prop help

[onmedic]

Fairly new to boating, have never bought a prop before. I need one. i plugged in all my info into a prop wizard typle program, well two of the actually and both came up with the same spec prop for my boat. I need a 13.25 X 17. The one that is on the boat is a 13.25X19. Obviously i will get more rpm out of the 17 which will put it into my power area as it was not before.
I have found a prop for sale locally. Its new and is the one i need. how do i know if it will fit. Is there several different spline counts? my current prop has the kit on it that fits inside the prop and is supposed to break off instead of wrecking the pop. I guess thats the "kit" that everyone says you need. Just don't want to buy this prop and find out it won't go on

Thanks

Bryan

 

[steelespike]

Re: prop help

We need a lot more info to help you out.Please read the stickies at the top of the page and the helps on the prop store page.Boat brand,model,dry weight.
motor brand,year and hp.Rpm rating. Rpm and speed with present prop.
Will be glad to help with any remaining confusion or questions after reading stickies.

 

[onmedic]

Re: prop help

motor is a 4 stroke 2003 mercury. rpm range is 5500 to 6000 at full throttle range. Boat is a 1999 sea nymph sportfisher gls 195. at full throttle is was getting 5000 rpm and doing 45, i have no idea what dry weight is. This is using the current 13.25X19 prop that was on the boat. all 3 blades have the very ends missing, skeg is fine its just the prop. no vibration is felt but it certainly needs replacing, obviously can't be spinning true anymore.

 

[steelespike]

Re: prop help

You can probably get the prop fixed and get new numbers.Easier to tell what you need with more accurate numbers.Is the antivent plate just above the prop visable on plane?
Are you sure the throttle opens all the way at the motor?If you can raise the motor 2 to 3" you could gain up to 2 to 3mph and some rpm.

 

[steelespike]

Re: prop help

motor is a 4 stroke 2003 mercury. rpm range is 5500 to 6000 at full throttle range. Boat is a 1999 sea nymph sportfisher gls 195. at full throttle is was getting 5000 rpm and doing 45, i have no idea what dry weight is. This is using the current 13.25X19 prop that was on the boat. all 3 blades have the very ends missing, skeg is fine its just the prop. no vibration is felt but it certainly needs replacing, obviously can't be spinning true anymore.

Horsepower?

 

[onmedic]

Re: prop help

sorry 90hp. I've had two guys, one a marine mechanic tell me that the prop needs replacing, its not spinning true and will take out seals sooner or later so it should be replaced. i agree. A local guy is selling a new prop, its a 13.25X17, just want to know if there are different spline numbers or how that works. If you have the kit, will these props work? I've already ran the numbers through prop wizard to find out what prop, so now i have the size and pitch i need which corresponds with all the info prop wizard took from me. Just need to know if with the kit, are props universal in fit?

 

[steelespike]

Re: prop help

While some brands share props; you need a prop for a merc. 2 or 4 stroke 90 hp
15 spline 77 on up.I believe Merc brand prop numbers begin with 48.
You could very well need a new prop but I think a prop shop can tell better if they can repair your prop and be cost effective.
Prop calculators are only as accurate as the amount and accuracy of the input.
I've seen similar boats with identical motors take props one or 2 sizes different.
Your 17 is in the ball park.Do you have your present rpm and speed?
You shouldn't change props without a tach.Your motor needs to run near the high end of its rated rpm, running too far above or below will eventually cause more serious problems than your bad prop.Not to mention suffering with inefficient poor performance.

 

[onmedic]

Re: prop help

ah, ok, now i'm getting somewhere. So, the hub kit does not make any old prop fit it still must be designed for a merc. Ok, that helps huge. The whole prop issue was not on my mind until a couple guys said "man i'd replace that prop" so to tell you the truth i didn't pay a great amount of attention to the speed and rpm, was more concerned with my kicked and getting 2.2mph for lakers. I've have her pinned and noted 5000 rpm and was doing 45 on the gps.

 

[steelespike]

Re: prop help

ah, ok, now i'm getting somewhere. So, the hub kit does not make any old prop fit it still must be designed for a merc. Ok, that helps huge. The whole prop issue was not on my mind until a couple guys said "man i'd replace that prop" so to tell you the truth i didn't pay a great amount of attention to the speed and rpm, was more concerned with my kicked and getting 2.2mph for lakers. I've have her pinned and noted 5000 rpm and was doing 45 on the gps.

If a prop has a replaceable hub ie: you slip it out and slip in a hub for your type prop
then yes that prop could work. Most props are dedicated to a specific brand and size
motor.
Before changing props you should fine tune your setup.The antivent plate(just above the prop) should be visable on plane.Raising the motor could gain both rpm and speed.
Assuming your motor is well tuned and reaching full throttle opening and the setup is right it does appear you would do better wth a 17" prop.

 

[onmedic]

Re: prop help

ok, thank you. boat is now out of the water and is going to the shop. I will make sure the mechanic checks to see that throttle is at full and maybe i'll just wait until after my first outing next spring and pay real close attention to full throttle rpm and vent.
Thanks again for helping a rookie

 

[steelespike]

Re: prop help

Sounds like a plan.