Dialing in the props...
 

Long story short I'm ready to set up my props.
I'm running out of the box 26" Bravo 4 blades on 1.3 ratio drives, spinning out.
I calculated 9-10% slippage.
1993 42' Fountain Non step with drive boxes and -2 lower B-max's
Turning 5100rpm now and would like to see 5500...Loosing 80hp a motor with that missing 400rpm.

So...
How much rpm/mph could be gained from a lab job?
Do I need to pull an inch or so out of the pitch?
I also need more bow lift?...I over trim it now to get the bow up enough at WOT.
Does lift have to do with blade rake?...or spinning them in instead?

Re: Dialing in the props...
 

Never delt with a twin set-up, but trying many different things is the only way to really find out!! Labbing the 26's should give you 200 RPM or so. Will 3-blade props work? Some 25 Mirage's may help to get you some more bow lift. I'm really talking from my ass when it comes to getting a 42' twin engine Fountain propped. :p Good luck!!!

Craig

Re: Dialing in the props...
 

Hi Mark,
Happy Holidays
Although my favorite holiday is July 4th. :p

The older Fountains seem to like Hydromotive props.
Guess I'd play with your Bravo props and see what you can get out of them.
If you have some time on your hands give Jim Hering a call - 360-659-4315
Fountain racing has since gone to Hering with excellent results.
Oh yeh, I have a few projects myself to attend to over the winter. :drink:
Dennis

Re: Dialing in the props...
 

:rolleyes:

Re: Dialing in the props...
 

Call throttle up,Matt or Julie.Great people to work with!

Re: Dialing in the props...
 

You would do better by changing to 1.5 ratio drives, then dial in the props.

Re: Dialing in the props...
 

The 1.5 ratio would most likely be a better gear ratio. But if you do not plan on changing gear ratio the Hydromotive Quad IV would be a great prop to start with. Many Fountains but when your boat was were factory equipped with Hydromotive props.

There are many considerations when making a prop selection and having prop work done. It's important to make sure that whomever you are working with understands your goals and works the prop or makes a prop suggestion that fits those goals.

Matt

Re: Dialing in the props...
 

Turning them in will give you more bow lift & usually a litle more speed on an older fountain. The hydromotive Q IV seems to work best. I have an old 10 meter & have played with many props.

Re: Dialing in the props...
 

Backfourmore,Labbing will get 250 rpm and our Bravo-Rator design will get the extra Bow lift and rpm you need ,I would not pitch them down just yet,give me a call when you can.

Darin 281-580-7767

Re: Dialing in the props...
 

Sorry to jump in ,

Darin, what would the cost be to repitch the 2) 26 hydro Q-IV's you labbed for me last spring up to 27".

Thanks

Re: Dialing in the props...
 

Happy Holiday's ,25.00 per blade satin finish,polished will be 50.00 per blade,you been good to me and I,AM MORE THAN WILLING TO GIVE YOU a Christmas present,send this in with the props and when we are ready to ship. I will call you ,oh! shipping and handling is 25.00 per propeller.Tanks for asking Darin,Later

Re: Dialing in the props...
 

Bow lift does have to do with the blade rake. A high rake blade design (the blades angle toward the stern of the boat) will induce bow lift. A low rake blade will induce stern lift.

I am surprised you need more bow lift. Most fountains need stern lift. I would try some Hyro's on your boat before you put money into the props you have now.
Have you raised the drive height?
Your slip seems a little low for your boat. Did you calculate slip with gps speed? Are you sure the tachs are accurate?

Matt

Re: Dialing in the props...
 

back four more,we will do what you want,send the props in and we will not charge you until you run them and are satisfied. Happy Holiday's

Re: Dialing in the props...
 

Thanks for the replies! :cool: