Jack Plate

dreamcatcher · March 11, 2018, 11:18:03 PM

I am thinking of installing a jack plate on my boat. I notice there are different "set-backs" 4" - 6" - 8" .......
What is the reason for the different increments ?

Princeton_Man · March 12, 2018, 09:30:26 AM

Quote from: dreamcatcher on March 11, 2018, 11:18:03 PM
I am thinking of installing a jack plate on my boat. I notice there are different "set-backs" 4" - 6" - 8" .......
What is the reason for the different increments ?

Set-back gives your motor leverage. A 6 inch set-back is usually plenty for most bass boats. Maybe an 8 if you're front heavy. Finding the best set-back is kind of like finding the best prop. Too much set-back and you'll loose handling.

dreamcatcher · March 12, 2018, 11:04:26 AM

Well that could be a problem if you get a manual JP. If i got one it would have to be a 6" or 4"....or whatever. I am getting one to try and raise my engine a bit so I can possibly gain some RPMs and speed

Bud Kennedy · March 12, 2018, 11:13:42 AM

What model of boat and what type of motor are your running. My jackplate is a manual and is a 4" setback but my old ranger hull has a straight transom and hull. New models often have a setback built in their hull design. A jackplate is a must if you really want to tune your performance. There are just so many variables to give you a straight answer without knowing your performance numbers and perhaps the water conditions you encounter in your fishing travels.

dreamcatcher · March 12, 2018, 12:14:56 PM

I have a 93' Champion, it's a model 201. I'm running an Evinrude 200XP with a 14 1/2 X 22 prop. I have a great hole shot, ...Like a rocket , but my top end should be more. I am around 5800-6000RPM but only getting 60MPH.

Princeton_Man · March 12, 2018, 12:48:29 PM

Quote from: dreamcatcher on March 12, 2018, 12:14:56 PM
I have a 93' Champion, it's a model 201. I'm running an Evinrude 200XP with a 14 1/2 X 22 prop. I have a great hole shot, ...Like a rocket , but my top end should be more. I am around 5800-6000RPM but only getting 60MPH.

The numbers suggest that 60 is about the best you can expect from a 22p prop. Your WOT is probably right there at 5800-6000 rpm. Here's a prop calculator. http://www.mercuryracing.com/prop-slip-calculator/ I don't know for sure what your gear ratio is... I used 1:85. Optimum slip would be between 9 and 10% You could have more than that but getting 60mph out of a 22p on that rig, you're doing really good.

You could probably turn a 24 and get another 3 or 4 mph.

dreamcatcher · March 12, 2018, 01:27:44 PM

Quote from: Princeton_Man on March 12, 2018, 12:48:29 PM
The numbers suggest that 60 is about the best you can expect from a 22p prop. Your WOT is probably right there at 5800-6000 rpm. Here's a prop calculator. http://www.mercuryracing.com/prop-slip-calculator/ I don't know for sure what your gear ratio is... I used 1:85. Optimum slip would be between 9 and 10% You could have more than that but getting 60mph out of a 22p on that rig, you're doing really good.

You could probably turn a 24 and get another 3 or 4 mph.

That's what I have been thinking ...going up to a 24. I am trying to figure out all the little details that mean so much. Such as my Engine Height, any set back with a plate, along with the change of prop size. .......

Princeton_Man · March 12, 2018, 02:03:55 PM

Quote from: dreamcatcher on March 12, 2018, 01:27:44 PM
That's what I have been thinking ...going up to a 24. I am trying to figure out all the little details that mean so much. Such as my Engine Height, any set back with a plate, along with the change of prop size. .......

Typically I've seen 21-22p OMC&Rakers on the 115-135 rudes. 22p-24p OMC&Rakers on the 150-200 rudes. Things do change with different brands of props too. A 24p will no doubt get you a few more mph but will cost you when it comes to hole shot. Adding a jack plate can help you tweak your hole as well as speed, but I think you need more a bit more prop.

If you can find someone with an OMC Renegade 23p who'll let you try it, you might be surprised. That's a 4 blade prop that I'm pretty fond of. I ran them on my old 150 Intruder which I'm told was more or less a 180. That's probably what was originally on that rig when it was new.

Bud Kennedy · March 12, 2018, 03:47:27 PM

It would be interesting to know what your prop to pad measurement is. If you are a tad deep on your prop the hole shot would be very good but not so good for total speed. If you know your measurement it would be nice to know also curious about how high your rooster tail is while on plane.

dreamcatcher · March 12, 2018, 07:38:38 PM

Quote from: Bud Kennedy on March 12, 2018, 03:47:27 PM
It would be interesting to know what your prop to pad measurement is. If you are a tad deep on your prop the hole shot would be very good but not so good for total speed. If you know your measurement it would be nice to know also curious about how high your rooster tail is while on plane.

It is little shy of 4"------

Bud Kennedy · March 12, 2018, 09:03:33 PM

Certainly shy of 4" is not bad given the traditional starting point is 3 1/2". If you did want to come up just a wee bit that jackplate would make the task a whole lot easier. Otherwise it sound like you may be ready for some prop help. I would think you should be able to run at least 65 but as I remember those old Champs are a bit heavy but an awesome boat in rough water.

dreamcatcher · March 12, 2018, 09:35:17 PM

Quote from: Bud Kennedy on March 12, 2018, 09:03:33 PM
Certainly shy of 4" is not bad given the traditional starting point is 3 1/2". If you did want to come up just a wee bit that jackplate would make the task a whole lot easier. Otherwise it sound like you may be ready for some prop help. I would think you should be able to run at least 65 but as I remember those old Champs are a bit heavy but an awesome boat in rough water.

Yes it is great in rough waters....a friend of mine told me a couple of months ago that he knew another guy with the same Champion , same motor and was getting 70MPH out of his, loaded. I don't know what kind of prop he had or anything like that, but that just got me thinking I SHOULD BE DOING SOMETHING IN THAT RANGE.

dreamcatcher · March 15, 2018, 07:04:08 PM

Well since I can't find out what the set back should be on a JP, I guess I'll have the shop raise my engine on the transom about an inch to see what that does .....

I'm looking for a 24" prop, or a 23". One of the prop shops here didn't have a 24 to try

There is another good one here that i;ll try next week

WVBassman · April 02, 2018, 10:34:23 AM

You could run a 6", 8", or 10" on that hull. With the 200 on it, you should be running a 24P Raker. Your prop to pad should be between 3 1/4" - 3 1/2" for best numbers. Depending on what year that motor is, your rev limiter may hit at 6100 rpm's.
Make sure to watch your water pressure while dialing it in. If your rpm's go higher and your water pressure drops too low, you've gone too high with the jackplate.
That boat and motor with the correct prop and j/p should be running in the mid 60's if the motor is healthy.

dreamcatcher · April 02, 2018, 05:55:34 PM

Quote from: WVBassman on April 02, 2018, 10:34:23 AM
You could run a 6", 8", or 10" on that hull. With the 200 on it, you should be running a 24P Raker. Your prop to pad should be between 3 1/4" - 3 1/2" for best numbers. Depending on what year that motor is, your rev limiter may hit at 6100 rpm's.
Make sure to watch your water pressure while dialing it in. If your rpm's go higher and your water pressure drops too low, you've gone too high with the jackplate.
That boat and motor with the correct prop and j/p should be running in the mid 60's if the motor is healthy.

Thanks. I have already ordered a 6" Jack Plate should be here this week, or early next week. I have a 24" prop I will try and see what that set up will get me. Hopefully I won't have too much of a headache trying to figure things out..and didn't shot myself in the foot !
I'm turning 5900 @ 60mph. with my 22"

dreamcatcher · April 28, 2018, 11:21:01 AM

Well....I got the 24 Prop. It is a Raker HO. Jack plate is installed. Set at about 3 1/2. Went out to the lake the other day and has a terrible hole shot. Played around with the vent holes and the best shot was with the ports closed. Still not as good as the 22" was. Top end speed didn't even get me up to 60mph.

$:-\$
I don't have a water pressure gauge on the motor, I have one ordered and will install and go back out to adjust the height some more

Getting a lot of water spray coming up to the Engine cover on the drivers side, not sure what that is, maybe the speedo tube...Didn't happen before the jack plate was installed
Not as easy as i thought it would be.

Bud Kennedy · April 28, 2018, 01:44:36 PM

what RPMs are you turning?

dreamcatcher · April 28, 2018, 01:46:53 PM

Quote from: Bud Kennedy on April 28, 2018, 01:44:36 PM
what RPMs are you turning?

About 5700

Princeton_Man · April 28, 2018, 07:24:39 PM

The HO is adjustable vents if I'm not mistaken? Are they open as much as possible?

dreamcatcher · April 28, 2018, 10:22:52 PM

Quote from: Princeton_Man on April 28, 2018, 07:24:39 PM
The HO is adjustable vents if I'm not mistaken? Are they open as much as possible?

If they are open, I can't get out of the hole.......spins out

Princeton_Man · April 29, 2018, 05:55:24 AM

Quote from: dreamcatcher on April 28, 2018, 10:22:52 PM
If they are open, I can't get out of the hole.......spins out

I think we're onto something. Those vent's need to be adjusted to allow your prop enough slip to spin up without bowing out. Once the prop spins up and begins to bite the venting will cease and all of the exhaust will route through the hub.

You can start by opening them half way. If it still has too much slip, close them in 1/8" increments until you find the best spot. Another way to reduce blowout is to lower the jackplate a little. Which is what I do for my more heavily modified prop because it's better vented than my Raker.