Properly Propped?????

Okay, here is my data on the boat. I feel like a little kid at school though, I don't have all my information and can't find it on the boat.1.1986 Anchor Industries Ski Deck I
2.Length 17' 10", width 7' 6", and I don't know the base weight-no decal.
2a. recommended HP is 135-185HP
3. 6 people(adults), 12-14 gallons of gas on boat.
4.Ski, tube, w/board, cruise
5.Shallow "V"
6.1986 Mercruiser, Model MCM 185
7.185 HP, I couldn't find the gear ratio at "sterndrives.com". On the stern drive itself, is the #0B426865, on the motor, it says "drive unit 0B414708". I don't know which is correct, and neither line up with sterndrive.com. Unit is an Alpha I.
8. Recommended WOT is 4400-4800
9.N/A
10.Not a bass boat, and don't know what a padded bottom is on a boat, although I have one on my backside.
11.HydraFoil, SE Sport 300
12.Quicksilver QA1916X, 14.5, 19P, Aluminum
13.3500 RPM WOT, 40 MPH, 6 people, 12 gallons gas, speed by speedometer
14.850 ft above sea level
15.Motor has not been tuned up in a long time, but sounds and feels very good.
16.New prop, exact replacement of older prop. Old prop had a few dings. I have only been able to get 3500 rpms out of the prop with the boat loaded. By myself, I get about 3900-4000 rpms.
17.None
18.Should I not be getting more speed out of my boat? Out of the hole, the boat is fine, but my rpms being so low compared to mfgs WOT spec, I am wondering if I have the wrong prop on my boat and if I could improve my top end speed? Would a 4 blade prop help me? or a S/S Prop. That why I have come for suggestions.

I know I am incomplete on some critical information on question# 2- base weight, #7, gear ratio, but I looked all over the boat and can't find it. Any help would greatly be appreciated in answering my questions. Thank You, Larry

Re: Properly Propped?????

LOL Larry, you sure tried hard enough I can't ask for more than that. I will see if I can find the other information for you.


H

Re: Properly Propped?????

Thank you, I appreciate your help. Read prop post half the night last night. Very interesting info. Larry

Re: Properly Propped?????

Larry, the gear ratio I found was 1.84:1 and evidently that is way off and not right as it shows a -17% prop slip. Take the serial number off the outdrive and call your local mercury dealer and find out what the gear ratio is. Here are the numbers for prop slip.

Prop Slip




H

Re: Properly Propped?????

I called Mercruiser and was told that the gear ratio is indeed 1.84. One of my numbers was the transom number and the one off the motor itself was for the stern unit. Again thanks for the help, I am wondering whats going on. Larry

Re: Properly Propped?????

You tach is not right, it is showing less RPM than you are turning. Try turning the switch in the back of the tach back and forth a few times to clear any corroision of the contat points.


H

Re: Properly Propped?????

That would make sense. Seems that I use to run at about 4000 rpms wot. Does that help any?

Re: Properly Propped?????

Borrow another tach of some kind and take the boat back out and get a WOT RPM and speed with a GPS, then we can figure out which prop you need. Beause even at 4,000 RPM it still shows a negative prop slip, which is impossible. LOL


H

Re: Properly Propped?????

I can get my speed with a gps, no problem. Don't know about the tach. Looked under the console tonight and looked at the tach. No visible corrosion. Knocked the light bulb out of it. (no biggie), just cant get to it easily at all. Might just have to wait and take it to the dealer. I know, the cowards way, but I am not mechanically inclined. Anything like a portable tach? Thanks, Larry

Re: Properly Propped?????

Yes, you can buy them at auto parts store.


H