Matching the Prop to the Motor

[FishinInMizzou]

I have an 87' 20' Suntracker with a Merc 50 Classic, which is actually a 45 h.p. motor. It has a great deal of weight in the rear and rides with the toons over 50% below the water level. The speedo does not work but WOT is about 5200 to 5300 r.p.m. When my oldest son or I walk to the front of the boat, you can hear the prop grabbing air or ventilating:confused. I have thought about putting a four blade prop on it, but am afraid to try and order one on-line. Iboats have several to choose from, but not sure. Any suggestions are appreciated.

Ken

 

[lmuss53]

Re: Matching the Prop to the Motor

It sounds to me like you have a prop that is too steep (Pitch is too high) for your boat. I would put a step or two lower pitch prop on to try to get that WOT RPM up around 55 or 5600. Go to the turning point website and run your boat and motor on their prop selection tool to see what they recommend. I usually go with the lower power prop recommendation and find it works well.

I've not seen or heard of a great deal of difference in performance on low to mid range HP pontoons with cheap 3 blade aluminum props, and the 3 or 4 blade or stainless performance props. I buy cheap stock props on ebay. I then sell the prop I didn't like and the cost is close to a wash.

 

[flycaster]

Re: Matching the Prop to the Motor

I have an 87' 20' Suntracker with a Merc 50 Classic, which is actually a 45 h.p. motor. It has a great deal of weight in the rear and rides with the toons over 50% below the water level. The speedo does not work but WOT is about 5200 to 5300 r.p.m. When my oldest son or I walk to the front of the boat, you can hear the prop grabbing air or ventilating:confused. I have thought about putting a four blade prop on it, but am afraid to try and order one on-line. Iboats have several to choose from, but not sure. Any suggestions are appreciated.

Ken

I would begin by checking what causes this.
From your indications, there maybe water in the toons.

 

[lncoop]

Re: Matching the Prop to the Motor

I would begin by checking what causes this.
From your indications, there maybe water in the toons.

+1 Tracker toons, especially ones from that time period, are notorious for developing leaks. The simplest way to determine whether you have any is to listen for sloshing when you trailer her. If you do, take the barge to a competent weld shop, preferably one that specializes in boats because they will have the most experience with aluminum. You can find one just by calling around. If you're not comfortable calling welders check with a local marine dealer. They'll be able to steer you in the right direction. What you need is a pressure test, which will determine whether you have any leaks that need repaired. It's not prohibitively expensive to have done. Good luck.

 

[lmuss53]

Re: Matching the Prop to the Motor

I guess I missed that 50% under water part the first read through. Check for water in the tubes then do the prop finder. Run the boat up on the trailer and pull it to a quiet corner of the parking lot. Give the whole rig a good shake and listen for water sloshing around in the tubes.

My '98 tracker cracked where the tubes were welded to the "M" brackets about the last 2 feet from the rear of the tube. When I beached the boat to fish the water would leak in.