Prepare me of whats to come!!

ifishhard

Petty Officer 2nd Class
Joined
Feb 26, 2008
Messages
137
Bare with me please:

I recently purchased a xpress x-18 with a mercury 150 xr6 2003 models....Well here it goes, the original (stock) prop that comes with this rig is a 23 pitch 4 blade prop. Well, the last owner tore the prop up and replaced it with a 23 pitch 3 blade tempest plus prop.

Now, when driving, I shoot about 20ft waves from the side at WOT, and only hitting 50mph. I know this water resistance is SLOWING me down tremendously. So, I went and bought a jackplate to raise my motor up to solve this problem. I havent took it out yet, but am planning on doing it this weekend.

Now, here is my question. Will I have to buy a new prop to match my recommended RPM'S? My concern is that the stock prop was a 4 blade and he replaced it with the same pitch, but a 3 blade instead! I am worried once I jack my engine up my with the jackplate and get my water presure right, that my rpms will be toooooo high with this prop? Right now with the three blade, and with all the drag I have in the water bc my engine is too low I am at 5600 rpms, WOT, which is the recommended rpms for this motor at WOT. My concern is that I will have to change props out once I raise my motor up to get the boat riding on the pad, bc I am at the reccommend rpms with my set up right now, want my rpms go ALOT higher once I raise the motor up with this prop?? I hope I do not have to blow $$$$ on another prop! OR will I be able to make this prop work with the right adjustments?? Thanks for any help!! :confused:
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Prepare me of whats to come!!

Silly question -- once on plane you are trimming the motor out, right?
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prepare me of whats to come!!

hold on; slow down little.
First while a jack plate may prove to be helpful you may not need it to raise the motor.Motor is setup with holes to adjust the height.
The antivent plate, just above the prop, even with the bottom is considered a starting point.most boats operate with plate about 1 in. above the bottom.
Usually a 4 blade is used to improve low end performance at a slight sacrifice of top end. Generally 2 props same brand same design the 3 blade will produce more rpm and speed.Yes you may need a pitch change once you raise the motor.You may be able to have the prop repitched.
Excuse my ignorance; is the Express X 18 considered a fast boat?
 

ifishhard

Petty Officer 2nd Class
Joined
Feb 26, 2008
Messages
137
Re: Prepare me of whats to come!!

hold on; slow down little.
First while a jack plate may prove to be helpful you may not need it to raise the motor.Motor is setup with holes to adjust the height.
The antivent plate, just above the prop, even with the bottom is considered a starting point.most boats operate with plate about 1 in. above the bottom.
Usually a 4 blade is used to improve low end performance at a slight sacrifice of top end. Generally 2 props same brand same design the 3 blade will produce more rpm and speed.Yes you may need a pitch change once you raise the motor.You may be able to have the prop repitched.
Excuse my ignorance; is the Express X 18 considered a fast boat?

i should be running around 60mph......And yes I am trimmed up at WOT. I hope I dont have to spend $$$$ on a new prop! I cant afford it right now..:(
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Prepare me of whats to come!!

Does the boat have trim tabs?
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Prepare me of whats to come!!

That's the trim on the motor. Does the boat have trim tabs bolted to the transom at water level? If it has them there will be one tab on each side of the transom.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prepare me of whats to come!!

i should be running around 60mph......And yes I am trimmed up at WOT. I hope I dont have to spend $$$$ on a new prop! I cant afford it right now..:(

If the boat causing the 20 waves out the side it may be plowing.If you can't get the bow up by trimming then you may have a deformed bottom with the boat on a trailer put a straight edge at least 3ft long parallel to the keel a couple of places along the the transom should be straight no hollow spots.
If the motor is making waves out the side it is probably way too low.
If the floor in the boat is soft the stringers may be rotted letting the bottom flex and deform.
 
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