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  235 Conquest, Verado 250: 3-blade or 4-blade

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Author Topic:   235 Conquest, Verado 250: 3-blade or 4-blade
Foulweather Jack posted 03-31-2012 02:09 PM ET (US)   Profile for Foulweather Jack   Send Email to Foulweather Jack  
I have a 235 Conquest, 2007 model, purchased last summer. I am wondering about propeller selection. The performance of my boat is sluggish, and nowhere near the quoted performance specs that are available online from the Whaler factory website. Complicating matters is the fact that my boat has bottom paint, and sits year round in the salt water here in Savannah, GA.

On the way to the marina this morning, with just me driving on smooth water, the top speed I could achieve at 6070 rpm was 27.5 mph after much experimentation with motor tilt and trim tabs. I like to cruise at 4500 rpm, and at that motor speed my speed through the water was only about 20 mph. I had the boat pulled from the water today, and there is significant barnacle growth on the hull, and I'm quite sure that accounts for much of the deficit in performance.

The previous owner sold it to me with what I presume is the original, 3-bladed MIRAGEplus propeller on it. The motor is a 250-HP VERADO. There are numbers stamped on the side of the prop as follows: 48-19838 15P. I don't know what those numbers mean.

The boat also came with a spare prop, a stainless steel, Mercury REVOLUTION4 four-blade propeller (diameter 14 5/8, pitch 15).

While I fully understand that much of the poor performance of the boat relates to the fouled bottom (don't worry, I'm getting new bottom paint, suggestions for type welcome) I was wondering if I should have the 4-blade prop put on the motor while the boat is in for service.

I recall from previous threads on this forum that there are some Verado propeller gurus somewhere in Florida that might be able to help me. Any suggestions are welcome; as usual, I appreciate the many unselfish people on this forum who are willing to share their hard earned knowledge.

jimh posted 03-31-2012 02:40 PM ET (US)     Profile for jimh  Send Email to jimh     
If the boat speed is only 27-MPH with the engine turning 6,000-RPM, there is something seriously wrong. What is the gear ratio on your engine?
Peter posted 03-31-2012 05:38 PM ET (US)     Profile for Peter  Send Email to Peter     
15P means 15 inch pitch. The Whaler performance reports indicate that a 15 inch pitch should be the propeller of choice in the Mirage Plus propeller line. Until you get the bottom of the boat cleaned up, there is no use in trying to optimize the propeller. I would not bother swapping propellers at this point. Swapping propeller is not difficult to do, takes all of about 10 minutes if you do it slowly.
Jefecinco posted 03-31-2012 06:40 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
Jack keeps his boat in the water somewhat complicating propeller changes. If he has a small boat available that should help.

Jack,

Do you have a trailer for that boat or access to one?

Butch

Teak Oil posted 03-31-2012 09:16 PM ET (US)     Profile for Teak Oil  Send Email to Teak Oil     
Peter is right, you can't do any testing until you fix the hull condition.

What kind of performance did you get last summer, when there was not a coral reef on the bottom?

Tom W Clark posted 04-01-2012 12:20 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
You cannot ask which is best, a three blade propeller or a four blade propeller? without specifying what model of propeller you are talking about.

If the question is: Which is better for this application, the three blade MIRAGEplus or the four blade Revolution 4? The answer is *probably* the MIRAGEplus, but it depends on how you intend to use the boat.

If you like to cruise at 4500 RPM, then the MIRAGEplus will be better.

If the question becomes: What is the best propeller for my application? The answer is perhaps NOT one of the two aforementioned propellers.

To find the best propeller for your boat, it is always best to test them and see for yourself how they perform and how you like the performance. As you already own two very good propellers, try those first. I agree you cannot tell anything from the test you have already performed because of the foul bottom.

The 48-19838 15P is indeed a standard rotation (right hand) 15-3/4" x 15" Mercury MIRAGEplus. It should be equipped with solid PVS vent plugs.

27.5 MPH with this prop at 6070 RPM through the Verado's 1.846:1 gear ratio suggests propeller slip of over 41 percent! I actually find that hard to believe, as the MIRAGEplus will loose all grip and simply ventiltate and allow the motor to race if it is slipping that badly. The Mercury Revolution 4 and the Mercury Enertia are two propeller models that you *can* power ventilate and allow to slip badly without giving up all grip, but not the MIRAGEplus so much.

After the bottom is cleaned up you may find the best prop is the 14-3/4" x 16" or 14-1/2" x 17" Mercury Enertia.

What is the condition of the MIRAGEplus on the motor now? Nicks, dings, growth?

What PVS vent plugs are in there now?

What set of bolt holes is the motor mounted to the transom with? In other words, how high on the transom is the motor mounted?

boatdryver posted 04-02-2012 12:40 AM ET (US)     Profile for boatdryver  Send Email to boatdryver     
Butch, I have changed the prop on my 4 cylinder Verado several times with the boat in the water just by backing into my slip and being careful not to drop anything.

JimL

Peter posted 04-02-2012 07:50 AM ET (US)     Profile for Peter  Send Email to Peter     
You can also pull up to a beach and make a change.
Jefecinco posted 04-02-2012 09:53 AM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
Jim,

It may be easy on your Dauntless or even on my Montauk but as I trailer I don't plan to try it on the Montauk. Our Verados are the same size so you can picture me on my little boarding platform reaching back trying to change the propeller. One hand to hold onto the rail and one hand for the job. :=)

It's probably easy to manage on Jack's Conquest, too, but I just assume it would be difficult. Beaching is a good option for most any boat. It's certainly warm enough here with water temperatures in the 70s in Mobile Bay.

Butch

Foulweather Jack posted 04-26-2012 01:56 PM ET (US)     Profile for Foulweather Jack  Send Email to Foulweather Jack     
Follow-up on the sluggish performance of my boat. After new bottom paint, top speed is back up to 42 mph at WOT (6000 rpm). I'm pleasantly surprised, because the bottom did not appear to be that bad. Then again, when I bought the boat last summer, I asked the dealer if it needed new bottom paint, but he told me no. It's amazing to me that the performance of the boat could deteriorate so quickly due to fouling of the bottom.
boatdryver posted 04-28-2012 10:50 AM ET (US)     Profile for boatdryver  Send Email to boatdryver     
Well, there's fouling and then there's FOULING.

To have such an increase in WOT boat speed just from cleaning the bottom and applying new bottom paint, the fouling must have really been something to see.

JimL

Thirsty Whaler posted 05-04-2012 08:03 AM ET (US)     Profile for Thirsty Whaler  Send Email to Thirsty Whaler     
There has been much already posted on this site regarding prop selection for Verados matched with your hull, as well as motor height on the transom. I have the same boat with a Verado 225hp that came with the same three blade inertia prop. I switched to a for blade Revolution 15"pitch with two overall results: 1.)better hole shot and fuel economy 2.)five knots lower top end speed(now 38knots).

Rectify your hull fouling issue first, then do your prop comparison to determine performance per your desired use of your boat. By the way, congratulations on choosing an excellent BW hull. I am very happy with mine.

kwik_wurk posted 05-05-2012 01:14 PM ET (US)     Profile for kwik_wurk  Send Email to kwik_wurk     
That was more than fouling if your boat speed was that low. I mean a 5 mph ok, but 14 mph; are you growing mussels, oysters? --- Any fouling around the lower unit would cause this, but since it is an outboard I assume it was tilted clear of the water.

But, hey sounds like you're up and running, now is the time to swap props around. Benchmarking your boat with a brand new bottom is a good idea, it will give you target performance to refer to. And testing a few weeks afterwards is suggested as the bottom paint can smooth out a bit from the original application.

Changing props you can do at the dock or beach, just back in to a corner and work from there. A helper is very useful, just to keep the boat from rocking back, or moving away from you. (And tie a string around all your tools and prop if it is deep.)

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