Over Propped Bass Buggy

[armysfcret]

I have an 18' 1997 Bass Buggy. Need new prop. Cannot find numbers on current alum prop that is badly chipped and burred. Currently turning 4200 to 4300 at WOT but need 5000 to 5500 on 60 horse Merc (Tracker). Could loss of RPM at WOT be due to damaged prop? If so, I believe current prop is original and should probably be replaced with same D and P. Does anyone know what OEM prop is for this set up? If not, what would be recommended prop size? Running at 4500 ft elevation and believe engine has been tuned for this elevation. Someone has suggested a 13" pitch but no diam given. Engine has auto trim and using whale tail.

 

[TennCain]

Re: Over Propped Bass Buggy

If is OEM prop you have on there now, the paint will be very thick and the numbers are very hard to find. Look where the paint looks just a little different and use a knife to scrape the paint off. The P number is there.<br /><br />A damaged prop could certainly cause a difference in rpms. (Less rpms if it is boogered up, and more if the hub is partially spun.)<br /><br />The rule of thumb is 200 rpm increase or decrease per inch of pitch. But that is not always true because of the efficiency of the prop. I have seen much greater variations.<br /><br />I would take that old prop to a prop shop and have them look at it. Tell them what you have and they can usually tell you exactly what you need--- for free. Most shops have "loaner" props to help you out.<br /><br />Id get those rpms where they belong. Its very hard on and engine to strain or over rev.<br /><br />Hope this was of some help.

 

[armysfcret]

Re: Over Propped Bass Buggy

TC. Will check through thick paint as you suggested. There is one place on the side of the hub that has about a 1.5 inch area that looks like lettering slightly smaller than this text. May run up to Tucson and see what they have to say also. Thanks for the tips. Anyone else out there to put in their .02 cents? Need all the help I can get.

 

[TennCain]

Re: Over Propped Bass Buggy

Those are the numbers you want, Buddy!<br />There should be a "P" preceeded by a couple numbers. Thats your starting point.<br />What rpms did it run before the prop messed up?

 

[rickdb1boat]

Re: Over Propped Bass Buggy

Most likely, you will want to run the 14 X 13" pitch prop if it is the Bigfoot lower unit, either from Merc. or a michigan prop. The merc # is 48- 77340A33. If it's not the Bigfoot, the run a 10 1/2 X 13", which has a large blade area. Merc Number is 48-816704A40.<br /><br /> Chec k Here <br /><br />Or:<br /><br /> Try Here

 

[18rabbit]

Re: Over Propped Bass Buggy

Michigan Wheel Corp makes OEM props for several motor manufacturers. You might want to look at their x-ref data base for your motor. It’s how we found the current prop number/size/pitch for a pre-historic Johnson prop with no numbers. From there you should be able to scale your prop up or down to meet your needs.<br /><br /> http://www.miwheel.com/

 

[rickdb1boat]

Re: Over Propped Bass Buggy

John and Jackie <br /><br />Is it the bigfoot lower unit?

 

[armysfcret]

Re: Over Propped Bass Buggy

Went to Blue Water Tackle in Tucson. Found out that we have a 12.5/9 Big Ear on there now. <br />Rick - No, not a bigfoot. <br />Don't believe there was a change in RPM after prop was bruised and Blue Water said that damage was minor on prop and should not affect WOT RPM. <br />Purchased 10.5/10 to see what effect it will have on operation. BW stated they will swap out if necessary once we have established what new prop does. I am also going to have them check the tach for proper setting. BW also suggested removing whale tail as pontoon does not need it.<br />Should all be ready for spring. Nice thing is we can put her in the water year around here in SE AZ.<br /><br />Thanks for the great feedback. Will keep you posted.

 

[armysfcret]

Re: Over Propped Bass Buggy

Finally got her back in the water this weekend. Still turning only about 4300 to 4500 with two to four adults aboard. In fact with only two on board, still only turning 43k to 45k. As noted above, I have removed the whale tail and put on the new 10.5/10. Now what?

 

[red10]

Re: Over Propped Bass Buggy

you really need to make sure your tach is accurate because it doesn't sound right or the motor is not running properly

 

[quantumleap]

Re: Over Propped Bass Buggy

J&J- Is this the same motor that was run out of the water, and if so did the RPM's drop after that happened?? Could be a motor problem.

 

[rickdb1boat]

Re: Over Propped Bass Buggy

John and Jackie <br /><br />What kind of speed are you getting?? You should be hitting around 20-22 MPH with that set-up...

 

[armysfcret]

Re: Over Propped Bass Buggy

Speed and RPM have not changed after changing prop. No speedo but believe we are moving at approx 20 to 25 mph. Went from 12.5/9 to 10.5/10. Also removed the whale tail. My mechanic says doesn't appear that engine was damaged in any way. In fact impeller was not scored or damaged either. At full throttle the anti-cav/vent plate is about 5 inches under water. Also noticed engine sounds louder but that may be due to removal of whale tail. Appears to run smooth with a slight vibration at idle. Very little oil smoke from two cycle also. I am very new to the boat world so not sure what sounds right or feels right yet.

 

[rickdb1boat]

Re: Over Propped Bass Buggy

If you are running 20-25 MPH, I'd really be suspect of the tach. You are running where you should be for that set-up. But, you must find out your WOT RPM's with a good Tach. in order to run the correct prop. If you were truly running 4300 RPM's, you would be closer to 12-15 MPH... I'd borrow or buy a new tach.. Also, look on the back of your current tach and make sure the setting is on "6".

 

[rickdb1boat]

Re: Over Propped Bass Buggy

Is the motor also a 1997 model?

 

[armysfcret]

Re: Over Propped Bass Buggy

Yes, 1997 Tracker by Mercury. Believe everything is OEM as this boat only has about 130 hours on it as per previous (2nd) owner.

 

[TPD211]

Re: Over Propped Bass Buggy

John & Jackie,<br /><br />Where is Elfrida, AZ.<br /><br />I lived in Rio Rico, south of Tucson. <br />I went to Sahuarita H.S. in Green Valley.<br /><br />I use to fish alot in Patagonia and Pena Blanca Lakes.

 

[armysfcret]

Re: Over Propped Bass Buggy

Sorry about the delayed posting. Didn't know the question had been posted. Elfrida is located about 25 miles north of Douglas/Mexico and 30 miles east of Tombstone.

 

[rickdb1boat]

Re: Over Propped Bass Buggy

John and Jackie <br /><br />Did you ever get it figured out??

 

[Andrew Leigh]

Re: Over Propped Bass Buggy

Hi<br /><br />Had a problem with a car that one suffered the same kind of problem...no top speed when under load. <br /><br />Found out that the throttle cable linkage arrangement was incorrectly set and therefor was not opening the carb fully.<br /><br />You may wish to check if you are physically getting "WOT throttle".<br /><br />Cheers<br />Andrew