New Nitro owner have some questions

[97nitrofisher]

hey guys I just bought a 17ft 97 Nitro 700LX with a 120 tracker. The boat is perfect. The gelcoat was a little chalky but i wet sanded it and it cleaned up nice.

what the boat came with.
New trailer
74lb trolling motor
lowerance 520C GPS fishing finder
120 tracker 2 stoke. Motor runs like a champ. not a hickup. low hrs. with new plugs, wires, and waterpump.
3 bank onboard battery charger.

i paid 3k for the boat.

Now for my questions.
the boat came with an aftermarket prop. 3 blade
when going into full throttle the boat gets an extra boost. owner told me it was because of the aftermarket prop
the boat only tops out at 48mph with me in it on the GPS, im about 200lbs. i have read it should be around 54-55mph
Could the prop have something to do with this. Higher/lower pitch maybe.

Second. out of the hole shots:
Trim all the way down. full throttle the boat pulls really hard to the right untill you start to trim it up. the more i trim it up the easier it steers and the nose of the boat levels out. It does not have a hydofoil either.
what could be causeing this.
Its like the steering gets really hard to pull back to the left.

can anyone maybe shine some light on my questions.

thanks Phil

[Jared LeBlue]

It's a good chance your prop is your problem. What kind of RPMs are you getting once you are on step and trimmed out? Do you have a jack plate? I would assume not but if you did you could play with it a bit to get better performance. It's pulling hard because it's working hard. You motor is probably sitting pretty deep so when its digging to get you up its pulling and putting a bind on your steering. Once you are up you have less motor in the water and it eases up. Unless you have hydrolic steering you will experience tight steering when coming out of the hole. If you have a jack plate you can adjust for this some. If not check an see what hole setting your motor is on. You may be able to move it up a some. This will not be an easy task unless you have a motor hoist or some really good friends. A better prop with a diffrent pitch will help this out too. It will get you out of the hole faster so you don't have to fight it as long. Also try adjusting your tarque plate which is located under your cavitation plate. If it is centered try moving it to the right. If that makes it worse then move it to the left.

[97nitrofisher]

thanks for the fast reply,

the boat is sitting around 5k rpm i would say but i can't really remember . yes it does feel like the motor is working hard. The hole shots are not bad but i does feel a little sluggish, until i trim it up. once i trim it to the sweet spot the nose levels off (centered) I will check to see what hole it is set on. I think it might be sitting kinda low or in the middle. It has a manuel Jack plate. the steering is cable steering which he said was just recently replaced. it does look new also.

[Nowsker]

I have a 1996 Nitro 170 TF (17ft) with a Tracker 115 and it gets to 57mph with just me and I'm 200lbs so it sounds like you should be getting more out of it then 48. I have no Jack plate but I do have a Stringray hydrafoil. My prop is a Quicksilver 26P stainless steal prop. One other note, I start the trim about 1/4 of the way up from all the way down. You will feel some pull early to the right but it sounds like you are feeling more pull than I have. What is the pitch of your prop by the way?
Also, It definately doesn't sound like your steering since the cable was replaced, which is pretty standard for that boat. Those cables last about 10 years. They start to fray up and become like fingercuffs and get really hard to turn.

$3000 sounds pretty fair for that boat. I am selling mine and asking $5500

[97nitrofisher]

thanks for the reply .

i will have to find out what pitch the prop is but i think that might be there problem.

best regards

phil

[fish herman]

I own a 2000 700LX with a 90HP merc elpto. I had similar issues with the stock aluminum prop. I went with a LaserII by mercury 13 1/2 X 22 pitch prop. Now I get only a little torq pull as she is going up on plane. My top speed 2 guys and gear is 45-48 mph at 5600 rpm. I agree with others that all of your problems are with your prop. Sounds like it has way too much pitch. Check rpm's at wide open throttle, and then speak to someone at a marine supply store, and they should help guide you to a better prop, oh and a jack plate never hurts, few hundred dollars, but well worth in in terms performance and economy.

[97nitrofisher]

My WOT rpm on the boat is 5500-5600 and on the GPS it maxed at 48.7. So it has to be the prop . motor ran like a champ. Would a hydrofoil help by cutting down on the top end cavatation?

what pitch and brand should i look into.

Phil 

[fish herman]

The hydrofoil may cut down cavitation, but at the expense of top speed. The jack plate is a few hundred dollars, but it will stop cavitation, improve hole shot, give you a better top end (2-4 mph is average), and better fuel economy, not to mention it will add value to your boat. As far as what pitch you should be using, thats always a tough one. It is like understanding the rosetta stone to figure prop configuration. Just a guess, 13 1/2 X 24 should do it, as far as brand, if you're 120 tracker is a Johnson/evinrude, I would go to a Johnson /evinrude dealer ask their opinion. I don't think its a merc, but if it is, the fury or the laser II are great props.

[97nitrofisher]

OK so i did some more digging on my boat.

Prop is a Laser 2 3 plade 24pitch prop.

im still trying to figure out what the max RPM on the more is (97 120 tracker made by merc)

Yesterday on the water:
Me at WOT the boat is sitting at 5400-5500 RPM @ 48.5mph on the GPS. Speedo is not working but they read high anways .

what could i do to gain a few MPH . Lower pitch prop? I think the motor is spinning at max rpm.

best regards,

phil

[fish herman]

The prop and pitch sound right, and your rpm's sound right. Here's another suggestion. Is your prop vented? You can identify this by checking the hub for either round holes or square holes. The factory says: by plugging the holes you will get better top end, if you remove the plugs, you will get better bottom end. The plugs are available from any Merc dealer. I have an older LaserII that has the square vents, and mine runs best with all of them plugged. The only other suggestion would be to try the jack plate.

[97nitrofisher]

thanks,

i beleive the motor is also sitting way to low in the water. Is there a rule of thumb to go by how low the lower unit must sit in the water at full trim down?

yes my lazer prop has 3 open holes i beleive on the prop.

so by plugging them it should give me a better top end speed?

[fish herman]

Wow, I didn't even consider that, but here it goes. The optimum setting of the motor in relation to the hull is, the cavitation plate (the large plate on the lower unit) should be level with the bottom of the hull. Now this can vary a little higher or lower, but for best performance, you would want it a little higher. If you move the motor higher, be careful that you don't raise it too high, or you can run into cooling issues. So try to get the cavitation plate level with the hull, and then add plugs to the prop one at a time, and see how she does. There may be balance so try one at a time.

[Ron Fogelson]

yes my lazer prop has 3 open holes i beleive on the prop.

so by plugging them it should give me a better top end speed?

No those are ventilation holes, plugging them will affect your hole shot they have nothing to do with top end.  They are there to allow the prop to spin up faster when you 1st take off, the vents let exhaust from the motor to mix with the water so there isn't such a load on the motor at take off so a boater can use a bigger prop and or raise the motor up without killing the hole shot.

[fish herman]

HMMMM, I disagree, and I can only speak of my own experience, with the type of boat that i have with this application, that plugging all of the vents did make almost a 2 mph difference (on GPS) in my top end.

[froghog]

i had a 640lx with a 90 hp merc, and what  i can tell you is that when i bought my boat from bps new, the boat was NOT set up right. the motor was all the way down. if you are a run of the mill fisherman that set-up will do just fine. but i wan't to get all the mph's i could. i bought a Cherie picker and raised the motor one hole at a time, to find the optimum setting for speed. i did not care about the hole-shot. i had a stilletto prop which i found worked best, better than the laser II at same pitch?? it was a 23 pitch prop. it was a dog out of the hole but i got 52 mph (gps) with rpm's at 5500. i could slam the throttle down all the way and not worry about over reving. in a nut shell to get what you want (being realistic)you need to fine tune (trial and error) your set up's 

[97nitrofisher]

i had a 640lx with a 90 hp merc, and what  i can tell you is that when i bought my boat from bps new, the boat was NOT set up right. the motor was all the way down. if you are a run of the mill fisherman that set-up will do just fine. but i wan't to get all the mph's i could. i bought a Cherie picker and raised the motor one hole at a time, to find the optimum setting for speed. i did not care about the hole-shot. i had a stilletto prop which i found worked best, better than the laser II at same pitch?? it was a 23 pitch prop. it was a dog out of the hole but i got 52 mph (gps) with rpm's at 5500. i could slam the throttle down all the way and not worry about over reving. in a nut shell to get what you want (being realistic)you need to fine tune (trial and error) your set up's

I just took a look at the motor.
when they say they bottom of the motor has to be level with the bottom of the boat. Do you mean the back bottom or the bottom bottom be back where on plan the water sits on the vvery back. where the drain plugs are for the boat??

[fish herman]

Yes it would be the very bottom, where the drain plugs are. Your cavitation plate ( the large plate at the bottom of the motor) should be level or even with that lower part of your hull. It could be a little higher and that would be no problem, but definitely not any lower.