1989 merc 45hp on a 14 foot bayliner prop?

[dkonrai]

i bought a 1989 merc, classic 50, 45hp motor. the boat is a 1986, 14foot bayliner capri. question is which prop should i use?? really confusing. i fish/troll, but also will use the boat for fun too. the original chrylser/force would do about 30mph (per gps) with me alone/gas 2x6 gallon/2 batteries.

the prop on the motor came with a 10 3/8 x 13 pitch. my mechanic put a 10 1/8 x 15 pitch. i am soooo confused which prop actually is better. or should i be installing a different pitch/size all together?

the force died, melted a piston. the prior shop fine tuned the motor, seemed that the timing was off and burned lean. bad combo. the motor i picked up isnt running yet. i got a great deal on the 89 merc, 100.00 bucks but needed some work and has a dead ignition (no spark). it came off a 18 foot bayrunner tin boat.

thanks
dino

 

[steelespike]

Re: 1989 merc 45hp on a 14 foot bayliner prop?

Read "read this first" at the top of the page.
Best way is to test drive with the 13 and the 15 props.Get us as much info as possible.
There is only one prop bigger than the 15 on the chart here.Can you tell us is the BayRunner a full dress 18 weighing over 1000
lbs or a stripped 300lb aluminum fishing boat?
Also would help to know the gear ratio.Remove the plugs and count how many turns of the flywheel to turn the prop once. Mark flywheel and prop so you can be accurate.

 

[dkonrai]

Re: 1989 merc 45hp on a 14 foot bayliner prop?

steelespike,
the 89 came off a heavy bayrunner, 18 foot cc.
the ratio of the lu is 1.81
motor is mounted on a 14 capri bayliner ( i cant seem to find info on weight of hull the original boat sticker is long gone)
thanks
dino

 

[steelespike]

Re: 1989 merc 45hp on a 14 foot bayliner prop?

I really feel the 13 is closer to what you need.But test it with the 15. as long as its on the boat.Boat is about 700lbs dry add the motor gear gas etc probably 1100 lbs or more.As I said the 15 is near the top of the list.Intended for light boats.
Without the rpm and speed the test doesn't mean much.
Also if the 15 is too much it could cause poor performance and premature motor problems.
The 13 could be right on but again without a rpm and speed no way to tell. A Tinytach is reasonable,easy to install and could be used on almost any motor. A gps for speed some cells have a app for gps.
If I was going to prop without a proper test and had to choose one of those props not would be the 13.

 

[dkonrai]

Re: 1989 merc 45hp on a 14 foot bayliner prop?

steelespike,
thank you for clearing things up. i plan on purchasing a tiny tach, and also my fish finder has a gps to help in the speed thing. i am amazed how many different props there are for this motor.
dino