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Author Topic:   Propellers for 305 Conquest
revsrobson posted 04-27-2006 01:02 AM ET (US)   Profile for revsrobson   Send Email to revsrobson  
HELP!!! I am about to take delivery of a 2006 Boston Whaler 305 Conquest with twin 250 hp Mercury Verados. The motors come with Mercury Mirage 3 blade props, but I believe I have read on this site somewhere before that Mercury Revolution 4 props in 17 inch pitch are the way to go. I asked my dealer to install the Revolution 4 props, and after he sea trialed the boat he phoned me and said that these were the WRONG props because he could only get the motors up to 5,300 rpm at WOT. Does anybody out there have revolution 4 props on this boat and if so, what pitch and rpm are you running. Thanks for your help.
Tom W Clark posted 04-27-2006 01:07 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
You need the 15" pitch Revolution 4s for this application. Mercury added a 15" Rev 4 to their line expressly for the Verados on large, heavy boats like the Conquest 305.
glen e posted 04-27-2006 05:57 AM ET (US)     Profile for glen e  Send Email to glen e     
I'm gonna make a prediction that the 17P will do just fine when a prop test is done the right way and the engines are at the right height. The 15P was expressly made for SINGLE engine big boat apps. The 17p is the right prop foR the 305, IMO. My boat is similar - 9K lbs, twin 250's and non stepped hull - with 17 rev 4's I can turn 6100 when the prop test is correctly done

No prop tests should be done on Verados with less than 20 hours, the engines are deliverd very "tight"....

handn posted 04-27-2006 10:11 AM ET (US)     Profile for handn  Send Email to handn     
My 305 Conquest runs 5600 rpm with 17p Revolution 4's and 225 YamaMerc efi 4-strokes.
These props rather than Mirages are the correct ones for the boat.
I am sure once your Verados are broken in and/or adjusted correctly they will spin at the correct rpm, as mine spin at the correct rpm with less horsepower.
If the 17p Mirages spin at a higher rpm on your boat, it is likely due to prop slip which becomes a big problem when you are trying to plane at lower speeds in rough seas.
Boston Whaler did an excellent job designing an efficient hull for the 305. It will plane at a speed as little as 10 knots when properly propped. You negate that ability if you run the boat with Mirages as they cavitate big time when you slow the boat down and try to run up big rollers.
Listen to the Verado guru glen e. Stay with the Revolution 4's, break you Verados in. If the rpms are still too low, adjust the motors.
kglinz posted 04-27-2006 11:04 AM ET (US)     Profile for kglinz  Send Email to kglinz     
The thing to keep in mind is that the Verado has a 1.85 to 1 gear ratio compared to 2 to 1 on the 225 4 stroke Yamaha built engine. The performance test for the 305 and Verado 250 combination on the BW website shows 15" Mirages at 6200 RPM. If the dealer will let you, I'd leave 15" props on until your breakin is complete, but I wouldn't hold much hope for 17" props. If Glens total weight 9k you may be 50% heavier fully loaded. Whaler test weight was 12,312, with 1/2 fuel.

Kemp Lindsey

revsrobson posted 04-27-2006 01:01 PM ET (US)     Profile for revsrobson  Send Email to revsrobson     
Thank you for all of your help and suggestions. I tend to think that if the 17p revolution 4's will only turn 5,300 rpm wide open, then I would expect that they won't improve to 6,300 rpm just because they get broken in. They might improve a couple of hundred rpm I would guess.

Secondly, I phoned Mercury and they don't make a 15p Revolution 4 in counter rotating design. The 15p is only good on singles.

Running 17p Revolution 4's on 225 Merc/yamahas is a different setup than 250 Verados.

I think Kemp is correct. Glen's boat weighs at least 3,000 lbs less than my boat and he only turns 6,100 so there is no hope that Revolution 4's on my boat is going to work.

revsrobson posted 04-27-2006 02:36 PM ET (US)     Profile for revsrobson  Send Email to revsrobson     
New info: The dealer just phoned and said that the Revolution 4 props he had on the boat when he sea trialed it were 19" pitch. He is going to put the 17 inch pitch on it and try it this afternoon. Maybe there is hope yet. Stay tuned.
Peter posted 04-27-2006 09:41 PM ET (US)     Profile for Peter  Send Email to Peter     
If the 19 inch Rev 4s only managed 5300 RPM, the 17 inch Rev 4s will only manage 5700 RPM, still much, much too low. Raising the motors up one or two holes will only yield 100 to 200 RPM at best. Even if you were able to manage 5900 RPM, the sea keeping ability of the Conquest in a heavy sea will be compromised with raised motors.

If 17 inch Rev 4 propellers were the right propeller for the Conquest, I'm certain Whaler would have done its performance reports with those instead of the 15 inch Mirages because the Rev 4 propellers provide much better traction than the Mirages do and I'm certain the Conquest, like my Whaler 27, could use all the traction it can get.

sideshow posted 04-28-2006 08:53 AM ET (US)     Profile for sideshow  Send Email to sideshow     
I have the 15inch Mirages on my 305. I raised my motors up to the highest hole and noticed a big improvement in the performance. I boat a lot in rough conditions and are yet to have any issues. I guess your decision depends on what type of boating and in what conditions.

What about the new inertia's that are soon to be released?

Tom W Clark posted 04-28-2006 10:49 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
The new Mercuy Enertia is out, but it is not at all like the Mirage Plus, contrary to what Mercury's marketing alludes to.

The Enertia is a very small diameter, small surface area propeller suited to very fast boats. It is comparable to the Laser II series, and is not made in a 15" pitch.

Tom W Clark posted 04-28-2006 11:23 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I have to take that back. I was just shopping the Enertias and I see they have pitches as low as 14". The lower pitches also have much larger diameters. The 15" pitch Enertia has a 15" diameter. Hmmm...
revsrobson posted 04-28-2006 11:42 AM ET (US)     Profile for revsrobson  Send Email to revsrobson     
Tom, can you get the 15p Enertia props in a counter rotating version?
Tom W Clark posted 04-28-2006 11:43 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Yes, the odd numbered pitches are all available in counter-rotating versions.
revsrobson posted 05-02-2006 03:21 AM ET (US)     Profile for revsrobson  Send Email to revsrobson     
Bad news. The Whaler dealer just called and said that the 17p Revolution 4 props are a no go. He said they are a big improvement getting the boat on plane but will only pull 5,700 rpm wide open. Looks like I am stuck with the 3 blade Mirage props that most people dislike. Anybody know when Mercury is going to come out with a 15p Revolution 4 prop that is counter rotating?
Tom W Clark posted 05-05-2006 12:24 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
One other option would be to have a 17" Rev 4 customized to reduce its pitch.

I have a 17" Rev 4 LH prop that was re-pitched to 16" that I am trying to sell. Let me know if you are interested.

handn posted 05-06-2006 02:21 PM ET (US)     Profile for handn  Send Email to handn     
Would someone answer my dumb question about Verados?
Why is 5700 rpm too low? What is the redline on those engines?
In the old days, outboards had a maximum and minimum rpm recomended range, usually 6000 rpm max and the boat was correctly propped if it ran in the middle.
Take if from me, a happy 305 owner, Revolution 4's are perfect for the boat, Mirages aren't because in real world, rough sea applications, they won't hold a plane at a speed low enough to provide a dry, comfortable ride. When going at sub planing speeds up big rollers, Mirages will break loose, guaranteed and the frustrated captain will constantly be adjusting the throttles.
Why can't Mercury and Boston Whaler talk to each other and either offer a geared down Verado or a 16p Revolution 4? I ask Brunswick why should glen e with a competitor boat have the advatages of great big boat props and why should I with competitor Yamaha engines have the perfect props for the 305?

prm1177 posted 05-06-2006 03:22 PM ET (US)     Profile for prm1177  Send Email to prm1177     
The RPM range for big block Verados is 5800-6400, so 5700 would be low. Target would be 6-6200 rpm.
Tom W Clark posted 05-16-2006 05:54 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Here is a 16" Rev 4 that might be a good fit for the Verado powered Conquests:

peter g posted 05-17-2006 11:29 AM ET (US)     Profile for peter g  Send Email to peter g     
This post is virtually the same as one I posted on the Verado site.
I have the same boat/motor combination and was considering lowering the motors to get more bite in rough seas, but instead, following info from Verado Club members, I changed to the Revolution 4 props and am very happy with the result. The props do not cavitate in rough water as the 15" 3 bladers did, I can plane at a much lower speed and I can trim the motors out more than before in all conditions which has improved the ride and speed. I am much more in control of the ride and handling now. When trimmed right out on calm fresh water, the motors rev out to 6000rpm.This was done immediately after having both fuel modules replaced, with the Dealer Mechanic on board at about 95 hours. The thing to remember is that although the props have a coarser pitch at 17", the diameter is smaller, hence the near same rev range.I did prop testing before and after the prop change and logged the data for speed and fuel burn at 500 rpm intervals. I overlaid the two results (15" v 17" pitch) in Speed and Litres per Nautical Mile. There is very little difference between the two props in the 3500rpm to 4500rpm range, which I regard as the "sweet spot", but above 4500rpm the 17" chews substantially more fuel per N.Mile. ie at 4500rpm 17" achieves 6.3% more speed and uses 8.3% more fuel but at 5000rpm the 17" achieves 4.9% more speed but uses 23% more fuel and at 5500rpm achieves 5.5% more speed but uses 23.3% more fuel. So if you are content to travel at 3500rpm to 4500rpm as I am (21mph to 33mph) then stick with the 17" pitch Revolution 4's. The Rev 4 prop probably weighs about twice as much as the original 3 bladers and I suspect that because of that, there is also a certain amount of "heavy flywheel" beneficial effect when loading up on the face of a swell or wave. Hope this will help you decide.
handn posted 05-17-2006 03:10 PM ET (US)     Profile for handn  Send Email to handn     
Peter G, I find your test results most interesting.
It seems obvious prop slip of the Mirages at higher rpms accounts for the very different speed, fuel economy profiles of the two props.
This raises two questions. First, could Mercury reprogram the fuel delivery and supercharger boost rates in the Verado computer to better match the characteristics of the 17p Revolution 4 prop at higher rpms? Second, is the owner of a Verado equipped 305 risking engine damage by running 17p Revolution 4 prop even if he runs the engines exclusively in the sweet spot, 3500-4500 rpms?
peter g posted 05-18-2006 06:35 AM ET (US)     Profile for peter g  Send Email to peter g     
There is no problem with selecting the Rev 4's as my motors will and have turned at 6000 rpm when correctly tested , which is within the Mercury recommended 200 rpm range of the maximum 6200 rpm. With the heavy BW 305, I think the choice of which prop to use depends on the type of sea and speed you like to travel at. I would use the 3 blade Mirage for high speed on smoothish water, whereas I would use the 4 blade Rev 4 for rougher seas at low and mid range speed. The Rev 4 is obviously not efficient (fuel burn) at the top end just as the Mirage is not efficient at the bottom end (cavitates) I was very disappointed in the original BW 305 handling in our rougher seas and was beginning to wonder how they got such a great reputation. With the right props (for me) the boat has moved to a new level of performance/handling and I'm loving it!
sideshow posted 05-18-2006 02:27 PM ET (US)     Profile for sideshow  Send Email to sideshow     
Does anybody have any feedback on the new Enertia props on a 305?

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