new to props!!! Question for you!!

[21270]

I have a 1993 Bluewater Mirage with a Merc 4.3LX Gen 2. I have had the boat two seasons now, it has an alum 3 blade 19 pitch, # on prop is 4878120A4019P. WOT is supposed to be 4400-4800, WOT and trimmed for max speed I am at 5200 at 45 mph per boat tach and speedo. I know RPM's are too high, so I dont run at WOT!!! I want to stay with an alum prop for those accidental bottom rubs but would like to get more top end and drop my RPM's to the safe spot. HELP!!!!

 

[21270]

Re: new to props!!! Question for you!!

Prop is 14 x 19 pitch.

 

[danie]

Re: new to props!!! Question for you!!

Until the prop experts like Walleyehed can reply, test a 21 pitch.<br />It will bring your rpms down to 4800 but holeshot will suffer.

 

[ob15]

Re: new to props!!! Question for you!!

Don't worry about switching to a SS prop. Get a SS prop with the same pitch with a nice agressive cup & it might work out real nice. Might even eb able to go up an inch or two in ptich depending on the cupping of the prop.

 

[TilliamWe]

Re: new to props!!! Question for you!!

jgw you can go to either a 21 pitch or 23 pitch, if that 5200 rpm figure is accurate. But your out of the hole performance will suffer. If out of the hole & cruising is what you want & need (since you say you don't run wide open, I assume that you just cruise) a four blade prop might be the answer for you. 20 inch pitch four blade should lower the RPMs to their acceptible range, and not hurt your holeshot as much as a 23 pitch 3 blade. Do you have a way to borrow props to expirement?<br />I too like Stainless over aluminum. How often do you "rub" bottom? And if you only rub, then stainless is truly better for you. Those "rubbings" cause damage to the AL prop, but wouldn't damage the stainless prop.

 

[21270]

Re: new to props!!! Question for you!!

Haven't rubbed yet, but when it does happen I would rather break a prop then shaft or gears. I eventually will get a prop for both (skiing) & (cruising) now just looking for the high end cruising and speed if I want it. So a 20 pitch four blade could do both ? I will contact the prop shop here and see if I could test one of those out.

 

[ob15]

Re: new to props!!! Question for you!!

How does the prop you have now work for skiing? Once again, you really should think about SS. Here's a post that may make you think about it. Kenny is one of the prop/setup experts and talks about SS versus Aluminum & lower unit damage. It's a long post but it's in there.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=40;t=000010#000032

 

[TilliamWe]

Re: new to props!!! Question for you!!

Originally posted by jgw:<br /> Haven't rubbed yet, but when it does happen I would rather break a prop then shaft or gears. I eventually will get a prop for both (skiing) & (cruising) now just looking for the high end cruising and speed if I want it. So a 20 pitch four blade could do both ? I will contact the prop shop here and see if I could test one of those out.

No, a four blade is not the best prop for top end, not on your boat. The three blade 23 I mentioned earlier will probably give you your best top end.

 

[21270]

Re: new to props!!! Question for you!!

Dave F. My holeshot isn't that good right now, even yanking a 240lb guy on a tube with 3 adults in the boat including me puts a hard strain on her. It takes a while to get her on plane, maybe prop and smart tabs. Thanks for the article, maube its best to go with SS now for the performance!

 

[ob15]

Re: new to props!!! Question for you!!

If your holeshot isn't all that great now, then it will be worse if you try to get more speed. A 4 blade may help but you will lose top end speed.

 

[Jdeagro]

Re: new to props!!! Question for you!!

jgw and you all:<br /><br />Let's look at the problem of getting out of the hole (Hole Shot) from a different view point. What is commonly recommended is to change the prop to a lower pitch (lower gear) so that the boat can climb up the hill and out of the hole. This means that the forward thrust (torque) is used to go climb up not push forward. <br /><br />What would happen to the performance if the boat never got into a hole? <br /><br />Instead of climbing up, how about moving forward. No change in prop is going to eliminate the hole, they will only improve the hill climbing ability. <br /><br />To keep the stern from dropping (into the hole) it needs immediate lift as soon as the boat starts forward. Trim tabs provide this immediate lift. The thrust of the prop is then used to propel the boat not climb a hill.<br /><br />After installing Trim Tabs, prop the boat to it's maximum efficiency at all speeds. Saves Gas Too!

 

[EZLoader]

Re: new to props!!! Question for you!!

What would you all think of having a prop that on-site you can:<br />1) adjust to 5 pitch settings<br />2) easily repair with replacement blades <br />3) adjust to fit different engines<br /><br />It is also:<br />4) corrosion proof<br />5) proven techhology with 3 year warranty<br />6) stronger than aluminum <br /><br />View the video and then comment:<br /><br /> http://www.propulse.se/english/index.html

 

[ob15]

Re: new to props!!! Question for you!!

Good point John.<br /><br />EZ, you know my opinion (its not a bad one).

 

[tdanzer]

Re: new to props!!! Question for you!!

Originally posted by EZLoader:<br /> What would you all think of having a prop that on-site you can:<br />1) adjust to 5 pitch settings<br />2) easily repair with replacement blades <br />3) adjust to fit different engines<br /><br />It is also:<br />4) corrosion proof<br />5) proven techhology with 3 year warranty<br />6) stronger than aluminum <br /><br />Thats a very interesting concept, has anybody tried one?<br /><br />View the video and then comment:<br /><br /> http://www.propulse.se/english/index.html

 

[tdanzer]

Re: new to props!!! Question for you!!

Here is a review on the propulse from a third party<br /><br /> http://www.olds.com.au/marine/propellers/propulse/propulse_test.html <br /><br />Overall they gave it a positive review

 

[walleyehed]

Re: new to props!!! Question for you!!

I'll never go against Smart-Tabs...I have them on my alum. deep-V and it's the only thing that keeps the ride under control at 55+mph.<br />My bow does not lift on hole-shot...it does not move like you think it would, it just stays flat. Now, and top speeds, I "then" raise the bow to disconnect from the water for increased speeds, in fact, the tabs have helped my top speed by not requiring as much trim....truely, I'll never argue smart-tabs..<br />AND, when you get a set, I'd go with a good quality SS in a 21P with vent holes.<br />Vent holes for low end grunt, not hole-shot improvement..the tabs will do that, but we still need some extra RPM on the low side if you're going to pull the occasional skier, and with a vented 21 SS, it's the only prop you will need.<br />Quick note on alum props...they bend easy..too easy. They can have bends in them you can't see that will cause more gear and Lower unit problems than SS ever will.