Jack Plate

[Revtro]

I'm so glad to see this board develop.  I've noticed that a lot of boat owners have questions about things like props, jack plate setup, etc.  This will be a busy part of the forum, I think. 

So I'll start with a question.  Is there a basic starting point for setting a manual jackplate on a bass boat?  I have mine set by trial and error, but I'm not sure how to properly measure where it is. 

Also, if you get chine walk, does the jack plate need to go up or down?  I lowered mine and managed to get rid of the chine walk, but am unsure if that's the rule of thumb or if I just got lucky.

[Lightningboy]

Well, how high to set the plate to start depends on the boat/motor combo we're talking about.  Let's have some details, and maybe then we can get a starting point.

After establishing a good starting point, you then make several runs, moving the plate up about 1/4 inch at a time.  Most rigs will increase top speed as the plate is raised.  Once you hit the point at which water pressure begins to drop below required minimum, back down 1/4 inch & you're set.

Raising the motor also tends to reduce chine walk, or at least raise the speed at which it begins.  Then you gotta actually start driving that sucker, cause there's a few more MPH there.

Darn glad to see this board.  I love to fish, but I also love going fast.  Modern bass boats are rockets, and can be an absolute blast in the right conditions.  Of course this ain't all about speed, since a well set up rig is also much easier to drive at all speeds.

Speaking of speeds, can we all agree to post only REAL top speeds?  Verified by GPS?  I see lots of guys on some boards who claim 80+ rigs; those kind of speeds ain't that easy in the real world.

[Revtro]

My rig is a 2004 BassCat PIII with a Merc 200 EFI and a 24p Trophy Plus on a manual jackplate.

I mispoke.  I raised mine to get rid of the chine walk, not lowered it. 

Yeah, I know what you mean about real speeds.  I have a hard time believing some of the stats I've seen posted out there. 

When I first got my rig it had a 25p Trophy Plus and I hit 69MPH.  Lately though, with the 24p and the jackplate raised a bit, I'm only getting around 64 MPH WOT.  I'd like to figure out how to get some of my MPH back. 

Is the general rule of thumb that if I raise the jackplate I'll get more speed?  I would think that if I raise it, more boat ends up in the water, thus reducing chine walk, but also losing some RPM because of additional drag.  That's what I've always assumed.  Does that sound correct?

My issue is that at WOT, I'm at 5800rpm which is where I should top out according to the motor manual.  So without going back to a 25p prop, which I can't do because it kills the holeshot, how can I get back some MPH.  I've already trimmed down my load as much as I can to get the weight down.  So aside from losing some more weight by eating less Taco Bell, I don't have anywhere to save on load weight.  So I'm wondering if I'll get more MPH with jackplate adjustments.  Thoughts?

[SethV]

The best way to know where your plate is set, is to know your "distance below the Pad".  More specifically, how far is the propshaft below the pad?

The best way to measure this, so you can talk apples-to-apples is to first level the trailer.  Not all boats sit on the trailer the same way, but it is the best way to make comparisions, especially with similar rigs.  Put a level on the trailer, crank the jack until it is level.  Next measure from the lowest part of the pad under the boat to the ground.  Next, level the caviation plate on the motor using the trim.  Then measure from the center of the propshaft to the ground.

Example:
Pad to ground = 17"
Propshaft to ground = 13.5"

You distance below the pad = 3.5"

Most bass boats run best between 3 and 4 inches below the pad.  When you raise the motor, you will get more speed, until you start slipping.  Once the slip increases, speed will begin to fall again.

Start with the motor on the low side of where you think it should run.  Note the speed, rpm and WATER PRESSURE at WOT.  Raise it 1/4" at a time until you see speed quit increasing or a decrease in water pressure.

Also, raising the motor does help reduce chine walk.

Seth

[VinceR]

Tom, I don't usually like to send folks away from this board, but the absolute best place to get the set-up info for your Bass Cat is the Bass Cat website's Owners' Forum. If someone there (including Rick Pierce) can't get you to where you want to be, nobody can. There's a lot of Bass Cat know-how there.

To answer one of your questions, raising the jackplate will usually result in higher RPMs. That will not necessarily result in higher speeds. It may, however, allow you to turn a larger prop, which could improve your top end. The down side will likely be that your hole-shot suffers.

Seth was absolutely correct in that you need to first, establish a base-line to work from. Getting the right set-up with a manual plate can be very time consuming, and the end result will definitely be a compromise between, speed, handling, and hole-shot (always paying very close attention to water pressure). Also, don't rule out the possibilty of a prop change.

I agree with your assesment of the validity of some of the speeds that guys are posting. The question that begs to be asked is how much tackle, fuel, equipment, was in the boat? What has been done to the prop (tuning, blueprint, thinning?)? Were they running with the current? With the wind? How long did they sustain that posted speed? My guess is that it would be reasonable to expect speeds in the 69-72 MPH range for your boat (with a normal load). 

[Revtro]

Agreed.  If I could get back to 69 MPH, I'd be more than happy.  I don't care what guys with 300's that go 80 MPH say... near 70 is more than fast enough for me.  You have to have pretty flat, calm water to go that fast anyway.  Most of the time in moderate to rough water, I'm lucky to cruise at 50.  When I can go near 70, it's not like I have a bunch of boats passing me by anyway.  Thanks for all the great advice so far.  I'm gonna measure it this weekend.

Vince, You're right about being time consuming.  It's a very slow process to pull the boat out of the water 5 times in one day to adjust the jack plate.  I went through that when finding the right prop.  It was kind of a long day.

[SethV]

Tom, what did your RPM's do when you went from the 25 Trophy to the 24 Trophy?  I think your setup would be best with the 25 Trophy or a 25 Tempest.  The 25 Tempest will give you better top-end, but won't lift or grip as well in the rough stuff.

When I ran a Cat years ago, I liked the Tempest.  The cats are light enough that bow lift is not really an issue.

One thing that may be slowing you down is the amount of "stuff" in your boat.  Weight is killer, especially weight forward of the console.  I know my Z21 is like a floating tackle shop, with way too much stuff in it.  Each 50 lbs forward of the console takes off 1 mph or MORE.  It make the motor work on lifting, rather than pushing.

One thing i would suggest for anyone, is that you get your prop balanced and blueprinted.  Not just for speed or hole shot, it just makes the entire rig run more efficeintly.  If each blade is a slightly different pitch (factory prop) it won't be cutting the water as smooth as it could.

If I can run low 70's, that is fine with me.  I would rather carry more stuff with me than go fast and not have what I need.

Seth

[Revtro]

There was a change in RPMs when I switched props.  I went from about 5650 to 5800 at WOT as expected.  However, on this rig, BassCat (Dave Pierce) told me to run a 23p.  But with a 23, the RPMs were too high.  I experimented all last summer and settled on the 24 for a compromise.  The boat jumped out of the water with a 23p, but I lost too much on the top end. (More like 62 MPH)  The 24 gets me out of the water fairly quickly and gives a little more top end back. (64 MPH) and the 25 put me at 69 MPH.  The 25 was just too much wheels tho for this rig.  I tried numerous jack plate adjustments with the 25 and couldn't get the rig on plane for nothin'.  It was a real dog.

I think a Tempest would help with the top end, but honestly, I don't like the slip you get with it.  I like the way the 4 blade grips the water in the rough stuff.  I ran a 3 blade for a while last summer and really noticed a big difference in handling. 

Like I said, I trimmed the weight as much as I can up front.  About the only thing I can do is try to move about 20 lbs of stuff to the back, but I don't have anywhere to move it to.  I'll try to figure that out this year and see if I can move some stuff around to redistribute weight.  Maybe that'll get me back up to 65 MPH.     Other than a couple of items, the rest is fishing gear... no spare trolling motor or any other heavy stuff.  Rods, one compartment of tackle, and one with rain gear, a Fish Hedz, etc.  Not much to speak of.  I really don't think the boat is overloaded with stuff other than my fat butt when I'm in it. 

I'd love to get my prop blueprinted.  Anyone local that does a good job?  By the time you add shipping, it's just too expensive for me to send it out. 

[SethV]

I don't know anyone local that does good prop work.  There are plenty of metal buchers, but nobody in Detroit that I would trust with my steel.

I like Rich Bogers work.  Not cheap, but they are sweet props.  Mark Croxten has a good reputation, and he is much cheaper than Boger, but I have not personally run his work.

I am surprised Pierce would suggest a 23p.  He should know better!   

Did you try pulling the PVS plugs when you ran the 25p?  It will let the prop vent more and help get on pad.  The 2.5L motor just does not have the torque of the big block, so it needs that slip to help build RPM to get into the power band.

I run the Tempest on my boats becuase I have the hydraulic plate.  It slips really bad in the rough stuff at the normal 3.5" below the pad, but I can drop it to 6" below the pad and it hooks up really well.  Boger also adds a ton of lift with his work.

Seth

[Revtro]

Yep, tried every combination of vent plugs.  Tried all sizes and went from one plug to all four in each size.  Short story.  Without the PVS plugs in or when using let's say 2 of the 4 in the large size, there was too much blow and the RPMs went thru the roof.  No matter what I tried, the 25p was just too much for my boat.  I suspect it has to do with the boat's weight also.  The PIII is a pretty heavy boat.  It's not as light as the older ones from my understanding.  I'll have to look that up to be sure.  I've heard Boger does good work.  I just can't afford to have it done right now.   

[smbassman]

Revtro - I believe you told me that your 200 efi was the old 2.5L block.  You are probably around the right speeds for that set-up with a normal to heavy fishing load (summer temps) and I think you are right on with the 24pitch.  The PIII is a heavier boat and is too much for a 25 trophy with the 2.5L engine.  My fishing partner has a P Classic which is ~3-400#s lighter and runs a 25 tempest with a small block 200efi.

You will probably find that running your boat this time of year, you could get away with the 25P, but it would not be an all around prop.  I have my boat set to run just below the limiter with summer temps and with a heavy load & 2 people, I will only see 66-68.  But last fall, by myself and 50 deg air temp I was at 73 with lots of trim left before the beepers went off.  Mine is a cougar FTD/ 225opti and 25 trophy.

BTW - another good sense check are the "efficiency" calculators that are available on the various websites.  You can enter prop pitch, gear ratio, rpms and GPS speed and you will know how efficient you are running.  Bassboats will typically be around 10-12% slip or 88-90% efficient when set up properly.

[Revtro]

Yep. 2004 2.5L block.  I guess losing the Taco Bell weight is my best bet at the moment!   

[SethV]

Tom-

I was thinking it was a Classic, not a P3.  Lots more weight in the front end of the P3, so I also agree that the 24 is prob best.

We don't have very many days where we can run WOT anyway.

Seth

BTW - never give up the Taco Bell!  Best thing about my new Z is the HUGE cooler!!      

[Lightningboy]

You might find you need both props across a season.  In the colder weather I run a worked 27 Trophy; hole shot is OK, top end insane.     As soon as the weather warms up, I switch to a 25 trophy.  Warm weather hole shot with the 27 sucks.

In fact, had one scorching, muggy night with full live wells where I felt I could have dropped to a 24 to get out of the water.

By the way, how much set back on the jack plate?  The original owner of mine started with a 6 inch plate, but added 2 inch spacers.  It made a big difference in overall performance.  I've got a buddy I'll ask on Monday about your situation; he's pretty knowledgeable on set ups.

A well worked prop does cost some money & time.  My 27 Trophy was worked by Boger (last owner).  But when you calculate $ vs. performance, it's probably the least expensive way to make gains.  I'm tempted to have my 25 worked too.  Somehow the CFO doesn't see the point... 

[Lightningboy]

Talked to my buddy, his 2 cents:

"Start at 3 inches below the pad.  Bump up in increments of 1/4 inch.  When you lose water pressure, or stop increasing speed, back it down 1/4 & stay there.

The 69 mph with the 25 trophy is pretty darn good for a 2.5 L.  Also try a tempest in the same sizes, can get you back the top end while dropping 1 pitch to improve the hole shot.  Tempest or trophy, use a cav ring & play with the plugs for best hole shot.  The cav ring will force the exhaust out the hub so you can control ventilation better.  Try 1/4 inch holes in all four plugs."

It's all just one big experiment...

[Revtro]

Thanks for the info.  Yep, got a cav ring.  I know what you mean about the big experiment.  I've tried every combo of vent plugs.  Sooo time consuming.  That's why I think I'm down to tweaking the jack plate.  I wish I could afford a hydraulic one. 

[Lightningboy]

Oh man, hydraulic is the cat's arse!  Now, I know what you mean about cost; I probably wouldn't have one if it hadn't come with the boat.  It makes a huge difference in rough water. 

Don't be afraid to give the tempest a try.  You may not have liked one in the past, but that may have been that particular prop.  They vary  quite a bit, otherwise there wouldn't be much of a business in prop work.

Something else to keep in mind is the new Fury comming out from Mercury.  You can't always trust the hype, but Merc claims it'll decrease hole shot a lot while being just faster than a tempest.  I know I'll jump at a chance to give a 25 a spin if I can.

[slsail]

The guys that know this stuff hang at fastbass.com. They run boats 80,90, 100  plus mph
bass boats that is
Jack the motor up until you loose water pressure.
then lower it back til the pressure goes back up.

[Andy]

I have a 97 200 2.5 EFI on my Champ 202, and am running 68 all day long(GPS) with a 24 trophy 4 blade but I turn 6000 on my tack, that is with out a jackplate so realy you are running well on your cat. A tempest will give you better lift than a trophy. Have you tryed a pair of trim extenders?

[Revtro]

Haven't tried trim extenders.  I'm reasonably sure I could get in that range at 6000.  But the manual says 5800 is the recommended top end for that motor, so I try to keep it at that.  Thanks for the info!  I'll have to consider giving trim extenders a try...what do you feel they have done for your rig?  I have no experience with them.