Should I consider a jack plate?

Status
Not open for further replies.

Douglasdzaster

Petty Officer 1st Class
Joined
Sep 11, 2020
Messages
306
Hello everyone,
I have a 1980s Monark 1652 aluminum Jon boat. It has a 2 stroke Yamaha 40 hp. Short shaft.
The boat’s transom was cut down to accommodate the short shaft. At wot I can look back and see the bottom plate just skimming the top of the water and the prop is hooked up running good. I’m getting told by a few people I should add a jack plate. I can’t raise it any higher w it doing well the way it is. My question is with a jack plate sitting the motor back away from the transom would I pick up any speed or run any shallower. Right now the top plate sits even with the bottom of the boat and like I said seems to run perfect. I want to start fishing the river and those guys are the ones telling me I’d run better with a plate. In my younger years we all had jack plates on our bass boats. 12” set back on 225 EFI Mercury. This is my first jon boat. I got it for a project boat and Ive done all the work myself (except for the help of a machinist a couple time) and the Yammi pushes it pretty well but I’ve still got some of that can I get a little more out of it in me.
 

Attachments

  • 3C535A69-38F6-4089-B899-0E335866F06E.jpeg
    3C535A69-38F6-4089-B899-0E335866F06E.jpeg
    5 MB · Views: 18
  • 11002761-9152-45A0-B7E8-5A750D0E6AFB.jpeg
    11002761-9152-45A0-B7E8-5A750D0E6AFB.jpeg
    4.9 MB · Views: 19
Last edited:

Douglasdzaster

Petty Officer 1st Class
Joined
Sep 11, 2020
Messages
306
Hello everyone,
I have a 1980s Monark 1652 aluminum Jon boat. It has a 2 stroke Yamaha 40 hp. Short shaft.
The boat’s transom was cut down to accommodate the short shaft. At wot I can look back and see the bottom plate just skimming the top of the water and the prop is hooked up running good. I’m getting told by a few people I should add a jack plate. I can’t raise it any higher w it doing well the way it is. My question is with a jack plate sitting the motor back away from the transom would I pick up any speed or run any shallower. Right now the top plate sits even with the bottom of the boat and like I said seems to run perfect. I want to start fishing the river and those guys are the ones telling me I’d run better with a plate. In my younger years we all had jack plates on our bass boats. 12” set back on 225 EFI Mercury. This is my first jon boat. I got it for a project boat and Ive done all the work myself (except for the help of a machinist a couple time) and the Yammi pushes it pretty well but I’ve still got some of that can I get a little more out of it in me.
When I said I did all the work myself. I mean with a lot of help here on the forum. Could not have done it without the advice and sharing of knowledge I received here.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,178
Let er be and go fishing while weather is good. Save up some greens over winter and see if ya can find a long shaft, heck of a lot easier to dial in on a plate
 

Douglasdzaster

Petty Officer 1st Class
Joined
Sep 11, 2020
Messages
306
Let er be and go fishing while weather is good. Save up some greens over winter and see if ya can find a long shaft, heck of a lot easier to dial in on a plate
This is definitely for the future. I’m going fishing as often as I can right now.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Hey Doug welcome back, we were missing your nice posts for boating perfection LOL!!.

If the water flow skims at speed/plane over the AV plate and the motor does not have prop aeration issues at close turns, choppy, windy water conditions don't install anything. As set can't run the lower leg any shallower or the prop wil inevitable aerate hard if the motor is risen more than it's now.

Have seen your transom's pics before, for me the edge is badly shapped does not maintain a perfect straight edge which should have been ideal to shape right before bolting the motor on transom. Hope the motor sits at a perfect straight 90 deg angle for the AV plate to ride fully parallel to the water level once on plane/speed.

What was the last max wot rpm and GPS speed achieved as loaded on flat calm no wind water conditions ? One down issue installing a short shaft motor on top of a modified L transom is that once the combo has come into a sudden stop while running at speed, the incoming wave formed at back transom will jump over the motor's sides and flood the deck, to avoid that uncomfy wet situation reduce the throttle gradually till a final stop.

Happy Boating
 

Scott Danforth

Grumpy old guy who plays with boats
Joined
Jul 23, 2011
Messages
41,999
a jack plate will allow you to raise the motor a bit. about 1" up for every 4" back as a rough rule of thumb

I agree with above.....go fishing now
 

Douglasdzaster

Petty Officer 1st Class
Joined
Sep 11, 2020
Messages
306
Hey Doug welcome back, we were missing your nice posts for boating perfection LOL!!.

If the water flow skims at speed/plane over the AV plate and the motor does not have prop aeration issues at close turns, choppy, windy water conditions don't install anything. As set can't run the lower leg any shallower or the prop wil inevitable aerate hard if the motor is risen more than it's now.

Have seen your transom's pics before, for me the edge is badly shapped does not maintain a perfect straight edge which should have been ideal to shape right before bolting the motor on transom. Hope the motor sits at a perfect straight 90 deg angle for the AV plate to ride fully parallel to the water level once on plane/speed.

What was the last max wot rpm and GPS speed achieved as loaded on flat calm no wind water conditions ? One down issue installing a short shaft motor on top of a modified L transom is that once the combo has come into a sudden stop while running at speed, the incoming wave formed at back transom will jump over the motor's sides and flood the deck, to avoid that uncomfy wet situation reduce the throttle gradually till a final stop.

Happy Boating
Boating perfection or lack there off. Lol I was just curious if the motor being set back farther would do anything more than wanting to raise the motor. I’m getting all I'm going to get as far as it being high enough. Im off by a pitch on the new prop. It’ll turn 6 k if I let it and run 35 mph. I have a lot of drag on the bottom of the boat from whatever the previous owner had put on it. It use to skip across the water until this stuff started coming off. I’m going to end up pulling the motor and putting the boat on it’s side and pressure washing it and see what I find. I have a feeling it’s covering up something as it’s thicker towards the aft . The new prop brings it right out of the whole ez. No aerate problems in turns and so forth. It’s got more cup than the old prop does. I definitely ez out of the throttle and don’t make sudden stops. Weather is to good now though I’ll be back on the water fishing as soon as I get it back from the welder from where the tree fell on it last week.
 

Attachments

  • 6DE342C5-2951-43CA-BCBD-16C95691DE23.jpeg
    6DE342C5-2951-43CA-BCBD-16C95691DE23.jpeg
    2 MB · Views: 7
  • 6AA44011-3773-410F-B28D-CCF14C06309B.jpeg
    6AA44011-3773-410F-B28D-CCF14C06309B.jpeg
    1,023 KB · Views: 7

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
If the max wot rpm range for said motor is 6K and already revvig there as loaded along achieving 35 MPH with near instant hole shot leave it there. Fix and clean the hull to slide better with least water resistance and that's it...

Happy Boating
 

TriBull

Cadet
Joined
Jul 7, 2022
Messages
13
I love the jack plate on my 1974 12ft aluminum StarCraft. Not only does it make for a nice ride, it frees up lots of space in the boat and on the inside of the transom. I used that space to efficiently mount a sport dive ladder and boat hook!
CC448EB4-6441-41D1-A344-AA4B63E685D2.jpeg665D652A-ED39-4C6F-8460-2A330249109C.jpegCE8779C4-65B4-4EE2-B900-A97D17C1B352.jpeg
 

Attachments

  • AB784CD0-0134-428D-AA30-173378A0EB0B.jpeg
    AB784CD0-0134-428D-AA30-173378A0EB0B.jpeg
    1.9 MB · Views: 7
Status
Not open for further replies.
Top