98 Nitro Savage 884 Planning Issue

Vlietboater

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Apr 3, 2010
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22
Ive always been an I/O guy wityh my 87 liberator 211, A friend of mine recccciently got a 98 nitro savage 884 with a 150 nitro mercury outboard bass boat. It has a 23P qucik silver 3 blade prop.

Problem is when acceleraating trimmed all the way doen the bow rises up and then it "no sure what one, cavatitates or ventelates" and you have to back off throttle let boat settle down and start over, if you baby it and let it slowly climb up leaving bow up in air you can feather throttle and get on plane. cant take off quick, like spinning tires in snow, was thinking motor was mounted too hight seeing paint missing on lower set of holes we lowered motor from 3rd hole to lowest setting and made reall no difference, order factor manal to check everyting over and see what factory setting are but believe this is the factory outboad for this boat even has the nitro logo on engine cover,, what would cause this and how can i make changes to correct, were agverating exp when trying to take off in windy / rough conditions.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
1. Look at the prop. Does it have holes in the barrel slightly aft (behind) the start of the blade at the blade root that are just under each blade? If so it's "ported". Ported props are commonly used on bass boats with high pitch props to get out of the "hole"....get the boat out of the water dead still to a position on top and blasting away. What they do is to cause the engine to rev when you firewall it in the hole. The amount of revving vs the rpms without porting would/should be around 1000 to 1500 rpms. This allows you to get your engine rpms up which gets your hp up which gets your thrust up...all faster than otherwise....and reduce the time it takes to get out of the hole and on top.

2. If you are not tucked in all the way, you can have some blowout in the hole, especially with a high hp engine like the 150 or so if you firewall the throttle in the hole. Tucking in the trim....bringing the lower unit closer to the transom, will put the prop deeper in the water and will be at an angle to help in forcing the bow down when the thrust is applied. Both can help to lower the hole shot time.

3. You can have your engine perpendicular (at a right angle....90 degrees) to the boat and firewall it there too. The engine will get the boat moving forwared and then you will have some blowout. When it occurs, the prop looses grip and the boat drops somewhat at the transom allowing the prop to get a better grip which propels the boat forward again, etc. 2 or 3 times and you are blasting away. The boat essentially porpoises in this situation but every time the prop grabs again, you feel a surge of thrust and the boat leaps forward, then blows out, then leaps, etc, and you are gone. Lot of fun.

So, first of all, answer question #1.
 

Vlietboater

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Joined
Apr 3, 2010
Messages
22
No Title

Sorry for delay been busy with work

#1 yes it is ported prop, see attached pictures
#2 outdrive it all the way trimmed down to a - angle to keep bow as low as possiable,
lowered motor to lowest hole avaiable on transom mount.

no matter if we jump on it or ease the throttle up the bow rises and then unless you back out and slowly allow it to walk up on plane the prop will loose its bite, bow drops, roost tail shoots out and you have to back off let wave catch up level boat and start over, feels like drive up a hill and hitting a patch of ice and loose alll momentive.

almost seems like bow is so steep that hull of boat is pushing more water away and starvs prop. thats why i thought lowering motor would correct issue, no luck yet, i will have to take a measurement from cavation plate to bottom of boat.

very frusterating and make it horriable if their is rough water,

boat also pulls the wheel hard believe to the left
 

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Vlietboater

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Apr 3, 2010
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22
i marked prop and hub and went out, everything still aligned? you can see the rooster tail shoot up when it slips like its getting air, i wonder if prop dose not have enough thrust to get boat up quick enough and the boat plows enought water away to create a wake to starve prop?? just a thought, deff not a lack of power, i will try to video it, just not sure when i will make it out
 

Vlietboater

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Apr 3, 2010
Messages
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Anyone have any setup tips i should check and go by, engine height from bottom of boat to engine, ??
 

smokeonthewater

Fleet Admiral
Joined
Dec 3, 2009
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9,838
The anti vent plate (flat plate over prop) should be even with (when parallel with) the bottom of the boat or about 1" above
 

NYBo

Admiral
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Oct 23, 2008
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7,107
Bet the boat is stern-heavy. Three batteries, big outboard, fuel tank.
 

Vlietboater

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Apr 3, 2010
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No Title

here is a few pictures of the back setup
 

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Vlietboater

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Joined
Apr 3, 2010
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22
almost 3" above bottom of boat
about an 1" below back stepped section

motor is at lowes setting steering slightly rubs fiberglass on this setting you can see where motor used to be highter
 
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