Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-02-2012, 07:24 PM   #1
Ensign
 
Join Date: Jun 2012
Posts: 3
Default New guy with a prop question

I have a 1990 maxum with a 50hp Force engine. Lost my prop last week and am looking for a replacement. I think I have the diameter at 10 3/8th but am torn with the pitch. 11 1/2, 12 1/2, 13??? Any suggestions? I'm only trying to get around to do some fishing. Not trying to pull anything.

Thanks in advance.
__________________

garbonzo06 is offline   Reply With Quote
Old 06-02-2012, 07:57 PM   #2
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default

welcome to the zoo....this is kinda hard to answer since 1) I don't know what your wot is supposed to be and 2) don't know what prop you had in the beginning....so...you need to find out what your max rpm at wot is supposed to be...this is gonna be some experimentation involved since your going to try a prop..run it wot..and then adjust either up or down in pitch size...

keep us informed...

SP
__________________

__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Old 06-02-2012, 09:32 PM   #3
Ensign
 
Join Date: Jun 2012
Posts: 3
Default

Seapuppy,

Thanks for the insight. I'm a little embarrassed but I have no idea how to check either of those. If I throw a prop on with a pitch that is too high what risk am I running? I'm not looking for a the smoothest ride possible but just something that is going to work and not ruin the engine. Any advice on how to check the RPM and WOT and any suggestions on what pitch I should start with? Thank again.
garbonzo06 is offline   Reply With Quote
Old 06-02-2012, 11:00 PM   #4
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default

well....I don't think you can ruin the engine with say a too high of a pitched prop...what will happen is that it will take longer to plane if at all....basically concider you pushing your boat up hill in 4th gear.....too low pitch and you'll be screaming and pop up on plane ..yet top speed will be something less than optimum........
so..to check wot rpm..do you have a tach???..your going to need a tach to check rpms.....your owners manual will have the correct info on what the wide open throttle rpms should be running at......

to check the prop pitch....check the hub..it's usually printed on the hub of the prop somewhere.......

might wanna swing by a prop shop and tell them what you have..they can usually recommend something to start with......


SP
__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Old 06-04-2012, 12:41 PM   #5
Moderator

 
shrew's Avatar
 
Join Date: Apr 2008
Posts: 5,588
Default

SP is on to it. I'd start with the getting the info. suggested:
1) Max RPM Range fro your motor.
2) Diameter and pitch of current prop.
3) Current Wide Open Throttle (WOT) RPM with current setup.

Now compare current Max RPM to Max. RPM range of manufacturer.

If your Current Max RPM is below the Max. RPM Range of the motor, you can go down in pitch. If the current Max RPM of the motor is above the Max RPM Range of the motor, then you can go up in pitch. You will be limited to the amount of size in diameter that you can change. A good propr shop should be able to help. There are also a lot of prop calculators out there.

You say you want to go fishing. That can be done in a canoe......with a paddle. What are you actually trying to achieve? Better hole shot (time to get on plane)? faster top speed? better fuel efficiency?
shrew is offline   Reply With Quote
Old 06-04-2012, 08:18 PM   #6
Commander
 
Join Date: Mar 2010
Location: Southern Maine
Posts: 289
Default

Please clarify "lost my prop" . Is it gone or damaged? Most props have stamped part #s. You could bring the part # to a prop shop and match it. If gone, for comparison my dad's 120 force on a 1994 1700 had a 19 pitch prop to keep from over revving it.
CountryME is offline   Reply With Quote
Old 06-05-2012, 11:58 AM   #7
Moderator

 
shrew's Avatar
 
Join Date: Apr 2008
Posts: 5,588
Default

Quote:
Originally Posted by CountryME View Post
Please clarify "lost my prop" . Is it gone or damaged?
Hmmm, I missed that one. Well then my reply makes absolutely NO SENSE. Let me se if we can dig some info. on that OB model.
shrew is offline   Reply With Quote
Old 06-05-2012, 12:28 PM   #8
Moderator

 
shrew's Avatar
 
Join Date: Apr 2008
Posts: 5,588
Default

I believe that the original part number on the Force 50 prop is A293265. I believe this is a 12.5 pitch. Unsure of the diameter, but believe it is somewhere between 11" and 13". To my knowledge there was only one prop for that model, so if you go by the part number you should be all set. Take a look around and use that part number. LEt us know if you have any questions or problems.
shrew is offline   Reply With Quote
Old 06-07-2012, 12:29 AM   #9
Commander
 
tglee's Avatar
 
Join Date: Feb 2007
Location: PA
Posts: 334
Default

Quote:
I believe that the original part number on the Force 50 prop is A293265. I believe this is a 12.5 pitch.
This is correct. 10 3/8" X 12.5" was the original.

You can change to 13.5" pitch for a higher top speed or a 10" pitch for better acceleration. I'm not sure of what the max RPMs at WOT should be.

The 1982-1994 models were different then the newer ones. 1995 and forward have a max of 5250. The older ones may have been as high as 5500, you need to find out for sure. The rule of thumb is 300-400 RPM difference when changing 2" on the pitch.
__________________

__________________
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote."

MMSI# 338052622
tglee is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 12:56 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.