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I have trim tabs (Lenco), trim/tilt on my Yamaha 150 and a Jack Plate on my 2008 Redfisher 18. I previously had a great 21’ Mako CC that ran smooth and dry always (didn’t have trim tabs, only trim/tilt). That boat had a 200 Evinrude and was perfectly powered  My RF is slightly over-powered with 150hp Yamaha but a lot of owners have this combo so it must be possible to achieve a good ride.

I have not figured out how to keep the bow of my boat from porpoising up and down, no matter how I configure the equipment. 

Here are a few observations:

1. The closest I’ve gotten to a smooth ride is to have the engine trimmed all the way down, the trim tabs fully extended down and the jack plate all the way down. The minute I try to adjust trim or trim tabs...bouncy, bouncy, bouncy!

2. The boat “squats” with the big Yammy on it. I wonder if I repowered with a 115hp instead of the 150hp, would I still be stern-heavy and subject to bouncing?

3. Could I still just not be used to the set up? Seems like I’ve tried every possible combination of trim and tabs so far. 

Appreciate any input from those who may have or are still experiencing this annoying performance. 

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try to borrow a PowerTech OFX 4 blade and go down 2 pitch. it generates a lot of stern lift. after switching to this prop my tabs are not needed to cruise anymore (yes i have a different hull but had the same problem with my 3 blade).

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My 2018 Redfisher 18 with 115 sho likes to porpoise as well. I only have 15 hours on it so I thought maybe I just need to “learn” the intricacies of the Hull.  I’m betting a 4 blade prop would help a ton

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You have the wrong prop on your motor as stated above.  If someone took their trick prop off the boat when they sold it to you..  and put on a cheap or spare prop that is a bow lifting design..  you will porpoise.  It is annoying as heck and not smart.  I have not been on an 18 with a jack plate, so I can't suggest a prop to try..

What prop is on the boat ?  Can you post a pic of the prop stamping info ?  Also, pics of the transom and motor on the jackplate.  Our RF guys can see that it is rigged properly.

Get the correct prop and you will be amazed at the performance !  Skiffs with max HP need to be trimmed when running.  With the right prop, you will be able to learn how your boat runs best, and how to trim and jump out of a pothole.. drop the bow into a chop.. etc.

Keep us posted.

M-1

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As said above, the right prop will make a world of difference.  I have a similar setup with jack plate and Lenco tabs, but on a RF 16.  I tried a bunch of props and some were great and some were awful.  But I was not able to fully cure the porpoising at mid-range cruising speed, without tabs,  until...  I took a friends advice and installed a stabilizer plate (foil) on the lower unit AV plate of my Yamaha VF115.  I narrowed it down to two choices:  the Bobs Machine Shop True Tracker, and the Permatrim.  They both have great reviews, but I chose the Permatrim because it mounts on top of the AV plate, which I thought would run with the least amount of drag.  Wow!  What a difference after installing the Permatrim.  Not only did it eliminate porpoising, hole-shot is better, the ride in a chop is better with less tabs needed, I can stay on plane at slower speeds without lugging the engine, turns are more stable with no prop blowout, fuel economy is as good or better and the boat tracks better at top speed without chine walking.  I am still learning how to use it, but basically, the combination of the jack plate, trim tabs and Permatrim allows me to change the ride any way I want.  The look of it takes a little getting used to, but I have no regrets.  Here is a link to some pictures of my setup:

Permatrim installed on a VF115 SHO

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14 hours ago, captpn said:

try to borrow a PowerTech OFX 4 blade and go down 2 pitch. it generates a lot of stern lift. after switching to this prop my tabs are not needed to cruise anymore (yes i have a different hull but had the same problem with my 3 blade).

That prop is amazing.

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Interested very much in this topic.....as I have a new Redfisher 18 w/150 SHO and 6" jack plate on order with expected delivery in a couple weeks.  The dealer mentioned using a Yamaha Reliance 13-3/4x21 pitch as matched prop to that set-up....would appreciate real world input about that specific prop or alternatives recommended.

Thanks in advance!

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21 hours ago, Moderator said:

You have the wrong prop on your motor as stated above.  If someone took their trick prop off the boat when they sold it to you..  and put on a cheap or spare prop that is a bow lifting design..  you will porpoise.  It is annoying as heck and not smart.  I have not been on an 18 with a jack plate, so I can't suggest a prop to try..

What prop is on the boat ?  Can you post a pic of the prop stamping info ?  Also, pics of the transom and motor on the jackplate.  Our RF guys can see that it is rigged properly.

Get the correct prop and you will be amazed at the performance !  Skiffs with max HP need to be trimmed when running.  With the right prop, you will be able to learn how your boat runs best, and how to trim and jump out of a pothole.. drop the bow into a chop.. etc.

Keep us posted.

M-1

I am so happy to have your input Mr Moderator! I will take photos of my set up and send to you. It kills me to have such a nice boat with such poor on-water performance. Look for my info soon and thanks. 

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I have a RF 18 with an F115. Not the Sho. With the K16 Yamaha prop that came on the boat when I bought it,  the  same thing would happen. Very sensitive to trim and weight. It would hop or porpoise and it took a combination of trim and more speed to get the boat to lay down. After reading some of the experiences others had I decided to try the Mercury Spitfire 4 blade in 17 pitch. Not sure about the 150 on a jack plate, but on my set up it was night and day better than the K16 Yamaha prop. The prop carries the boat well, responds well to trim. The hop is reduced, I can still make it do it by over trimming it, but their is a much broader area that I can trim the motor and the boat is still set. Midrange cruise rpms went down and the MPG went up to 5 running 30 mph. Boat loaded with 2 people fishing tackle drink coolers, fuel tank full ran 42 mph at 5700 rpms.  Havent tried the Powertech line as I was happy with the Spitfire. May do some more prop testing soon and will call Powertech. 

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Changing props or adding plates to the motor all all after the fact solutions to a basic design / use problem.  The weight distribution on the boat is way off. The center of gravity and center of buoyancy do not line up.There is too much weight aft of the center of buoancy. This is not the measurement of half way from bow to stern but the weight distribution.  You need more weight forward.

I don't know  the layout of battery and gas tanks (stuck with its  location) but try to move as much forward as possible 

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Nolezone,

Don't send me the pics.. Post them on this thread !  We have members with 18RFs that can help the most.  There are a lot of opinions about this, but if there is a basic problem with the setup, they will see it. The jackplate is a tool, like the powerpole or trolling motor..  It allows owners to skim over really shallow flats if they have a 4 blade that likes running high.  I have no experience with an 18 with a jackplate. I have a lot of days running one with a 2 stroke 150 in the Keys.. Fast, fun boat !!  It requires knowing how to trim it. These light hulls are not a set-it-and-forget-it boat like your Mako.  You have to learn the boat and compensate for wind, waves, RPMs and loads.. 

It is true that there are balance considerations. You need to move weight to trim the boat sometimes.  The 6" jackplate does change the balance and can promote porpoising.  I would be interested to see what prop the factory/dealer recommends for the new RF 18 with a jackplate. That may be the place to start and prop test.. The Powertech! OFX props have solved a lot of handling issues caused by the wrong prop design.

Is the '18 Redfisher the same hull as this '08 ??   Check out the post above by JJS on the Yamaha Reliance prop for his new RF..

What kind of prop is on the boat now ?   Photos !  Photos !     Let's solve this !

ps Most boaters scoff at the whale tails for the cavitation plates.  I have seen miraculous results for select boats with handling problems/ wrong props just like Geeviam.  You can lift the bow just with the trim & tilt, with no downside besides the look.

Mod Marc

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How do you “try” props? Are there operations that will lend you props to try? 

I changed props a few times in the past...is it still just a cotter pin and large nut to remove to pull the prop?

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On 7/29/2018 at 11:05 PM, Moderator said:

You have the wrong prop on your motor as stated above.  If someone took their trick prop off the boat when they sold it to you..  and put on a cheap or spare prop that is a bow lifting design..  you will porpoise.  It is annoying as heck and not smart.  I have not been on an 18 with a jack plate, so I can't suggest a prop to try..

What prop is on the boat ?  Can you post a pic of the prop stamping info ?  Also, pics of the transom and motor on the jackplate.  Our RF guys can see that it is rigged properly.

Get the correct prop and you will be amazed at the performance !  Skiffs with max HP need to be trimmed when running.  With the right prop, you will be able to learn how your boat runs best, and how to trim and jump out of a pothole.. drop the bow into a chop.. etc.

Keep us posted.

M-1

I am so happy to have your input Mr Moderator! I will take photos of my set up and send to you. It kills me to have such a nice boat with such poor on-water performance. Look for my info soon and thanks. 

 

Below are are the pictures of my current set up:

2008 Hewes Redfisher 18’, 150hp Yamaha VMAX 2 stroke, Lenco recessed trim tabs, jack plate, 4 blade Solas 14X21 pitch

Problem...almost uncontrollable porpoising no matter how I configure the set up. ONLY way to minimize is to run with engine trimmed all the way down, jack plate all the way down and trim tabs fully extended down. Looking for some of you pros to tell me what the heck is wrong!!

8CBD0083-6368-4B6E-B87D-E5769445B8D2.jpeg

FC121B1F-74EF-49C4-9E29-C4C638F5BEBA.jpeg

B23B34BF-8249-4E56-BA73-CFF4DF63119E.jpeg

70E8E09E-C985-4597-87C6-EF34372609BB.jpeg

B2EB708B-41BF-4553-9FAC-D0F11F202CEF.jpeg

9BB36C7D-CFB5-44B2-A965-E6EEE22C760B.jpeg

44622D63-9B81-4D65-A848-6EDBE64BB8EC.jpeg

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I have a friend with a RF18 with Yami 150 SHO.....it runs great and does not porpoise at all.

He is running a PowerTech OFX4-19

 

 

IMG_1039.JPG

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Power Tech OFX 4  Hit up Funky Monkey on this site, he’s a prop god that works at Power Tech. Or call Power Tech props in Shreveport Louisiana, ask for Marcus.

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My older (Lappy) 18 would sometimes porpoise..with 140 on the transom I had added 60 lbs.  move weight forward (batteries to bow). Learn to use tabs. Stern lifting prop will help. 

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2 hours ago, Tarpon1215 said:

Power Tech OFX 4  Hit up Funky Monkey on this site, he’s a prop god that works at Power Tech. Or call Power Tech props in Shreveport Louisiana, ask for Marcus.

Thx Tarpon, spoke with Marcus today (Mr Funky Monkey @ Power Tech) and he’s helping me diagnose my needs by doing some on water trials before just jumping into expensive new equipment. What a refreshing approach! We’re going to diagnose and treat this bouncing illness now infecting my RFer and keeping me from fully enjoying my investment. I’ll post when we get it all figured out. 

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Just now, Nolezone said:

Thx Tarpon, spoke with Marcus today (Mr Funky Monkey @ Power Tech) and he’s helping me diagnose my needs by doing some on water trials before just jumping into expensive new equipment. What a refreshing approach! We’re going to diagnose and treat this bouncing illness now infecting my RFer and keeping me from fully enjoying my investment. I’ll post when we get it all figured out. 

BTW...turns out I have an el cheapo Chinese “Solas” SS prop with probably the wrong pitch anyway! 

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Good Luck.....will be learning right along with you.!!!! Although my boat is pretty good, I love messing around to see what the effects of doing different things, like motor height, props and weight distribution make.  Weight distribution is pretty much set, all three batteries are in the console and fuel tank is in the front. Wont be changing that.  Will be playing with props and motor height. I have no Jack Plate so moving the motor up is a little more complicated. Not too bad though.

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On 7/31/2018 at 3:49 PM, fishmanjj said:

I have a friend with a RF18 with Yami 150 SHO.....it runs great and does not porpoise at all.

He is running a PowerTech OFX4-19

JJ, a couple weeks ago you posted this: http://mbgforum.com/topic/7576-what-prop-are-you-guys-running-on-your-rf18-with-150hp/?do=findComment&comment=62058

Is it the same boat?  If so, did they change from the Yamaha 3-blade to the OFX4 because of a porpoising problem?  Also, just curious - is there a jack plate installed?

Nolezone - Marcus is right.  That's a lot of pitch on that Solas prop.  It is a Solas Titan HR-4 (HR for High Rake), and it is advertised as a bow lifter.  Redfishers don't always play well with high rake, bow lifting props.  Looks like the OFX4 gets the most votes around here, by a large margin.  You're on the right track with Marcus helping you.  Good luck.

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He did not have a porpoising issue....but he does like the stern lift and handling of the 4 blade now. He said the 3 blade was faster...but overall, the 4 blade handles better. Bob's jackplate.

This is a 2018 model boat....I'm not sure if the hull is exactly the same as they were in 2008. That would require some research....

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2 minutes ago, fishmanjj said:

He did not have a porpoising issue....but he does like the stern lift and handling of the 4 blade now. He said the 3 blade was faster...but overall, the 4 blade handles better. Bob's jackplate.

Good to know.  Thank you.

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2 hours ago, Nolezone said:

BTW...turns out I have an el cheapo Chinese “Solas” SS prop with probably the wrong pitch anyway! 

Stepping in right direction now..in my opinion you are definitely not over powered. You get it propped right and it will be bad to the bone and should see 55 MPH plus trimmed out. I fish with a. friend who had that engine and it screamed. He repowered with a 4 stroke 150 when it let go which is heavier but it still runs shallow and is fast. Very fast. Still a 55+ boat w no porpoise issue.  He has all his batteries forward and runs with fuel topped off most every trip so that helps a bit too. 

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