My Solas AMita is too much, alternatives?

[paczowski123]

Well as it states last year I went with many people recommendation of the Solas AMita 14.25X19 prop. This is a great prop and pops me right out of the water, but it's disconcerting to have my boat running so close to redline while skiing (i.e 4300-4600 depending on passengers for 33-34 mph from what i remember. My boat came with a 23 pitch prop, can't remember the the diameter, which I have now switched back to, and I got up no problem today with my GF and her friend in the boat, but feel that with a couple more in the boat it could prove challenging.

My question is what are my alternatives, could I do a 21 pitch 4 blade? I know that's fairly close to my 23 3 blade with the calculation,but would it make a slight difference? It seems my boat only needs a little more to be perfect. Or even go to a 21 3 blade which seems what most I/O come with? The 19 was just too drastic, any recommendations?

Btw: anyone looking for a 14.25X19 Amita I'd be happy to sell mine, I've only used it about 6 times not a knick on it.

 

[steelespike]

Re: My Solas AMita is too much, alternatives?

Remind us of your boat/motor. 4300- 4600 isn't a red line for most Mercruisers.
I think 4300 is below the low end of the rpm rating.Is the 4300-4600 at wot?
One reason it pops you right up is its ability to get right into its power band near the max rpm.
A 21 4 blade may take 300 to 400 out of the rpm Could put you below the rpm range all together.
Remind us of the rpm and gps speed with the 3 blade 23.
Your motor will be happier revving freely within the range. The motor will be straining less with the 19.

 

[paczowski123]

Re: My Solas AMita is too much, alternatives?

Boat is a 98 bayliner 1850 SE, with a merc. 4.3. I've never GPS but with the 23P I'm right about 4700 and 45-50 depending on water and passengers trimmed out. And no that RPM is not at WOT it is at enough to get the boat to 33-34 and at 36 it prob right at 4600 more so. I can't give the boat WOT or it will go past redline. If its ok for the boat to be operating that close to the redline that's ok with me, especially if it is better on it. I RARELY even go over 30 when cruising and ski at around 33. I just got worried having the boat that close to redline in fear of someone not familiar with my boat driving it or pulling me and cornering it and overrevving.

 

[steelespike]

Re: My Solas AMita is too much, alternatives?

OK, if your controlling the rpm with the throttle with the 4 blade 19 the 19 will deliver great performance. If you have multiple operators and your afraid some one may go over the redline for an extended time at wot you may want to go with a 20 or 21 in prop.
Still will have an over rev issue but less severe.
Momentary jaunts over the red line say 5000 from wave action or turning is no worse than taking your car momentarily to 5000
on hard acceleration.If it happens dozens of times a day then maybe a 21" is better.Normally you should trim down for a turn to control venting in a turn.
A 21 may lower the wot rpm about 300-400 from the wot of the 19".
What is the hp of your 4.3?

 

[steelespike]

Re: My Solas AMita is too much, alternatives?

OK, if your controlling the rpm with the throttle with the 4 blade 19 the 19 will deliver great performance. If you have multiple operators and your afraid some one may go over the redline for an extended time at wot you may want to go with a 20 or 21 in prop.
Still will have an over rev issue but less severe.
Momentary jaunts over the red line say 5000 from wave action or turning is no worse than taking your car momentarily to 5000
on hard acceleration.If it happens dozens of times a day then maybe a 21" is better.Normally you should trim down for a turn to control venting in a turn.
A 21 may lower the wot rpm about 300-400 from the wot of the 19".
What is the hp of your 4.3?Do you know the gear ratio?Sometimes on the outdrive.

 

[jestor68]

Re: My Solas AMita is too much, alternatives?

If your Bayliner's tachomater is like mine, there should be a black plastic connector(3 prong) on the back of the tach.

Try pulling the connector off and cleaning the pins with electrical contact cleaner. When the pins get dirty, it causes my tach to read higher than normal. The prop slip calculator indicates that your rpm readings are higher than normal for your gearing and pitch.

 

[paczowski123]

Re: My Solas AMita is too much, alternatives?

If your Bayliner's tachomater is like mine, there should be a black plastic connector(3 prong) on the back of the tach.

Try pulling the connector off and cleaning the pins with electrical contact cleaner. When the pins get dirty, it causes my tach to read higher than normal. The prop slip calculator indicates that your rpm readings are higher than normal for your gearing and pitch.

JESTOR I have noticed sometimes my tach will read way high,but will usually return to normal, and sometimes when first starting after sitting it will kinda bob up and down while idling. Maybe i need to try cleaning as you said. i guess i can access this connector from inside the life vest compartment behind the bow driverside passenger seat back, or will i need to pull the cluster.



STEELSPIKE i believe my boat is the 190 Horse not sure though, i have my serial number in my info section for the motor and outdrive, but i dont know how to look it up or find hp. ive never had an overrev problem and my GF knows to watch the revvs and like i said when skiing its never over revving and she generally pulls me. I was more so worried if it would be bad to operate the boat at that high rpms if its redline is 4800.

 

[steelespike]

Re: My Solas AMita is too much, alternatives?

My info indicates a 190 uses a 1.81 gear ratio.23" prop at 4700 rpm,12% slip indicates 49.8 mph.
Pretty normal. By your description your fine and the 19 4 blade should handle your requirements easily.

 

[paczowski123]

Re: My Solas AMita is too much, alternatives?

Yeah, I just felt like running that close i.e. 500 rpms off redline seemed close to me, it felt like I was running the boat to almost max potential just to get to ski speed. If its normal and those rpms are actually in the power and which means less strain on the motor it works for me.

Steelspike how do you calculate slip and what not. I looked up the prop selector but didn't know what to put in the boxes such as slip percentage and actual vs. wanted rpms etc

 

[carey965]

Re: My Solas AMita is too much, alternatives?

i have a 21p 4 blade amita and i consider that my ski prop, good hole shot and about 45 mph on gps with my 18ft tahoe that weighs about 2500 lbs and has a merc 4.3, from what i have heard and learned a 21p 4 blade equates to a 19-20p 3 blade

so your essentially running a 17-18p 3 blade which if your boat is anything like mine a little on the low side

i would say if you want a 4 blade all around the 21p is a good choice, i am really happy with mine, but i want more speed when im not skiing so im trying to get a 23 3 blade

 

[jestor68]

Re: My Solas AMita is too much, alternatives?

JESTOR I have noticed sometimes my tach will read way high,but will usually return to normal, and sometimes when first starting after sitting it will kinda bob up and down while idling. Maybe i need to try cleaning as you said. i guess i can access this connector from inside the life vest compartment behind the bow driverside passenger seat back, or will i need to pull the cluster.


With your gear ratio and a 12% slip(normal) with a 19 pitch prop you should be turning about 4000- 4100 rpm at 35-35 mph.

That's why I suggested to look at your tach connectors. My tach acts goofy when the pins get dirty.

 

[jestor68]

Re: My Solas AMita is too much, alternatives?

i have a 21p 4 blade amita and i consider that my ski prop, good hole shot and about 45 mph on gps with my 18ft tahoe that weighs about 2500 lbs and has a merc 4.3, from what i have heard and learned a 21p 4 blade equates to a 19-20p 3 blade

so your essentially running a 17-18p 3 blade which if your boat is anything like mine a little on the low side

i would say if you want a 4 blade all around the 21p is a good choice, i am really happy with mine, but i want more speed when im not skiing so im trying to get a 23 3 blade

Actually, it's the other way around concerning 3 blade versus 4 blade. If you put the same pitch 4 blade on there, you can expect a reduction in rpm compared to the 3 blade(more blade area). That's why it's recommended to reduce an inch of pitch when switching from 3 to 4 blades in order to maintain rpm. That assumes the same material from the same maker. When you start switching material and/or brands, the results can be all over the place.

 

[carey965]

Re: My Solas AMita is too much, alternatives?

everything i have read says when going from the same pitch 3 blade to a 4 blade you will gain hole shot and lose top end, is that not correct?

essentially that is like going down in pitch on a 3 blade (for example 19p-17p) because the 17 will give you more out of the hole but kill your top speed now i know its not perfect math by any means buts it is a bit of an example

 

[batman99]

Re: My Solas AMita is too much, alternatives?

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On my Bayliner, factory was aluminum 3-blade 21P. This is for empty boat and assume 2 people. Anything more and its too "sluggish". For my comfort range and typical usage, I use 3-blade 19P for cruising and 4-blade 17P tubing. The 3-blade is good for long distance cruising (re: gets good MPG) and 4-blade has better traction (for hole shot) but needs more energy (which means less mpgs) to turn it.... For a large Bayliner with 3.4L engine, 4-blade 19P (tubing or extra loaded) and 3-blade 21P (for average loaded & cruising) sounds reasonable. Especially if factory aluminum 3-blade 23P is sluggish when loaded down.

 

[jestor68]

Re: My Solas AMita is too much, alternatives?

everything i have read says when going from the same pitch 3 blade to a 4 blade you will gain hole shot and lose top end, is that not correct?

essentially that is like going down in pitch on a 3 blade (for example 19p-17p) because the 17 will give you more out of the hole but kill your top speed now i know its not perfect math by any means buts it is a bit of an example

From the Mercury Marine propeller 101 discussion section: "If you are upgrading from a 3 blade prop to a 4 blade prop, remember that many 4 blade props generally turn 50-100 rpm less than a 3 blade prop of the same pitch."

It has less to do with actual pitch, and more to do with blade area. The 4 blade has more blade area than the 3 blade of like pitch. The increased blade area is what accelerates you out of the hole faster and causes more drag at higher speeds, usually resulting in a slight lose of top speed, as well as a reduction in WOT rpm if you stick with the same pitch.

 

[jestor68]

Re: My Solas AMita is too much, alternatives?

I'm still scratching my head over the OP's results with this 23 pitch prop.

Bayliner would normally supply a 21 pitch prop on their 18 ft boat with a 4.3L Alpha(1.81) combination. The Mercury prop selector also recommends a 21 pitch for that boat, and calculates it's performance as 46 mph @ 4600 rpm.

I believe the tachometer is reading too high; on the order of 400-500 rpm high. With a 23 pitch prop, you more likely would be turning 4200-4300 rpm at WOT on that boat.

 

[paczowski123]

Re: My Solas AMita is too much, alternatives?

Jestor it could be my tach is off, I will get in there and clean it this weekend and see if it changes. Like i said it has acted funny in the past, hopefully this could be a solution. I will post my results with the 23p 3 blade after and see of it changes.

 

[callen369]

Re: My Solas AMita is too much, alternatives?

I think you'd be very happy with a 14.5x21 in 3 or 4 blade. Sounds like you are pulling skiers a bit, so I would go 4 blade. I run the Turning Point Express 14.5x21 4 blade on my Sea Ray 190BR with 4.3 190HP. Dropped my WOT RPM's from 4800 to 4450 compared to 14.5x21 merc 3 blade. Still runs 45/46 and has great hole shot and stability. Low speed handling is a bonus as well.