Jump to content

Jackplate on an 18.5 MA??


whichwaysup

Recommended Posts

Hey all - 

I miss the jackplate I had on my last Master Angler, but this newer MA is much different, and has a larger engine (150 vs. 115).  I like the JP for the "insurance policy" when running the marsh, getting that engine up 6" can make a huge difference at mid-tides.   Not concerned about top end speed, just the ability to run skinnier with a little less worry.

I've seen that the 17' MA is NOT recommended for a jackplate, but curious if there are similar concerns about it with the 18.   

Link to comment
Share on other sites

whichwaysup,
Just my opinion, which may differ from others... The first question I would ask myself is: Will a little gain in draft due to some stern squat that will occur when the weight of the 150 is moved further back be acceptable?  If the answer is yes, I would not hesitate to install a jack plate under the following conditions (learned through trial & error):
You need more than 6" of setback for several reasons:
1.  To offset the increase in motor height that is built-in to all jack plates, which can cause loss of grip in turns and cavitation when trimmed up.
2.  You will most likely want to add a setback spacer (or use the one built into the 8" Atlas), to customize the motor height, to get the prop down lower into cleaner water for better grip (pics of mine attached)
3.  So that the hydraulic steering will have enough transom clearance to tilt your motor up for trailering with the jack plate all the way down (like the JP manufacturer recommends).
4.  More setback = better performance.  Just look at all Allison race boats and most tournament bass boats and you'll notice that setback of more than 10" is common.  However, some MBG models have a generous amount of setback already built into the transom pocket of the hull, which should be considered when calculating setback.

So, IMO - I like my setup with the Atlas 4" plus a CMC 2.5" setback spacer.  I ended up drilling new holes 1-1/4" lower in the setback spacer to get my motor down as low as possible and the hydraulic steering still clears the transom.  This eliminated the loss of grip in turns that I was experiencing before I installed the jack plate.  I can now turn hard at any speed with trim tabs at any level, and the prop does not blow out.  I can now take advantage of the jack plate's full range of travel, with the increased setback and adjusted mounting height - lower than standard.  Note: They call it a Atlas 4" jack plate, but it is actually measures at 5" of setback.  So my total setback is 7.5".  The smallest Bob's Action Jack is 6", so you could do the same thing with it but you would increase the total setback to 8.5"
After many hours of obsessive tweaking and testing, I am finally happy with how the boat handles and performs and I'm having fun with it!

Side note:  Lurem and I shared ideas along the way with this and he chose the Atlas 4" Micro-Jacker JP for his Yamaha 115 setup because he was concerned about weight on the transom and increased draft.  The Atlas Micro-Jacker was designed without as much built-in lift in motor height.  It works very well for Lurem and he does not have any "loss of grip" issues.  Maybe he will chime in here as well.

 

 

 

 

 

Link to comment
Share on other sites

thanks all!  Those are really good considerations Geeviam!  Thanks for taking the time to walk through that!  I already have an issue with my prop blowing out in turns, even when the motor is trimmed fully down.  I am getting exactly the performance I should, otherwise, and I may take it in to be cupped a bit - hopefully that will alleviate some of the need to for set back, too.   I don't plan on running the boat with the jack plate up except when I'm back in the creeks.  

Mitz - specific to the MA - is there any risk to the transom with a Jackplate?  What did you go with, and anything you would have done differently?

Link to comment
Share on other sites

To gain any advantage in running height, you will have to go with a minimum of 6" maybe more setback. If your're thinking 4" don't bother.

For me moving the motor back 6+" might upset the balance of the boat. If I have 2 adults on the boat, I have to use some tab when running, add the motor setback and it might take more. Mitz will prolly give you the best feed back, wonder how much setback he had.

Link to comment
Share on other sites

balance was a major concern of mine but see for yourself how she sits. Ill try to dig up a pic w/o jp for a comparison. When i initially bought the boat it had the crank in the starboard rear compartment, and the 2 TM batts in the console. As we all know, w a full live well and don't even get me started on a full release well! you are gonna need to use tabs, no way around it. I wanted to add a house batt anyhow so decided to move the TMs to the front, crank along w a group 27 house batt to the console. This did help with weight distribution. 

In the end temptation and the great price i found on a CMC JP got the best of me. My theory was that added weight effect of having the engine further back was balanced by the movement of all the batts forward. Yes, moving the batts forward did hurt the top end a little but that was almost gained back by the jp. fastest combo would be batts in back plus jp but that wouldn't be practical. 

The setback of the CMC is 5.5 inches plus the setback of pp bracket (.25-.5?) so close to, if not 6 inches total. Agree that 4 inches wouldn't be with it nor would i go to 8 inches as i believe the 6inch keeps the boat in harmony.

Can't comment on stress to transom as I'm not an engineer ;) but since my neighbor and good friend now owns the boat i can tell you he hasn't had any issues with it. All kidding aside, i can't see why it would hurt it unless user error.

Speed gained top end should be about 1-1.5mph, and avg increase of 100 rpm and that was with the 20 pitch ultima. saw 56.5 with minimal speed runs and 5.4krpm. My buddy switched back to the 2+2OT which has a smaller dia and 22 pitch. Im curious to see what we can get out of her now. my guess is 5.3-5.4krpm and over 57.

Link to comment
Share on other sites

Mitz's post reminded me... I forgot to mention that, of all the larger jack plates, the CMC Power-Lift HS with 5.5" setback added the least amount of built-in height lift, which would be good if you were concerned about too much setback (and rear weight), but still needed to cure some prop blow-out issues.  You wouldn't need the 2.5" setback spacer that I use, to keep the prop lower into cleaner water with the CMC JP like Mitz used.  I bought one, but sent it back for a refund because it had a minor defect.  I wish I would have replaced it and tried another one because it has an awesome design (patented).

CMC Power lift jackplate.mp4

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...