Set-up help

[Miniton]

I really need some help from the experts if possible.

Boat - 1994 Astro FSX20 Fish n Ski (21')
Engine - 1994 BlackMax 200 efi
Props: (3 tested)

Manual recommended WOT = 5250-5750rpm

1. Tempest 48-825864 A45 23p , SS 3 blade (think it has been worked on.)
2. Trophy 48-825942 25p , SS 4 blade
3. Aluminum - 48-832832-C1 21p , alum 3 blade

So my problem is that I am getting really bad performance. It it very poor on holeshot and when I am fully loaded I can barely get on plane. In tight turns it seems to "slip" and i have to back off throttle and let it "catch" up. When I initially take off, the holeshot "slips" a lot also and I have to gradually throttle up to speed. I tested all 3 props today with a normal load and the results are:

Tempest 23p = Slow, gradual holeshot to plane. WOT=5300, top speed = 58mph(gps)

Trophy 25p = seems like very poor holeshot. WOT=5300, top speed=54mph (gps)

Aluminum 21p = Real good holeshot. WOT=6000, top speed=54mph (gps)

The 2 SS props are vented props but I have no plugs for them. The Tempest was apparently vented by previous owner and I cant buy plugs. I dont know if the Trophy is worth keeping so I have not invested in that one. My engine mounting on transom has 4 holes. It is currently installed on second hole from top, so the motor can go down 1 more or up 2 more.

I just want good solid performance that I am not constantly having to mess with. it is making it difficult to enjoy my toy.

I appreciate any of your help, thx in advance.

 

[steelespike]

Re: Set-up help

"Good solid pewrformance"Is a little vague.When you jump around different models and materials with no particular plan you just get a bunch of numbers.If you read the stickies at the top of the page and the helps on the prop store page it will help you understand prop selection better.
Hole shot and top end don't really go together there has too be some comprimise.
You need to be more clear what performance you favor.
Not an expert but based on the Tempest numbers I would I would get a Tempest in a 21' pitch.Would give you some hole shot and come close to 58 mph figure.
And add "about" 400 rpm.
The antivent plate,just above the prop, should be visable on plane.
If the new prop still vents then you may have to lower it a hole.
Be sure there is nothing on the bottom or transom that disturbs the water close to the prop.

 

[Miniton]

Re: Set-up help

Okay, I measured my motor height which is 5 1/2" below pad right now. How does this effect the above problems?

 

[steelespike]

Re: Set-up help

Normally a ss prop would resist venting.
I'm not aquainted with a pad setup but it appears from your venting problems
you need to lower the motor.

 

[Dhadley]

Re: Set-up help

Okay, I measured my motor height which is 5 1/2" below pad right now. How does this effect the above problems?

OK, can we assume you mean the centerline of the propshaft is below the pad? Hopefully you're not talking about the AV plate.

 

[Miniton]

Re: Set-up help

Yes, centerline of prop shaft.