Who runs a 4 blade prop?

[geneseo1911]

Finally got my old boat working the way it should this fall, so my wife and I got to spend less time worrying about whether the boat is running or sinking, and more about trying to get up on our wakeboards. She has managed to get up and ride for 30s or so, but I have not done as well.

I have a four part plan for success next summer:

-lose weight (I'm down to 270 from a high of 280, I hope to be down to 250 or better by Memorial Day 14. I'm 6'4, so I'm not sloppy fat, just big & heavy, with a belly that has crept up on me over the last 10 years)

-looking for a LF Trip 146 (I have an older 142cm board, and I suspect it might not be enough for my weight)

-get some weight in the bow; the boat goes bow up and I usually fall when the bow drops as the boat comes on plane. I'm going to fill a couple old, small tubes we no longer use with water and see if a little ballast helps smooth the transition. The boat has enough power (19' BR, tower, 260 HP Mercruiser), but all the weight is in the back, like every other sterndrive. Eventually I'd like to go to aluminum exhaust, intake, and maybe even heads to get the weight down a little.

-I'm considering going from my current 21P 3 blade SS to a 19P 4 blade SS.

Those of you that have 4 blade props, how much difference does it make with regard to planing at lower speeds and getting on plane faster? Does it exacerbate bow rise? Solas vs Mercruiser?

I'm currently running 51 MPH at 4300 RPM max, so I think I have room to go down in pitch without giving up a lot of top end, but I do like to go fast, so I hate to lose much. Any other ideas?

 

[skydiveD30571]

Re: Who runs a 4 blade prop?

There's a big difference in hole shot when changing 3bld to 4bld. You will notice it. It will also plane slower. Be prepared to lose several mph on the top end (I lost about 4mph).

Having said that, getting up on a wakeboard is all about technique. You have more than ample power right now, and once you get the technique down you'll be able to get up effortlessly even behind the 3bld with no ballast up front.

Fyi I'm 6'2" and about 235 so I'm not little either. I have a Ronix Mana 143.

 

[sickwilly]

Re: Who runs a 4 blade prop?

I would go with the Solas Amita 4 blade, probably 21 pitch from right here at iboats. Its like $130 to your door. Its a great all around prop. I also have a 23 pitch merc high 5 that I compare it to, and a 20 pitch 4 blade merc alpha. That amita has more cup than the alpha. It is a hell of a prop for holding lower speed planning for wakeboarding.

Also (get ready for the hall of iboats to echo with a big fat, no, get smart tabs) throw a hydrofoil on that outdrive. Nothing better for wakeboarding! Smart tabs will mess up your wake.

 

[haulnazz15]

Re: Who runs a 4 blade prop?

I run a 4-blade Solas on a an older runabout as well, Ford V8. I went from a 15x21p 3-blade, to a 15x16p 4-blade. I top out at 40mph now at 3800rpm (my rpms will be lower than yours due to my outdrive gear ratio), but that thing is a rocket out of the hole, and will stay on plane at lower speeds as well (15mph or less). I would imagine for wake boarding you'd WANT more weight at the back (and overall) to sit deeper in the water in order to create a larger wake. I don't wakeboard, so I can't help you there, but the acceleration for slalom skiing is great.

 

[Augoose]

Re: Who runs a 4 blade prop?

X3 on the four blade. Made a huge difference for me and I bought the Solas as well. Kept my 3 blade SS as a back up.

 

[rowlex]

Re: Who runs a 4 blade prop?

go with the 4 blade. you will never put that 3 blade back on except emergency. I lost 10MPH...

this might just be my boat, but if i put all the weight in the back of the boat the bow will shoot up and not plane off.

 

[geneseo1911]

Re: Who runs a 4 blade prop?

Also (get ready for the hall of iboats to echo with a big fat, no, get smart tabs) throw a hydrofoil on that outdrive. Nothing better for wakeboarding! Smart tabs will mess up your wake.

Yeah...the boat had a hydrofoil on it when I got it, and I took it off primarily due to the very low opinion of them on here. In hindsight, I think it actually helped the boat out a fair bit as far as time to plane and bow rise. I really hate to drill holes in the cav. plate, though after I paid to have it repaired. I think I'm going to try the Solas, as it sounds like most folks are happy with them. If that doesn't do it, I might try one of the no-drill foils.

So does 19P sound right for the 4 blade?

BTW, I'm down to 265...getting there.

 

[rowlex]

Re: Who runs a 4 blade prop?

from what i recall.

pitch= distance the prop would travel in one revolution in a solid material(jello for example). so a 19pitch prop would travel 19" in one revolution.

I've got a 21.5' bayliner with a 5.0 v8 with a 19p 4-blade. It's great for hole shot, i did loose 10MPH switching from the stock 3 blade. (55mph - 45mph)

im pretty noob to boat props. but you have a smaller boat and bigger engine then me. I assume you could go up in pitch if you didnt want to lose much top speed. or go with the 19 and your holeshot would be better as well as holding speed.

also, once you learn how to get up on the wakeboard holeshot doesn't matter. what i have found does matter is holding speed while behind the boat. without cruise control this is very hard for the driver. the smaller 19p may help in regard to this.

 

[geneseo1911]

Re: Who runs a 4 blade prop?

rowlex, what pitch was your original 3 blade? Were your old and new props aluminum or SS? I really don't want to lose 10 MPH.

Everything I read says to drop 1-2" pitch when going from 3 to 4 blade. I'm a little low on RPM's now, so selecting the correct pitch for the 4 blade becomes a little harder. Especially considering what the things cost; I have to get it right the first time.

 

[skydiveD30571]

Re: Who runs a 4 blade prop?

In regards to "getting it right the first time", many dealers both local and online have trial periods with propellers. You can try them out and send them back if it's not what you want. That's because of the natural uncertainty that comes with changing props, as well as the ease of installing/removing them.

How low are you currently on rpm's? About a couple hundred correct? If you go from a 21p 3bld to a 19p 4bld, you'd be gaining 400rpm from the pitch drop, and losing about 100 due to adding a blade. So in essence you'd be at about 4600rpm compared to your current 4300rpm. As other's have said, you'll have much more holeshot but you'll lose some top speed. I lost about 6-7mph going to a 4bld prop. It's up to you to decide which is more important.