Bass Tracker with 40HP Mariner Speed issues

Ok, have a question for all you Bass Tracker guys... This is a 16ft tracker, with a 40hp mariner on it. I got it out to the lake over the weekend. Once I got through half a tank of bad gas, the motor ran fine. However, it was next to impossible to get it up on a plane. Max speed according to GPS was 16MPH at full throttle and on about as close to a plane as I could get it. Played with the motor angle, no change. Just curious how fast people's boats with similar engines are running and how fast you can get it up on a plane? Does 16MPH top speed sound right? Any ideas what would cause the slow speed if not? 16MPH was only achieved with just me in the boat, no gear, no trolling battery or motor, only about half a tank of gas, and the front deck hasnt even been put back in.

I've never owned a Tracker, but I hear they're notorious for having water logged foam under the floors, that would make sense if your motor was running good but the extra weight of the foam was dragging you down. My friend had a 17' Pro Team with a 40 Merc and I'm thinking his ran in the low 30's...

All the floors were ripped out and new foam installed(yes, the old foam was water logged, you could squeeze it out of the foam). As far as I can tell it has to have something to do with the engine or prop, but I cant think what would hurt the performance THAT much! Especially if his ran in the 30's with a 17ft... I am new to outboards and boats in general. I can fix just about anything on a car, but I'm lost here. Thanks for the input!

Do you have a tach in the boat? If so, what kind of rpm's are you getting? If the motor is revving good but you're not moving any faster, it could be the prop is spun. If it's not revving very high, it could be any number of things...

I do not have a tach so I have no idea what the RPM's were. Im actually trying to find one for it now. It sounds like it is reving fine, if that makes a difference. What does it mean for the prop to be spun? How can I check that? Thanks again!

A lot of props have a brass hub inside that fits over the driveshaft/sheer pin, then between the brass and aluminum is rubber. A prop is "spun" when the rubber spins out so the hub and prop are no longer locked together, it's meant to break before any of your lower unit parts do incase you hit or jam the prop with something.

The easiest way to tell if it's spun is to take the prop off, use a permanent marker, and mark a line on the inside on both the hub and prop. Ride around in the boat a few minutes, take the prop back off and see if the marks are still lined up, if not then you know the prop is spun

Thanks! I will check this. I just purchased the boat used, and the prop does show severe dings, so this may be the case. Would a spun prop not result in complete failure to move forward under throttle? Or can it be incremental? Thanks again for answering my questions. This forum has been great for a newbie like me.

Put your motor in gear make sure the key is off and try to turn the prop if it spins and the motor dosnt turn then the rubber insert is shot out. Don't throw the prop out as you can buy a replacement for it at most boat shops. I have a 16 bass tracker with a 40 Johnson it will do an easy 30 mph

I put it in gear, and tried to turn the prop. It is hard to turn and just turns the engine over. So Im guessing that means the prop is good? Any other ideas on what to check? Thanks!

You mention the prop being beat up, how bad is it? Post a picture if you can. I trashed prop could easily be the cause of your trouble

Here is a picture of the prop. It definitely bent. It has 3x11.4x12 stamped on the side. Im not even sure that is the correct prop size for the motor. Ive been reading up on choosing prop size, but it looks like a tach is required to figure that out.

Wow, from the pic it looks pretty well trashed. If I were you I wouldn't run it anymore with that prop, if it's as bent as it looks it probably would wobble enough to eat up the seals/races/whatever in your lower unit. As far as prop selection, I really have no clue on that. You could look for recommendations on Tinboats, iBoats, an owners manual for your motor, I think Mercury's website has a prop selector...

So you think thats the problem? Thanks!

Put it in neutral with engine lowered get a bucket or something that you can rig a cloth hanger on. make an S shape in one end to loop tightly over the edge of bucket. Now slide the out running end towards the prop till it touches the aft edge of the prop flute. Now turn the prop around to see if the other flutes hit the hanger end or misses it by much. IF you have more then a 1/8 th wobble in it it will give you some vibes.
Next if that looks fair grab a sheet of stiff cardboard ( I use an old beer box) and trace out the best looking floot and do it with as much care as possible. once finished cut it out and align it up with the others if they are way out of shape it will show you your problem is cavitation. This will cause the motor to run OK but the prop isn't grabbing the water thus just spinning out bubbles. If the cutting edges of the prop are SHARP it will do the same because a prop must have a slight blunt edge.
Let us know your results. I own and have owned many boats these are just easy ways to test your prop $$ as you know. I run a fleet of tour boats and captains will do the Da??ist things.
Grog Hog

I will do that. I do know that one of the flute's(I guess thats the correct term for the blades?) is curled over on the end, probably about 1/2 to 3/4 of an inch.

Not to change subject, but Im trying to find the manual to see what the original prop was. According to this chart https://www.storesonline.com/site/573683/page/608047 and my model #40ELTO 6E9 L 502617 the motor is a 1988 I believe? It also has a small g in the lower right corner of the tag, which I found somewhere said it was an '88 as well. I just want to make sure Im seeing this right before investing in a manual. Thanks.

start with a 10p prop, a bent prop can cause problems. i have to use a 9p on mine when i have 3 people.

I will almost always be carrying 3 people, on occasion 2, and rarely 1. So should I just go with a 9p? Can you give the exact size of the prop you are using? What is your top speed with that prop and load? Thanks!

i have a 1448 side console, with a 20hp 4 stroke. with three people and the 10 i was running 13. with the 9 18. i also moved some weight out of the back and made a world of difference. i run with huge tacklebox, cooler, TM, TM batter, 4-10 rods, anchor. 3 gals of fuel. full floor and front deck. with just me i run 26, another adult 25, with the 10p. i took alot of weight off the back and moved it forward, made a huge difference.

Wow! So there is definitely something wrong. My 16ft with 40HP and 12P, 1 person and no gear barely made 16MPH. I hope it is just the prop being bent up... I'm running out of money