Incorrect Prop?

[Oldblokesbro]

I've picked up my Nephew's Sea-Ray 185 (A 2001 Model), from a local Marine/RV service and Storage facility where he's kept it for the past 6-8 years. Since he has been working out of state, and other life commitments have prevented him from using this boat since 2011, I volunteered to bring it out of storage, check it out and service it, cleaning it up and get it ready to sell. To shorten the story, after inspecting and servicing with help from a friend who retired from Nat'l Park Service (Was a Boating Safety Instructor and is pretty knowledgeable on Marine systems, both electrical and mechanical) . . . We put the boat in the water and ran it for a couple of hours. I'm located in Colorado, and the reservoir where we ran the boat is at aprox 7200' elevation. The Boat is powered by a very clean Merc 4.3 and outdrive. Had been serviced professionally prior to storage and appears that all fuel had been properly purged so start-up was without drama and engine sounds good. Shows only 425 hrs on the hobs . . hydrollics work well, batteries charge well . . . in other words, the boat could go back into service with what looks to me like a minimum effort.
My question regarding the prop: Its equipped with Mercury 15" x 16P 4 Bladed Alum prop. It was sluggish coming up onto plane, and never able to bring RPM up beyond 3500-3800 and even using up a lot of room on the lake, I don't believe we passed 30-32 mph. We had my 16 year old grandson, and one of his friends along with us as well as a large cooler . . so 4 men and a cooler. My knowledgeable friend thinks the prop might be a tad too aggressive on the pitch . . would a 3 bladed prop be a better fit I can't see how my nephew could have pulled a skier with the current setup . . . and maybe the altitude and engine tune might be the culprit . . .Engine sounds and runs good . . smooth without any roughness . . . maintains oil pressure and Temp nicely . . with electronic ignition, I can't see it needing new plugs.
Thanks for any suggestions you folks might give me. I'm contemplating buying it myself . . its that nice.

 

[Sea Rider]

Welcome to Iboats,

Your main issue is altitude and prop. What's max wot revs for that engine ? A high altitude jet kit along less pitch prop will work much better to improve overall water performance. Being that oldie check if prop is spun or in its way to become one soon.

Happy Boating

 

[steelespike]

We could get a little better idea of your setup If you do a wot run with just the driver.Get us a careful rpm and gps speed.
If I remember right 7000 ft costs about 21% of power.What hp is the 4.3?
Is the timing advanced electronically?

 

[Oldblokesbro]

Just to update . . .I put the boat in the water at small ski lake nearby, elevation around 4500'. I believe HP rating of the 4.3 Merc to be 175 + ? . . . at lower elevation, it comes up on plane within (iust guessing) 100' - 150', and WOT around 5200 RPM, producing 34 MPH per GPS . . . taking maybe 10 or 15 seconds to reach that speed. I guess I was expecting a snappier performance from that HP . . but visited with some helpful boaters at the ramp who say my experiences are not uncommon for this altitude. One of the more serious folks had Supercharger on his boat. (He competes in Bass tournaments). Finer pitch prop was suggested if I were to use the boat only at the higher altitude, but consensus was my prop is a good compromise . . as most boating destinations here, are below 3000' elevation.