Prop question

[Capt. Ronnie]

Anyone using a 4 blade prop on a Parker deep vee with a yamaha 4stroke ??

 

[Outta Here]

I have a Rev4 on a 225-4 and 23DVCC. Love it. Raise motor a hole. Same or better top speed, planes and hold plane a little easier, better hole shot, no ventilation.

Side benefit, no chance of spinning a hub.

 

[B-Faithful]

Fishfactory upgraded his to a Merc Revolution 4. He has a f225 on a 23cc DV..

Send him a note.

***edit - he was typing while I was***

 

[captbone]

15 pitch or 17 pitch Rev 4?

What kind of RPMS are you getting at WOT. Thanks

 

[Outta Here]

It's 17 pitch. Mine came from SIM. According to Andy, use the same pitch as your black SS Yamaha as long as you are reaching correct RPM. I don't remember exactly what my WO RPM is. I haven't tried out the adjustable ports for exhaust tuning. Be sure to raise up motor to benefit from the extra bite.

Mercury has a good prop calculator at their web-site. I'm sure B-Faithful has the link.

Overall, I can't say enough good about the Rev4.

 

[esfishdoc]

I'm expecting a Rev 4 any day... F225 2520XL.

I'll post my results. I'm anxious to see what it will do.

Richard

 

[B-Faithful]

see the prop selector on this site:

http://sites.mercurymarine.com/portal/p ... ema=PORTAL

Here is my Rev 4 on my family cruiser (as you can see there is a lot of blade surface over a 3 blade) :

 

[DaleH]

Here is my Rev 4 on my family cruiser (as you can see there is a lot of blade surface over a 3 blade) :

B:

Did that give your hull any BOW rise? I tried a 4-blade prop (different model) on my 14-degree deadrise 2520 and the 4-blade raised the bow soooooooooooooooooooo much that I had to use too much tabs, and it killed my miles per gallon efficiency.

Curious your results with even lower deadrise. So far, from limited testing, we tend to be seeing better results with 4-blade props on deep-V hulls. But then again, your boat is so light to begin with ...

 

[B-Faithful]

Dale,

It did change the attitude of my boat some. However, I cannot tell if it gave me more bow rise or transom lift as the prop bites so much better than the AL 3 blade I had that engine tilt now more noticably affects the trim. I do know most say with the cup of the Rev 4, it is supposed to give transom lift. I personally cannot tell for sure.

What I do know for sure is that I gained ~10% efficiency, speed, and bite around the dock.

My hull is quite a bit different than the parker 25 in the sense that I have a shallower deadrise, narrower beam with the 3:1 ratio, lighter hull, and much sharper bow entry. With the sharp entry getting the bow more out of the water may not be a bad thing for my hull in calm water for more speed or efficiency. As I mentioned before, the engine tilt does now affect the run angle of the boat more.

Next time you are in Naptown USA, I would love to take you for a ride.

 

[esfishdoc]

OK... I've never seen an explaination.... how does a prop give bow or transom lift? :roll:

 

[captbone]

B-faithful

I am sure that you mentioned this before but

What RPM and Speed did the 15pitch Rev4 give you?

What RPM and Speed did the 17 pitch Rev4 give you?

What RPM and Speed did the 17 Pitch Mirage give you?


I am getting ready to Rock and Roll on my project boat and will have pictures very shortly. I am getting ready to run a 3.0 Liter Optimax 30inch shaft on a custom knotched transom 25ft Bertram Mark II Flybridge. I am think that I maybe able to swing a 15Pitch Rev4 or hopefully a 17 pitch Mirage. I am aiming for 5500+ rpm very light which is how it will be when I first launch it. It will be 4800lbs wet.

If they are both too steep than it will be a 15Pitch Mirage Plus or a 16pitch Enteria.

Thanks!

Here is the first sneak peak! Its getting Awlgrip (Fighting Lady Yellow) soon. It will be redone from top to bottom.

 

[B-Faithful]

esfishdoc: I am not sure how a prop causes stern/bow lift but it is said that cupping adds lift. ( http://www.mazcoprops.com/faq.htm ) . The best explanation I can find on the web to how props work is here ( http://sites.mercurymarine.com/portal/p ... ema=PORTAL ). However, it really doesnt explain how some props create transom/stern lift. Also Merc can lab finish props to increase bow or transom lift ( http://www.fishingkeywest.com/mercury_l ... ellers.htm )

Captbone, with my 17 Rev 4 I now hit ~5350 with a full load and e10 gas (I was hitting ~5400-5450 before). I hit the rev limiter of 5750 easily with the 15" rev 4. With the mirage plus I was blowing out at the top end. Comparing pitches though is difficult to do as my hull is a lot different than yours as well as the Parkers. My Opti is also geared differently than the Yammies. I am geared at 1.75:1 while the Yammie 4's are lower at 2.00:1

 

[captbone]

B-Faithful


Thanks, that does help alot. I was worried that even the 15pitch Rev4 would be too steep to swing but like you said the Optimax is very stout and has a 1.75 ratio.

While are hulls are different, the weights will be similar load. LOA for my hull is 24'9 and the beam is 9'11 with a 14+ degree deadrise in the transom. With power and fuel the boat will be just over 4500lbs with nothing else.

I am hoping for a cruise at 4000 RPM at 25mph and WOT at 5450 of 37mph with the REV4 15pitch.

 

[B-Faithful]

i cruise at 3950-4050rpms at 28-29mph on flat water with normal load. At ~5350 my boat has run slightly over 42mph according to the gps. That is with a 17" rev 4 on my hull and a 1.75:1 ratio.

 

[Outta Here]

i cruise at 3950-4050rpms at 28-29mph on flat water with normal load. At ~5350 my boat has run slightly over 42mph according to the gps. That is with a 17" rev 4 on my hull and a 1.75:1 ratio.

Wow, same top speed as a 5991# Parker 2520 powered by anemic 225-4 Yamaha. The Yamaha gets over 2 mpg at WOT.

Source: Yamaha Performance Bulletin.

 

[B-Faithful]

Hmmm... two boats below are the same hull. One with a 225Opti, the other with a f225. The opti can regularly hit 42 with a regular load. The f225 powered boat can muster 38 with regular load :wink:

Source: REAL WORLD PERFORMANCE STATS

BTW, at 28-29mph according to the gps, I am at a mere 10gph 8) (in calm water of course) Trolling I burn a mere 0.3-0.5gph too

 

[captbone]

How much is your ballpark wet running weight? Thanks

 

[B-Faithful]

I am estimating ~5000#-5200# before people and carry on gear (tackle, coolers, etc)

 

[grouperjim]

I bought a 2006 2320 a few months ago. I previously owned a 2004 parker 23 dv cc. I ran a both a 3 blade mirage and a yamaha sws 19 pitch. Both props provided a bow lift on an already light bow. After reading the above posts about the 4 bladed rev 4, I went out and bought the mercury rev 4 19 pitch. It was hard to find. All I can say is WOW. I raised the F250 to the hole second from the top. It was in the top hole. The prop provides excellent stern lift. The boat handles better in turns. Top speed is still 48 mph. Speeds are still the same or slightly better per old rpms. 4500 rpm is still 35 mph 2.8 mpg. However, now 3500 rpm is a new sweet spot at 25 mph 3.1 mpg. Traction is excellent in rough seas. Just set the rpm and the speed barely fluctuates while pushing through a head sea or climbing the backs of waves in a following sea. Even the factory trim tabs seem to be more responsive. I can't say enough great things about my new engine/prop configuration.

 

[Outta Here]

I raised the F250 to the hole second from the top. .

That would be the secret. :wink: