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Prop Size Selection/Material
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Author:  millhaven_nice_guy [ Mon Jan 21, 2008 2:56 pm ]
Post subject:  Prop Size Selection/Material
I have a 2001 Horizon H260 with 7.4 Gi and a duoprop. I need to purchase a spare prop and was wondering if anybody has tried the new "plastic" ones?
Also I would like to increase the top end speed a bit. I currently have a F5 set on the boat that pushes the boat to about 48 on the speedo at WOT of 4800 rpm. Should I get a size 4 or 6?
Author:  jnizi [ Mon Jan 21, 2008 5:24 pm ]
Post subject:  Re: Prop Size Selection/Material
We increased our hole shot by dropping to a F3 from a F4. We lost about 2 mph on our top end. My guess is that you would be looking at the F6. The only thing to watch is that you don't exceed the engine RPM at WOT.

We have thought about getting a set of the composites as spare but I have also been keeping an eye on ebay for a SS set for now. Still a few months before she is back in the water.

Don't forget your DP wrench.
Author:  cozzy530 [ Sun Jun 01, 2008 9:14 am ]
Post subject:  Re: Prop Size Selection/Material
I just bought the pirana 4 bladed composite prop. I did not get more than 300 feet from the ramp when a blade broke after hitting something at clutch speed in soft mud. My aluminum blade cut through mud pretty easy so I am not impressed with the composite. On the plus side the blades are replaceable so I do not need to replace the whole prop. I only got the boat in the water this week so I haven't been able to really test it.
Author:  M3eater [ Sun Jun 01, 2008 10:02 am ]
Post subject:  Re: Prop Size Selection/Material
The F6 is higher pitch and the F4 is lower pitch. You'd want an F6 for more potential speed. The F4 would give a faster hole-shot, but higher RPM at any given speed.

The F6 has more pitch and will, therefore, likely lower the WOT RPM by a couple hundred RPM, and may give a couple/few MPH. It will also lower your RPM at any given cruise speed. If you're doing 4800 on an F5 set (fully trimmed for higherst RPM and speed), I'm not sure that you want to lower the WOT RPM any lower than the curent 4800 rpm.

Four Winns states that the 7.4 in this year should top out at about 5000 RPM and be running in the low 50 mph range. Both your RPM and your speed seem a bit low. Are you sure that you are properly trimming the drive for best speed .... when that is the goal?

Your boat weighs just 300 lbs (more or less) than our 245 Sundowner and we had the 5.7Gsi-DP (280hp) with an F6 prop set. I could just tickle 50mph with the canves down, four people, smooth water and a proper trim.

I would be looking at why your boat seems to be, maybe, a bit sluggish. How many hours? Any recent "tune-up" work? Are you carrying a bunch of gear that would make the boat a lot heavier than normal (we had quite a bit of gear on our 245)?

If there are now composite sets for the DP, I can only recommend them as emergency spares on a heavy, high HP, boat.

Edit - In ref. to the DP composites, I found this too:

http://www.piranha.com/show_article.php?id=12
Author:  230 Mike [ Sun Jun 01, 2008 2:16 pm ]
Post subject:  Re: Prop Size Selection/Material
I echo Gordon's thoughts exactly. You should be making closer to 5,000rpm with the F5's (assuming they're the stock configuration - call FW if you aren't sure), and the last thing I'd recommend is decreasing that even more by up-propping for the sake of a couple mph.
Author:  Flying Sushi [ Sun Jun 01, 2008 3:55 pm ]
Post subject:  Re: Prop Size Selection/Material
I have a F6 in my H260 and it feels just right.. The big block has torque in low RPM so hole shot is not a issue even with 10 people on the boat. Our boat tops out around 54hph and it is not bad for such a big bowrider. If we cruise around 40 to 45 mph and punch the throttle the boat will take off….. Great feeling… (although I can hear gas pump is calling me)
Author:  Blessed [ Sun Jun 01, 2008 5:12 pm ]
Post subject:  Re: Prop Size Selection/Material
FS - Is that a late 70's Pantera you have in your driveway? For Real? If you have one of those, man you have gotta post no doubt everybody here can appreciate such a cool ride . . .
Author:  Flying Sushi [ Sun Jun 01, 2008 7:10 pm ]
Post subject:  Re: Prop Size Selection/Material
Blessed:
Wow you have a good eyes...

It is a 87 Pantera GT5-S. I also own a1970 Mangusta which I am restoring for last 9 years as well.
Author:  Blessed [ Sun Jun 01, 2008 7:31 pm ]
Post subject:  Re: Prop Size Selection/Material
:shock: YOU HAVE A '70 MAGUSTA :shock: ? OMG that must be like in my top 5 of all time favorites . . . I think along with a Late 60s E-Type, Macleran F1, Mucialago and 63 Split Window Vette. I have have always wanted a Pantera - Especially a GT5. I looked for years to find one I could afford but alas my priorites changed with the resources I had available to me. But a Magusta . . . Wow, I never imagined there were any of those anywhere except maybe in Jay Lenos collection. You're not really Jay Leno are you? OH, PM me a couple pics of the Magusta - if you have a couple right handy.
Author:  millhaven_nice_guy [ Sun Jun 01, 2008 8:24 pm ]
Post subject:  Re: Prop Size Selection/Material
Hi guys!
Thanks for reviving this post. My memory was foggy when I posted the supposed specs.. I had only had the boat in the water twice late last Fall.. I will redo some tests when I get a chance... We had another miserable cold and rainy weekend here in Canada so my boat is still sitting in the yard waiting it's first launch of 2008.

I managed to pull the covers off for twenty minutes before it started to pour and I got soaked putting them back on !!!!
Author:  St. Louis Dave [ Sun Jun 01, 2008 9:15 pm ]
Post subject:  Re: Prop Size Selection/Material
Flying Sushi wrote:
I have a F6 in my H260 and it feels just right.. The big block has torque in low RPM so hole shot is not a issue even with 10 people on the boat. Our boat tops out around 54hph and it is not bad for such a big bowrider. If we cruise around 40 to 45 mph and punch the throttle the boat will take off….. Great feeling… (although I can hear gas pump is calling me)


I love that mid range acceleration too. I run a nice cruise at 35-38 MPH and then punch it and I look at the spedo and I'm in the high 40's right now. The boat is quick!

I'm wondering about my props too. I am able to run about 51 on the GPS, but my tach is only showing about 4400. I think I have F5's, but I need to double check. I may want to look at F6's too just to allow my boat to max RPM at the right level.
Author:  M3eater [ Sun Jun 01, 2008 9:30 pm ]
Post subject:  Re: Prop Size Selection/Material
Dave,

I would recommend that you hook up a test tachometer, you may not really be turning 4400. 4400 rpm at 51 mph seems a bit unlike an F5 prop set for your boat. The 51 mph seems OK, but the RPM is low. If it really is turning 4400, and you do have F5 props, then you would want to go to F4 to raise the WOT RPM.
Author:  St. Louis Dave [ Mon Jun 02, 2008 9:53 am ]
Post subject:  Re: Prop Size Selection/Material
Thanks M3.

Next time I am in the water and can look at my props it will answer a few questions. I'm also curious how acurate my VDO tach is so a temp tach needs to be added before I start spending $$$$$ for new props. I like the performance now and am happy with it, but if I can make it better!!!!
Author:  St. Louis Dave [ Sun Jun 22, 2008 8:40 pm ]
Post subject:  Re: Prop Size Selection/Material
I ran the boat today with two people, 95% fuel and was able to run 49.9 mph at 4,500 RPM. I am running F6 props. I wonder how I can turn more RPMs to get me to where I should be with these props. FW Guide says I should be running 54-56 mph.
Author:  M3eater [ Sun Jun 22, 2008 10:17 pm ]
Post subject:  Re: Prop Size Selection/Material
Dave,

You're turning too low RPMs with the F6 set. You should have F5s. The only way you'll make the F6 set perform at the proper WOT is to add HP and or torque from the engine ........... All ya need is a little ol' supercharger .......

Anyway, you really need the F5 set, if for no ther reason than to not work the engine so hard.
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