Another "which prop" thread

[Nathan R]

Hey guys, I am in a situation where I could use your advice. I bought a 1996 lund tyee 1950 magnum gransport with some transom damage and no motor. I am in the process of fixing the transom and I bought a 1999 mercury optimax 150 to power the old girl. The opti had a brand new factory powerhead installed in 2011 by a certified merc technician and has only 30 hours since the rebuild (the guy went up to a 225). With that known, I don't think it will have any age related power loss. I have looked at Mercury's prop calculator and it 's telling me that I should get something like a 16x 16p in a three blade aluminum or a 14.5x 17p four blade prop. A friend of mine is telling me that he doesn't think that is enough prop. So tell me what you guys think.

Specs :

Boat :
-1996 lund tyee 1950 magnum gransport
-weight : 1650 lbs
-length : 19' 8"
-beam : 90"
-fuel : 60 gallons (full)

Engine :
-1999 mercury optimax
- hp : 150
-weight : 432 lbs (dry)
-rpm : 5425

I would guess that most of the use will be for fishing with 2 guys, but I will be taking the kids out tubing from time to time. Fishing will be mostly walleye, but we go out to lakes superior and Michigan salmon fishing probably 4-5 times a year. Your advice is greatly appreciated. Thanks - Nathan

 

[jestor68]

Re: Another "which prop" thread

So what is it; a 150 or a 225?

I split the difference and called it a 200, since the gear ratio is the same up to 200.

Dry boat/motor is 2082. Add 500 for people/gear and 50 gal gas and you've got operating weight of about 2867.

Using 200 HP it recommends a 21 pitch right down the line and says it might do 47 mph @ 5400 rpm.

 

[Nathan R]

Re: Another "which prop" thread

Well the engine that I am going to be using is a 150 horse. Sorry if that was unclear in the list of specs, I didn't mean to confuse you. The previous owner of the engine that I am buying went up to a 225 on his boat which is why I was able to buy this motor . Thanks for the reply, but I need info for the 150.

 

[Nathan R]

Re: Another "which prop" thread

Through my research I think I have decided to go with a 4 blade prop. The calculators are telling me that a 14.5 x17p will be a good fit for my boat. Any thoughts on the Solas Rubex or Amita line of props?

 

[steelespike]

They are good props.They are the same but the Rubex has a removable hub.

 

[jestor68]

Re: Another "which prop" thread

Well the engine that I am going to be using is a 150 horse. Sorry if that was unclear in the list of specs, I didn't mean to confuse you. The previous owner of the engine that I am buying went up to a 225 on his boat which is why I was able to buy this motor . Thanks for the reply, but I need info for the 150.

Use a 17 pitch.

 

[Nathan R]

Thank you steelspike. I didn't know that they were the same prop. I will look at them more closely.

Thanks Jestor. I dont mean to sound ungrateful, but I don't see how either of your posts have helped me in my situation. Telling me to prop for a 200 horse motor when I have quite clearly said that I have a 150 doesn't help and could quite possibly lead to a costly mistake if I spent money on the wrong prop. Your next bit of advice is "use a 17 pitch." A 17 pitch what? This is where I am in danger of sounding ungrateful because of my own ignorance, but everything I have seen is telling me that I need to have a diameter and a pitch to get the right prop. I appreciate the replies, but muddying the water (so to speak) is making it more confusing than helpful.

I ended getting a 3 blade 15x17p from a local guy. I am going to give it e try and see how it fairs. At least it will be a starting point.

 

[jestor68]

Thank you steelspike. I didn't know that they were the same prop. I will look at them more closely.

Thanks Jestor. I dont mean to sound ungrateful, but I don't see how either of your posts have helped me in my situation. Telling me to prop for a 200 horse motor when I have quite clearly said that I have a 150 doesn't help and could quite possibly lead to a costly mistake if I spent money on the wrong prop. Your next bit of advice is "use a 17 pitch." A 17 pitch what? This is where I am in danger of sounding ungrateful because of my own ignorance, but everything I have seen is telling me that I need to have a diameter and a pitch to get the right prop. I appreciate the replies, but muddying the water (so to speak) is making it more confusing than helpful.

I ended getting a 3 blade 15x17p from a local guy. I am going to give it e try and see how it fairs. At least it will be a starting point.

It's cool. It was actually my fault (reading comprehension) in that I read that he put a 225 power head on it.

A "17 pitch" means exactly that. The Mercury prop selector lists all their 17 pitch props(al and SS). Some have slightly different (1/4 to 1/2 inch) diameters than others based on the prop material and design. But the answer/recommendation is based on pitch.

A 15 X 17 Black Max was on the list as well. A 14.5 X 17, and a 15.5 X 17 is also available by others. The performance difference between all might be 100-150 rpm.

You should run about 5300 rpm with the prop you selected.

 

[Nathan R]

Thank you Jestor. 5300 rpm should be a good max operating rpm.

 

[Nathan R]

That's confusing for someone who doesn't know anything about props. A q uick search on ebay shows 17p props everywherefr om 12.75 up to 16 inches in diameter. That's a difference of about 25 percent in the size of your "wheel." To a layman like me that seems like a lot.