19p to a 15p on force 125

[Deimus]

was looking to purchase a "tubing prop" for my little speed boat. problem im havin is im on and off plane because prop is too tall. runs great for speed or for adult tube rides but I need 1 for the kids. (always sayin slow down, or we're bogin out"


contantly on and off the throttle has the fuel consumption through the roof. would like to buy a prop just for tubin.

would a jump from a 19 to 15 be too drastic. I think it willl give me a lot more throttle and boat control when I want it.

any insight greatly appreciated.


or buy a 17 and a 15 and make a cool little prop box with wrench on the trailer.(its an idea)

 

[Dhadley]

Re: 19p to a 15p on force 125

I think you're on the right track as to the pitch. If the 15 is too small you can always have a prop shop add bite. Props in a box on trailers tend to come up missing. Doesn't seem to matter if it's locked or not, they have a habit of leaking out.

 

[JoeCrow]

Re: 19p to a 15p on force 125

19 to 15 seems like quite a jump
What are the rpm's like now?
If they're in range, a 15p prop might put you through the roof as far as rpm's go
I dropped my planing speed drastically by adding a set of smart tabs
and at about $100 they're probably cheaper than a decent prop
Joe

 

[Frank Acampora]

Re: 19p to a 15p on force 125

Planing speed is a function of hull design and load distribution inside the boat, not prop pitch. If your hull planes at 18 MPH and you are dragging the kids at 15, it isn't going to plane with any prop. Or if you have a whole bunch of weight in the stern, your planing speed will be higher; but again, it will be the same with any prop.

So take the advice above regarding trim tabs, try a removeable hydrofoil, (Yeowch--can't believe I'm recommending that) or simply redistribute load in the boat to see if that helps.

Without knowing RPM, and the size of "your little boat" I can't really comment on pitch, but a 19 to 15 pitch change will increase RPM about 800 at wide open throttle. You will probably have a great hole shot but your top speed will be lower.

 

[walk-on]

Re: 19p to a 15p on force 125

I went from a 19 stock to a 17 inch hustler and kept the same top speed with better hole shot which really surprised me so going to a 15 might not be such a stretch. When I have my kids on the tube I just keep the motor trimmed down then trim up if needed to achieve the speed they want.

 

[triumphrick]

Re: 19p to a 15p on force 125

I just dropped down from a 17 to a 15 and it really helped the rpms. I found an interesting site when I was shopping props. It lets you enter your motor and boat info along with gallons of fuel plus any extra weight you may carry and spits out a couple of recommended props. Here is the site...
EDIT;
Can't allow this direct link to competition...we sell many brands of props right here, and if consultation is needed, we got the best of that here too.

 

[walk-on]

Re: 19p to a 15p on force 125

HaHa that's so funny! I bought my prop from Dan's two years ago but he didn't factor the boat into the equation back then. Two props were chosen for my setup - 17 for sport and 19 for speed. I'd say it's probably right on.

That's great info triumphrick!

 

[Deimus]

Re: 19p to a 15p on force 125

boat seems to be running great with adult or adolesent tubers. slighty lugged but OK. problem being " MY KIDS" are 7 and 8. just startin the tubin think and are always sayin I need to slow down. I think a smaller prop will give me a better "stick feel" to fine tune the fun. am I correct in this?

Been a while for me and first couple times for my family!!

some pics to follow,(hopefully)

http://i104.photobucket.com/albums/m196/Deimus77/Firstboatru007.jpg

http://i104.photobucket.com/albums/m196/Deimus77/Firstboatru013.jpg

http://i104.photobucket.com/albums/m196/Deimus77/Firstboatru014.jpg

http://i104.photobucket.com/albums/m196/Deimus77/Firstboatru008.jpg

Thanks for all the good info.

BONUS QUESTION: any body know of a cool fold down swim ladder?!!

 

[Deimus]

Re: 19p to a 15p on force 125

searchin around and found an old post of mine. never got a good answer.

What about Paranha props? worth tryin?

could have the bag of "fins" under the seat.

Its a thought.

http://i104.photobucket.com/albums/m196/Deimus77/bike007.jpg

 

[imported_Voyager]

Re: 19p to a 15p on force 125

You might consider going to a 4-blade, 15 pitch for pulling tubes. The increased blade area lowers rpm a bit from what you'd expect with the pitch change, gives lots of thrust and (reportedly) will let you plane at a lower speed. If rpms are too high, you could have the pitch adjusted up at your prop shop.

 

[rndn]

Re: 19p to a 15p on force 125

You might consider going to a 4-blade, 15 pitch for pulling tubes. The increased blade area lowers rpm a bit from what you'd expect with the pitch change, gives lots of thrust and (reportedly) will let you plane at a lower speed. If rpms are too high, you could have the pitch adjusted up at your prop shop.

I was able to lower my planing speed on my Baja by 4-5 mph by putting a 4 blade SS Stiletto prop onto it's 5.7 liter Mercruiser Alpha One. It also helped the hole shot and improved fuel mileage. It's a lot more money than a set of smart tabs, but I just wanted you to have the information.