Picking A 4 Blade Prop For My 4.3L Cuddy

[hostage]

I noticed that I have am having issues getting on plane and having issues getting to speeds I use to. I have been using a slightly damaged prop that came with my boat when I bought it used, after my old man killed the new prop I had put on there ><. Revenge I guess...

Make: Maxum
Model: 1900SC
Year: 2000
Motor: 4.3L Mercrusier
Drive: Alpha One Gen II
HP: 190HP
Current Prop: Michigan Match: 3 Bladed AL, 13.75 diameter, 21 pitch SN: 031026

I really could care less about top end speed and I was reading that a 4 bladed prop will give you better hole shot and be better fuel economy wise.

I use to get a top speed of 46mph on a good day. I think I hit 38mph and I noticed it is painful to get on a plane. There is some damage to the prop, though I don't know if that is the only source for the sluggish performance.

Anyway I am trying to figure out what would be the best 4 blade prop. I don't know whether or not to assume that the current prop is the proper size. I do see that my boat could have two different gear ratios 1.62 and 1.81.

PROPELLER MATERIAL BLADES DIAMETER PITCH ROTATION
Turning Point AL 4 14.5/14 17/19 RH $139
Merc Marine AL 4 14 17,19 RH $159
Solas Amita AL 4 14.25 19 RH $115.37
Solas Amita AL 4 14.50 17 RH $125.98


Do any of these seem like a good match. When I tired mercrusier's tool, it said either a cheap 3 blade or really pricey 4 or 5 bladed SS props. ><

 

[hostage]

I saw some good reviews on the Turning Point and it is sold locally, it is almost double the price as I need to buy a hub kit. I would have edited, though it looks like that option is disabled

PROPELLER MATERIAL BLADES DIAMETER PITCH ROTATION
Turning Point AL 4 14 19 RH
Turning Point AL 4 14 .5 17 RH
Turning Point AL 4 15 15 RH

 

[H20Rat]

Don't expect any change in fuel economy, and if anything, a 4 blade will make it worse. One more blade to drag through the water. You also missed the most critical piece of information, RPM at WOT. Without knowing that, nothing else matters. You might be ok with a 4 blade 21p, or a 4 blade 19p.

Based on my quest a month ago to find the perfect prop, I learned to stay far away from Turning Point. Absolute garbage, no quality control. I ended up with a Solas 4 blade Rubex prop that I like. (you mentioned Solas Amita, that isn't a good choice for your boat)

Not going to name retailer names, but there is one GIANT one out there that will return props after they have been in the water. Local guys might do it, but ask before you lay out the credit card.

 

[alldodge]

To help with a prop we need

WOT RPM
WOT speed GPS
Motor
drive ratio
current pitch prop

Have provided most and , If your speed is GPS we can get close by plugging in the different drive ratios, but have to have RPM

 

[hostage]

Don't expect any change in fuel economy, and if anything, a 4 blade will make it worse. One more blade to drag through the water. You also missed the most critical piece of information, RPM at WOT. Without knowing that, nothing else matters. You might be ok with a 4 blade 21p, or a 4 blade 19p.

Based on my quest a month ago to find the perfect prop, I learned to stay far away from Turning Point. Absolute garbage, no quality control. I ended up with a Solas 4 blade Rubex prop that I like. (you mentioned Solas Amita, that isn't a good choice for your boat)

Not going to name retailer names, but there is one GIANT one out there that will return props after they have been in the water. Local guys might do it, but ask before you lay out the credit card.

From what I read the Amita is the same as the Rubex, though the Amita has a built in hub, while the Rubex is swapable.

I am having issues figuring out the gear ratio, they might as well write all the serial numbers and details in chalk. All I know is I have one of those two.

I think my RPM was in the 4000s, I can't recall. I also wonder how much of an impact it has as the blade has damage on it? Wouldn't RPM be important to know with a good condition prop?

It is hard to get out, since have a kid.

 

[Maclin]

What are the specs on the prop that worked well but got destroyed?

 

[alldodge]

21 pitch 3-blade
With 4000 rpm and 1.62 drive your slip is 22.6%
With 4000 rpm and 1.81 drive your slip is 13.5%

Need to get your WOT (with accurate tach) RPM closer to at least 4400, if not upper range to 4800
Tells me (if info is correct) you need at least a 19 3-blade 13.75 or 17 3-blade 14.25
The 4-blade need maybe a 15 pitch

Remember more blades takes more power, will increase lift, and with more lift you may have porpoise issues

 

[hostage]

I will have to take a look at the prop. The prop was installed by my old mechanic and I don't know if I would trust what he installed. Is there a place on the boat or lower unit where I can see the ratio?

When I said 4000s, I meant it was above 4000 IIRC, so it could have been 4800 or 4400.

In theory wouldn't the RPM value be irrelevant, if the prop is damaged?


Granted I could always drop $70 (14x21) on this prop:

https://rochester.craigslist.org/bpo/d/mercruiser-propeller-21-pitch/6675014233.html

It looks in great condition and then I could use that as a benchmark for the prop I actually want to buy, then I could just relegate this one to a backup?

 

[alldodge]

Yes, a damaged prop will have more slip

Without real numbers were just guessing

 

[FBJR]

I need to follow this. I heard nothing but good about the TP and ordered a 14x19 4b for my 18ft bowrider, 4.3ltr alpha with 2 ratio

Had a 13.25x17 3b on it and it revved easy over 5k and didn't want to get on plane.

 

[H20Rat]

I need to follow this. I heard nothing but good about the TP and ordered a 14x19 4b for my 18ft bowrider, 4.3ltr alpha with 2 ratio

I had 2 different 3 blade stainless steel turning points less than a month ago. The 19p was unusable, the hub wobbled enough that the vibration would have ended up destroying other parts. The 21p wasn't as bad, but it didn't run as smooth as my beat up merc vengeance prop.

Didn't spec the props out, but on the 21p it looked like the inner hub wasn't installed perfectly centered in the outer prop hub. The front appeared to be, but it was off-kilter in the aft end. The 19p had that problem, as well as the outer prop hub being out-of-round a visible amount.

On my previous thread, someone warned about not handing over money before you inspect the prop. I second that and go one further, make sure you buy from a place that will return a wet prop. On the bench, these props looked ok, the defects aren't very visible unless you get out measuring tools. If you spin them on a shaft, you can see the wobble though.

 

[H20Rat]

From what I read the Amita is the same as the Rubex, though the Amita has a built in hub, while the Rubex is swapable.

yeah i was thinking the amita high-thrust. I still personally like the replaceable hub, but the initial cost is higher.

 

[Cortes100]

I've been using the Merc Spitfire (Quicksilver Nemesis) 4 blade and very happy with the performance. Excellent pulling power. Good top end. Also noticed when goofing around with tight turns, it holds its grip and have never seen it cavitiate.
Can't tell you what pitch to use until you figure out the other stuff, but the prop itself is a good quality performing prop. FWIW, I've always had good luck running a Merc prop on a merc engine. Prices are no higher that the other brands

 

[FBJR]

My prop will be here today. Ordered online and will check it out well before I install. I can even check it on my lathe for true.

I now have a solas and TP hub so if I replace it is just the prop.

By the boat is a 93 chaparral 18ft bowrider running at sea level in fresh water. Mainly used for fishing and pulling the kids.

 

[GA_Boater]

Guys - This a thread started by Hostage about his situation. It is not a general prop topic thread. If you have a prop question, start you own thread. All these questions are not helping Hostage, in fact the thread is becoming very muddled. Some are not even prop questions, as in missing lower unit parts questions

Thanks.

 

[89retta]

@ GA I also noticed the topic Hostage posted is totally different then his post. Two different boat and engine combos

 

[WesNewell]

Would one of mods fix this thread? thanks

 

[GA_Boater]

Would one of mods fix this thread? thanks

We aren't miracle workers.

As 89retta said - Title says Cajun w/OB and the post says Maxum w/4.3 MC.

Watta you got, hostage?

 

[WesNewell]

Well, I wasn't talking about content, but that it always went to the first post when you selected go to first unread. Som one was a miracle worker I guess, cause it's fixed now.

 

[hostage]

Bah, looks like the mods accidentally collaborated with the hijackers. I do not have and never had a Johnson or a Fishmaster. The title was imPROPerly changed, sorry had to throw that in there.

Again my specs are as stated in the OP. I forgot to turn on email notifications for this thread.

I've been using the Merc Spitfire (Quicksilver Nemesis) 4 blade and very happy with the performance. Excellent pulling power. Good top end. Also noticed when goofing around with tight turns, it holds its grip and have never seen it cavitiate.
Can't tell you what pitch to use until you figure out the other stuff, but the prop itself is a good quality performing prop. FWIW, I've always had good luck running a Merc prop on a merc engine. Prices are no higher that the other brands

On Thursday I bought a 4 Bladed Nemesis 14" with a 21" pitch. I got this according to the Quick Silver prop selector tool based off recommended weight. I selected the gear ratio of 1.81 as according to many people in the Maxum forum all the boats they have seen with that year range and setup came with a 1.81, I also know 1.81 is the most common from what I read. From an old archive parts list, I see the 190HP 4.3L for the 1900 SC being pared with a 1.81 and a 14x23 prop: http://www.maxumboatparts.com/2000/sportboat/1952ns00/Output/ns62.htm#1024241

So I took it out for a couple of hours on Sunday for testing with the new prop:

Conditions:
Wind SSW 10MPH
Waves w/ occasional white caps as the lake runs 16 miles North to South.
WOT: ~39MPH @ ~4200RPM via boat's pitot and tach

I do think I saw it got up to 41MPH, though the conditions were less than perfect. I noticed the boat leaped on a plane, with just two adults. Even when we had the boat loaded w/ 4 adults and 90lbs of children getting out of the hole was a lot easier. The boat seemed to be able to trim up with less porpoising than the damaged 3 bladed prop. On the initial runs of the day when trimming the boat up, it seemed like the RPM would jump and the speed would drop. I am guessing some type of slipping? Didn't see this later.

In theory dropping my pitch from 21 to 19 would be the best option, and it should in theory give me about ~4600 RPM @ WOT. The a couple of questions that I am wondering:

1) I am wondering if my old mechanic, which I was referred to by the former owner accidentally swapped the out drive for one with a 1.62. He was a crusty old salt who was far from professional or organized in any sense. The Prop that I bought my boat used had a 13.75x21 on it. I have sense quit using him for more than a few reasons. Only

2) Is my 18 year is putting out less power than it use to? Any suggestions on what to try to look at? I did have about 13Gals of older gas in it, I did put 5 gals of 93 Octane in it to help offset it the day I tested out the prop. I am trying to burn off the fuel, though it is a little hard when we don't go out as much and people we like to go out like to just chill on the boat and not do water sports. Anyway any good suggestions?

3) Should I just buy a 19 pitch and give it a shot?