is this the right prop or is there something better

[freddiejip]

I have a 2007 Polarkraft 16' with a 60 hp Evinrude E-tec. With me and my uncle in the boat, about 550 pounds we can run between 26 and 28 mph. If my memory serves me right it is running right around 5700 rpms. Just wondering if the speed was about right. If not what would a different prob do for me? I am very green at the whole boatiing thing but am a big time fishing lover. My prop is 13.5x15, whatever that means, and is a 3 fin. Thanx for the info.

 

[freddyray21]

Re: is this the right prop or is there something better

your prop numbers mean it is 13.5 inches across and a 15 pitch. Pitch is the theoretical distance a prop will push a boat in one revolution. In your case 15 inches. It never works out that way as there are too many other factors affecting that number. IMO your tach is about right, but it may not hurt to go down to a 13 pitch and you will gain about 2-300 rpms. You will in theory loose a little speed, but gain in holeshot.

 

[5150abf]

Re: is this the right prop or is there something better

Boats are different than cars in that they have one "gear", the prop, so imagine finding one gear for your car that will fit all situations, too small and you over rev, too big and it lugs.

Boats are propped to reach a target RPM so you need to find out what your operating RPM is and prop to that.

For that boat and motor it sounds about right, I have a 16' v-hull with a 50 and run about that same speed(25-28 GPS) and have read several test on new boats in that HP and size range and that is close to top speed for that set up.

Speed on water is hard to come by.

 

[hwsiii]

Re: is this the right prop or is there something better

Freddy, if you really want to see if you can gain more speed with your boat I have a couple of forms I can send you to fill out and we can use those to see if there is a better prop for your boat. I just need your email address.

H

 

[steelespike]

Re: is this the right prop or is there something better

Assuming you have the factory 15" prop your about right.
The tests I've seen of similar boats they run 15" props at about 5,700 rpm.
28-32 mph depending on the boat.If your looking for a little more speed you might try a Turning point prop.they give close to stainless performance at aluminum prices.If you have no venting(cavitation) problems You could try raising the motor a hole.careful weight distribution and motor trim will help as well.Don't look for a major speed increase but a couple of mph may be possible.You might confirm your speed with a gps.

 

[freddyray21]

Re: is this the right prop or is there something better

H you have a pm

 

[Rancherlee]

Re: is this the right prop or is there something better

Is that GPS speed? I think you should be getting 30+ mph out of that boat, honestly. My 16' Mr.pike with waterlogged foam, 3 people, 3 deep cycle batteries, full livewell, and a cooler would run 25mph with a 79' 55hp johnson (less than 50hp prop rated). Redid the foam, floor, carpet and it ran 27mph with the same load. Bolted on a 70hp Johnson 4 stroke and get 35mph out of it with the same load. I would expect a modern Deep V hull to be more efficient than my Older Semi V Lund also.

 

[freddiejip]

Re: is this the right prop or is there something better

No that was not gps speed but what i have checked with a gps its not far off if any. Mine is aluminum and it is a fairly heavy boat. I think one thing that might be dragging me back is the fact that it has 5 keels if I am calling it the right thing, they are under the boat anyways for stability. It also has a 17 gallon inboard tank. When i am alone in the boat I am taching about 6100 and the boat is flying, well i think it is anyways for me. I can take my parents me and my wife in the boat and it planes off no problem, but it takes awhile to get there and I am still running the same speed, about 5700 rpm's. When i am alone at between 6-6100 rpms, it is between 30-31 mph. I'm not really looking for more top speed i just wanna be able to get up out of the hole and plane off alot quicker and not really lose much top end. I know if someone could figure it out they would be a millionaire.

 

[hwsiii]

Re: is this the right prop or is there something better

Freddie, I am sorry but I have to go right now, have to take my grandkids out to eat. But in my opinion you are wasting a lot of toque and horsepower on the 13.5" prop, as you don't need that much diameter prop to push the boat with the motor and load you are carrying. I do want to know the manufacturer and model of the prop you are now using, because I could be wrong, it could have a very low blade surface area but that is not normally true. If we decrease the diameter and increase the pitch I expect you to have a better holeshot with a higher speed. Normally these two things are at odds with each other, when you increase pitch to attain higher speeds your hole shot goes down and it takes longer to get on plane. But when the diameter of a prop is larger than required for the boat, load and horsepower all it does is absorb the load developed by the horsepower and torque from your motor eating up the excess power with no useful purpose other than to lower your RPM.

H

 

[freddiejip]

Re: is this the right prop or is there something better

The prop is what came on it when i bought the boat and motor new in 2007. It had a yamaha 40 on the boat but i told them i was extremely unhappy with the performance of that motor because we had me, my wife, brother in law and mechanic in the boat and the speedo would not even move. Alot of arguing and convincing and i got the e-tec 60 put on for $900 extra. It was a hurry up and get it mounted thing so they may not have matched the prop for the boat. If I am really pushing some water, part way between just idling and planed off it seems to have a real hard time coming up to plane with a load in the boat.