Prop 3 or 4 blade
 

While cleaning out our new boat I cam across (2) 4 blade props the previous owner didnt tell me were under the seats in the cabin (bonus) maybe he forgot them.

My question is, and dont jump on me too bad because IM NEW to powerboating. I have 3 blade props on our Bravo1's now. What will the 4 blade props do for us?

Re: Prop 3 or 4 blade
 

What do you have for a boat, what power, and most important, what exactly are the props, both the 3 blade and the 4 blade?

Re: Prop 3 or 4 blade
 

lutz the 4 blades will usually hook up better and carry the bow higher out of the water. less wetted surface usually means faster except you now have one extra blade dragging through the water which means slower. so you will have to experiment as to which is better. the formula is a heavy boat so the 4 may help get the boat out of the water. you may gain in mid range and lose on top end. what 4 blades are they.

later

Re: Prop 3 or 4 blade
 

Four blade props differ in characteristics. Hydromotive Quad IV's for instance are designed to lift the stern, not the bow. On my 311-SR1, which is an ass-heavy boat, the Quad IV's were a definite advantage over the Mirage 3 blades the boat came with. By lifting the stern up, I reduced drag, kind of like having a shorter "X" demension. I gained 6/7 mph at cruise speed (3300 rpms) and 3 mph on the top end. This was measured by GPS.

Other boats, depending on their natural ride attitude might suffer from a stern lifting prop.

Like "Later" said, 4 blades will put you on plane quicker and easier, generally give you a stronger midrange, and top end will depend on the boat and what prop you run.

In general circumstances, whatever that might be, when you go from a 3 blade to a 4 blade, you should go down an inch or two in pitch, to counteract the additional drag as "Later" pointed out. Again, in my own case I actually went up one inch in pitch. Ultimately it's a case by case situation.

Put em on and see what happens.....

Re: Prop 3 or 4 blade
 

formula and Later, Thanks. I have a 311sr1 with 454's and bravo 1's. Im not sure of the pitch of the 3 or 4 blade props but will ck when at loto this weekend. Im assuming the 3 blade are standard from Merc with the Bravo 1 drives.

Re: Prop 3 or 4 blade
 

If your 454's are Mags (365 h.p.) and 1.5 ratio drives , you should be turning 23 pitch Mirage (3 blade)props on this boat. The pitch is usually stamped into the barrel of the prop. This is a decent prop for stock power, but as Formula Outlaw said, there are potentially some performance advantages with 4 blade props. A 22 pitch 4 blade should work well with your set-up, but you need to put them on and try them. Make sure you put the props on in correct rotation (turning outward). If you switch them, the boat will go backward when shifted into forward, and move forward when shifted into reverse.

Re: Prop 3 or 4 blade
 

Lutz, try to get your hands on a pair of Quad IVs. Think you will be impressed. The guys at Hydromotive spent about thirty minutes on the phone with me and told me exactly what I could expect and why. They nailed it right on the money. Your boat will love the Quad IV's as mine did. The Hydromotives are a totally different prop than the Bravo 1 four blades. The Bravos, I believe, I more of a "bow lifting" prop. Eithe way, try what you have and see what happens. If you get a chance, try a set of Quad IV's. You won't be sorry. Russ

Re: Prop 3 or 4 blade
 

Just thought of this. I run in salt water which usually allows a boat to perform slightly better. As you are in fresh, you may not see quite the same results. I'm only guessing here, but the thought crossed my mind.

Re: Prop 3 or 4 blade
 

Often the mid-range speed increases several MPH at the same rpm, but at a loss of a few mph at the top. Also, hydromotive's pitches are about 3 more than bravo in real-world use. ie a 24 hydro motive is similar to a 27 Bravo (if such a thing existed) or a 27 mirage. I'm repeating what my engine builder told me, not my personal experience.

Re: Prop 3 or 4 blade
 

Lutz they are probably junk so you should just sent them to me.... :D:D

Give them a try. Chances are there is a reason that they were in the bilge or were ever you found them LOL. However ya never know they may suite your driving style. You may also find that they had them on the boat before they did the motor mods. If this is the case then they will be pitched to shallow. If there is a HUGE pitch difference from one to the other then I would guess that the 4 blades were from before motor mods.

Jon

Re: Prop 3 or 4 blade
 

I had my 1991 311 with 502 mags out a few weeks ago. I am spinning 24P labed bravo ones. I started with them turned out. With four people in the boat and full of fuel it saw 68 on GPS. I when jumped into the Cold St. Croix river and switched them so they spun inward. I figured I would gain one or two mph, so being cold would be worth it. Running the same strech of river with the same conditions I lost 1 mph! I was not only cold but, slower! What's going on. I thought spinning them in would increase mph not lose. Confused and cold!

Don

Re: Prop 3 or 4 blade
 

I spoke to the prop guys at Mercury last year and asked what the best prop was for my 89 311 454mags (nice guys, real helpful) and told me my Mirage 23 were as good as it gets for the boat. Didnt reccomend swapping props around or anything like that. Does anyone have a way to reach hydromotive, I'd like their input (and a set of loaners!)

Re: Prop 3 or 4 blade
 

Someone is feeding you a line. My 89' 311 came with 23inch Mirage. Swapped to 24inch Hydromotive Quad IV's. NO COMPARISON WHATSOEVER IN ANY WAY. The Quad IV's gave me 6/7 mph increase at cruise (32/3300 rpms) and 3 mph at WOT. Spinning out.

Hydromotive's # is 330-425-4266
website: www.hydromotive.com

They spent half an hour on the phone with me telling me exactly what I could and expect and why. I've had mine now for almost four years and could not be happier.

Re: Prop 3 or 4 blade
 

dgdock13 - did you run mirage or mirage plus before? If so, what did you see for difference in changing to bravo 1's.

Re: Prop 3 or 4 blade
 

FYI, I have a 1990 292SR1 w/ 454 mags. When I got it, it was running using 23P Mirages. it seemed that it turned as much as 5200+ RPM. This seemed to be too many RPM. So, I called Hydromotive and a couple of shops regarding an alternative. I eneded up with a set of 24P Bravo 1 4 blades. Man, I love the way the boat runs! The holeshot and midrange are awesome! Even my cruise speed is 5-6 MPH higher. However, I'm embarrassed to admit that I haven't run it WOT yet! :o My kids won't let me leave the house without taking them (I set a speed limit for them, despite many chants to go faster!) :p !!!

Re: Prop 3 or 4 blade
 

Formula1 - I would be curious to know what your WOT diference is with your new props. I am running 23 mirage+ at around 4800+ rpm on my 336. I picked up a set of 22p bravo 1 props that I have not tried yet. I hate to loose top end but I spend most of my time cruising at 50-55mph. I may ave to break down and pull the boat out and make the change.

Re: Prop 3 or 4 blade
 

Powerguy, I might go out one day this week solo. If I do, I'll try to make a WOT run and see what the difference is and post it here. I almost bought a set of 22's by the ol' rule that go down a pitch, good thing I didn't!

Actually, I searched boattrader online and found some similiar boats (there wasn't that many!) and saw what kind of props they were running. It was interesting the different information I rec'd. :cool:

Re: Prop 3 or 4 blade
 

Mr Outlaw, are your Quad IV's stock or labbed and blueprinted?
Thanks...MM

Re: Prop 3 or 4 blade
 

Bone stock. I believe the Quad IV's lift the stern slightly more than the Bravo's do. I got basically the same results as Formula1 seems to have gotten. I don't have a clue as to "which prop is better". I'd think it would come down to the particular boat. I just know what results I got, and it was EXACTLY what Hydromotive said I'd get.

Re: Prop 3 or 4 blade
 

Yeah, everything I've read point's to them being ideal, and my '89 292 is always gonna be even more arse heavy than your 311. I currently have a pair of 23" Mirages. Hmmm, I'll struggle to afford a new pair of quad iv's, I wonder if I can find someone with a used set that won't mind shipping them to the UK.

I have a friend who I need to catch :D:D:D

Re: Prop 3 or 4 blade
 

I just missed a nice set of 24 pitch Hydros right here on the classifieds section. Emailed the guy,,,,,,,, gone. $450.00 for both!!!!!!!!! :mad:

Dammit, I wish I'd have seen those a little earlier.

Re: Prop 3 or 4 blade
 

Yeh, I saw those and was drooling.

Re: Prop 3 or 4 blade
 

I ran my 22 bravo 1's today and was not impressed with the results. Cruise rpm/mph was about the same as my 23 mirage + props. Hole shot was definitely better but top end was off a couple mph at similar rpm to the mirage +. I did not have a lot of time to play with trim settings but my first experience was so-so. I might have to go to 24 bravo 1's labbed.

Re: Prop 3 or 4 blade
 

Ran a set of 23 hydromotives today. Water about 1' chop and 1/2 tank of gas (80 gallons) ran 61-62mph at 4400-4450 rpm. Boat definitely felt like it was more out of the water that with the 23 mirage plus props. What would be suggested to get my rpm up to the 5000 range? What would I gain by just dropping a pitch or two? Lab finish?

Thanks

Re: Prop 3 or 4 blade
 

i've just bought a 311 sri, its has 29 four blade 17" props, and takes an hour to get its lazy gas guzzlin fat ass out the water and on to a plane.

Sounds good though, just that with all that noise the gathering crowds expect you to be goin fast than 10 mph for the first mile of your journey

sounds like 24's are the way to go.

i put the props on after the boat was shipped over, should i swap them port to starboard, will that make a difference?

Re: Prop 3 or 4 blade
 

Powerguy, I think each inch of pitch equals around 200 rpms or so.

CWUK if you swap the props port to starboard, vice versa, just remember forward is reverse and reverse is forward.

Re: Prop 3 or 4 blade
 

29 down to 24 is a massive jump in pitch!!! You'll be bouncing off the rev limiters. With the props I think you've got (spinnelli cleavers?), I'm not surprised it takes a long time to get on the plane. 24ish would probably be right for a pair of 454 magnums, but I can definately see a pair of superchargers there!

Re: Prop 3 or 4 blade
 

CHINE WALKER you can not just swap SSM props side to side you have to swap the entire drive!!!!! If you just swap props you will be running your trannies backwards. First find out what direction they are turning (in or out) and then get back to us. Also a exact measure of the X dimension would be good. Of course this is after you fix the gas issue!!!

Jon

Re: Prop 3 or 4 blade
 

Jon, you're right, I forgot he was running those drives, I just had "bravo's on the brain". LOL

Don't know if I've ever seen a boat actually take THAT long to get up on plane.

Re: Prop 3 or 4 blade
 

Looks like he's had enough!! :D
http://cgi.ebay.co.uk/ws/eBayISAPI.d...e=STRK:MEWA:IT

Re: Prop 3 or 4 blade
 

guys the gas issue is sorted for now

i simply took the cover off and opened all windows for 10 minutes

easy,

so back to props cos i'm still taking 40 seconds

how do you measure the x dimension ?

matt - spinnelli cleavers does ring a bell should they take 40 seconds

still need to find out for AudioFN if i'm spinning in or out.

Just waitin on next week pay check up to be able to run the engines for five
minutes

i've lots of testin to do - going for speed run with gps on and new trimming knowledge - goal- to beat fast lane traffic on motorway next to the river i play on.

if you don't hear from me again i may be on the river bed.

Re: Prop 3 or 4 blade
 

Seriously, running the boat before the fuel leak is fixed is a hand grenade with the pin pulled.
http://news.bbc.co.uk/1/hi/england/cornwall/3552504.stm

Re: Prop 3 or 4 blade
 

nobody wants a grenade for breakfast

i'm doing the leak, seriously it's next on the list,

i just need to wait until i have a buddy to help like on the weekend

i really just want to see the magic 80, 85 i don't recon but possibly 90 mph crop up just once before that though

gonna check the tides n weather tommorrow.

boatin boatin boatin

Re: Prop 3 or 4 blade
 

What was your previous boat?

Re: Prop 3 or 4 blade
 

used to have Baja HAmmer 7.4 great fun fast good on fuel towed well.

would have another one if it was Boss hammer

that link looks minging. Petrol boats are a crazy idea like "tommy cookers" Sherman tanks.

Bring on fast diesel boats - you don't have to fix your fuel leaks cos you ain't gonna blow up and the fuel cost less than half price ( in the UK anyway)

i do remember being in hospital earlier this year after my jeans set on fire at a BBQ, that was bad enough.

still would like to see 85 mph.

ok covers off windows open 15 minutes, 10 minutes blower on, open engine cover 10 minutes bilge everything outside the lock gates.

10 mile test

use up all the fuel

sort tanks out on week end

sorted

Re: Prop 3 or 4 blade
 

? I also have a 1990 292 SR1 with 23p Mirages my top speed on gps was 67 mph what was your cruiseing speed and what rpm.Im looking to upgrade my props and im not shure what to get

Re: Prop 3 or 4 blade
 

I also have a 1990 292 SR1 with 23p Mirages my top speed on gps was 67 mph what was your cruiseing speed and what rpm.Im looking to upgrade my props and im not shure what to get