motor should not perform as specified by the manufacturer. (5250-5750 rpm)

I'll bring the boat back in this week and have the dlr raise it one hole. Hopefully I'll be able to get 54-5600 r's.

[wannaeye]

I have a simalar set up, 17' Fisherman with 150 HP Optimax. I am still in the break in period. I only have about 5 hours on the motor, but I also am getting about the same RPMs and speed. I am happy with the top speed but I would like to see higher RPMs.I have only tried it in short busts but I am hoping the RPMs increase to the 5800 range after the break in. Please let me know how you do with raising the motor. ( my motor is set up all the way down)

[Surface Tension]

Your in the lower recommended RPMs now and no blowout when trimmed up. Go ahead and raise it one hole.

[Payday]

Had the motor raised 1 hole on Thursday. On Saturday with my wife and 2 kids I was able to get 5600. Very good hole shot, full trim range. Overall I'm quite pleased, it should only get better.

[mnfishman]

How much water pressure you are getting on your motor? If you don't have a gauge then I would get one installed before you melt the motor down.

[marine_man]

Water pressure is important and should not be overlooked. However, moving the motor up one hole in the stock mounting holes should not pose a problem.

It's when you're using a jackplate that water pressure really becomes important.

marine_man

[camdu7]

How many hours on the motor? I have the same motor on a 1850 tyee. The opti is mounted one hole up and I'm running a 19p Laser II ss. I was a little frustrated at first cause it would only turn 5100 but as I have gotten around 10 hrs on the motor she is gaining RPMs. RIght now I'm getting 47 mph on the gps with me and the GF and the boat fully loaded including the kicker and turning 5400 fully trimmed. That is on a cool calm water. I'm sure I'll lose some as the water and air warm up.

[mnfishman]

Quote:

---

Water pressure is important and should not be overlooked. However, moving the motor up one hole in the stock mounting holes should not pose a problem.

It's when you're using a jackplate that water pressure really becomes important.

marine_man

---

Anytime you are raising the motor with or without a jackplate water pressure needs to be watched. If you raise the motor to the last hole and it is on the transom you can still raise it high enough to limit the amount of cooling water to the motor. You may not notice it idling around but once you are up on plane it will pull even more of the motor out of the water.

A prime example is what I just experienced last weekend. I recently installed a jackplate on my boat to help with adjusting the motor some to improve performance. When I installed the plate I made sure to keep the motor the same height on the plate as it was on the transom. (took a measurement from the prop shaft to the pad of the boat). When I ran the boat at the same height I had my pressure gauge pegged at 30 psi. I then went back to the landing and raised the motor 1" on the plate. My water pressure dropped from 30 psi or more to 21 psi. That was just a 1" increase in height.

What I am trying to say is it doesn't take much to start losing water pressure and all outboards need a certain amount for cooling. Also it doesn't matter if you are using a jackplate or raising it on the transom you are still pulling the lower unit out of the water.