: 3 blade vs 4 blade props
06-20-2002, 10:09 PM
Ok...I found a 4 blade prop for my boat, but need to convince my dad that we need it. what are the performance advantages of having the four blade? http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/wink.gif
06-20-2002, 10:56 PM
Usually out of the hole grunt, three bladed usually would be faster.
06-21-2002, 12:24 AM
It all depends on what boat you have.
If you have a runabout with a 3, 4, or 6 cylinder engine you will want a 3 blade. *3 blade has good hole shot and gives you the highest top speed out of any prop. *Going to a 4 blade on this type of boat will maybe give you a little better accel and pulling torque but you will lose top end. *
4 blades and 5 blades are for Bass boats. *The reason is that bass boats have a speed hull and are normally going faster then a runabout. *At the high speeds that they are capable of you need a 4 blade or 5 because they give off less vibration at high speed, *They also have less torque steer so the boat will be less like to Chime or bounce side to side at high speed. *
If you have a bass boat go for the 4 but if you have a runabout get your self a nice 3 blade stainless steel high pitch prop and you will be happy.
06-21-2002, 12:56 AM
I've got a big heavy 18' fibreglass with a 190hp 4.3L V6 I/O. I have a 3 blade 19deg prop which works pretty good, but I still think the motor should be capable of a better holeshot, especially with a bunch of people in the boat or for pulling skiers/tubes. The way I look at it is that the 4 blade will pull more water and so should be more "powerful" The 4 blade I found is also a 19deg pitch.
I'm gonna see if the guy will let me borrow it for the weekend to see if it makes any difference.
06-21-2002, 01:00 AM
If you want more holeshot and the capability to pull out skiers and a boat full of people go with the 4 blade. *But you will lose a little bit of top end.
What i would do is rent a prop from a local marina. *A lot of marinas will let you try a prop for a weekend as long as you give a credit card number just incase. *Its up to you to deside what the perfect balance is between accel and top end.
06-21-2002, 01:27 AM
Marina??? I live in Saskatchewan....lucky to find a dock you can stand on never mind a marina....
06-21-2002, 01:28 AM
For what you are looking for(ski'n and tuge'n)you would be better off with the 4 blade. *All you have to decide is how much top end you are willing to sacrafice and what angle you want.
If the main problem you have is getting on plane,you don't have to go out and buy a 4 blade.Ways to fix the problem are many. Solutions range from installing a hydrofoil on the anti-ventilation plate,drilling exhaust vents in the prop,adding trim tabs to the transom.A 4 blade will also help but that paticular style boat is nnnnnnever going to plane very well.
You did mention you do skiing/tubing.The participants generally like the largest wake possible for these activities.This long planing problem creates a big fat wake and the flatter the boat remains as it brakes on to plane,the smaller the wake will be. http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/wink.gif
Good luck brother *http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/biggrin.gif
06-21-2002, 04:27 AM
Be advised that the stingray or similer hydro foils are the best darn thing that you can do to get on plane. Trim it right also. And Those 4 and 6 cyl. mercs can't have much prop added over stock . It lugs the motor to much causing to much stress usually on valetrain components. Our marina does alot of repair work do to prop indused stress.It usually kills your gas milage also by a very notisable amount. Keep your eye open for a new take out 5.0 l(305)liter merc as this is a great swap. Fuel consumption usually stays the same or gets better since the motor isn't working harder do to all the extra torque. I've seen them go for *$1000 To 2000 US. And they will work with your alpha drive with a gear change.These are common things around our cottage.
06-21-2002, 10:29 AM
Try it if you can. *If they want to sell it, they should let you try it out. *Its really the only way to be sure what it will do on your boat.
But I really don't think you will like the results, for the reasons the guys above have pointed out.
Sounds like a good excuse to get a new boat if you ask me. *Of course, I can find lots of reasons to get a new boat.
06-21-2002, 04:24 PM
*But I bet your wife will find plenty of reasons not to buy one.He HE http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/tounge.gif *I wa talking to a old boss today and him and his wife have a new rule she calls the 25% rule. She gets to spend 25% of the amount of money he spends on any unneeded purchase over $500. So a $20,000 boat would cost you $25,000. Ouch. I found it funny, he wasn't amused but has no choice.
06-21-2002, 04:50 PM
ATTENTION ANY MODERATOR
PLEASE DELETE THE ABOVE POST BY SLED DOG, BEFORE MY WIFE HAPPENS TO SEE IT!!!!!!!
Geez, you gotta be one sick puppy to think that's funny.
06-21-2002, 05:12 PM
OH that is to darn fgunny fish hog. I find it funny but then again I'm single. My boss is buying a new stove and all new carpet this weekend. *you gotta admit it is fair because how many woman buy large purchases?
06-21-2002, 06:27 PM
I still say the best set-up for you is the variable pitch prop try one you'll agree.
06-21-2002, 06:28 PM
The 4 blade should help you pulling and drop your cruse rpm down and may help mpg. I do think if your 19/ 3 blade pulled the correct rpm for your engine, the 4 blade 19 will pull it down to much.
It's up to you and the boat if it likes it, We have put 4 blades on big offshore boats and almost all like it.
06-23-2002, 04:31 PM
There is no one set of rules for what prop to use for what boat and motor and purpose. Just because it's a bass boat doesn't necessarily mean that you want a 4 blade. Just as using a 4 blade doesn't necessarily mean a loss of top end. On my bass boat right now, which is a 20' 3" Champion dual console with a 225HP EFI. With a 4 blade 26p I had a wicked hole shot and a top end of 81 MPH @ 6100RPM (GPS). Now: as soon as I put my gear in the boat along with a fishing partner I dropped to 69MPH @5800RPM. The reason? A four blade gives pretty good bow lift, but falls flat on it's face if you over load it. A three blade will give more and stronger vertical lift and lift the whole hull out of the water. I am currently running a Yamaha 25p 3blade with the motor jacked out of the water to the point of losing water pressure. I still get a very good hole shot (fully loaded) , the hull lift is amazing, I'm running about 78MPH @6000RPM, and the boat feels light as a feather. If you don't like chine walking, stay with a 4 blade. *But I just love it when it gets up on the last 6" of the pad and rocks back and forth between the first chines out.
Oh, and my opinion on your prob? Try a 4 blade 20 pitch from Mercury. You may even be able to run a 22p. For what you want to do, I think it would work for you.
06-24-2002, 01:30 AM
Thanks for the advise...I tried out that four blade, and it was too much prop for the engine. I need less than 19 pitch if I go to 4 blade, so its going back to the shop where I bought it. Wish I had the cash for a variable pitch http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/mad.gif *http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/nervous.gif
Lets all pitch in so Adrian can get his variable pitch prop.
I'm good for 20 bucks. *http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/wink.gif
06-26-2002, 09:51 PM
I'm low on cash.. how about my kids water wings and a rubber duck? *http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/smile.gif
tell him 4 is more than 3, so its much better http://www.snowmobileworld-s2.com/forums/iB_html/non-cgi/emoticons/smile.gif