Jack plate recommendation 2002 Cobra 180 Mercury XR6 150HP

[VinnieTheFish]

Picked up a 2002 Cobra 180 recently from a guy in the San Diego, CA area (sea level). Towed the boat back to AZ (2000-3000’ elevation) and plan on running two different props due to the extreme heat we get in the summer. Boat currently has no Jack plate with a 23p Tempest Plus, but doesn’t seem to have the performance I’m looking for. Thinking about adding a jack plate before messing with the prop or prop plugs. I would also like to eventually rig the SI transducer off the jack plate as well and considering one of the newer 3 in 1 lowrance transducers using a bracket off the jack plate. Not sure I have the budget for one of the new hydraulic jack plates so probably looking at a manual one.

Which jack plate and size would you recommend for this boat? Any that I should avoid?

Thanks.

[TomM]

6" jackplate. CMC, Bobs, T-H Marine and Detwiler all make good ones.

Tom

[digthemup]

Vinnie,
Before anyone should make any recommendations, we need some specs like:

what numbers are you running with current prop, RPM, MPH, WP, and P to P.
What hole is your motor mounted to the transom?
What PVS set up are you running? has prop been B&B?
What is your motor's compression? and last full tune up?
Are your cables and house long enough to accept a JP?
a JP is going to give you the benefit of adjustments, but that is no where you start in performance improvements, unless you just want to show your pals that you have a boat with a JP.

[VinnieTheFish]

Vinnie,
Before anyone should make any recommendations, we need some specs like:

what numbers are you running with current prop, RPM, MPH, WP, and P to P.
What hole is your motor mounted to the transom?
What PVS set up are you running? has prop been B&B?
What is your motor's compression? and last full tune up?
Are your cables and house long enough to accept a JP?
a JP is going to give you the benefit of adjustments, but that is no where you start in performance improvements, unless you just want to show your pals that you have a boat with a JP.

i just want a jack plate to show off my rear end ��

no seriously I’ve had a Cobra 201 before with a 6” jack plate and know how to tune my boat. Was wondering for this model boat the consensus I found was most were running a 6” jack plate. Since I also want to mount a new Lowrance 3-n-1 transducer I’m considering going with a larger jack plate. Is going 8”, 10”, 12” with a 150HP XR6 too much or just stick with the 6”. Is anyone else running a larger jack plate on the Cobra 180? What was your experience like?

[digthemup]

i just want a jack plate to show off my rear end ��

no seriously I’ve had a Cobra 201 before with a 6” jack plate and know how to tune my boat. Was wondering for this model boat the consensus I found was most were running a 6” jack plate. Since I also want to mount a new Lowrance 3-n-1 transducer I’m considering going with a larger jack plate. Is going 8”, 10”, 12” with a 150HP XR6 too much or just stick with the 6”. Is anyone else running a larger jack plate on the Cobra 180? What was your experience like?

Must have been an old 201, since my '02 originally came with a 8" Slidemaster for the '03 225EFI. I wouldn't go any bigger than 8" since you would be changing the fulcrum point of the boat/motor putting the motor in much cleaner water giving it a big bit to the prop kicking the RPMs down as well as your holeshot.
I went from an 8 to a 10, and I could not use my 26p Trophy Plus in summer since my RPMs went down about 200 at around 5600.

[VinnieTheFish]

Must have been an old 201, since my '02 originally came with a 8" Slidemaster for the '03 225EFI. I wouldn't go any bigger than 8" since you would be changing the fulcrum point of the boat/motor putting the motor in much cleaner water giving it a big bit to the prop kicking the RPMs down as well as your holeshot.
I went from an 8 to a 10, and I could not use my 26p Trophy Plus in summer since my RPMs went down about 200 at around 5600.

it probably was an 8” on my old one didn’t look too close. Having been down this road before I wanted to add the jack plate first, play with the height to figure out the best placement based on what my lower unit water pressure would handle, see how my Tempest Plus 23p would handle the setup, play with the PVS holes and then test out other props. That way I’m not wasting money on changing props until I have the motor in the right spot. I’m more concerned with how it rides in rough water, getting on plane and mid range fuel economy than top speed. I already know in Arizona I’ll need two props (summer and not summer) since we really only have two seasons.

[digthemup]

Vinnie,
If you are going with a 6", TH Marine Z Lock JP is a very good choice for around 350.00
If you are going with a 8", I would suggest you find a very nice used Slidemaster JP, which the last 1 I sold to a BBC member 325.00 TYD in very good to excellent conditions.
My very best to you,
Frank

[VinnieTheFish]

Had a chance to take the boat out early this morning without the kids so I could shake a few things out. Picked up a brand new 23p Tempest Plus from someone local for $280. I previously had a 23p Tempest Plus on the boat but it had a few dings and scratches from the last owner. With just myself and a full tank of gas I was able to get the boat to 57.2 @ 6000 rpms going into the wind down the lake and 58.0 @ 6000 rpms going the other direction. Boat had no problem getting on plane and I worked out the correct starting procedure for the XR6 which is a little cumbersome with the enricher. I’m not 100% sure I can trust my tach so I may have my mechanic install one of the digital tach/hour meter gauges since the 2002
2.5L XR6 isn’t smartcraft capable along with a volt gauge and a water pressure gauge in the
missing dash hole blanks.

Assuming my analog tach is correct which direction would you go from here? Try a 24p prop to drop the rpms and increase too speed or add a jackplate/gauges before messing with different props?

[digthemup]

Vinnie,
Something is wrong, since that motor should only turn MAX 5600 RPM, and the rev limiter should have kicked in long before 6000. So, unless someone removed the rev limiter, it is allowing you to go 6K, which at some point soon it will blow the heads.
Obviously, your old prop is hosed, and good only for emergency spare. I would get your gauges sorted out prior to doing any more hard runs, and taking a risk of damaging your motor.

[VinnieTheFish]

Vinnie,
Something is wrong, since that motor should only turn MAX 5600 RPM, and the rev limiter should have kicked in long before 6000. So, unless someone removed the rev limiter, it is allowing you to go 6K, which at some point soon it will blow the heads.
Obviously, your old prop is hosed, and good only for emergency spare. I would get your gauges sorted out prior to doing any more hard runs, and taking a risk of damaging your motor.

yeah I’m not sure I trust my Tach. I have a buddy with a 24p tempest plus I’m going to swap with and see what my numbers look like. When I get my boat in the shop I’m going to have my mechanic replace/recalibrate the the tach, add a volt & water pressure gauge and see if he can setup one of those digital tach options to get a better tach measurement. I’m going to see if I can locate the rpm limiter to ensure a previous owner didn’t try removing it. With used boats you never know.

i did read the rev limiter kicks in at 5900 but I would prefer to get my WOT rpms down to 5500-5600 max.

[dixieman18]

Doesn't sound to bad without a JP. For reference, I have the same boat with a 175 Evinrude that will runs consistently in the low 60s so you're in the same ballpark. A JP will definitely help you get that boat dialed in though. I originally had a 6 inch on mine that was junk and got a good deal on a 10 inch. No significant performance gain or loss between the 2 in my experience. The boat may sit a little more nose high when at rest. I will say I also had a slight problem with my hydraulic steering hitting the top of the transom with the 6 inch plate when the motor was tilted all the way up. Moving the motor back with the bigger plate cured that though.

I'm thinking the rev limiter will be 5900 as well. If the tach is right though, you're running about 20% slip with the current setup and about 15% if the tach is closer to 5600. Verify the tach before going much farther though.