Engine/Prop Set-up

Question
Bert-

Unused horsepower and performance is a pet peeve of mine, especially with boats.  I grew up around them, I've spent summers cleaning them.  I've owned five of them from 15' Rinkers to 28' Carvers.  I've now settled into my second Crestliner.  I have no formal training and have been a "learn by advise and mistakes" boat owner.

I have a 2001 17.5 Crestliner Fish Hawk.  It's 17.2' in length, Max. beam is 91", Dry weight is 1100#, Max. Hp is 115hp, Engine weight is 347#,I'm guessing the loaded weight would be around 2,000#, the hull is aluminum.  I'm running a two stroke 115 Mercury Outboard with a 12.5" x 23p Aluminum prop.  Engine spec. calls for a 4750rpm - 5250rpm W.O.T.  Currently, with two adults full tank and gear I'm running at 4,950rpm - 5,000rpm.

I experimented with raising the motor on the transom one hole up from the bottm and would "blow out" with the slightest trim.  I lowered the unit to the lowest hole and improved both top end and limited blow out.

Based upon previous experience and the right "feel" for optimum trim.  Which in my world means, I've trimed as much of the hull out of the water without blow out.  The water spray from the side of the hull is currently near the last six inches of the back of the boat.  It seems like she could come out more but the prop won't "bite".  When I exceed the trim, the prop doesn't blow out or over rev., but it seems to let loose a bit and sounds like it's surface piercing and just gradually becomes less efficient.  It almost seems like I need to lower the unit another inch into the water but I'm limited by the transom and standard mouting from Mercury.

In researching props, some manufactures claim their prop has more or less lift and some claim to have surface piercing props but few give examples of set ups and what equipment their using.  

Question:

(1)Would one diameter/pitch prop give me the ability to trim up farther over another?  Say, drop an inch of diameter and add an inch of pitch or vise versa?
(2)What performace could be gained from S.S. vs. Aluminum.  Would I need to adjust the pitch?
(3)I currently have no hole shot problems and seem to have plently of low end torque, but would a hydrofoil fin help contain the wasted thrust when I'm trimmed up?

I'm not looking to set water speed records and don't have the cash to find the ultimate set-up but maybe your advise would help me get closer.

Thank you!

Answer
Hi John----Sounds like you have been there and done that!
 Answer-1.taking diameter away from prop will cause you to loose thrust.
       2.Stay with the stainless,the aluminum props are for rookies.
       3.  ALL hydrofoils are junk,biggest ripp-of ever done to the boating public
      
        Try adding more cup to the trailing edge of your ss prop should give you more trim by holding more water,  good luck