Tracker targa purposing need help!

[chaoticbaits]

Hi,
I have been on this site many times and gained a wealth of knowledge when it comes to boating topics...But I am stuck I have a 2000 tracker targa 175 with a 1999 mercury 125 hp elpto and i can not get it to ride smooth. I've added a manual jack plate 6" set back with 6" of travel. Current prop is a stainless lazer II 22" pitch running 5200-5400 RPM at 40-42 mph but steering torque is ridiculous it will run good with the wind or until i cross a wake or in more then 6" of chop then it will start hopping hard.i've tried moving weight around with no noticeable change. I've rewired the boat and moved 2 of the three batteries forward in the boat no change. The boat has heavy steering torque and will not reach top speed without proposing. I've tried different motor heights without improvement the best i seen was motor anti cav plate 3.5" above keel but motor would cavitate when trimmed not reaching over 30 mph.any lower i get the steering torque and porpoising.I have tried a few different props and the best was a 19 pitch aluminum quicksilver it gave the boat a good hole shot and held the bow up much better before proposing getting 33 mph at 5400 rpm but i am only at 3/4 throttle and it is way to easy to push it just a tad to far and bounce it to 6000 rpm. my most recent addition was smart tabs this helped to get the boat on plane but did nothing for the purposing problem. with the 19 pitch prop and smart tabs at the highest setting the boat ran smooth until i crossed a wake or was running against the wind then bounce bounce.I have tried different motor heights different props added the jack plate added the tabs moved weight around checked the hull for cupping and its straight. Im at my witts end the boat is rated for 125 horse is it just too much motor??? Another issue when i had all 3 batteries in the back and stood on back platform water would come in through splashwell drains that is what prompted me to move batteries forward. i have even gone to the extent of unhooking front two trolling batteries (24 volt) and trying them in different positions in the boat and i cant seem to find a happy medium. I want the boat to run smooth so my wife can drive it from time to time but with the steering torque and proposing its just not possible.Please any help would be great im over $10,000 into a boat i am not happy with and that my whole family cant use.
Thanks in advance
Dan.

 

[KYsean]

I think the WOT RPM's should be 5250 max. If that's the case, a 22" 4 blade would help a lot.

 

[jestor68]

If you trim out to the point that it porpoises, trim in a little til it stops.

If trim won't get rid of it, contact Tracker for the cure. This has happened occasionally on brand new Tracker boats and they know how to stop it. It has to do with welding a little bead across the bottom at the transom. Tracker knows how to fix it.

 

[Teamster]

For the steering torque I would check the torque tab on the motor, It might need to be adjusted,...

With a 125 hp would try a 19 pitch High Five prop,

I know on my heavy glass Fisher FX18 with a 150 the 23 High Five gives good bow lift and the proposing stopped, Mine is a little sluggish on hole shot but works great when working waves,.............I might try a 21 High Five to see if I can make things even better,...........

 

[hwsiii]

Dan, you have two major problems here that are definitely not good. Let's start with the porpoising problem and get that fixed and then we will work on the steering torque afterwards. Although by stooping the porpoising we may fix the steering torque problem because you will be able to trim the motor up enough to remove the torque problem because the higher trim on the motor will offset the torque problem. I have to assume with everything that you have done that no matter where you adjust the trim tab to that it will not stop the prop torque, although if you have a bent skeg that would definitely be a problem.

Basically porpoising is caused by the center of gravity longitudinally being in the wrong place at any particular point of speed and/or increased trim of the motor, and as the speed increases the porpoising usually only increases intensely as more speed and/or trim is applied, although some of the time if speed is increased enough you can power through it because the center of gravity moves to a better point on the hull and thus the porpoising stops.

This problem can be controlled through choosing a better prop for your particular boat design and motor combination in almost all cases. In reading your post it is very obvious that you have tried almost all of the normal procedures and spent a tremendous amount of money to alleviate this problem, and I feel sorry for you that none of these worked.

I am going to mention some of the different prop characteristics that can either help or exacerbate porpoising in a boat, so you can have a better understanding of what these characteristics in a prop accomplish.


Progressive Rake The most Bow lift available with good speed, great holding power at high speeds and Rough Water and less cavitation and ventilation
Flat Rake Has Great Bow lift and not quite as much holding power or Bow lift as Progressive Rake
Blade Tips Cup Adds Bow Lift because it increases the rake and usually increases Speed as well as lessens Cavitation and Ventilation
0 Rake Best prop for Stern lift and produces the most power, it is the best prop for boats that have a tendency to porpoise
Trailing Edge Cup Adds Stern Lift, acceleration and theoretical pitch and reduces ventilation as well as increases speed but lowers RPM

In high speed racing boats props are usually twice the pitch as the diameter with progressive rake and if there are problems or the owner wants maximum speed they will even have the blade tips cupped and the prop balanced and thinned.

I would recommend a 22" pitch Solas Amita 4 blade prop to pick the stern up and move the center of gravity to a place that will stop the porpoising.


H

 

[walleyehed]

hwsiii has hit pretty much on what I was going to mention. I have an 18ft StarCraft with over 200hp on it. I've ran countless props in testing and I also have 6" plate and Mobster tabs. I have found that some props have TOO MUCH bow-lift for this boat and they want bow up to a point the water-line comes behind the CG point and the porpoising starts. I went back to a 4" jackplate and a turbo1 prop and found my best combo. I would be inclined to try a 4-bld and see if that helps but 125hp "may not" be enough hp on that platform to hold the bow up with a 6" plate (moves CG aft) and a LaserII, which was built to perform best on light, fast boats with a bit of natural bow lift....that hull has stern lift built into the design being a deep-V. Have you moved you tab cylinders on the tabs in or out?