Should I install a jack plate?

cp4000

Seaman
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Sep 17, 2010
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55
I just bought a 93 Nitro 180FS with a 93 150 Mariner. It needs steering cables and that would be the time to install a jackplate if I was ever going to. Can the boat/transom handle it? Ive heard some things about boats not designed for it and causing stress/damage? One reason why I am considering it...I was always told the cav plate should be about an inch above the lowest part of the boat. Mine is about 6" above. It is close to being even with the recessed area in back but not the actual bottom. In storage, the skag is almost touching the ground the way it is so I really can't lower the motor on the boat. If not for performance reasons, I would be able to lower the motor on the boat and raise it via the jackplate to store it. (Can't tilt it...no room in garage.) So I guess another question is, on a boat like this, should the cav plate be around the actual bottom or around the recessed area/cutout. I heard the recessed area is to allow better water flow to the prop, so is this the correct orientation? Would a jackplate damage this boat? Thanks for any help.
 

Chris1956

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Mar 25, 2004
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Re: Should I install a jack plate?

Gee, I think you should benchmark some actual performance, on the current setup. Get some RPM and speed numbers and post them. Jackplates are all about performance, however, like most things, you get some speed but give up other performance aspects.
 

Dhadley

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Feb 4, 2001
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Re: Should I install a jack plate?

Most Nitros do benifit from a jackplate. But let's look at a couple of things first.

Are you considering a manual or hydraulic jackplate? Since you mention steering cables - and you are correct, now is the time for the plate - we need to consider cable routing if we add setback. Typically we'd add 4-6" steback on that hull. Take a look at where the cables come out and imagine them going back 4-6" and up as much as 6". If that creates any sharp bends that's an issue. If they can be routed or rerouted so there are no sharp bends then you're good to go.

Just a step further - if you were even considering hydraulic steering this might be a good time for that too.

As for your current set up, yes the AV plate will be somewhat even with the step in the transom which will be higher than your pad. Depending on the technology in your prop you could end up higher than you are.
 

cp4000

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Sep 17, 2010
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Re: Should I install a jack plate?

I can't get any benchmarks, I've winterized the motor because it's dipping in the 20's here at night now. Ice will be forming quickly. I haven't made up my mind on manual or hydraulic because I wasn't sure if I wanted to put one on yet. Leaning towards hydraulic. I did think about routing the cables and they would never make the bend on the current setup. Was thinking of making a seperate hole for the cables if I went that way, the bend is tight the way it is now w/o a 6" setback. Hydraulic steering?? I do not know anything about it...What are the pros and cons? Sounds more expensive, I'm not afraid of work but would be curious as to how hard it would be. Is there redundancy or fail safe? I have two cables on mine. I have a 22p high five prop and the AV is even with the main step on the transom, from the sounds of it, this is a correct placement? Now is the time to get all the work done and setup right as the winter is setting in and I got a good garage heater:)
 

Dhadley

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Re: Should I install a jack plate?

Nothing wrong with rerouting the cables including making a new exit point. As for hydraulic, check out the Sea Start system from Teleflex or the system from U-Flex. Basically there's a helm (pump), 2 hoses and a cylinder on the motor. Very common today although a bit expensive.
 

j_martin

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Sep 22, 2006
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7,474
Re: Should I install a jack plate?

I have basically that same setup. It's an 88 Tracker with an XR4 on it. It has a 6 inch manual jack plate, and the engine is set up so it just barely cools at full trim pulling a 24 pitch High Five at 6000 - 6100 rpms. You must have the small lower Mag/II engine because a 22 inch high five is a 4 inch hub prop. If you ditch the "advance" module and tune it up right on spec except WOT timing at 23?, you'll be looking for a 24 pitch prop also.

Original steering was Teleflex dual rack, which ruptured a cable about the time I acquired the boat. I replaced it with Teleflex dual rack NFB. The original cable ruptured because the cables were routed through the original routing hole, putting a severe bend in the aft cable. When I installed the new cables, I put a second oval hole in the back of the cap for the rear cable. Now steering for docking etc is a one finger procedure. In relatively smooth water, you can let go of the helm at any speed. Not recommended, but possible.

Hydraulic would be a step up from that.

A couple of factoid's I've acquired at some expense, free to you:

1. The secret to dual cable steering is adjusting all the backlash out without causing it to bind.

2. The weak link is the single bolt that connects the steering link to the steering arm. Use the right one, and inspect it frequently. Going swimming ain't a big deal. It's going through the gunwale on the way to the lake that hurts.

3. Steering cables are lubricated for life with a light, probably synthetic oil. If you force grease into the steering tubes, probably possible only on the forward one with a stock setup, it'll get into the cable and bind it up. It can be cleaned and relubed, but it takes a home made tool, SeaFoam, and a bunch of work.

4. You gain top end with the engine set back and raised so you're slightly surfacing the prop. You lose mid range handling. I have to sandbag the bow to take an old timer fishing so I can get on plane without killing the poor guy, and run at less than 40 mph without porpoising.

hope it helps
John
 

cp4000

Seaman
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Sep 17, 2010
Messages
55
Re: Should I install a jack plate?

Thanks for the info!
I am going to go with hydraulic steering. I continue to hear nothing but good things about it. Just to clarify...the helm is basically the pump, its it electrical or a mechanical pump? Looks like two hoses going back to a cylinder mounted on the motor, that is fine for that HP-150? Compared to the dual cable setup i have or is there a more complex system I need to check into? The hoses would be much less rigid I take it for ease of routing?
Going back to the jack plate / hull. It should be strong enough to handle any extra stress added by a jackplate? I guess that is one of biggest concerns. I would go hydraulic.
Smaller Mag/II engine? Not sure of the markings of the motor. Its a 93 Mariner 150, 2.5. Thats pretty much all I have been able to find out about it without the manual yet. Serial is 0D222***.
"If you ditch the "advance" module and tune it up right on spec except WOT timing at 23?, you'll be looking for a 24 pitch prop also." Haven't heard about this but will try to do some research on it, and probably removing the oil injection too.
 

Dhadley

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Feb 4, 2001
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Re: Should I install a jack plate?

Yep, that's all there is to it, The helm (pump), 2 hoses and the cylinder. No wires, nothing else. You can add the "blinker" switches to run the plate and trim if you like. Makes for a very neat installation. Very handy to have both switches right by your steering wheel so you don't have to let go of the wheel to make adjustments.
 

j_martin

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Sep 22, 2006
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Re: Should I install a jack plate?

Smaller Mag/II engine?

The clue that spawned that remark is that High five props come in even pitches at 4 inch, and odd pitches at 4 1/2 inch. If you have a 22 inch high five on it, and it fits the LU properly, ie not a lot of space between the hub and the LU, it's a 4 inch lower. The XR/4 and Mag/II came with that lower.

If well maintained and not overpowered, they do well. If anything isn't right, or you put extra ponies into a 3 blade surfacing prop, it'll put the pinion out the side. One beautiful characteristic of the high five is that it doesn't have a lot of potentially destructive torsional vibration, even if it pierces the surface a bit.
 

cp4000

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Sep 17, 2010
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Re: Should I install a jack plate?

That's interesting and I had another post in the prop section about it. I did remove the prop and felt there was alot of shaft sticking out past the prop even after the lock nut. Maybe an inch after the locknut. While cleaning the boat I found a thrust washer, looked up the part number stamped in it and was right. (Is it a spare? Did it come with the High5 or did it needed to be removed when putting on the High5?) The way the prop is currently there is a stepped washer against the lower unit, then the prop, then the shear sleeve, a locking sleeve, a thin tabbed locking washer and a nut. So will need to find a parts diagrahm or call High 5. I think a 4 1/2" prop would fit nicely on there so maybe the wrong one was on there? Will have to do some research...
 

Chris1956

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Mar 25, 2004
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27,036
Re: Should I install a jack plate?

The gearcase I have on my '93 Merc 135HPV6 was from an clamshell cowling ('88?) Merc 150HPV6. It is 4-3/4" in diameter. I would think your would also be the larger gearcase.
 

j_martin

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Sep 22, 2006
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7,474
Re: Should I install a jack plate?

That's interesting and I had another post in the prop section about it. I did remove the prop and felt there was alot of shaft sticking out past the prop even after the lock nut. Maybe an inch after the locknut. While cleaning the boat I found a thrust washer, looked up the part number stamped in it and was right. (Is it a spare? Did it come with the High5 or did it needed to be removed when putting on the High5?) The way the prop is currently there is a stepped washer against the lower unit, then the prop, then the shear sleeve, a locking sleeve, a thin tabbed locking washer and a nut. So will need to find a parts diagrahm or call High 5. I think a 4 1/2" prop would fit nicely on there so maybe the wrong one was on there? Will have to do some research...

Ya better check the diagrams. There should be a thrust hub (washer) that fits on the taper of the shaft under the prop, holding it firmly away from the seal or metal of the LU. On mine there's then the prop, a tabbed washer receiver, the tabbed washer, and the prop nut. The shell of the prop should fit inside the shell of the LU about 1/4 inch, and spaced very close to it but not touching it.
 

j_martin

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Sep 22, 2006
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7,474
Re: Should I install a jack plate?

The gearcase I have on my '93 Merc 135HPV6 was from an clamshell cowling ('88?) Merc 150HPV6. It is 4-3/4" in diameter. I would think your would also be the larger gearcase.

The XR4 came with a small gear case. Most v6 engines since 1990 have the larger gearcase. They are bolt interchangable.
 

cp4000

Seaman
Joined
Sep 17, 2010
Messages
55
Re: Should I install a jack plate?

Well I bought a used hydraulic jackplate from a boating shop. Its the TH Marine, High Speed Hydro Jacker 6". I do need to get a wiring harness for it...been looking with no luck yet. Anyways, I have heard good and bad things about em? Any experience or feedback? Won't be installing until I get some new steering cables which brings me to another point, saw another post on here that said a dealer told him to stay away from hydraulic steering. I guess he has some customers where it failed on them causing injuries? I do like the redundacy of two cables even if it isnt as nice. Any reassurance of hydraulics out there?
 
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