getting on plane ?

[boneil]

I have a 2008 Nitro Z8 with a 200hp merc. When I go to get on plane the motor revs up significantly just as it gets on plane. It feels as if the prop is spinnin but not pushin water. It only lasts for a second because I let of the throttle for a moment. I was just wondering if this is normal or do I need to change something? I have a 26P fury prop.

Thanks

[R520dvx]

Sounds like the prop is blowing out ..... what size plugs do you have in the prop vent holes ??

[Way2slow]

Are you keeping it fulling trimed in until it starts to lay over?  You might be triming out too soon.

Other things that can cause it.

As mention, cavitation holes in prop too large.

Motor set too high

Something funky with prop, I've have brand new props do this before having them tuned for my setup.

One cheap, sure cure, put a SE Sport 300 hydrofoil on it.

[Wayne P.]

Lots of setups are like that. The cavitation is to allow for the motor to get up to higher rpms for optimum power as the boat gets on plane. All the small hub props do that unless a blow ring is installed on it.

For an under powered boat or heavy boat it is the fastest way to get on plane and keep top end speed.

[boneil]

Plugs?  there are no plugs, should there be?

Next time out I will try trimmin down further

[Wayne P.]

Does that statement mean that you did not have the motor set to full negative trim before taking off?

[boneil]

Does that statement mean that you did not have the motor set to full negative trim before taking off?

Correct,  it's close but not all the way.

[fishfordollars]

Tuck the motor up under the hull(Trim down) and punch it. If it blows out (Or spins the hub) getting up send it to the shop and have them check it out.

[Glenn]

There's your problem.  You need to trim all the way down before taking off, and then start trimming up when the boat starts to get on plane.  Continue to trim up as it gains speed (you may have to stop and then start again a few times, depending on how fast it gets to top speed).  

At top speed, play with the trim to find the "sweet spot".  If you reach a spot where trimming up causes the boat to slow down, or the RPMs to go up without any speed gain, you've gone too far (typically you'll get a big rooster tail when you do this).  Back it down a bit until the boat picks up speed again and you'll be at the "sweet spot".

[boneil]

Thanks guys, I guess I never really payed too much attention to if the motor was trimmed all the way down when taking off.

[yetti]

Trim down all the way.  If that doesn't work, lower the motor on the jackplate 1/16th at a time until your problem stops

[Uncle Leo]

There's your problem. You need to trim all the way down before taking off, and then start trimming up when the boat starts to get on plane. Continue to trim up as it gains speed (you may have to stop and then start again a few times, depending on how fast it gets to top speed).

At top speed, play with the trim to find the "sweet spot". If you reach a spot where trimming up causes the boat to slow down, or the RPMs to go up without any speed gain, you've gone too far (typically you'll get a big rooster tail when you do this). Back it down a bit until the boat picks up speed again and you'll be at the "sweet spot".

Glenn has it pegged. I also have a Nitro and believe this may be something in the hull design, it took a bit to find the sweet spot and would porpoise like heck. I also added a hydrofoil which completely took away the porpoise problem unless the water is pretty rough. I have a 2004 700 DX with a 90Hp so maybe my problem is a bit less.

As soon as I read the title I knew it was a Nitro Boat,