03 nitro 901 speed=chin walk

[Amoneyv11]

Guys I bought this 03 nitro 901 with a Mercury 200 optimax and boat runs so smooth motor wise but anytime I get it 64 plus it starts to walk away from me on calm days.  I know the boat has the power to do 70+ but I just can't put the pedal to the floor or the think will walk away from me.  I have a nice 3 blade stainless prop temp test plus not sure of pitch.  Can anyone help me adjust this thing to handle so I can get speed out of it.  I do 40 drives to fishing spots regularly.  Rams not sure as of now or pitch or height of prop to plate but can get that soon

[merc1997]

most of the time the walking is due to motor height.  it is amazing how even an 1/8 adjustment will do to be perfect or all over the place.  back in yesteryear, you had to learn to drive a boat at high speeds because most of the time regardless of what you did, they were just a handful to drive at high speeds.

i know i read a lot of talk with bass cat owners about having to learn to drive through the chine, but i have not seen a basscat yet than i could not dial in to drive like a car down the road at wot.

if you have plenty of water pressure, i would most likely start tweaking up a bit at a time, providing you have an adjustable plate.  if not, you will need one to ever get it right.

hope this helps.

bo

[Ron Fogelson]

That 901 won't normally go much faster then what you have now,, 65/66mph is about average.

Do as Merc1997 suggested but the person you bought it from may have had it set up to run well over all... if he did and you are not much bigger/smaller and haven't changed to load drastically you may be right where you need to be.  Try trimming down just a hair when it starts to walk and if able put it in a slow left turn and I mean s l o w just nudge the wheel a tad left if you have the room.

Seat time will help, Nitro's aren't known to walk maybe a little if the motor is way high or way low but they run easy with a little practice.  The hard part is learning to feel what the boat is wanting to do as it rocks it seams like everything is running nice and flat and then wham it's walking but it's not it has been rocking the whole time that's why it got worse and to the point you notice.

Set up should be about 3.5 inches below pad based on prop, your weight, the load in the boat that will be close to the best running you will see.  As Merc stated if able and if you have good water pressure keep coming up 1/4 of an inch until water pressure drops, or you gain rpm but not speed.  then drop an 1/8 or even a 1/16th of an inch.

The Nitro 9's are a great fishing platform, keep at it it will get better. 

[Amoneyv11]

Well this is my second boat but first that does over 40mph.  It seemed to me that the motor was adjusted down to low so once I get boat planned out I trim up.  I can hit 70mph but the trim is up an boat throws 20ft rooster tail.  Yes I could trim down just a touch to stop chine but will loose that few mph.  Also if I recall when trimmed up to where it's rooster tailing the water pressure is around 12.  I'll check and see exactly where I am set at height wise and trim and pressure.  Thanks for the tips so far guys.

[merc1997]

first, if you are throwing that kind of rooster tail, you are out of tune height and probably trimming too far.  also, at wot, i would think only 12 lb. of water pressure is too low.  most of the time, you should be running 20 at wot.

throwing a rooster tail, is pretty much a sure sign that you are blowing water and not hooking up.  you really should not have anything much more than the height of your motor or less.  the trick to getting a boat to really run, drive and ride is to get the boat lifting all at the same time.  this means that your back corners of the boat are lifting not just the nose sticking up in the air.

also, you just may not have the right prop for your boat.  all boat, even the same brand, year, and model can each run the best with different types of props.  perhaps, some of your issues can just be you need to try a different style of wheel.

you have not mentioned what pitch of prop you are running and what rpm either.  you did mention that you have a tempest plus.  perhaps, you might need to try a tempest or a fury, or a 4 blade.

are you checking boat speed with a speedometer or by gps?

hope this helps and makes sense.

bo

[Amoneyv11]

I am checking speed off gps and I've checked it off my phone app and they are accurate.  I know the rooster tail is to high i just did it to test and see if it gives me more top end or not, which it did somehow.  I will check on pitch of temp test plus tn.  Does it normally say on prop?  I also have a 4 blade prop for the boat as well but I have read that u get better top end with a 3 blade.  What should be a good water pressure?  Tonight I will let y'all know approximate rpms I've been running.  Note most of my gauges aren't working guys and I'm in the process of repairing all these as well.

[Ron Fogelson]

If you are seeing 70 by gps with that boat you are doing well.  If trimming full up gives you best top end the jack plate can come up more as long as the prop can still carry the load.  The tempest plus is one of the best all around props for the Nitro 9 line a furry will help carry the boat a bit better and can offer more speed in general.  But depending on your rpms' you may need to stay the same pitch or drop down one. 

Yes the pitch will be on the tempest prop, with a 200 You should have a 23 or maybe a 25 the 4 blade tends to help carry the load of the boat better over all, give a better hole shot if propped right but may or may not drop your top end based on how it lifts the boat out of the water sometimes a 4 blade can give you better top end then a 3 blade.  The right prop for your boat, load and driving needs is key to getting the most out of your boat for what is important to you.

If top end is the end game, then you may find the need for an over sized pitch "if it can carry the load" to gain a few more mph,,,, your hole shot is going to suck, and it can be tricky to get up on pad in bad weather or stay on pad safely in hard turns with the motor raised high enough to turn max rpm's.

Need to check max rpms sounds like someone raised the motor to high and the only way to get top end is to trim it all the way,,,, I like my psi around 20 or a bit more but if it drops to 18 in turns I'm ok with that as long as it jumps right back up once I straighten back out,,,,, I'd never run my motors WOT at only 12 psi but maybe that's just me.

Need your max rpms' at WOT, need to know what prop your running, need to know the height of the motor above/below pad, need to know the prop size and need to know what kind of load you are running,,, average, heavy or light tournament load.  3.5 below pad is about the best I found on my 929 and the 901 in general runs about the same,,,,, but even 929's can run different,,,, some times you will find a very light boat or a very strong motor and the best is if you get both paired up.

68 mph was my average with a 225 opti pop on my 2003 929, saw 70.4 and 70.6 running a 26 tempest + but in the heat of the summer my hole shot sucked, and dropped back to 68.5 to 69.  Running a 25 tempest + I was running 69 to 69.4 all year long so going up in pitch only helped a couple months out of the year.

If you are seeing true 70 mph in the 901 you are above average no matter what others post around the net,,,, I believe Nitro's own web site had the 901 with a 200 listed at 62 to 64 top speed,,,,, but it's been a few years, I could be off on their info.

[merc1997]

If you are seeing 70 by gps with that boat you are doing well.  If trimming full up gives you best top end the jack plate can come up more as long as the prop can still carry the load.  The tempest plus is one of the best all around props for the Nitro 9 line a furry will help carry the boat a bit better and can offer more speed in general.  But depending on your rpms' you may need to stay the same pitch or drop down one. 

Yes the pitch will be on the tempest prop, with a 200 You should have a 23 or maybe a 25 the 4 blade tends to help carry the load of the boat better over all, give a better hole shot if propped right but may or may not drop your top end based on how it lifts the boat out of the water sometimes a 4 blade can give you better top end then a 3 blade.  The right prop for your boat, load and driving needs is key to getting the most out of your boat for what is important to you.

If top end is the end game, then you may find the need for an over sized pitch "if it can carry the load" to gain a few more mph,,,, your hole shot is going to suck, and it can be tricky to get up on pad in bad weather or stay on pad safely in hard turns with the motor raised high enough to turn max rpm's.

Need to check max rpms sounds like someone raised the motor to high and the only way to get top end is to trim it all the way,,,, I like my psi around 20 or a bit more but if it drops to 18 in turns I'm ok with that as long as it jumps right back up once I straighten back out,,,,, I'd never run my motors WOT at only 12 psi but maybe that's just me.

Need your max rpms' at WOT, need to know what prop your running, need to know the height of the motor above/below pad, need to know the prop size and need to know what kind of load you are running,,, average, heavy or light tournament load.  3.5 below pad is about the best I found on my 929 and the 901 in general runs about the same,,,,, but even 929's can run different,,,, some times you will find a very light boat or a very strong motor and the best is if you get both paired up.

68 mph was my average with a 225 opti pop on my 2003 929, saw 70.4 and 70.6 running a 26 tempest + but in the heat of the summer my hole shot sucked, and dropped back to 68.5 to 69.  Running a 25 tempest + I was running 69 to 69.4 all year long so going up in pitch only helped a couple months out of the year.

If you are seeing true 70 mph in the 901 you are above average no matter what others post around the net,,,, I believe Nitro's own web site had the 901 with a 200 listed at 62 to 64 top speed,,,,, but it's been a few years, I could be off on their info.

if i read his post right, he stated he was running 12 lbs. of water pressure.  most opti's i have been in run at least 20 at wot.  i don't know about raising the motor height until one is sure of what the water pressure should be.  what water pressure did you run on your 225??  should be the same as his 200.

bo

[Amoneyv11]

Ok guys here's some answers....

It is a temptest plus 24p

With motor trimmed almost all the way down I am 5" below bottom of boat.  Which as I read is way to low.  Which might be why I am running the trim so high and throwing roaster tails and chine walking anytime I hit 65+ mph.  And because it's trimmed up so much I might not be getting the correct water pressure.  Yes looked at gauge just now and it's only running anywhere from 10-14 psi. 

So putting everything together here (correct me if I'm wrong) I need to raise motor to about 3.5"-3.75" and then run the trim down further driving.

Sound right guys?  Hopefully I don't lose my 70 mph though.

Thanks for all advise so far guys

[Ron Fogelson]

Better find out what The min Water pressure needs to be.

Also when measuring its the center of the prop to the ground and then the lowes point of the back of the boat to the ground the difference is your messurment that should be around 3.5 that not s with the boat level and the motor trimmed down until the flat plate on the foot is level

I think the min is 18 psi but I don't remember if that's the min or that's what my mechanic said d not to run below

Also you said some of your gauges don't work,,, make sure the WP is working it will save you a ton of $$$$ down the road to double check its right. Heck you may only be getting 6/8 psi and its reading 12.

Also before you move the jack plate mark it so you know exactly where it was so you can put it back


Also yes Merc is right if you are running 12 psi do not raise it up more until you know for sure what the lowest safe psi is or you will smoke your motor

[Amoneyv11]

Yes my measurement came from the lowest point of boat which is under the plug to the ground, which was 14.5" and then lowered motor until the trim said almost all the way down, if I would of lowered anymore the lower fin would of been on concrete, that read 9.5" from ground.  14.5"-9.5"=5" below bottom of boat.  And yes wp is way low but tht could be from me trimming it up to high

[Ron Fogelson]

I've never been able to trim so high I dropped water pressure while running 

Just making sure the boat was level when you checked.

Need a level under the pad,,, run front to back and have someone raise or lower the jack on the front of the boat until its level. 

Now set that level on the cavitation plate on the motor and trim up/down until it's level.

Next measure from the bottom center of the pad to the ground and again from the center of the prop shaft to the ground.

if you did all of that and are still 5 below pad and your water pressure is still low,,,, the water pump may need to be replaced or the gauge could be bad or there might be something in the line but I'd be very careful running it until it had been checked out.

[Amoneyv11]

Pad? What is this pad y'all speak of?  I want to get this set up right tonight. 

[Ron Fogelson]

hope this helps

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[Amoneyv11]

Yea I found that same picture.  So I was incorrect earlier guys water pressure at wot was 24psi but because I couldn't open it up due to chin walking I never saw it get that high.  Pad was 16 5/8" and motor shaft was 12 3/4" from level ground.  Leveled boat and motor prior to measurement.
  16 3/4"-12 5/8"= 4.125"
4.125" - 3.5"= .625" raised motor up.

Handling is 100 times bettering can now be wide open on throttle but lost some top end.  Tested it out today and max speed was 67mph with 2 guys and 1/2 tank.

Thanks guys for responding and teaching me how to get control of my boat better.  It's hard enough driving the Great Lakes with 2 ft waves let alone an uncontrollable boat.  Now problems are solved and I owe everyone a huge thanks. 

Will put the 4 blade prop on in next week or so and will let everyone know how boat responds to it.