winter discussion- props and their effect on...

[mattyboy]

the 16 and 18 classic hull with a volvo aquamatic 200-290 series.
what does blade shape and size have to do overall handling, bow lift ,stern lift ,chine walk. do things like cup and rake or flare rings make one prop more stable or squierrely. Is it the reaction of the prop to the hull or to the drive or is it a little of both??? Does the shape of the hub have any effect ???
I have done some testing but not enough here are example of the props some i have run some i have not. So let's hear it what do you guys think???
the first a cleaver 14 x 25

[mattyboy]

a chopper 14.5 x 25

[mattyboy]

a custom spinelli 14.5 x 21

[mattyboy]

an ultra 14.25 X 22

[mattyboy]

around ear 15.5 X 23

[joseph m. hahnl]

Matty: do you have any info on the ones you tested? I'm looking at that cleaver you got , Remember when I fell off the back of the boat and hit the prop with my calve>I think some one could get killed on a knife prop like that "cleaver". Maybe it is time for a ladder?


any way: it looks like it would be hard to disguish what is what with each prop having different pitches as well as different shapes.

joe

[SideshowRob]

That's a great post Matty, I am curious about that as well. I'm not sure what is on my boat right now, it's stock Volvo prop though. The boat came with another prop too though. Also a Volvo 14 X 24 LH. I'm interested in knowing how much difference props will make, I mean I know the basics, but I am still pretty green.:biggrin:

[mattyboy]

Joe,
that was part of my question why what how does the shape of the blades effect the boat, does pitch have anything to do with handling or is just a matter of forward movement and engine performance??? my testing is incomplete as the drive has changed on the boat so I have not run all the props and on the new drive but here's what i know so far on each
I have not gps'd them so I'm judging speed on running with a gps'd 60 mph boat kenny's cig and my gauge

cleaver just un packed it boy i can't wait til spring

chopper controlable wot 4500 wot 4600 rpm
torque steer minimal
porpoise yes
ventilates yes
cruise speed around mid 30's at 3000 rpm
top controlable speed around 53-54 mph
overall impressions: I like to run this prop at the evnts it seems to give me a higher cruise to keep up with the bigger boats with out pushing it hard, seems to react predictable with all loads me or 4 people in the boat
porpoise mildly planes ok you can feel it ventilate then you feel it hook up but gets squirrely at high rpm's the need to use trim tabs somewhat

spinelli Controlable wot 4700 rpm wot 5100
porpoise yes
ventilates no
cruise speed low 30's mid to high 30's rpms
top controlable speed around 50
overall impression: this prop was designed for skiing and has no slip or ventilation you punch it and the boat jumps on plane pulled the shoulders out on a 235lb skier throttle response immediate, cruise is slower at higher rpm's than other props does not react the same to different loads a handful when i am alone in the boat the need for tabs all the time the best run 4 adults all over 200 lbs full tank of gas and glass like water ran a few seconds at 5100 probably near 55 mph . alone you feel the prop climbing out of the water taking the ass end out with it then you get that pucker factor feeling it doesn't chine walk it rub rail walks

the round ear
i had on the boat for a total of about 3 minutes
it cavitated, torque steered ,porpoised wildly you could feel the boat being turned by the prop it handled so bad i was afraid to take my eyes off the water and look at the gauges

the ultra
controlable wot rpm 4950 wot 5075 rpm
porpoise no
torque steer no
ventilates yes
overall impression cruise is ok would be better with a 24 pitch , reacts the same thru all loads the need for tabs is almost nil best speed seen so far is 57 mph still probably a a tad more but you can feel the boat start to wiggle
overall i like the prop the best just wish i could get a 24 or so this is the only prop were you feel the boat is being carried not the bow or the stern it seems for lack of a better term to be in balance

now can anyone tell me why each prop does what it does???

[mattyboy]

That's a great post Matty, I am curious about that as well. I'm not sure what is on my boat right now, it's stock Volvo prop though. The boat came with another prop too though. Also a Volvo 14 X 24 LH. I'm interested in knowing how much difference props will make, I mean I know the basics, but I am still pretty green.:biggrin:


Sideshow,
that volvo ultra 24 is by far the worst most dangerous POS prop out there
and cause i am concerned with your health and well being I must take it off your hands ;) :p better put that baby in your will :)

[SideshowRob]

Well now I'm curious :confused:
What's the deal with my prop, when I saw it was a Volvo, I kind of figured it was just average. You know aftermarket stuff tends to be better????
Now, about the prop that's on the boat.... Could it explain why the boat was so squirrly when I had it out? I didn't realize it made such a difference with handling..... I feel so naiive :redface:

[mattyboy]

Bob,
the volvo ultra you had posted pics of is probably one of the best props to run on a volvo driven classic i was just trying to talk you out of it ;) don't let that prop go you'll regret it. the only problem I am aware of on the ultras is that the factory hubs might be a little weak with our higher hp aplications.
can you post pics of what prop you have on the boat.
I was hoping for some more input here, in seeing the new solas prop offering from Big Grizzly they have massive amounts of blade area but don't seem to have the torque effect on boat from what I have heard
so size i guess really doesn't matter :p shape is more important

[mrfixxall]

Im with you matty,,the volvo ultra by far is the best prop yet!!!

[mattyboy]

don't agree with me I have not made a statement and my results are incomplete and any way that's usually tieing your horse to the wrong wagon ;)
I asked a question as to what makes a prop work or not work on a classic
is it better to spin a bigger prop slower or a smaller one faster?? what does the shape have to do with it does weight of the prop have anything to do with it what about over all depth of the prop???

[JimG]

Matty, don't know all the reasons why one works and one doesn't. But the difference between my aluminum Volvo props and my Ultra is night and day! The boat is almost undrivable with the aluminum. Very distinct and violent torque steer, both on acceleration and let-off. Speeds were similar, but the Ultra is very benign with no bad habits that I've seen.

BTW: I know who has the original Ultra molds. He's here in Houston, says he knew the designer of that prop personally. Would probably build new Ultras if he were asked.