Help with a Nitro LX640 with 60 HP Merc

[RippnLipz]

Well you have a starting point now. Sounds like you were very under propped for one. Ideally your best option is to find someone with this prop so you can test before you buy, I would also test one pitch up. At about 4-500 for the mercury vengence prop its a bit spendy when you dont know exactly what you want. I see the 4 blade solas is under 200...I have heard a few guys say going to a 4 blade gave them some more torque. Im afraid you need to do some testing, which can be challenging without spending money.

 

[Larry]

Great! Maybe I could pick up a few on ebay (not used) to start. The lake is shallow with big stones here and there, so my props get nicked easily. Any suggestion how high to go up on the pitch from 13? Like 14, then 16?
I have to get the # off the engine and get a technician's manual like you suggested. Thanks again!

 

[RippnLipz]

I probably wouldn't go more than 1 or 2 pitches up, but it doesn't hurt to test if you have the prop to try. Depends on prop manufacture too, they all are a bit different. You will know if you go too high as you will not be able to hit max rpm( its key that your motor hits this limit. Start with boat trimmed all the way down, then when it gets out of the hole and bow drops trim up until you find sweet spot, you will hear and feel it when its there). Is your motor a 2 or 4 stroke? With 2 strokes you want the prop to be able to easily spin up into the power band, four strokes have pretty even power bands. Your tech manual will have a prop table like this with all the manufactures listed

 

[Larry]

Okay. Is it true that a stainless would be a bad choice with the shallow bottom and rocks? I always used aluminum on the Delaware. Once I bent the lower shaft. Someone was able to repair but eventaually the motor gave up the ghost.

 

[Larry]

Sorry it's a 4 stroke Mercury 60HP.

 

[olefisherman456]

White River claims that the original prop for a 2005 Nitro LX with a 60 HP Mercury 4 stroke is 10.5 x 13. Can I replace that with a higher pitch or diameter. Will it help to pull more weight? Will it prevent me from finding the sweet spot on the trim to get the motor from 3500 to 5500? HELP!

my thinking is that the 60 hp is just about maxed out with normal fishing load . any additional weight or drag will really be obvious. with mine even a full livewell is notesable

 

[RippnLipz]

Okay. Is it true that a stainless would be a bad choice with the shallow bottom and rocks? I always used aluminum on the Delaware. Once I bent the lower shaft. Someone was able to repair but eventaually the motor gave up the ghost.

No stainless is your best option....hitting rocks is bad no matter what. In my area we have a lot of sand and it seems to be pretty abrasive on aluminum props wearing them quickly in some cases. Even small changes in prop blades can effect performance drastically. Some of the speed guys even get brand new props blueprinted and tuned before use.

 

[RippnLipz]

my thinking is that the 60 hp is just about maxed out with normal fishing load . any additional weight or drag will really be obvious. with mine even a full livewell is notesable

Ya I dont think it will ever be enough to drag tubes and skiers efficiently. Dialed in it will make a great fishing/cruising motor though.

 

[Larry]

Sorry it's a 4 stroke Mercury 60HP.

 

[Larry]

Is there someone out there who owns a Nitro LX 640 with a 60hp mercury 4 stroke that uses it to tow kids on a tube or ski?

 

[Pat Dilling]

Larry, it sounds like you may not be familiar with how the power trim function works. The trim function is like shifting gears in a car. All the way down is like low gear. It makes it easier for the motor to get the car moving. Raising the trim part way is like shifting into second, and then into high gear at higher speeds. When you are intially starting to move the boat, the trim should be all the way down(1st gear). This keeps the nose down and helps the boat get up on plane. Once it is up on plane, start raising the trim (2nd gear). Doing this lifts the bow of the boat out of the water. This reduces the water resistance on the hull and allows the boat to gain speed and the motor RPM to increase and generate more power (higher trim = high gear). You do not need to raise the trim all the way on the gauge to get the best performance. If you trim too much, the prop can lose its bite on the water, like losing traction with a car. Or, it may cause the bow of the boat to bounce up and down, called porpoising. Your moving the two heavy batteries to the front of the boat will make lifting the bow more difficult. Why did you move the batteries? How much other "stuff" do you have in the front of the boat? The balance of the boat and center of gravity is a key element of the boats performance. Hope that helps.

 

[Larry]

I am learning about power trim although I had a Tracker ProV 16 with a 2 stroke merc for 20 years and I never had to trim like I do in my Nitro. I was able to fish, ski, and tube without making adjustments.
The transom was almost under water when I had the trim down all the way. The previous owner had 3 batteries in the back (2 for a 24 v trolling motor). The tank is in the back as well. When I return to dock slowly because I'm the lake is shallow (12-18inches at my dock), I have to trim down to get the transom from submerging. There's no weight on the bow except the trolling motor and two 8lb anchors.
I weigh 175 lbs. The grandkids to are 50-80 lbs. No more than 3 people get on board.

 

[RippnLipz]

I would also move those batteries back to the stern. Its not helping your hole shot any to have them up there....unless of course you have a particular arrangement that requires them to be there. With tubes you are just dragging, but with a skier you need to be able to get em up and also get the boat up to get on plane so its got some inertia and speed to pull. Weighing your bow down will hurt you in this case.