need to know original prop?

justarobb

Cadet
Joined
Sep 8, 2008
Messages
13
I have recently purchased a 1989 sunray "express" it has a 2.3l 4cycl. ford. with an OMC stern drive. the hole shot is really bad. it has a 17x13 spline prop. top speed is 42 MPH@4700 rpm. I do not know anything about the specs of the boat other than that. I would like to know what prop was sold with the boat. I have looked everywhere on line but can not find a web site for the boat and engine. any help would be appreciated.

thx Robert.
 

zbishka

Cadet
Joined
Aug 24, 2009
Messages
22
Re: need to know original prop?

I recently purchsed a used 1986 19' Sportcraft Ski / Fishing Boat with a 175 h.p. Merc. engine (sterndrive?). Mercruiser Alpha One Power Trim XD. Anyways my prop is all chewed up and I'd like to get a new one but I don't know the specs on it such as the pitch of it. The diameter seems to be 13 1/2 - 14" if my ruler is correct. It is a 3 Blade prop. There is a number stamped on the propeller itself reading 4878120A4019P. When I went on the prop page on this site and put that number in and it wasn't recognized so now what do I do? Any help would be appreciated. Thanks to all in advance. Mark
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: need to know original prop?

Robert, welcome to Iboats prop forum and we will try to help you as much as we can but without more information no one can help you, and I will tell you I need more information than anyone else. But if you would like my help fill this form out and I will help you as much as I can, if you would prefer to not go to this much trouble there are other people who will gladly help you.

Iboats Boat and Motor Info

1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
2a.What is the maximum recommended HP for your boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make. manufacturer and model of motor
7. HP and gear ratio of motor IMPORTANT
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape a c ross the prop and the lower unit and then cut it between the prop and the housing and turn the motor until the tape lines up with each other, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches, use a board under the keel and stiking out to the anti ventilation plate for a referene
10. Is it a bass boat or does it have a pad bottom
11. Does it have a hydrafoil, dolefin or trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. Make sure you trim the prop up until it starts ventilating and then just trim in until it quits ventilating. If you do not have a tach you can buy a Tiny Tach for $ 50
14. Are you at sea level or a higher elevation, give us the elevation in feet
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way, checked compression, and looked at the plugs and checked spark, all of the foregoing could be the reason your prop is not attaining full RPM
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop
17. Does the prop show any damage that you can see
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations
19. If you are trying to attain a better cruising speed and fuel savings or trying to attain a faster speed I will want you to take your boat and run it with 1 or 2 people and give me the RPM and speed readings starting at 3,000 RPM in 500 RPM increments all the way to WOT.

REMEMBER, The numbers I give you will be NO better than the information you give me

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.


H
 

mud1070

Recruit
Joined
Jun 18, 2009
Messages
5
Re: need to know original prop?

Hey there lieutenant!
I am also curious, about the proper prop size. Here are the specs.:
1980 Carver Santa Cruz 2667
25 ft. x 8 ft. beam x 5400lbs.
228 Merc I/O w/ 1.50:1 gear ratio
fuel capacity 100gal. typical 1/2 tank.
Has Trim tabs, but not currently working.
Engine is good, tune-up every season.
Current have a 17 pitch and cavitates around 4000RPM.
Was Recommended a 21 pitch, but wantd to know more.
I have a tach, but no speed. (and no GPS)
What else do you need. Let me know. I appreciate the help. Thanks
Jay.
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: need to know original prop?

Jay, that is definitely too high a pith for your boat setup, whoever told you that has no idea what they are talking about. Explain to me what you mean by avitating at 4,000 RPM, that doesn't make sense unless the prop has damage. Do you mean that it won't turn any more than 4,000 RPM. I also need to know the make and model with diameter as well of the prop you have on the boat now. I need a speed, you an use a handheld GPS and many phones have built in GPS.
I an guarantee you that buying a 21" pith prop for that boat will make a nie exhibit sitting in your den, beause it ertainly won't let you reah the reommended RPM for your motor.


H
 
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