Alloy props flex under load.
Load means going very fast and or pushing a very heavy boat/barge.
Propping for a plaining hull starts at boat weight and HP at the prop.
"Std Prop" no such thing...a boat is proped to the above and end use... end use maybe towing skiers, or general use, or trolling.
If well powered then one has enough reserve power at any given rpms to be able to uase an all round prop selection.
Min powered or less, then people have a prop for 'pulling the kids around, and another for general fishing.
Then we throw another factoer in.. trolling, thats not on the plain...which then means the hull is basically a displacement hull.. totally diferent kettle of fish.
So need some info.
1/Current prop pitch and diameter/ number blades.
2/ Is the motor correct height?
THIS IS VERY IMPORTANT.. it is a waste of time going any further if it is not...
At fast cruise speed, flat water, best trim for that speed, the bottom of the cavitation plate is in the water, top surface has a few droplets running down the surface.
3/ Motor HP (115 hp)
4/ motor model/ gear box ratio. (2.59)
5/ Manufacturer WoT rpm Range (5000 to 6000) Unless a a race boat, this should be boat fully loaded, midway or slightly below ...
6/ Total gross weight on the water
And/or WoT speed/ rpms at best trim for that speed on flat water. (34kt @6000rpms calc to approx 1350/1400kg)
Rpms and speed at trolling
7/ Rpms and speed, flat water, starting around 3500 rpms in approx 500 rpm increments thru to WoT.
IE set rpms at 3500..then bring trim up to just before cavitation and/ or porpoising... note rpms and speed.
Then set to 4000 rpms, re adjust trim.. slightly higher as above , and repeat each time.
8/ Boat make/model.
Ball park min powered boat between approx 4.5 and 6m will have a WoT speed around 42mph 18/19" pitch prop.. and a well powered 46 to 48 mph..19/21" prop When engine height is correct and no extra drag stuff like a permatrim, or tabs down.
If the boat is min or well powered you will not need the permatrim.. the permatrim in the water at trolling speed adds a lot of drag../ fuel use. A prop with more rake is the correct way to lower the bow/ lift the stern if need be.
Going on current limited info. assuming engine correct height Prop correct diameter etc
115 hp 34 knt (39 mph) 6000rpms
2.59 gearbox
Total gross weight on the water 1350/1400kg
you have a 19 pitch prop assuming the grip/ diameter is correct
A 4000 rpm cruise speed approx 24 mph.
I do suspect that the prop diameter/ cupping maybe incorrect and pitch maybe too high.
Better data required.