2009 Merc 150 Optimax

[shodan]

I have a new package
2009 Crestliner Raptor 1850 TE with a 2009 Merc 150 Optimax. It came with a 19p aluminum prop.The motor was mounted in the second hole. On the water the standard prop "blew". All my beer drinking boat buddies said to drop the motor all the way down to the last hole.I now get 4800rpm at 42mph.I tried lots of stainless ,on loan, from a dealer.The best... so far... was a 17p Stainless Enertia.BUT still at 5000rpm and 43 mph.
Soooo...back up how many holes and what pitch ?? I tried a 4 blade SS but motor too far down to turn this.
Any help/ideas.
Thanx.

[staylor]

...and stick with the 17 Enertia for a bit since it ran best down low. You may have had the 19 alum venting because its not a performance prop- or because it just plain had too much pitch for your rig's set-up. Also, take a look at the cav plate on the motor when it's trimmed to be parallel to the bottom of the boat. It should be running just about even with the keel line of the boat for a rig running 40s with an SS prop. If you run into venting at the higher engine heights, try a Tempest Plus- it has more diameter than the Enertia which will help at higher engine heights. You've got to get that Opti up into the 5500 rpm range for it to be putting out full power, and you should be able to swing a 17 at 5500 rpm easy- as long as the prop isn't buried way down below the bottom.
Doug

[shodan]

Thank you for your suggestion.
Just so that I am clear, do you mean for there to be two vacant holes above the top mounting hole? Just as long as the cavitation plate is even with the keel.
Yes the spec on the motor is 5200-5750 rpm range.
I am fortunate that we have a Merc dealer that (with a refundable deposit)let me take several props to try. The saying is tho...if I bang it , I bought it !!! Fair is fair.
Again,thank you.

[staylor]

The informal convention for motor height is based on a typical dealer set-up where the motor is set right down on the transom. Each hole that you lift it up off the transom is considered as a "hole up". Thus, 2 holes up is a motor lifted up 2 mounting holes from the hole where it is touching the transom. I think you are saying the same thing as me in your last post. This method of rigging assumes that the manufacturer picked a transom height for a severely underpowered rig based on the max horsepower rating for the boat. As a secondary check, I like to see where the motor's cav plate is relative to the keel line of the boat. This is because some manufacturers like to be extremely conservative and run a very low transom that kills speed and screws up handling when a rig is powered up near or at its max rating. In general, a rig running 40 mph typically will have the cav plate even with the keel line for best performance. At 50 mph the cav plate should be about 1 inch above the bottom, at 60 mph it should be 2 inches above, etc. This is a rough rule, since hulls vary dramatically between different manufacturers. Note that this is measured from the keel line- the last 4-6 inches or more near the transom may not be on the true keel line, since some makers will add notches, angled edges, etc right at the transom for various reasons. When you start lifting the motor you generally keep going up until the venting gets excessive in a cross wind chop or on turns- and even this differs from owner to owner. As for rpm on the Opti, I run a 150 Opti also, and the motor is happiest running top ends in the 5500-5600 range. You are not supposed to prop an Opti so that it will exceed the 5750 limit- the compressors and other parts will have their life greatly reduced. This is totally different from the older carbed motors- I used to routinely set up the old carbed OMCs to run with light loads at 200 rpm over the max rated rpms. This seemed to give best overall performance. If you do this with an Opti the computer logs an over-rev for the dealer and Merc to see-and parts may fail
Doug

[eye4aneye]

The enertia is hard to beat, best I've found too. I would raise that motor up ate least two holes. My old 1850 Cliner with a 150 I ran at something like 4 holes up. It was about 3 inches above the transom lip. you'll be surprised at the performance difference. Watch your water pressure on the Smartcraft guage, you need around 12 PSI at WOT.

[Tapped Out]

Break in is ten hours of extra oil and fuel programmed in to computer or E.C.U. so power is down on break in.
You are also should evoid hard runs of wot in this time of ten hours. After that the motor wakes up the more hours you put on it. My 08 opti 150 gained 250-300 RPMs from 2 hours to 30-40 hours so keep that in mind!

[Senderofan]

I have a new package
2009 Crestliner Raptor 1850 TE with a 2009 Merc 150 Optimax. It came with a 19p aluminum prop.The motor was mounted in the second hole. On the water the standard prop "blew". All my beer drinking boat buddies said to drop the motor all the way down to the last hole.I now get 4800rpm at 42mph.I tried lots of stainless ,on loan, from a dealer.The best... so far... was a 17p Stainless Enertia.BUT still at 5000rpm and 43 mph.
Soooo...back up how many holes and what pitch ?? I tried a 4 blade SS but motor too far down to turn this.
Any help/ideas.
Thanx.

If you can have someone driving in the boat with you...get on plane ..trim to max efficiency and see where your cav plate is. It should be skimming the top of the water. There's a great article about this on the Verado site. I messed around with my height...finally got it right. I'm about 1 1/2 to 1 3/4" above the bottom of the "V" on my 2001 1800 Fisherman. I'm turning a 19" pitch Viper...on a 175 hp motor ( 2009 ). When I started...the motor was mounted as low as she would go...I could only turn 5200 rpm trimmed to the max...with a top speed of 47 mph with a light load. I'm now in the highest hole....turn 5700 rpm with a light load...and 51 mph...just to show you the difference in performance. Here's a picture of my cav plate while we were underway:

Good Luck,

Wayne

This whole "X" dimension is a bit of unusual...every hull is different...and it takes some experimentation. I would recommend working on getting your motor height set before investing a lot of $$$ on different props. Also, dragging too much of that lower unit through the water is going to lower your fuel economy and lug the motor..which might decrease its service life.

[shodan]

Thank you all for your help. I STILL can't get motor above 5400 rpm and best speed is 43mph.I am running at the second hole.The local Merc dealer is very puzzled.I have at least 30 hours min. on this motor.I have tried 17P, 19P , tried 3,4 and 5 blade props. I told the Merc dealer that if these stainless can only do this I may as well stay with my tin prop that came with the boat. Just can't justify spending 7-900+ $ on a stainless to gain...so far..300rpm and 3mph.After our long weekend, he said that he will bring a big box of props and we will spend a long day at the lake testing different props.
Sceptical but hopeful.

[Hot Runr Guy]

are you SURE your tach is correct?????? I'd ask him to bring a a SmartCraft Tach or system monitor along too, as well as the data cable, and confirm what your tach is showing.
Stranger things have happened,,,,,,
HRG

[eye4aneye]

You can buy brand new props on Ebay, an enertia goes for about $420.

What elevation are you running your boat at? If you are at 4000' or more, you aren't going to do any better. Also, I found that with my motor it took about 60 hrs on the clock before it really performed at it's best for top speed and RPM.

[lundeepv]

Just ordered a Tempest Plus 19 pitch. The 21 pitch would only allow me to get to 5100 rpm top range, this should hopefully get ~ 5500 rpm. There may be a 21 pitch Tempest Plus for sale on here real soon!!!

[lundeepv]

Just got the 19P installed last nite and took the boat out for a run. I can now get ~ 5500 rpm. A 1 mph increase in top speed and it really comes out of the hole now too. Anyone need a 21P Tempest Plus??

[merc guy]

are you SURE your tach is correct?????? I'd ask him to bring a a SmartCraft Tach or system monitor along too, as well as the data cable, and confirm what your tach is showing.
Stranger things have happened,,,,,,
HRG

I have to agree with HRG, at times I can gain 200rpm just by flicking my tach with my finger. Smartcraft system monitor is now going in my dash, just waiting on the cable.