Boat question

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Crjmech

Crjmech

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This might not be right place for this but...I’m sure there’s a few guys in my my situation. I got a free boat from a buddy of mine last year. It’s a 16’ tracker pro guide with a 50hp Mercury 2stroke. I tried talking him into the 75 when he bought it new but he decided to save the money and go with the 50. Im not going to complain about a free boat but as you can imagine, it’s rather under powered. I really don’t mind the boat. It handles big water pretty well. I’ve got 2 props for it and neither make much difference. I’m considering repowering. 2options im looking at. Either a new 75hp 4 stroke or a used reman 75 2 stroke like an optimax. I’m wondering what to realistically expect on top end speed going from the 50 to a 75. I get 26mph on a good day now. Anyone in a similar situation with real input? I’m leaning towards an optimax due to weight and price.
 
What is your end goal? Push more gear around better? More speed? We have a 18’ fish hawk with a 115 and our top speed is low to mid 30’s. If speed is your end goal personally it would take like 20mph difference for me to want to power up. Maybe you would get that out of a bump to a 75, not sure?

If you’re in dire straits getting a loaded boat up fast or something it might be different.

One more thing to think about is you probably get amazing mileage out of the 50, of also guess you’re not bumping up your gas tank size with a bump in motor.

Just some thoughts.
 
I had a Lund 1660 with a 60 HP 4-stroke Merc. With two people in it I would get around 30 MPH at Powell. i don’t think you would get a lot more with a 75 HP 4-stroke.

If MPH is the primary concern, I’d try to go to 90 HP. And a 2-stroke will likely have a higher top end than a 4 stroke.
Personally I don’t think I’ll ever own another 2 stroke outboard (outside of an etec). Just too loud, smelly, inefficient.

If I were in your shoes I’d likely either keep the boat as is or sell it and buy what you really want.
 
Dungee Fishing said:
What is your end goal? Push more gear around better? More speed? We have a 18’ fish hawk with a 115 and our top speed is low to mid 30’s. If speed is your end goal personally it would take like 20mph difference for me to want to power up. Maybe you would get that out of a bump to a 75, not sure?

If you’re in dire straits getting a loaded boat up fast or something it might be different.

One more thing to think about is you probably get amazing mileage out of the 50, of also guess you’re not bumping up your gas tank size with a bump in motor.

Just some thoughts.
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I’d be happy with a 10mph gain. I feel like the boat just doesn’t get on top of the water very well and wanting to fish Powell more, I’d like to not be in everyone’s way plugging along at 25.
 
I have the Tracker 16’ V-Guide, it had a 25 Mercury Mariner and could barely get on plane. I re-powered to a 60 hp Mercury 4 stroke and at wot it will do 30 to 32 mph with 2 people/gear. It sips gas. Very happy with this upgrade. Sq
 
I do not think the difference between the 50 and the 75 is gong to do much for you. I am also of the opinion that most of your cruising should be done at way less than max rpm's if you want that motor to last. my guess is that if your current max speed is 26 mph at say 5500 rpm, your cruise speed would be 22ish at 3500 rpm -- if you move to the 75, your 3500 rpm cruise speed might be 26 or so -- lots of money to spend for not much mph -- I also would suggest selling the 16ft boat and get something with a lot more HP already installed.
 
I had a tracker tournament v 17 with a 85hp 2 stroke Yamaha -- it would do 40+ at Powell and cruise at 32 to 35 all day long. That was a great boat if the waters were calm.
 
davew said:
I do not think the difference between the 50 and the 75 is gong to do much for you. I am also of the opinion that most of your cruising should be done at way less than max rpm's if you want that motor to last. my guess is that if your current max speed is 26 mph at say 5500 rpm, your cruise speed would be 22ish at 3500 rpm -- if you move to the 75, your 3500 rpm cruise speed might be 26 or so -- lots of money to spend for not much mph -- I also would suggest selling the 16ft boat and get something with a lot more HP already installed.
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Oh trust me, I’d love to get a different boat but momma wants a new car first lol. I’m thinking repower to get a few more years out of the free boat. Id like to be able to get 5500rpm. I have an 11p and 9p prop and neither will get 5500 at Powell. I’ve always thought maybe something was wrong with the motor. I suppose a 500 rpm gain would be worth a few mph. Maybe I’ll let a shop take a look before making the plunge. I’m thinking a half again gain of hp would make a difference but maybe that isn’t the case. That’s why we pose these questions lol
 
Squirrel said:
I have the Tracker 16’ V-Guide, it had a 25 Mercury Mariner and could barely get on plane. I re-powered to a 60 hp Mercury 4 stroke and at wot it will do 30 to 32 mph with 2 people/gear. It sips gas. Very happy with this upgrade. Sq
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I considered that switch as well but from what I understand, the weight difference between the 50 2 stroke and the 60 4 stroke is too much for the 10hp increase to do much. Now going from 25 to 60 would be huge
 
you need to find out why you are not getting to max rpm -- for the 50 -- the max rpm is 5000 to 5500 -- if you can not hit that, your engine is working to hard at ALL rpm ranges. I would 1st talk to a prop provider -- they will be able to point out some items. -- how are you checking RPM's? many of the dial rpm gauges are off -- you can get a photo laser tach from amazon for $20 ---https://www.amazon.com/CyberTech-Digital-Photo-Tachometer-Contact/dp/B001N4QY66 --- that will tell you what you need to know on rpm -- then adjust prop to get to the 5000 to 5500 rpm --
what is max HP allowed on the boat?
 
I switched on my 17’ boat from a 90 2stroke to a 115 4stroke. Went from 32 mph at 5800 to now running 42 at 5200 and using less gas. 44 wide open. It’s tough to find the right prop on 4strokes to max things out. Don’t come out of the hole fast but up lake 15 mins faster and less gas. Can carry a conversation now without yelling while cruising. Worth the switch.
 
I would check what the max hp is for your particular boat before a change in motor. Look at the weight distribution in the boat as well. Then see a prop guy like was mentioned. If you are operating at Powell check to see if it has the appropriate jets in if it is a carbed motor for altitude. I had that happen to me once on a new boat. Sea level jets.
I guess I'm saying rule out the cheaper stuff before getting a new motor. Good luck
 
One thing on my Tracker said max hp is 40 hp. The 40, 50 and 60 hp Merc 4 strokes weigh the exact same. They change the hp with ignition and exhaust modifications. I also reinforced the transom with 3/8” aluminum diamond plate. I’m happy with the repower. Sq
 
Unless your boat is way loaded down, it’s hard to believe it won’t get to WOT RPM with a 9 pitch prop.
 
Where do you live? here at Powell or down low in the valley?
Remember when up here in the summer you will only get 75% of your rated horsepower due to altitude (actually density altitude) on a warm day. So you are running with about 37 hp.
Make sure your motor is running right to begin with. When was it looked at last by a competent shop. Ignition, plugs, fuel delivery etc.
Next look at what wide open throttle does with RPM. It HAS to be delivering full RPM even up here for the highest HP delivery. What is the rated RPM? If it doesn't turn that you need a different prop. If its turning that RPM and you don't like the speed THEN you need more motor IF the boat is rated for it.
 
The boat is rated for 75hp max motor weight of 400 ish. Can’t remember exactly. It came from Colorado. We ran at 5500’. Maybe I’ll take it to a shop. Haven’t heard anything good about any shops around here.
 
Check carb fuel jets Even if it came from Colorado it may have never had high altitude jets put in.
Just remember you'll need the low altitude jets back in if you ever go down to low altitude to run it. That's the bad part of carbs.
 
Cliff said:
Where do you live? here at Powell or down low in the valley?
Remember when up here in the summer you will only get 75% of your rated horsepower due to altitude (actually density altitude) on a warm day. So you are running with about 37 hp.
Make sure your motor is running right to begin with. When was it looked at last by a competent shop. Ignition, plugs, fuel delivery etc.
Next look at what wide open throttle does with RPM. It HAS to be delivering full RPM even up here for the highest HP delivery. What is the rated RPM? If it doesn't turn that you need a different prop. If its turning that RPM and you don't like the speed THEN you need more motor IF the boat is rated for it.
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Not trying to nit-pick, but you are only down a little over 9% in HP at Powell - you lose 3% for every 1000’ in elevation.

coming from Colorado, I always have thought of Powellas a low elevation lake.....😎
 
Try again-
Its not physical altitude but DENSITY ALTITUDE that counts in that computation. Call up the airport weather service for Page airport and get the DENSITY ALTITUDE read out for the day and then figure your 3% per 1000' Most days in the summer are 7500 feet for density altitude.
We have to figure that in for every takeoff at high altitude airports. Temperature affects the density of the air making it "thinner" than what the physical altitude would lead one to believe.
7500 feet of density altitude equates to about 3/4 of your rated horsepower. A 200 HP airplane engine makes 150 HP at 7500 feet. Basic pilot stuff.
The 3% only works on physical altitude if it is a "Standard Day" and that means the temperature drops with altitude. Here in the summer the temp never gets down to Standard Day Temperature

This is what kills a lot of pilots from the low altitude airports going to a high and hot airport for the first time.
 
I’m an A&P mechanic so im good with all the altitude stuff. Atleast on an airplane you can Adjust your mixture. Too bad boats don’t have a mixture knob. I also fix ATVs and side by sides but I hate boat motors for some reason. Just one more reason to go efi or dfi like the optimax lol. I may just buy some jets and see what I can do. But, even a 500 rpm increase will only see 2-3 mph gain so I’ll be chugging along at 27-28mph instead of 25-26. I know these carbs have never been opened since the boat was bought in Denver. Maybe I’ll call basspro and see if jetting is something they even do prior to delivery.
 
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