could it be propped wrong?

[jere1972]

Re: could it be propped wrong?

I'm all for looking for a cheap test prop on CL. my issue is I don't think I'll know what I'm looking at, what exactly is a big eared prop, I've seen props that looked like Micky Mouse ears, circular in shape no point, kinda what was on early Johnson/Evinrude shearpinned props, any way to tell for certain if the prop will hang on a Bravo 1, with the original thrust washer,

 

[jere1972]

Re: could it be propped wrong?

my buddy says he has a timing gun with a digital tach ....would that be usable?????? for a test tach??

 

[jere1972]

Re: could it be propped wrong?

iBoats shows a Solas 15 1/2 x17 Amita 3 -Eplus #1511-155-17
says it's for heavy boats???? is this considered a big ear prop??? it's only $122
my buddies bringing his timing gun and were gonna run the boat on the river tonight and compare readings between his gun and the boats Tach

 

[emilsr]

Re: could it be propped wrong?

A digital tach would be great. Measure throughout the rpm range.

A Johnnyrude prop probably isn't going to fit. Gotta match splines as well as hub diameter.

Be advised, different props will respond differently to trim inputs. Bow lift is a good thing for your type of hull. That means you're loking for more rake and/or cup....which is lacking in your current setup.

No worries. You'll sort it out. Boating isn't as simple as you'd think.

 

[Tail_Gunner]

Re: could it be propped wrong?

Products


Amita 3 - E Plus
- Exclusive squeeze cast process
- Larger blades than the Amita 3 series
- Superior thrust
Aluminum - Suitable for heavy boats
3 Blade Propeller - Thru-Hub Exhaust - Pressed Rubber Bushing - See Amita 3 Video
Pitch Diameter Rotation Mfg Part Number
13 16 R 1511-160-13
15 15.8 R 1511-158-15
17 15.5 R 1511-155-17......
19 15.3 R 1511-153-19
21 15.3 R 1511-153-21
23 15.3 R 1511-153-23

Solas Amita Aluminum Propeller (1511-155-17) - iboats

http://boatpropellers.iboats.com/Me...17.00-Pitch_Propellers/786/?*******=821097240

As alway's one assume's the hull of the boat is squeaky clean and smooth as a baby's but..

 

[jere1972]

Re: could it be propped wrong?

well ran out on the river Sunday, checked rpm with a digital tach/timing gun, not real certain but in the higher RPM range 4k up seemed to be a bit off, the analog tach appeared to maybe be 75-100 over, again maybe, depends on your angle to the tach, and the yelling back and forth over the engine noise, forgot the gps so could not gain any more insight as to speed vs. rpm. should have just ran it on the trailer, but was afraid of over reving the old 7.4

So is it looking like new prop time? and would the one mentioned earlier suffice as a big eared prop (Amita 3 e-plus 15.5x17) or should I stay with a 19, don't remember if they offered a 16, but I don't believe I have an issue hitting my RPM, and a 16 may be way low,

 

[emilsr]

Re: could it be propped wrong?

well ran out on the river Sunday, checked rpm with a digital tach/timing gun, not real certain but in the higher RPM range 4k up seemed to be a bit off, the analog tach appeared to maybe be 75-100 over, again maybe, depends on your angle to the tach, and the yelling back and forth over the engine noise, forgot the gps so could not gain any more insight as to speed vs. rpm. should have just ran it on the trailer, but was afraid of over reving the old 7.4

So is it looking like new prop time? and would the one mentioned earlier suffice as a big eared prop (Amita 3 e-plus 15.5x17) or should I stay with a 19, don't remember if they offered a 16, but I don't believe I have an issue hitting my RPM, and a 16 may be way low,

Maybe. Your slip % is lower but still higher than it should be. It would have been best to get a good WOT rpm number, but at least you know your tach is reading on the high side.

Are there any prop shops or marinas around you? Many have prop loaner and/or rental programs so you can "try before you buy". Sometimes it costs a few bucks, sometimes they'll waive the fee if you purchase from them. It's worth looking into before you start collecting props.

This is coming from a guy with a good sized prop collection.

 

[jere1972]

Re: could it be propped wrong?

honestly I don't know if there is any shops, most are mickey mouse repair places, mercruiser is not a big thing around here anymore, everything is outboard driven, not certain where to look, most likely have extremly high mark ups, guess I need to do some investigating locally, looks like my collection as all ready started I have 2, maybe soon to be 3 or 4, I was reading on Bow lift vs. stern lift props????I know I don't need sternlift.

 

[QC]

Re: could it be propped wrong?

If your hole shot is good, I would not go down in pitch. This could be a problem though as reducing slip may also reduce RPM, but you have to start somewhere. If you end up at 4200 WOT, and your hole shot is still acceptable, that would be a success in my book. The risk of ending up below 4200 is low in my opinion.

 

[Tail_Gunner]

Re: could it be propped wrong?

You really need to find a 16-17 for a positive finding. A 26' boat 5000lbs with a 454 is not going to push a 19...maybe not...:lol: Dont get caught up in the 454 its really old..i have one now and begining to understand its design along with limitation's..in its state of build think a modern 350 pushing a 26" boat Now slap some differnt heads and cam..500 in a minute. but for now its 300. Maybe a 16p 4 blade...now that would or should leap out of the water and pull like a tractor to 40 and change which its desinged for...

 

[Tail_Gunner]

Re: could it be propped wrong?

If your hole shot is good, I would not go down in pitch. This could be a problem though as reducing slip may also reduce RPM, but you have to start somewhere. If you end up at 4200 WOT, and your hole shot is still acceptable, that would be a success in my book. The risk of ending up below 4200 is low in my opinion.

QC your boat is 26' is it not close i think...whats your prop gearing and hp along with speed and you have a go fast hull.

 

[QC]

Re: could it be propped wrong?

QC your boat is 26' is it not close i think...whats your prop gearing and hp along with speed and you have a go fast hull.

My boat is probably a bad example. It will pull a 24 empty, but I run a 2 inch Bravo 1 4 blade, but all the way out to 5200 RPM (6.2)

I am betting the 19 will work as he can afford to lower his WOT RPM with the good hole shot and the bullet proof, low rated 7.4. He is pulling a 19 now

 

[emilsr]

Re: could it be propped wrong?

honestly I don't know if there is any shops, most are mickey mouse repair places, mercruiser is not a big thing around here anymore, everything is outboard driven, not certain where to look, most likely have extremly high mark ups, guess I need to do some investigating locally, looks like my collection as all ready started I have 2, maybe soon to be 3 or 4, I was reading on Bow lift vs. stern lift props????I know I don't need sternlift.

Yea, you want something that will lift the bow. You also need/want to be able to trim out enough for the prop to lift the bow.

My guess.....only a guess as it's almost impossible to diagnose with a keyboard....is you're propped correctly, just with the wrong prop. What I mean is that trimmed out you would be at 4700 on the tach, which in reality is 4600 or right where you want to be. As QC pointed out, that's the high end of the range.....if you wound up at 4400 (or a little lower) that would be okay too as your recommended rpm range (if I remember right) is 4200-4600.

Adding some cup to your current prop might work. Might not. The only way to really know is to test.

I'd check out the "mickey mouse" repair places. Never know what you'll find. I've gotten a couple of good props (and tested a few others) out of places like that; doesn't need to be a full on Mercruiser repair facility to have a pile of props in the back.

 

[jere1972]

Re: could it be propped wrong?

yeah guess the mickey mouse shop was a stab from me, since most of my outboards and advice came from those mickey mouse shops, I'll retract, I've looked @ the 4 blades, however I would be concerned about my bow lift, they seem to boost stern from what I read, I'm rethinking my goal now, It's really not the speed, I believe I'm trying to beat more out of that hull then what she was designed for, however I would like to optomize her to her fullest, I want to pile a few buddies in load up on ice head out 60 miles and know I'm running as effecient as I can run, I'm guessing with all the prop slip all i'm doing is burning up fuel, one thing I failed to mention was reverse control, at the ramp she'll back up and turn, in open water with current and wave she'll go backwards but not vary well, and forget about steering control in reverse. any opinions on tail gunners suggestion of the 4 blade????? Is an aluminium prop gonna have a negitive effect on bow lift?

 

[emilsr]

Re: could it be propped wrong?

There are some 4-blade props that provide good bow lift. Mercury's Revolution 4 is one of them.

However....

Sometimes a more neutral lifting prop can provide good cruise performance albeit with a loss in WOT speed....or maybe not, depending on boat and conditions.

Just for situational awareness and not direct comparison:

At sea level and up to about 2,500' density altitude, my boat (26' deep v, 425 rated hp) ran best with the Rev4. Now that I'm boating at 4330' elevation and up to 9k' density altitude (20% loss in power) I get better results from a Bravo I which is a neutral lift prop. Conditions vary, and as a result the "best prop" also varies with conditions.

Good luck with the prop fetish it sound like you're developing. I'm not one to judge as I have 8 or 9 props sitting around right now.

 

[Tail_Gunner]

Re: could it be propped wrong?

http://forums.iboats.com/prop-questions-topics/4-blade-disappointment-195031.html

http://forums.iboats.com/prop-questions-topics/prop-slip-280773-2.html

http://forums.iboats.com/prop-questions-topics/14-1-2-x-17-vs-15-x-17-solas-wow-572940.html

http://forums.iboats.com/prop-questions-topics/alum-vs-ss-w-numbers-322756-2.html

try the 17....due to the fact you have a high tourqe low rpm motor it should work out wel wind the thing to 4800 and watch the slip ratio.....Bondo..Don any harm gearing a 454 to 4800???l....Now QC let's not get into tourqe and rpm until he mounts a lower pitched prop.

 

[jere1972]

Re: could it be propped wrong?

Been awhile but been busy with lifes issues, getting back to my boat, picked up a used SS Mach 4 blade, 16"x17 got a fairly good deal on it I think ($160), hoping this may help with the high prop slip but had to make a last second decision to buy it ...any one know anything about Mach props did not find much online about them! or did I pick up another prop to add to my pile?