Another 192 prop question

V8192

New to the forum just purchased a '02 Captiva 192 I pick it up next week. Took it out for a "sea trial" and it runs great but

I believe it is way under propped. Its a 5.0 Mercruiser and the current prop is a High 5 17p it has smart tabs, the boats jumps on

a plane instantly but hits the rev limiter at about 30mph on the speedo almost instantly. so the question is what is everyone

else running? I'm afraid to just go to a 19p and still be under propped as I don't feel I have a good baseline to calculate from.

Mostly recreational, tubing, skiing, cruising and boarding at 5600ft altitude. Not sure yet on the drive ratio.

I like the High 5 but don't need a $500 paper weight to go with the one I have.

Thanks for a great forum!

Black_Diamond

Look at this for a nice explanation: http://boatpropellers.iboats.com/propeller-tutorials/rpm/

V8192

I have read that info, thank you.

My problem is I don't know what RPM I would achieve at WOT since it hits the

rev limiter so soon before being close to full throttle. It seems too far off to

make a educated guess. I could just buy a 21p aluminum and start from there instead

of an expensive SS prop that is wrong.

Black_Diamond

The engine manufacturer will have the rpm number you need to know.

V8192

I know that I should be 4400 to 4800 rpm, the electronic rev limiter cuts power at 4800

so not knowing where I would be to obtain a pitch number that would lower my rpm enough,

I was hoping for some feedback from people with similar setups to baseline from.

The rev limiter is something I have not had to deal with on previous boats.

I usually run old junk!

raybo3

Welcome to the RBOC and good luck with your new ride. I am sure a 5.0 is not undersized for your boat and you will get it fixed....

212rowboat

I kinda just graduated props101.. not that I really know what I'm talking about, yet, but this notion should hold somewhat true, if your numbers are accurate:

5k rpm, 17p, 30mph...

We're guessing the throttle remains the same at its limiter of 5k rpm.. you'll come down some, all the same, though..

So...

4800rpm, 19p, should put you around 38mph..
4800rpm 20p, 40~43ish mph...
4800rpm, 21p, 45~47ish mph..
4800rpm, 22p, 50~52ish mph..

You'll find it harder to achieve rev the steeper the pitch because you're putting the work more on the engine side of the leverage mechanism... a 24p likely won't let you over 4600 or so RPM..

Could be I'm way off.. don't mind if I am, but the relationship is somewhat like this pattern..

V8192

Thanks guys, I've played with pitch on my other boats so I know its not always easy to find

a prop that's perfect for each person or boat. I'm not familiar with the boat yet but I would

bet good money at this altitude you would be right 24p wouldn't let you get to even 4600rpm.

My old Charger with a 5.0 liked 19p but it was a heavy boat. I have the opportunity to trade

my 17p High 5 and a few $ for a new High 5 when I pick the boat up at the marina just would

like to get the right one on the first try as they won't likely do it again. Not asking for much haha.

mvn

24" sounds like it might be too high. If you get me your drive ratio and recommended WOT rpm, I can get you close. For comparisons sake, a 192 with a 4.3L runs great on a 20" for watersports and will slightly over rev (so you have to know your WOT rpm numbers) but runs spot on with a 21" for efficient cruising.

I posted a prop pitch calculator somewhere on this site.

Mark

V8192

That's what I'm looking for, I was thinking 21p would be a decent prop and keep the 5.0

at the edge of the limiter I think the 19p would put me in the same "boat" as the 17p.

This motor cuts power if you try to over rev. Won't have the drive ratio until next week

when I pick it up.

mvn

Sounds good. I'll repost my prop calculator so you can play with some numbers.

Mark

mvn

Here's the spreadsheet I created to play with props...

 

Mark

V8192

Thanks!!

V8192

Well finally have the boat. the drive ratio is 1.81 so that might explain a little.

Guessing it was the high altitude option. So I might be able to jump the pitch higher than

I thought.

Michael T

V8192. Many marinas will allow you to try a number (usually 3) different props. The rules differ but all will make you buy it if you break it. Some will charge a flat fee to try them and they keep it if you don't buy a prop from them, but will credit you with the fee if you buy one. If you are hitting the rev limiter on a 192 (I owned one) with a 5.0L at 30 mph you either have the wrong drive ratio, wrong prop or are dragging a couch. Of course, you will have to adjust your specs for the altitude you are at but, in my opjnion, not that much. Try a couple out if you can. Good Luck MT 

V8192

Now that I've had the boat out on the lake we live on and I'm getting familiar with it

I can get it to 35 on the speedo. We don't have any local marinas that will let you test out

props, the lakes are small compared to what a lot of you guys run so the marinas have

a few slips, sell gas and pop. The dealer I bought it from has a "pond" to test boats on and

will buy my undamaged high 5 for +/- $250 and sell me a new one for $593. I'm thinking

keep the 17 as a spare and buying another.  Drewactuals last post has me thinking if he can push

a 23 with the same drive ratio and a 4.3 in a bigger boat I might want to go higher than a 21 myself.

I'll try to find a friend or neighbor with something close to try.

212rowboat

Fwiw, here is a brief of the different props with a 4.3l carb'd, alpha one 1.8:1, 212 liberty edition:

20p 14" four blade aluminum by Michigan wheel was taking too small a bite.. I hit rev limiter at 5200rpm at a little over 40mph.. jumped on plane, though, and held a really low speed plane at around 16~17mph as determined with the speedometer NOT GPS.. I'm willing to bet I could pull even a really heavy slalom skiier out, but I didn't like running barely on plane and anywhere from 2800 to 3200 rpm depending on conditions..

21p 14.25" three blade was wounded, so I don't want to sell it short by saying a whole lot..

23p 14" four blade aluminum by solas.. slower out of the hole, but I still bet I could drag a skiier up and out.. extended plane time by full third, likely.. didn't take it to wot, but could no doubt hit at least 4400rpm... Held plane at 3000-3200rpm and right at 25mph, was at 45mph right at 4k rpm.. stern lifted high, easy to trim, spray a little behind helm... The only thing that's weird that I'll have to get used to is idle speeds feel a lot faster.. as in I noticed it instantly.

22p s/s 14.5" three blade.. dunno who made it... Will come back and edit this when I get some time on it... It's going to take something impressive to get me away from the 23p four blade.. the stainless may be able to do that, though..

Oh, another Fwiw: solas is superior to michigan wheel in craftsmanship.. at least comparing the two I've had.. no obvious and painted over beads, smooth paint, hub MUCH better..

Michael T

I used to gret great props for go fasts from an outfit in Indiana - I believe it was called Precision Propellor. You could send them your data and they'd match you up 100% every time. Their props were beautifully blueprinted/balanced and polished with an aggressive cup that providied bite right through the rpm band.These props were reasonably priced and works of art. It's the cupping and lack of distortion that made all the difference to meith ss over aluminum propellor. I'm sorry but if you have any kind of load or horsepower I consider aluminum crappy. 99% of the time 3 blades will go faster than 4. 4 blades will give the hole shot and pulling punch. MT

V8192

I have a 4 blade Solas on the Merc outboard on my old boat I like it better than any other I tried,

I was too cheap to put a SS prop on that boat as it would be like a $5000 stereo in a $500 car.

212rowboat

I refuse to go stainless until I dial in the precise pitch diameter and blade count, even though I realize the ss will still alter that... From what I've been told, and from what i gather reading from the experts here, swapping to ss will make a predictable change.. as in a 150-200rpm drop in rpm, and steadier run instead of flexing.. I'm looking forward to trying the ss22p14.5"3blade... I'm almost willing to drop a benji the guys here are telling me truth about it being perfect.

V8, where is your spray when you're on plane and trimmed out? Mine, with the 23p and just under wot, is about even with the pedestal mount of the helm chair.. maybe a touch behind it.. that's a lot more boat out of the drink than the 20p managed.. it sprayed right under the console at wot trimmed out.. this four blade (23p) raises the stern quite a bit more than either the 21p14.25"3blade, and a bit more than the 20p14"4blade..

My developing theory is: if you drop pitch, add some diameter.. if you raise pitch, drop diameter.. this is another reason I'm thinking the ss 22p14.5"3blade is going to rock.. it'll be the biggest prop I've turned, but less a blade and drop a pitch.. I'm crossing fingers it will be just right.

mvn

MT is right about Precision Props in Indiana. I had a 4 blade 20" pitch on a 192 with a 4.3L Volvo. It ran (and still runs) great. I believe Precision also makes the Stiletto line as well.

I now have an 18" 4 blade Michigan Wheel on the 226 and it is very nice as well. I'd like to get a 19" 3 blade for cruising.

Mark

Michael T

V8192. I tried out a whole bunch of props (my friend was a marina owner) on a Rinker 190 with a 350 mag way back in 94 or so. The high five was a beautiful propellor. You could pull stumps off the shoreline with it on your boat, but it was a dog at the top end. Also, on my boat the 5 was real weird at certain speeds almost like it was shifting the stern. Unless you are using your boat almost exclusively for high load, low speed - I'd be careful with a five bladed prop. As well, if the fives are slower at top end when at sea level (I live at sea level) doing the math on it at your altitude level might be scary. If you can't test dealer props in your area I'd try out with aluminum before dropping the roll on s.s. Do you have any friends with mercs  who have different pitches and blade configuratiopns that you guys could meet for beers and swap some props for try-outs? MT

212rowboat

I'm standing by for fire with this comment, and I haven't done it myself- but a Yamaha 15 spline will work on a merc IF you use the yama thrush washer.. a guy here who works on boats swears this to be true, having done it for years, and never having a problem.. thoughts?

V8192

MT the high 5 came on the boat so I don't have any other comparison yet but we live on the lake so

any one of the neighbors probably has something to try, all of my spare props for my other boat

are dinged or lower pitch. It's great to hear all of the experiences people have had.  

V8192

Was just out today on better water (less chop and traffic) hit 36mph tops at redline trimmed out

spray behind the helm seat not much in the water with the lift of the high 5 that being said cutting

wakes even at 36mph makes it a little unstable.

Michael T

DA, I've heard the same thing. In fact with several other props too. Never done it though MT

Michael T

V8192, with your altitude and the 5 blade - 36 mph might be close to correct. You will definately lose some performance due to altitude. I think the 5 blade will reduce your top end too. If you are also running in higher temp with some humidity that would do it. "Normally" a 5 liter, factory alpha gear ratio set for sea level with a three blade should see 40 plus mph in that boat, no problem - in my opinion. Please keep us posted with your "experiments", I find it interesting and bet the other guys do too.MT

V8192

I would agree and think even with the "high altitude" gearing it should get close to 50 with all

things in place.

mackoy

What size of props and pitch your running right now? Im compering mine too.