planing

[Rick olivas]

I recently bought a 1999 NITRO 886. It has a 2007 mercury opti max 150 direct injection motor. When I take off I am having problems getting on plane. I have to put a person in the front to get the boat up. I have it trimmed all the way down, I have tried it from a dead stop, from a gradual increase and nothing works. the boat is rated for a 175. Will a hydrofoil help me with this issue. Once on plane the boat runs great 55-60 no problem. Any help would be greatly appreciated!!!

 

[David Janssen]

My 288 has the same issue. I am looking at lowering my prop pitch from a 19 pitch to a 17. Given what your top speed is I think this might be the issue for you as well.



Be sure you talk to a certified tec before switching but I will try explain what has just recently been taught to me (still learning this myself). I am sorry if this is too rudimentary for you...but others may find it helpful.



Props are similar to gear ratios in a trucks transmission. They can be higher for speed or lower for power and acceleration.



Theoretically, a 19 pitch prop will move the boat 19 inches in one revolution. So a higher pitch is better for higher top speed. A 17 pitch will give you much better hole shot. But it may cost you a few MPH at the top end.



However, the lower pitch prop is easier for the motor to spin so it is possible that the motor will hit its RPM limit easier. So you want to see how close you are to your RPM limit with your current prop. If you are not coming close to hitting that limit you might want to prop down for better hole shot.

 

[Scott Hammer TOXIC]

Need all the measurements to know how to solve. Where is the motor mounted on the plate? Prop to pad? What prop do you have? WOT RPM's and water pressure. There's a lot that goes into boat setup and performance.

 

[TrepMan]

Get Tox, Bob and the other bright guys (and gals) the measurements he asked for, that will help a bunch in figuring out the solution.



My current boat came with a Hydrofoil, I took it off, got the right prop, and hole shot is better, top speed is better, and cornering is MUCH better!!



Trep

 

[Rick olivas]

I will get the info you asked for. Geve me a couple of days I'm not sure how to get you the exact info you are asking for but I can have my boat mechanic help me. Boat had a 4 blade 25 pitch prop, at full throttle I was getting 5200 rpm's. The person I bought the boat from said the mechanic that installed the new motor said it needed to have a 23 pitch prop. I put a 4 blade 23 pitch prop and ran it this weekend. No help getting on plane but I did gain in rpm's at full throttle 5,900. I will get back to you as soon as I get the info you asked for. Thanks for the help!!! When I bought this boat I thought I was going to be able to go fish w/out any issues. NOT!!!!!

 

[Scott Hammer TOXIC]

They ALL have issues brother, some just more than others.

 

[Rick olivas]

Toxic I haven't been able to get with my mechanic yet. My water pressure guage wasn'T hooked up whrn they installed the new motor. Do I need yo get this fixed? (probabily stupid question). Second question. If I could find a prop with say a 17 or 19 pitch should I try that? 4 blade 23 pitch is on now! 3rd. For what I'm trying to solve "planing" do you have a preferance 3 blade or 4?

 

[Mini]

A four blade will give you a better hole shot than a comparable 3 blade...more blade surface area providing the thrust needed to get the boat on plane in a timely fashion. BUT the engine needs to be able to produce the right horsepower to get to that point of "breaking" over (when the nose drops and the speed begins).



Couple things that were not mentioned here....



How your load is placed inside the boat....is all your heavy gear towards the rear of the boat? What do you have in the front compartments? Rear compartments?



Do you have a "plus" prop with PVS (Performance Vent System) holes installed? They are exhaust bypass holes on the barrel of the prop that allow exhaust bypass over the prop blades to get the motor to rev up to the powerband before the prop "grips". Mercury makes plastic plugs in various sizes that fit in the holes on the prop to custom tailor the amount of exhaust the is bypassed to the blades during the holeshot. If you do have the PVS holes please let us know how many and what size the plugs are.



Is the prop a large barrel or small barrel? A small barrel (or hub) will leave an opening (about a 1/4") around the circumfrence of the prop where it meets the lower unit. This allows some bypass like the PVS. Most people run a weed ring to cover the hole. If it is a large barrel (hub) prop there will be no gap between the lower unit and the barrel of the prop.



I am pretty sure that a 23in pitch Trophy SHOULD pop that hull up pretty quick provided it is vented correctly and your carrying load is good. Optimax motors are notorious for being finicky about prop slip @ hole shot to get the motor into the proper RPM range to produce enough power on hole shot. Once you mash the throttle down (trimmed down all the way from a dead stop) you want to see that rmp needle JUMP to about 3500-4000 rpm. If it lags at 3000 rpm forever trying to get on plane you need to adjust SOMETHING.....PVS, LOAD, Engine height, etc.



I DO NOT recommend dropping all the way to a 17 or 19....you WILL over rev @ WOT. KABOOM! = $$$$



Yes you need a water pressure gauge. Have you measured your engine height (prop shaft centerline to pad)?