1993 Euroline Ski/Runabout Prop HELP :( ?? Stumped

[baja4wd]

Picked up a clean 1993 Euroline 175 with a 3.0 Merc I/O. Came with a 3 blade 15 by 17 pitch. Decent hole shot, wot 32mph trimmed out 2 riders at roughly 350#'s with a full tank. RPM's only reach 4000-4100. I hit something and chipped a blade beyond repair thus had to buy a new prop. Shop only had 14.5 on the shelf that went from 16 up to 23 pitch. They sold me on a 4 blade 14.5 by 17 stating better hole shot etc. went out today with 2 adults 4 kids totalling about 800 #'s in riders plus fuel and 75# coolers contents. Pulling one rider boat took forever to plane out or get up. Switched to 2 riders after my kids kept begging. Planed out quicker and pulled good, 3 riders was also the same result. Tube pulling RPM 4000, WOT no tube 27-28 @ 4100 RPM per GPS. Guess my question being, I've researched with no luck on this model/year boat engine - anyone that may know the factory prop or any ideas as to what I might need. I would think with proper setup the boat should reach 40mph with a good hole shot with proper configuration. Again problem is I can't locate anything about this boat. Hate to be long winded but wanted to cover all, also engine runs like a champ, know it's not a rocket nor will it be but I've had bass boats with 75hp outboards that would run / pull circles around this one. Appreciate anyone's help..thanks

 

[steelespike]

A normal 17 to 19' 3.0 I/O is one of the easiest boats to prop.A well tuned healthy 3.0 will turn a 21" prop up to about 4800 rpm and about 40 mph.
May struggle with water sports or a heavy load. A 19" prop will usually do better with a load and water sports.With an over rev caution. with a light load.
If a full load and water sports a 17" prop usually works But again the caution of over rev with a light load.
Your boat is struggling with a 17" with 2 different props. Normally when going to a 4 blade you would lower pitch at least 1"
You need to check out your motor.Do a compression test.Check that the throttle opens all the way.
Check that it is timed right and advancing as it should.
Does the boat respond to up trim.
Does it ride oddly like its glued to the water?

 

[baja4wd]

Thanks Steelspike, boat will trim out and it will pick up 2-3 mph until the point of prop spin out being up to high. If trimmed to that fine line the steering gets tight, pulls to left unity il I drop it down some and it's silky smooth with fingertip response, engine 4100rpm wot. Motor doesn't audibly sound overloaded or stressed at wot. I will try to do a compression check this week and check carb to see if opening up all the way. Honestly has me wondering if I should gave gone with a 16 pitch 4 blade instead of huge 17 pitch. I'm assuming the 14.5 diameter vs my original 15 isn't a factor?

 

[steelespike]

A 15 or 16" 4 blade would help mask your problem.Diameter is a secondary consideration. If you look up various pitches you may note that as pitch goes up
diameter often goes down.
You may notice the typical sizes I mentioned(17,19,21) are significantly higher than props we have talked about.

 

[inthedirtagain]

Might also be waterlogged. I'd have the boat weighed and and compare against anything that closely resembles it. I had a 3.0 in a 17.5 Invader that would do close to 40mph. Didn't keep it long enough to figure out weight/pitch possibilities. Pulled down low just fine, tho.

 

[baja4wd]

Well I installed a new 15 by 17 3 blade and the rpms hit 4800-4900 at 35mph (GPS) fully loaded, quick hole shot and feels like a different boat. Pulled wakeboard today and response was really surprising. I did install a new hub kit so I'm leaning to the old hub possibly slipping attributing to my isdues. I will install the 4 blade with new hub kit and see what I get compared to the last outing. Appreciate everyone's input..