Z19 Sport fish and Ski Porpoising solution

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Alan Ponder

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Joined
Oct 16, 2019
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Location
Katy, TEXAS
I have a 2018 Z19 Sport fish and Ski with a Merc 175 and Mercury Tempest plus stainless three blade 22 pitch prop. Motor runs great, can make 60 mph, before I shut it down, with 4 ppl, all the gear, and fully trimmed out windy day.

BUT, this boat has a terrible porpoising response at low speeds, I can't see out of the front from the seat. Planes pretty quickly over 30 + mph.

What are your thoughts/suggestions on the porpoising issue?:
  • Different prop, 4 blade different pitch?
  • Whale Tail on the outdrive? - easiest/cheapest remedy so far.
  • Jack plate ($$$ ouch!)
  • Thoughts
Thanks
APTX
SE Sport 400 No-Drill Hydrofoil, Fits Engines Over 40 HP
StingRay XRIII Hydrofoil Stabilizers For Boat Motors
 
I put a SE Sport bolt on and a 4 blade prop on mine. The whale tail helped immensely.
 
My Ranger R-93 (mercury optimax 200) bass boat did the same thing after I moved the motor back on a motorized jack-plate. The transom has a lot of clear water setback anyway, and was on the verge of doing it before hand. What I did was... There is a cavity ahead of the front storage box under where the trolling motor mounts, as far forward as it gets. I took some gallon freezer bags, 1/2 filled with sand and allowed them to settle into place conforming to the shape of the cavity and one another. Clean up the area first of fiberglass strands and edges which may cut the bags. I added bags until it stopped at 70lbs, with a full tank of gas. The fuel weight shifts balance rearward. I did this with all the normal amount of gear I keep in the boat and the live-well flooded the way I would use it - solo.

The boat can't sink since it is fully foamed and is immediately responsive to the throttle at any speed without a hint of bow bounce even on glass smooth water. The added benefit is when I'm up forward on platform, the transom is less down in the water and the boat draws less water. I only weight 180lbs. dressed.
 
I have your same setup but in a 2020. I was having that same issue when I was braking it in. Until I realized I was unbalanced (left to right). When I am level I don’t have that issue. I do think my motor is low but have not confirmed it. Thinking about getting a jack plate. I thought I heard the 2021s come with one or are an option. Hinting we should get one also.
 
I thought I was the only one with this issue. From ~25-40MPH I get porpoising as well, regardless of how many people I carry (2020 Z19 Sport). My prop is a 24P Tempest with a 150. Anything above 37-40MPH is great. I can trim it up and run 55 MPH all day. When I'm running lower speeds, I usually end up trimming the motor way down - almost to the bottom. This is the only thing I have found that helps. I generally dont run that slow unless I have some young kids in the boat with me - which isnt very often.

I'm hesitant to install a whale tail due to the added stress on my lower unit (which is still under warranty). I may try to raise my motor to see if that helps.
 

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