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Max Online: 36273 @ 01/23/13 02:34 PM
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#12405654 - 08/29/17 07:42 AM Porpoising Issue
David W Offline
Outdoorsman

Registered: 05/30/11
Posts: 38
Loc: Leonard, Tx
I figured I would ask the experts because I certainly am not one. I have a 22' Sea Hunt center console with a 200 HP mounted on an Atlas jack plate. The issue I'm having is when I get up on plane and get to 30-35 mph, the front of the boat will start bouncing (porpoising) and will not correct itself until I throttle back. I have it completely trimmed down and the jack plate is on it's lowest setting. It did it to me the other day when the water was like glass. What am I missing? I do have trim tabs that I can use to help resolve it but I'm pretty sure that is not what they are intended for. Is it a weight distribution issue? Any suggestions would be greatly appreciated. Thanks in advance!!

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#12405682 - 08/29/17 08:11 AM Re: Porpoising Issue [Re: David W]
Muzzlebrake Online   content
Extreme Angler

Registered: 12/26/14
Posts: 1614
Loc: Euless
I wish I knew the perfect answer. I helped my boat by going to a 4 blade prop with less pitch and more cup to get more stern lift and moving as much weight as I could toward the front and middle. I think mostly it comes from boat hull design. The prop change allow me to get on pad about 10mph slower which is exactly what I needed. Funny thing is, I didn't lose any top speed and maybe gained 1-2 mph
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#12405730 - 08/29/17 08:39 AM Re: Porpoising Issue [Re: David W]
tmd11111 Online   content
Angler

Registered: 04/30/17
Posts: 414
Loc: San Angelo
I'm guessing you're running a 3 blade prop with a lot of rake and small blade surface area. While good for top speeds they tend to loose grip for lifting the bow at mid range speeds especially on CC's and bay boats with wide beams.. I had the same issue with my bay boat. Went to a stern lifting 4 blade and problem gone. Other advantages to a stern lifting 4 blade on a bay boat or cc is they will plane off faster and stay on plane at lower speeds. They usually will give better performance in the midrange as well. About the only trade off is in most cases you may loose 1-3 mph on the top end.

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#12405831 - 08/29/17 10:23 AM Re: Porpoising Issue [Re: David W]
Pat Goff Offline
TFF Celebrity

Registered: 01/29/05
Posts: 5264
Loc: Marble Falls/Seadrift
Get a set of electric trim tabs, your issues will end.
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Pat Goff
Marble Falls/Seadrift TX



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#12405932 - 08/29/17 11:40 AM Re: Porpoising Issue [Re: David W]
Capt Craig Online   content
Extreme Angler

Registered: 08/25/09
Posts: 1427
Loc: Richland-Chambers
If you are running your jackplate at the lowest settings, try raising it. It can be a weight issue, but I have also seen it as a depth/thrust issue. With the amount of thrust much lower than the hull, it provides a lifting effect. Raising the jackplate places the thrust closer to the hull and therefore less lift of the bow is created as the force is inline.

In the event that all else fails, yes, trim tabs will resolve it.
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2013 Nautic Star 2110 Shallow Bay Boat
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#12405937 - 08/29/17 11:43 AM Re: Porpoising Issue [Re: David W]
Pat Goff Offline
TFF Celebrity

Registered: 01/29/05
Posts: 5264
Loc: Marble Falls/Seadrift
Sorry did not read your entire posting.
You have trim tabs, use them. A little down will cure your bounces.
_________________________
Pat Goff
Marble Falls/Seadrift TX



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#12405991 - 08/29/17 12:13 PM Re: Porpoising Issue [Re: tmd11111]
tmd11111 Online   content
Angler

Registered: 04/30/17
Posts: 414
Loc: San Angelo
Originally Posted By: tmd11111
I'm guessing you're running a 3 blade prop with a lot of rake and small blade surface area. While good for top speeds they tend to loose grip for lifting the bow at mid range speeds especially on CC's and bay boats with wide beams.. I had the same issue with my bay boat. Went to a stern lifting 4 blade and problem gone. Other advantages to a stern lifting 4 blade on a bay boat or cc is they will plane off faster and stay on plane at lower speeds. They usually will give better performance in the midrange as well. About the only trade off is in most cases you may loose 1-3 mph on the top end.


I guess I left out motor height plays a factor too

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#12406164 - 08/29/17 03:17 PM Re: Porpoising Issue [Re: David W]
reelswift Offline
Pro Angler

Registered: 01/26/13
Posts: 582
Loc: West Texas
Use the trim tabs that is what they are designed to do.

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#12406295 - 08/29/17 05:04 PM Re: Porpoising Issue [Re: David W]
V-Bottom Online   content
Extreme Angler

Registered: 06/18/16
Posts: 1618
Loc: Galv. Cnty
A 50# sack of play sand up front may help
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