Boat Planing Issue

[Slayton]

To start the boat is a 2007 Bass Tracker PT190. It’s equipped with 3 batteries (2 of which are in a compartment mid boat/bow area), 2 10ft power poles, 6” Atlas Jack plate, and a 90hp optimax 2stroke. The boat used to have an 18 pitch vengeance prop which would cause the boat to over rev like crazy. Eventually I bought a 22 pitch Laser II, the rpms seem to be more in the ball park but once trimming when trying to plane it eventually starts to rev past the limiter (5800rpm). No matter what I do it feels it still wants to plow water. Could my engine be sitting to low not allowing it to plane? Do I possibly need to raise the jack plate after hole shotting and before trying to trim up? Can my current prop be cupped to lower the rpms a bit? Would a 4 blade prop work? Was thinking about investing in a 23P Trophy Plus if that would cure the issues. If anyone’s got any ideas they would be much appreciated. Any questions that need to be answered just let me know!

[A-Jay]

Hello and Welcome to Bass Resource ~ 

So you're running a 22P on a 90hp motor, the boat will not plane out but your motor over revs ?

Is that right ?  Seems like a rather unusual situation. Your rig is rated for 60-135 hp - so at 90hp, you're sort of in the middle right there. 

While I will attest that I'm NOT a Prop expert by any means, I can offer some info for reference.

I am running a 21P Tempest Plus on a 200HP V-8 Pro XS - on the back of an 18 ft Aluminum Hull Pro-V Bass boat and it's pretty much perfect.  I had a 22P on my rig initially and it was clearly Too Much Prop for 200hp 2 stroke Optimax I was running at the time.  Can't imagine 22P on your 90hp is going to improve anything. 

Has your rig been re-powered ?  

How long have you had this boat ? 

What other rigs have to had or run in the past ?

 

Also, you can always contact Tracker and or Mercury Marine and ask them for some guidance.

 

A-Jay

 

 

 

[Big Rick]

2 hours ago, Slayton said:

Eventually I bought a 22 pitch Laser II, the rpms seem to be more in the ball park but once trimming when trying to plane it eventually starts to rev past the limiter (5800rpm).

Something is bad out of sorts here.... Almost sounds like the prop clutch is slipping??  Surely not on a new prop....

[Slayton]

Yeah believe it or not, 22P and over revs to I’d say 5900rpm or so. That’s with full tank of fuel (21G) lots of fishing gear and 2 220lb guys, and we hit 35mph but plowing water. I’ve had the boat for a year or so and has never planed since I’ve had it. To my knowledge it’s still a 90HP unless someone got the computer flashed to a 115HP before I bought it, not sure how I could tell. The prop has the PVS plugs and I have 2 out and the hole shot is great but once the bow drops I try to trim and it has a hard time lifting the bow and doesn’t plane, just plows. I’ve had a 1988 Bass Tracker tx17 with a classic fifty in the past and I used to plane that out no issues. I saw in a previous forum someone said a PT190 with a 23P Trophy Plus is the best set up but then you see others running 18P. Not sure what the big determining factor in prop size is here. The only way I would think the prop hub kit could be slipping if maybe it’s the wrong one but I would think I wouldn’t be able to hit 35mph if that was the case. Not sure though??

[Big Rick]

Well, the keel on the BT is very deep or low for ride comfort. It actually extends below the bottom of the rest of the boat. So, if you're used to another boat that isn't that way you may be feeling that keel digging in. I don't know, I'm just suggesting this since I have a friend that runs a BT similar to yours and am familiar to the boat a bit. On the other hand my G3 is built with a slight and ever increasing rake to the bow and it will flat move! But it is a rougher ride in the bigger swells than my buddy's BT.

 

My G3 is 18 ft with a Yamaha 90 and will top out at 42 with all my gear and a full tank. So, with your bigger boat with two people, more gas and gear, and the deeper keel might not run any faster than 35. Again, just trying to give you something to compare to. 

[Slayton]

Yeah you could be totally right, may honestly be all she’s got. Saw a G3 1910 LE at my local fishing hole the other day and the guy had a Yamaha 150 on the back and man was he moving! Those boats are gorgeous!

[Way2slow]

If I had to guess, it sounds like a cavitation problem.  Look at your prop, the section of blade the hub and motor, and see if there's a spot about the size of a half dollar that looks like it has been sanded.  That's a sure sign of cavitation. The air pocket eats the prop there.  Aluminum props show it very easy, SS props may just loose their shine and be dull looking in that area.

A motor can't gain rpm and not speed without something slipping.  Too much outward trim, engine too high or prop does not like the boat. 

 

Go to one of the online prop slip calculators and put your numbers in.  On average, you should be see get 8 to 11% and a bass boat setup properly.  Something like and STV may get down around 5%, and they definitely can't make more speed than the pitch prop you are running.  A 22" prop on that motor at 6,000 rpm would probably be running 55mph.

[Slayton]

I’ll definitely take a look at that tomorrow, the motor sits extremely low. The jack plate was mounted on the lowest setting and the motor is mounted to the jack plate on the lowest setting too. So I can’t imagine it would be getting air but I’m no expert so you could be right. I guess I’m just not sure when to stop trimming up when trying to plane as well. I eventually get to a point when the motor sounds a little bit louder and sounds like a droning sound. I never really push it past that because I don’t want to ruin something and I’m usually full throttle and the more I trim the higher the rpm. Wonder if I have to pull the throttle back a bit, trim up, then add more throttle. I’ll admit I’m still new to boating so I’m certainly not a pro at planing boats to begin with. Not too mention this one has a jack plate as well so there’s that to play with too. I’ve only had experience with one boat prior to this. 

[Way2slow]

the reason the motor changes the sound it makes, the prop is sucking air, ie cavitating.  This is very easy to do if the boat is running bow heavy from poor weight distribution.

Things to look or listen for when trimming a motor out. 

The prop wash is noticeably higher then the top of the motor.

The tach increases in RPM and the boat does not gain speed proportionally.

The motor changes pitch, normally changes to a more hollow sound. Trim back down until it goes back to it's normal sound. In extreme cases, you will actually feel the steering wheels feedback change and sometime even start torqueing to the left.

 

I have very little experience with aluminum boats above 14' - 15' so I don't know how they respond when trimming.  A glass boat with a pad, when the weight is properly distributed on a good setup, you will feel the bow actually pop up and if there is a little chop, the boat will feel like it's just skipping along on the rear portion of the pad/hull.

I have a feeling, from where you say your batteries are mounted, the motor/prop combination can't develop enough lift to get the bow up.  If it is popping the bow up and you are still trimming up from there, again, you are over trimming.  If it has a front live well and you are filling it, that  just adds to the problem.

Another less common problem is the prop does not match the setup.  I have used anti-cav plates to remedy this problem, the SE Sport is my preferred one for that.  They also make a big difference in getting on plane.  Great tools, just dorky looking a all heck.

 

 

 

[Slayton]

That all makes a lot of sense. Thank you for the info! The only reason the batteries are moved up a bit is because the local marina recommended that for my planing issue saying I was to heavy in the rear and needed to balance it out a bit more. Even before I moved the batteries it was doing the same thing. If anything moving the batteries slightly helped but not enough! I’ll do a little investigating today and get my prop to pad measurement and go from there and check for signs of cavitation as you stated earlier.

[Slayton]

So I couldn’t find any dull spots on the prop, also checked the prop to pad measurement and it’s 3.75” below the pad if that helps

[Slayton]

Just wanted to add a little update for those who have the same issue. Took the boat out today and played with the trim a bit and different speeds and I can get the boat to plane when going a little

slower, gonna talk to my local prop shop and see if they suggest cupping this prop or if I should change props as I need a couple hundred more rpm and a little more lift.

[A-Jay]

Time for a repower

?

A-Jay 

[WRB]

I didn't read the entire thread so may have missed that you already checked the prop hub clutch rubber packing? It sounds like a spun hub to me. No way your 90 hp can swing a 22" pitch Laser II 3 blade over 5800 rpm. 20 P Laser II would be about right.

3 1/2" below the plane surface to pro shaft center line with engine trimmed parallel is about nominal 1/4" lower shouldn't cause your boat to nose down. You can't  expect a flat bottom aluminum hull without a pad to have high speed performance, it isn't made for bow lift and you are trying with a jack plate and over pitched pro that either blowing out or slipping.

Tom 

 

[Goldstar225]

Im far from an expert but I'm inclined to agree that the hub needs to be checked.  Just as a point of comparison, I have a 2018 PT190 with a 115.  With the original 21 pitch 3 blade I would hit 5500 RPM at 48 MPH (GPS).  With my 4 blade 19 pitch X7 prop I'll max out at 6000 -6300 RPM st 46-50 MPH (GPS) depending on conditions and load.

 

Are your speeds GPS or speedo?  The speedometer on my boat consistently reads 5-7 MPH high when above 35 MPH.

[Tim Kelly]

A friend of mine has an RT188 with a 90 opti, pretty certain he runs a tweaked 23 or 24p Laser 2. I think the 90 opti had a lower geared lower unit, much like the current CT motors.

[Way2slow]

I think I read the motor is as low as you can get it but if not, try going down another inch or more.  Contrary to what many think, higher is not always better.  On my Javelin with it loaded to the hilt with everything, I have to run a custom tuned 26" Raker that's set for more bow and stern lift, at 5" below the pad to get good bow lift and to keep it from cavitating just as the boat lays over getting on plane. 

The idea of running the motor higher is generally, that creates less drag and more speed.  However, it can also make you run slower if you are not getting full lift and dragging more hull in the water.  If I raise mine, I start loosing top end speed because I not getting the lift I get at 5".  If I go down to 5 1/2", I get a little better lift still but then loose about 2 mph.

 

Also,, when you use it again, watch your tach.  If it's starts increasing RPM at WOT and not boat speed, something is slipping.  Also, as I mentioned, run you numbers through a prop slip calculator and see what it show.  Anything less than 8-9% would probably mean something is slipping.  Anything over 12-13% means you might need to work on your setup and weight distribution. Prop slip calculators are great tools for getting a boat dialed in, use them.