2011 115hp OptiMax Issue

[Saskberta Sportfisher]

I took my new 17.5ft Tracker Fish/Ski out for the first time. The boat with that motor is rated at 42mph. All I could get out of it was 33mph. I found it was sluggish out of the hole and topped out at about 5000rpm. I found I could not trim the engine very much before it would cavitate. I have room to move the engine down on the transom another 1.5". Any thoughts? Thanks.

[hillclimber]

Just wondering, did you go through the break in period? When I got my new boat in '07, I was told not to go go over 2500 rpm for the first 10 hours, then work the throttle through different rpm ranges for the next 10 hours, never holding rpm's longer than 5 minutes.
When you get a new boat, that is the longest 20 hours of my life!!
Next option might be prop. I had to go down to a 17, from the stock 19 to get my rpm and hole shot. Lost a little speed, but all round performance was better.
Hope I helped,
HC

[hillclimber]

Forgot to add, the dealer told me there were rev limiters in place for the break in duration. And if something happened they could pull the brain and get all the data they need to diagnose the problem/cause.

[Tredeb]

Originally Posted by Saskberta Sportfisher

I took my new 17.5ft Tracker Fish/Ski out for the first time. The boat with that motor is rated at 42mph. All I could get out of it was 33mph. I found it was sluggish out of the hole and topped out at about 5000rpm. I found I could not trim the engine very much before it would cavitate. I have room to move the engine down on the transom another 1.5". Any thoughts? Thanks.

sounds overpropped. what prop are you running? You should be running around 5700 RPM. A lower pitched prop will have more bite and may reduce your blowout.

Make sure your motor is at the right height and go from there.

[ATF]

Try a different pitch prop. The speed you expect is probably an overstatment from a dealer or manufacturer. An opti should be running from 52-5700 rpm full bore. You may need to dial down to a 17P prop even. Different props will get you better hole shot but be prepared to experiment.

[Saskberta Sportfisher]

Thanks for the notes. I talked with Mercury and Tracker and it looks like my engine was mounted too high on the boat. Mercury told me if I can mount the engine with the cavitiation plate level with the bottom of the transom it would be best. Tracker just mounted the motor wrong. They also said I might want to go to 13x17p prop. Thanks.

[Tredeb]

Originally Posted by Saskberta Sportfisher

Thanks for the notes. I talked with Mercury and Tracker and it looks like my engine was mounted too high on the boat. Mercury told me if I can mount the engine with the cavitiation plate level with the bottom of the transom it would be best. Tracker just mounted the motor wrong. They also said I might want to go to 13x17p prop. Thanks.

Personally, I would try the prop first. You will lose rpm and speed if you lower your engine.

[Buck9]

SS my boat is a little older a 2005 17ft lund outfitted with a 115merc opti. I have a 13P and 19P props that came with the boat when I bought it. Test drove it with the 13 pitch and lots of hole shot but no top end think 26mph. I also had the same problem as you with my 19 pitch could only get about 5000rpm and would start to cavitate, but speed was about 40mph. Hole shot was sluggish and could barely get out of the hole with 4 adults in the boat. I ended up finding out the WOT Rpm's for this particular engine and the manufacturer said it should run between 5200-5600rpm. Ended up buying a 17P stainless and now performs great. Runs around 5400 rpm and 44mph, also great hole shot. Of note my motor is as low as it can go on my transom.

[Saskberta Sportfisher]

Thanks for the advice. I took it back to Bass Pro and they are going to lower the engine 1.5". Once this is done it should take care of the cavitation problem. I still have this feeling that I might need the 17p prop to get my RPMs up. It can only get better. Thanks