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ContinuousWave: Whaler Performance
Propeller: 4-blade vs. 3-blade
|Author||Topic: Propeller: 4-blade vs. 3-blade|
posted 09-17-2002 07:04 PM ET (US)
[Hi,] [I] have a 1986 Striper model Whaler with a 2003 50-HP Mercury 4-stroke[.] [I] need to know what prop you would use[.] [I] currently have a 13-inch pitch[,] but the boat planes off at 3200 rpm and only runs about 28mph top end[.]
posted 09-17-2002 11:40 PM ET (US)
Some more details would help.
I run a 1999 Merc 50/4 stroke on my Montauk, it is mounted with the top two holes above the bolts and I am running a Merc 13 pitch aluminum prop. My gross weight when running is around 1700 pounds and I get 33 mph at 5800 rpm. I don't pay any attention to when it falls off plane.
When I get my new Trophy Sport 4 blade SS prop I will post results with it.
posted 09-18-2002 01:14 AM ET (US)
Dick, that 4 blade prop isn't going to help your performance, all it will do is get you out of the hole faster, nothing on the top end.
One question, why or who is making you feel the 4 blade is going to help.
Far to many engine dealers try to pawn these 4 blade props off on guys who really don't need them, or don't understand props, guess they make more money off them, as their certainly not cheap, or even reasonable.
Four blade props are mainly for bass boats, guys who fish in 2 ft of water & need to get up on plane very fast, no help on the ocean.
It's the type of prop that determines the boats performance, not the amount of blades.
You could do much better buying a quality s/s 3 blade, as far as hole shot & top end speed.
posted 09-18-2002 09:57 AM ET (US)
William....what is your RPM at top speed? I think you are underpropped(too small). What are you measuring speed with? If speedo, discredit that and get a gps.
Sal...I "hear" the 4 blades work well in the ocean because they bite better so in rougher seas they grab. I also hear if you run a jack plate or pierce the surface they help. I have NEVER run a 4 blade so I have no experience, just going by hearsay. They(conventional 4 blades) will shave top speed due to drag. My bud has a 27' Progression with twin modified 300 promax's. He runs almost 100 and runs 32" lab finished 4 blade cleavers....trippy looking props to the tune of $1300 each.
posted 09-18-2002 09:58 AM ET (US)
I happen to be the prop dealer who talked me into it.
An engine dealer gains nothing by selling a prop that doesn't do the job it was sold for but he does have an unhappy customer. Proping a boat is not rocket science but it does take a little brain work, maybe some testing and possibly a call to Merc Propeller .
Bass boats do use some 4 blade props but many boats can and do improve with the use of a 4 blade. Makes no difference if you are starting out in 2 ft of water or 200 ft.
I bought a 3 blade SS when I bought the boat 3 years ago, the 4 wasn't available then. I wasn't happy with the performance at all. Having run 4 blade props on other boats I expect to loose a little on the top end but gain on the hole shot and hold better in tight turns.
posted 09-18-2002 04:10 PM ET (US)
Dick, i'v seen to many 17, 18, & 22 ft whalers that should be performing far better then they are, with 4 blade $600 props.
It only stands to reason that, when a dealer sells a $300 prop his profit is 10 to 40%, by selling a $600 prop, he makes more.
Many dealers are "NOT" prop savy, & most John Q Public pweople don't even know what their top rpm rating is.
For instance, a good friend of mine bought a nice boat & powered it with a 225 FICHT, he turned barely 5,000 rpms with a 21 pitch prop, trimmed to max, ultra light load, yet he was happy.
I drove his boat & told him he's over propped & really needs an 18 pitch to reach 5,800 rpms, but they don't make an 18, so i suggested he run a 17 pitch as it would turn close to 6,000 with no load & 5,800 with a normal load.
He felt the dealer knew his stuff, until I loaned him a 14.25 x 17 s/s Stiletto that i had in my garage.
His fuel economy jumped & his engine dosen't hardly work near as hard as it did before, his mph is still about the same, but his engine is far happier, & less prone to failure because of lugging.
Merc props are far better then OMC props, & I still say Stiletto, or Michigan Raptor are the best bang for the buck, as they cost around 1/2 what most engine manufacturers charge & produce as good, if not better, as they have more cup & rake then most any OMC prop does.
I'v tested props for more then 45 years, as I raced unlimited 21' hydros to 3,000 hp, & outboards.
A decent 3 blade prop will hang on just as well as most 4 blade props, in rough or skinny water.
The only real advantage is, the hole shot with a 4 blade.
Most people want performance, or top end speed, & in most cases, a 4 blade will do nothing for them.
Why do you think we run 2 blade props while racing?
posted 09-18-2002 04:19 PM ET (US)
Maybe a little off the subject, but I had a "HIGH FIVE" prop on my 1991 BW 21WA with a 1995 225 Merc. The guy I bought the boat from said he tried several different props to find the one with the best performance out of the hole, top end and cruise. He said the "High Five" five blade prop was by far the best. The boat came out of the hole quickly and would run in the mid 50s MPH with no problem. I think it was a 21 pitch.
posted 09-18-2002 05:14 PM ET (US)
All this prop talk... I guess I'll look in the box of "extra props - 3 or four at least" that came with my 25'O. I just assume the best one was on the boat. On my old 235 Johnson... top end should be around 5500-5800 or so. I just assumed I was heavy and the engine was tired and ready for a rest... but she is so reliable. It may be that I'm significantly over-propped running just over under 4000 WOT on a good day down a wave.
Guess I'll do an hour of reading about props via Jim's fancy search machine...
posted 09-18-2002 07:35 PM ET (US)
Seabrook, mid 50s, with a 225 merc on a 21' outrage, certainly isn't setting the water on fire with that 5 blade.
I'm running a 1980 - 20' outrage with a 2000 - 200 hp Evinrude FICHT, with a 14.25 x 21 Stiletto 3 blade, up on the 3rd holes, out of the hole she's on plane in 1.5 seconds & 60.3 mph in less then 10 seconds.
That 5 blade is a total waste of money, as that 225 should blow you out of the hole so fast with a 3 blade, it should darn near break your neck.
Absolutly no reason for a 4 or 5 blade prop on a Whaler, with enough hp.
As I said before, the extra blade "ONLY" helps you out of the hole, & with 225 hp on a 21' boat, theres certainly no need for extra blades to get you up.
Capt Tidy, if your only getting 4,000 rpms at wot, your either running on 4 or 5 cylinders, or your about 9 inches to much on the pitch [ which i doubt ].
A sure way to kill that engine, is to over prop it.
That engine wants 6,000 rpms to breath.
My guess on your 25' boat with a 235 is, a 15 x 15 - 3 blade s/s prop, unless your running a 15 x 23, you have a major problem.
When is the last time you did a compression check ?
If in fact your running a 15 x 15, wanna bet you have at least 2 cylinders at 50 or 60 lbs compression.
posted 09-18-2002 08:59 PM ET (US)
I'm not proping a race boat. I am proping my Montauk to perform the way I want it to, if I max out at 30 mph I am happy.
posted 09-18-2002 10:37 PM ET (US)
Sal: I'm running a 22-inch Guardian with a four-blade Trophy. I also own a three-blade Mirage that I have used twice, and is collecting dust. Both props will spin at 5,800-RPM or a bit more depending on load. The boat does an honest 52 with a full tank and two people on board, I figure I lost a few MPH when I added radar, or the conditions weren't exactly the same because I used to get 54. Yep, I know, I'm setting the water on fire :)
Anyhow, I find that the four-blade propellers really help in rough water, especially when climbing rollers, or plowing through steep chop. They also keep the boat on plane at lower speeds, which is also very important to my kidneys in really bad conditions. I never really cared about time to plane since the boat has no problem doing it with either prop; but I'm seeing around 2.5-seconds to plane vs 1.5. Am I timing it wrong?
Which three-blade prop you are running that works better offshore? I am willing to try anything for grins and giggles, besides I can always trade the Mirage for something better.
posted 09-18-2002 11:16 PM ET (US)
Dick & Louie.
I'm going to recommend a site for both of you to click on, so you will both understand what i'm saying.
Then go to boat prop characteristics, then just follow the prop help , propellor basics.
Theres Diameter, Pitch, cupping, & Rake. read what each of them does.
Here is a very simple explanation by them.
3 blades or 4.
We recommend 3 blade props for recreational boats with 3, 4, & 6 cylinder engines & i/os, these props provide good hole shot & top end performance.
We recommend 4 blade props for bass boats & boats with high performance hulls running high horsepower outboard engines.
Compared to 3 blades, they provide better "hole shot" performance, with less steering torque, & less vibration at high speeds.
This is important.
Many of todays propellors incorporate a cup at the trailing edge of the prop blade.
This curved lip on the prop allows it to get a better "bite" on the water.
This results in reduced ventilation, slipping, & allows a better hole shot.
A cupped prop also works very well where the motor can be trimmed so that the prop is near the surface of the water, resulting in higher top end speed.
As you can see, a 4 blade really does nothing for your application.
Props are a complex piece of machinery, with Diameter, Pitch, Cupping, & Rake all doing something different.
If both of you put the right 3 blade on your boats, you would see the difference in all around performance.
If your 3 blade is blowing out in choppy water, it needs either less [pitch or more rake to correct it.
Please take my word for it, a 4 blade is not needed in either of your applications,.
Go to that site, & you will come back much wiser.
Thats only one site, if you really want to get into performance props, i'll send you to another site, but these 3 blade props will cost you a minimum of $2,000 each.
posted 09-19-2002 12:12 AM ET (US)
I have been a Mercury prop dealer for over 30 years and think I know what I am doing.
I thank you for your input but it does not apply to my application and I place much more value on Mercury's input.
posted 09-19-2002 12:22 AM ET (US)
Sal, you seem to know a lot more about props than I do and I concede that. As for comparison purposes regarding your comment about "setting the water on fire", my boat was not an Outrage, but a 1991 21' Boston Whaler Walkaround. Yes, the hull is very much like the newer Outrages, but nothing like the 1980 20' Outrage your compared it to. The 21' Walkaround is a BIG boat. It is deep, wide and relatively heavy. A 1980 Outrage 20 is much smaller. I spoke to others with the same boat and same HP motor the one I had seem to perform very well. Still, I do not doubt what you are saying about props because I know better than to challange someone who is obviously more informed than me. I just wanted to make the clarification on what type of boat I used for an example and that it is very different from the one you used.
posted 09-19-2002 11:55 AM ET (US)
I also went to Merc and boats.com sites, both IMO promoted 4 blades. Unless I read it wrong, the trade off seems to be some top end speed. The sites also seem to reflect what Dick and I are seeing with these props.
I found a great article at boats.com
Are you recommending a Stiletto, or Michigan Raptor? In your opinion will they outperform the Mirage sitting in my garage? I should mention that low and mid range performance is more important to me than top end (especially if itís only going to be a couple mph more).
posted 09-19-2002 01:05 PM ET (US)
Thanks Sal (Sir Sal sound better)...
In my box of extra I found a new 14 1/4 x 23 stainless steel and a good/excellent 14 x 17... I think I have a 14 1/4 x 21 stainless on it. And the engine is going in today for a complete tune. Previous owner indicated used 5500-5800 as max rpm.
Guess I have some work to do. I'm been so busy working on the hull... and looking for a set of twins 225s for this beast... guess I'll see what I really have under the hood.
Thnaks for a starting point for the prop..
posted 09-19-2002 01:40 PM ET (US)
2-thirsty-5's either redline at 5500 or 5800 depending on year. 225's(OMC) redline at 6k.
posted 09-19-2002 01:58 PM ET (US)
Excellent name for this thirsty bastard... I would be worried about the compression if I didn't do my buyers test... pulling each sparkwire in turn and watch the pig die out. I don't think this thing has ever been tuned... maybe 50-75 hours on same oily plugs etc. The 235 is not a harbor cruiser! Its like a nervous bride back there jumping around.
WOT is really run... just don't look down and watch the gauge. It moves just like a swiss clock. I always thought the tank should be in dollars versus 1/4s.
posted 09-19-2002 02:43 PM ET (US)
She'll do better with a smaller prop....not much.
posted 09-19-2002 08:37 PM ET (US)
In regards to bad performance, my 84 Yamaha 150 was having trouble getting an 18'OR out of the hole, once reved up she was ok, but- I thought I had taken on some water (alot of discussions about water in the foam,etc,. so, as it turns out I had a bad "control box". You know, the black box on the side of the engine that determines the firing sequence. Yep, it was only firing on 4 of the six cylinders. I had a bad statter too, but anyway...she jumps out of the hole like a jack rabbit now! The compression is still great.
posted 09-19-2002 09:01 PM ET (US)
Mercury makes three kinds of 4 bladed props, one for Bass boats (Trophy Plus), one for Offshore fishing/cruising (Offshore) and one for Stern Drive engines in go-fasts (Bravo 1).
I think Louie is correctly using the 4 blade Offshore, and Sal is referring to the 4 blade bass boat props. These are completely different animals, for different purposes.
Mercury advertizes the Offshore for heavier twin engine Offshore boats, requiring great holding and lots of lift. They indicate it will lose a few MPH off top end.
posted 09-19-2002 09:39 PM ET (US)
[The initial post and its author seem to have abandoned this thread, which is now discussing 4-blade propellers, thus the change in TOPIC; was "prop selection"--jimh]
posted 09-19-2002 09:55 PM ET (US)
Larry: You are right about the Offshore; my post contained a typo (more like a brain fart) stating that I was using a Trophy. I actually ran out to the boat just to confirm what it was, and yes it is an Offshore.
I'm kind of thinking out loud here but, doesn't the description for the Trophy look like it would better suit my boat:?
PS the one collecting dust is a Mirage Plus.
posted 09-20-2002 03:36 PM ET (US)
Louie - I don't think you would want a Trophy Plus prop. I've never heard of them being used on a 3.0 liter Merc, only the 2.5 liter engines, 135-200 HP, and smaller. They are a mid range size prop, 4 1/4" gearcase, for 75-125 HP engines on Bass and Flats boats, and when they use them on an XR6 150HP engine, the exhaust actually blows by the edge of the smaller hub. V-6's normally use a 4 3/4" hub prop.
For 3.0 liter 225/250's, the Bass boat guys use the 3 bladed Mercury Tempest Props. It is for elevated engine heights and delivers max speed, but they don't promote it for offshore duty.
If you're looking for a trade in on the Mirage, you might consider the 3 bladed Laser II's that I use. Although, once again, the Mercury prop guys seem to indicate the Laser's are best on 2.5 liter and smaller, and Mirage's are preferred for the 225/250's.
The Laser II is recommend for light weight hulls (relative to the HP) and gives great bow lift and top speed. The Michigan Wheel Rapture and Stiletto's are basically knock-offs of the Laser II, but not as raked as much. They look a little more conservative.
I'm surprised you don't like the Mirage Plus. Most new Whalers come with those, but I have no experience with them.
posted 09-20-2002 03:41 PM ET (US)
I would think the Mirage as well. I had a Laser II on my 21 Scarab with a 260+hp I/O. Everyone said it is an outboard prop but I needed the nevt holes for hioleshot. Was the fastest 21' on Barnegat Bay....almost:)
posted 09-20-2002 06:48 PM ET (US)
Larry: I don't hate the Mirage; it ís just that the offshore REALLY outperforms it in everything but top end (which IMO is really over rated).
My thinking was that I could trade it for something better.
posted 09-22-2002 12:39 AM ET (US)
3 blades vs 4 blades in a nutshell: Four bladed props supply more power at lower revs. Three bladed props are more efficient at the higher revs. If you ever saw a tugboat on the railways chances are that the props are four bladed.
posted 10-07-2002 09:11 PM ET (US)
I ran my Montauk/50 Merc 4 stroke yesterday with the new Merc SS Trophy Sport 4 blade.
I lost about 1 mph at the top end, and had expected that. Topped out at 32.2 mph at 5600 rpm.
I have never ran a stopwatch on time to plane but the 4 blade is much quicker and seems to hold plane at a little slower speed.
posted 10-07-2002 09:47 PM ET (US)
Dick, what pitch prop did you get? When I was discussing this prop with the guys a Mercury they suggested an 11 pitch.
posted 10-07-2002 10:31 PM ET (US)
I went with the 13 pitch. Sorry I didn't include that in my post.
I was thinking towards the 12 pitch but the guy I talked to at the Merc prop dealer desk thought the 13 would be a better all around prop.
posted 10-08-2002 07:12 PM ET (US)
Fixed long URI--jimh.
posted 10-08-2002 10:57 PM ET (US)
Thanks. I was getting dizzy trying to read this thread.
posted 10-08-2002 11:48 PM ET (US)
Thanks for getting rid of my double post. I never got the "Thanks for posting" message and hit submit again.
posted 07-17-2009 06:40 PM ET (US)
I have a question, [I] have a 200-HP [M]ercrusier. [It] has a 19 pitch 3 blade prop. [The] rpm range on that engine is 4400 to 4800. [It is] turning almost 6000. [W]ould a 23 pitch prop be suffice? [A]lso the question on 3 or 4 blade. [I] use my boat to joy ride and pull occasionally. [I]t runs about 45[.] [N]ow [I] know that the 3 blade 23 will lower my RPM and give me higher speed. [W]ill the 4 blade increase my speed as well? Or should [I] stick with 3 for the better performance? [Which] would [I] like the best? [I] want the handling but [I] don[']t want it to go any slower. [E]ither stay the same or faster. [W]hat do [you] suggest?
|Tom W Clark||
posted 07-18-2009 01:13 AM ET (US)
I don't think Dick is going to answer you. You are about seven years too late to the party.
I suggest you start a thread of your own to ask a question instead of dredging up seven year old discussions.
You never know, we might have learned a thing or two over the last seven years and may be able to assist.
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