Gulfstream F250 Propeller - Must Read

lgusto · May 29, 2011

All,

I have been reading a lot about props on this forum and others and decided to try a new prop because my single F250 Gulfstream struggled to get on plane with a full load. I had heard a lot of good things about the "Prop God" and decided to call them. The owner spent several minutes asking about my boat, its usage, and its performance.

After hearing all of that he said that my boat was over propped with the factory default 3-blade 17 pitch. That surprised me because I was sure I needed a 4-blade due to all my reading. The Prop God guaranteed I'd love his recommendation, a 3-blade 15 pitch, and if not he'd keep swapping props until I was happy.

Long story short, the new prop was a breeze to install and it turned my lumbering Gulfstream into a speed boat. It now snaps up on plane, produces far less cavitation during turns, and in initial tests burns less fuel. I would have bet a grand this was not possible just by swapping to a lower pitch.

Needless to say, I'm delighted. I have no affiliation with the Prop God but highly recommend his service - http://www.propgods.com.

Ballard Boy · May 31, 2011

Hi Larry,

I am new to this Forum and just read your posting. I have a 1999 Gulfstream with an '05 F250 Yamaha 4-stroke. I assume the prop is the factory default prop.

I love the boat, but the motor is driving me nuts as I feel it isn't enough. With a total of 3 guys, our fishing gear on board, bottom paint and half tank of fuel, I have to run at about 5400 rpm to get 29-30mph out of it on fairly calm water.

I do a lot of fishing on the ocean off the west coast of British Columbia, Canada and if seas are rough, this thing really struggles to get on top of heavy seas. I hate running it at such high rpm all the time, but much less and the ride is too slow.

Did your 3 blade, 15 pitch prop really work wonders?

What kinds of speeds are you getting at various rpm's?

I am honestly so frustrated I am thinking of selling and moving to twins on my next boat, but other than the motor, this boat is set up perfect.

Thanks for any more specific info you can share.

Thanks,

Paul

Legend · May 31, 2011

When you installed the new prop did your tach stay withing the recommended RPMs?

lgusto · May 31, 2011

Legend, yes, Yamaha recommends max 6,000 RPM and that's what I'm getting WOT. I understand there's a limiter that kicks in at 6,200 and hope to never hit it.

Paul, yes, we're still running at relatively high RPMs to get much speed out of the boat. With a hardtop, full curtains, bottom paint, "normal" load, 15 3/4 x 15 stainless prop, here's our figures:

22 knots @ 4,300 RPM
25 knots @ 4,600 RPM
30 knots @ 5,100 RPM
34 knots @ 6,000 RPM (WOT)

But, the engine seems to work much less with the new prop - it just sounds different. I don't need my trim tabs to get on plane. With my factory 15 1/2 x 17 stainless prop we burned 70-80 gallons on 100 mile round trip offshore days (horrible, right????). I'll post figures for my new prop this weekend but the "Prop God" tells me I should expect better fuel economy due to the lower strain on the engine.

Ballard Boy · May 31, 2011

Thanks Larry.

I will call the "Prop God" this week and have a chat with him. My big concern is that I believe we have much rougher water up here off the west coast of Washington/British Columbia then you lucky guys experience in the warm Florida waters. It is a rare day when we can cruise out to the off-shore fishing grounds in anything less than heavy seas or significant chop and having the torque to battle through the waves is a real challenge. I'll probably buy the 15 pitch and see how this works. I appreciate your help.

Another question is, do you know or has anyone posted on here about their experience with the new 300hp Yamaha on a Gulfstream? The local GW dealer is really pushing trade in plus cash to upgrade to a 300 as it will work on the existing bracket. Any thoughts on whether that is worth it or has been discussed?

Thanks again,

Paul

lgusto · May 31, 2011

Paul,

Like you, I envy the lucky guys in Florida. I boat in Maine where I believe the waters are pretty similar to yours except for July and August when we typically experience perfect weather.

I've not read of any specific Gulfstream experiences with the new 300. To be honest, I was almost ready to pull the trigger and replace my 250 with the new 300. But the prop change has completely assuaged my complaints about a single engine Gulfstream. I am, as they say in the local parlance, all set!

Best,

Larry

Ballard Boy · Jun 1, 2011

My mistake Larry. I think I looked at the Prop God website and saw he was in Florida and assumed you were. I see now where you have Maine in your signature block.

Thanks for the info. I will order a 15 pitch prop and give it a try.

Paul

bea5454 · Jun 4, 2011

Larry:

Thanks for a great post. I have similar Gulfstream/F250 and top-out at 5600 rpm w/17" pitch. Couple of questions for you -

Is your new prop a Yamaha SS2 stainless prop?
At what RPM did you top-out with your original prop?

Thanks and have a great season.

BJB

lgusto · Jun 4, 2011

BJB,

The new prop is a stainless Quicksilver, made by Mercury. Using the stock Yamaha 17 pitch I was only able to make 5,700 RPM and occasionally 5,800. Now I can hit 6,000 very quickly.

Initial fuel consumption tests show roughly a 33% improvement. I'm now getting better than 2 mpg.

Makes you wonder....how can a company like Grady White allow their Gulfstreams to be fitted with what is clearly the wrong prop. I put about 500 hours per year on my boat. When I think about the fuel I've wasted over the past four years it makes me pretty angry.

Best of luck.

spike · Jul 14, 2012

Hey Larry,

I was just reading this old string and I have to agree. I have the same setup as you - a 2005 Gulfstream with a F250. Most of the time this motor feels sluggish and I have wondered about the prop. I know you said this "propgod" swore that a 15 3/4 x 15 was theright setup. I just noticed that the 2012 grady gulfstream with the 250 is now spec'ing the 15 3/4 x 15. I assume you are still happy with yours ? I am now seriously thinking of switching. I can't find the performance test of the 2005 gulfstream but the one for the 2012 is
http://www.gradywhite.com/232/performance_data/1/F250

and I dont think i am seeing anywhere close to those MPG. I am typically am running 1500 or below as i exit my harbor and then 4000-4500 while i am cruising. Looks like this prop is the right setup for this boat. I have to agree with your older posts on how did they screw this up so bad and spec the wrong prop ?

lgusto · Jul 15, 2012

Spike,

Here's the figures on the 2005 setup, which states a 15 1/2 x 17 prop:

Performance Tests at Optimum Conditions
RPM MPH GPH MPG
1500 6.9 1.9 3.61
2000 8.0 3.0 2.65
2500 8.7 4.6 1.9
3000 10.3 6.2 1.65
3500 13.1 8.0 1.64
4000 22.1 10.2 2.18
4500 29.2 12.5 2.33
5000 34.1 14.7 2.32
5500 37.7 17.7 2.14
6000 42.4 21.4 1.98

I'm usually pretty well loaded with fuel and gear, and have bottom paint. I have to run at least 4500 to comfortably stay on plane, but we usually run around 5000 when the seas permit and that delivers about 30 knots per hour and 1.9 mpg. I can say that moving from a 17 to a 15 pitch was like buying a new speed boat. Huge difference, worth every penny of the $400 or so I spent.

I feel GW made a big mistake with their original prop. The Gulfstream is too heavy for the F250 to properly come up to RPMs with a 17 pitch. I just wish I had found the Prop God a few years earlier.

Good luck, let us know how you make out.

Larry

Vic H · Jul 15, 2012

spike said:
Hey Larry,

I can't find the performance test of the 2005 gulfstream but the one for the 2012 is
http://www.gradywhite.com/232/performance_data/1/F250

Please keep in mind that the new F250XCA (4.2 liter) motor has a gear ratio of 1.75. The 2005 F250 (3.3 liter) has a gear ratio of 2.00. That would make a difference in computing the correct prop pitch.

'84Offshore · Jul 15, 2012

i Have a 24' Offshore w/ a 300+HP I/O.

I would think a 23" Gulfsteam w/ a single 250HP is way underpowered........

Harpoon · Jul 21, 2016

I have the F250/232 package. I don't have any problem cruising at 20-22 kts. Go fish some downeast boats that cruise 14 and you'll love 20!

Harpoon · Aug 2, 2016

Larry, after running about another 100 miles this weekend I decided to try the quicksilver 15.75 X 15 from the prop gods. Hopefully I get similar results. I dinged my 17P prop on a piece of debris, so a good time to try the 15.

generalee · Aug 3, 2016

Harpoon,
Please post your results. I am seriously considering purchase of the 15.75 X 15 Quicksilver prop to for our 2005 F250 on a Gulfstream. The 17 on it now is OK at best. I am intrigued by the prospect of improving the sluggish take off and overall performance numbers.
Thanks,

Harpoon · Aug 5, 2016

I just took delivery of the prop so I'll have results on Monday. BTW I noticed the on the Grady site they use a 15P prop on the new 232 with a single 300.
I was out last nigh in some major windblown chop. I'm liking this old 232 more every day.

Harpoon · Aug 8, 2016

Ok so I had a chance for a quick ride with the new 15.75X15.

Out of the hole and on plane very quickly.

WOT 5900 - perhaps 6000, (I was in a 25 kt wind.) I thought it would have been much higher like 6200-6400. I don't recall the speed. 28-30kts?

At 4500 - I was cruising at 20kts, 10.5 gal per hour. Previous (with 17P) 4500rpm the engine seemed to ask for more throttle in most conditions and was 12.5 gal/hour. The stern feels higher with 15P prop at 4500 and its a very stable cruise. From what I can tell it looks like optimum cruse will be 46-4700 at something like 22-23 knts and 12.5 gal per hour.

I need to screw around more this evening on the ocean. But this prop is DEFINETLY a major improvement over the Yamaha 15.25X17P stainless. Its clear why Yamaha is now offering some props with less than 17P now.

generalee · Aug 8, 2016

Harpoon,
Thanks a lot for sharing the information on the new prop performance. Looks like I definitely need to spend the bucks on the 15.75X15 prop.
I will appreciate reading anything else you share on this topic.
Thanks again.

Harpoon · Aug 9, 2016

Ok, so I went out for a ride along the beach last night in light chop to flat seas, with no 30kt winds. This prop feels like somebody added 50+ horse power to the motor. And, much to my surprise the RPMs fall into a much netter cruising range. I could cruise at 41 -4300 rpms in all conditions, and fuel burn was 9.5-10.5gph speed 20-21 knts. For me, when I have a 30-40 mile run, this will be my go to cruise speed.

At 4200 I'm at 21kts, at 9.7 gph

At 4600, I was screaming 26kts, 12.3 gph

WOT 6000. fast... 20 gph.

As Larry mentioned in his original comments the engine sounds totally different, like its not working very hard at all.

If anybody is still using the Yamaha 17P, I'd highly recommend you spend the 460 (with hub kit) on the quicksilver 15.75X15. Fuels savings in 2-3 months will likely pay for it.

Gulfstream F250 Propeller - Must Read

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