285 jackplate/prop question

05 285xl Pro
150 Vmax carb
6 inch Slidemaster jackplate
Yamaha 25m prop
2 3/4 below pad
67.1 mph on GPS full of gas, ready to fish


Bought the boat back in early summer had a 23M prop on it would run 63-64 but would go 61-6200 rpm. Bought a 25M to lower the rpms, stuck it on and it will run good up to 65-66 just as smooth as can be at around 5900-6000, bump the trim once more it goes 66 and starts dancing a little not to but not to bad, bump it once more and it will go 67 and then it starts dancing to the point you have to back out of it a bit to settle it down. When it runs 67 rpms are back to 61-6200, and it actually drives and feels like it is over trimmed due to the dancing, and you can hear the motor get louder also, but it still picks up speed. I believe it would pick up some more if you didnt have to feather the throttle or bump the trim back down to settle it......My question is which route do I need to go to correct this or improve this i?....Jackplate higher or lower, try more prop?....I'm new to this so take it easy on me, any any comments will be apprecitated...Thanks.

Lowprofile - That may be the fastest 285ProXL ever. What is the max RPM's on that Hammer? I would think, if you are trying to correct the chine walk, move down 1/8" on the jackplate.
I have an '04 285Pxl and Johnson 150 carb 6" Slidemaster with a 24 Raker at 3.25" below pad and best I can get is 62 at the 5500 RPM max for the motor. You have got to be happy at anything over 65 on that hull.

Are those GPS speeds or from your speedometer? If it is from a GPS, you do have a great running 285. Is the 150 Yammie Stock or has it had a couple of Hydro-Tec parts added to it?

You shouldn't be able to turn more than a 25 with a stock 150. You could try swapping to a 25 Tempest. I ran one of those on my '04 285 and LOVED the prop.

Says GPS in his signature.

That is one bad 285. Best I get is 64 GPS out of mine and it really wants to chine walk at that speed. If I trim it down to stop the walking, it slows down. I have an opti 150 with 24P /tempest turning 5600. Same JP as him about 2.75 inches below.

Get your trim set to the sweet spot and then raise your jack-plate while watching your water pressure. As soon as the WP drops, bump the jack-plate back down a little to recover adequate pressure and you are now as sweet as can be. Sounds like it is chine walking when over trimmed... gotta learn how to drive with this sometimes. Prop torque is causing the boat to fall off of the pad. All boats are capable of doing this if they are going fast enough. Recover steering can help control / prevent this.

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http://www.bassboatcentral.com/smileys/doh.gif Yeah, see it now. I re-read the body of the post, just didn't look at the specs again. http://www.bassboatcentral.com/smileys/Laugh.gif

I've heard of one other 285 that hit 67. It also had a 150 carb'd Yammie, but it was a very light load/no load. If you're hitting 67 and the rev limiter with a full load of fuel (36 gallons isn't it?) and tackle, there's something special about that motor.

I had an 03 185 DC with 150 Johnson & 8" detwieler with a 24' original Raker that would run 63 at 5300 rpm full tank under a heavy tourney load & the single consoles with 150 Yamaha would only run 60.8 to 61 so I'd say you running very well. You may infact be trimming so high that your getting out of angle & picking up excessive chine walk.

The speed was on GPS, and the motor is bone stock, only change is the prop. One thing i forgot to mention under 65 or so the rooster tail is below cowl, but when i give it those few extra bumps of trim the rooster tail gets a foot or two above the cowl, and thats when she starts dancing real bad and I have to trim it down or back out of throttle a hair to calm it back down. I agree I think the over trimming is causing the walk because it is on rails at 65. Water pressure is still very good stays around 24-25 all the time, so could I come on up on the jackplate to keep from trimming so much? Holeshot is great with the 25m, can't tell much difference than the 23m on the holeshot. Like I said the motor was set at 2 3/4 and has been like that since i got it, how high should I raise the motor?

I am not sure you need to adjust the jackplate. I think your comment about the rooster tail height should be a clue "One thing i forgot to mention under 65 or so the rooster tail is below cowl, but when i give it those few extra bumps of trim the rooster tail gets a foot or two above the cowl, and thats when she starts dancing real bad ". I think you should trim to have the tail at cowl height only. Maybe go up 1/8" on the JP and keep an eye on WP to make sure it doesn't drop below 20? Seems to me you are right in the sweet zone.
Jason you ran that 25 Tempest at 2.25" propshaft right? I think Lowprofile has adjustment somewhere within a .25" range to be perfect.

Ive got a 03 185 with 150 vmax carb single console with 6in pro hijacker and 25 turbo lightning best I can get is 68 with full load and 2 people with just me I can get 60 5300 rpm thats gps.I really havent figured out how to measure the prop to pad yet but im wanting to change to a m series prop.I was lookin at a 23m wasnt sure if it would push a 25m.I need to get my rpms up I think rev limiter on this motor is 5650 not sure though.If I move my jackplate up will it bump my rpms up? I tried to measue my prop to pad but when I tried to level my motor the skeg would alwas hit before I could get it level maybe my plate is way to low I know nothing about it.Id like to get on up in the 63-65 range.

Yes go up. You will gain RPM. You sound too low if you are getting only 5300 at WOT with that prop. Start first by leveling the keel with the trailer jack, then if you can't level the cavitation plate without the skeg hitting the floor raise the motor until you can. The go to the Super Tips section (on the left on the home page) got to Setups and see the directions on how to measure your motor height.
I suggest start at 3.5" Propshaft to pad and work up from their keeping an eye on water pressure and performance. 1/8" moves make a big difference. Punch mark or pencil a scale on th jackplate with 3.5" as your baseline, then mark your final position with a scribe or take notes and put them away in a file.

Back to my setup should i try it at 2.5 and see what happens?

Sure. Give it a whirl and see what happens. http://www.bassboatcentral.com/smileys/thumbsup2.gif

Sounds like you have a mechanical Jack Plate... take wrenches with you to the ramp and try raising in small increments. Rooster Tail at cowl level WOT is desired.

I wrestled with set-up for a while with different props. They make a lot of difference. If all else fails, try a different pitch/blade combo until you get what you are looking for.

Good luck. http://www.bassboatcentral.com/smileys/thumbsup2.gif

Yes I have a mechanical 6' Slidemsater. When it is running 65 rooster tail is at cowl level, after that when u trim it to get it to 66 and 67 it is about 2 ft above the cowl. If the river will ever get out of floodstage I am gonna raise it up and try it just to see what happens.

Keep in mind that Yamaha's have a lot of trim available, so you can very easily over-trim it.