Hmmmm......I donno...
Admittedly their ad hype does stop just short of promising bust enhancement, or curing baldness.
(Note that getting "more power in reverse" will not cost you $8K -- about $1.5K for a feathering two blade would do the job.)
OTOH, they do offer a money-back guarantee on the product. Worse comes to worse, you would be out of pocket for two haul-outs... the second one to put your prexisting prop back on.
Note that "extending" the shaft to allow more prop diameter gets into potential balance and shaft support problems, and conflict with the rudder.
Putting the prop wash too close to the rudder blade will cause steering mal-forces that may reveal why the original proportions were designed the way they were.
Food for thought.
Loren
Admittedly their ad hype does stop just short of promising bust enhancement, or curing baldness.
(Note that getting "more power in reverse" will not cost you $8K -- about $1.5K for a feathering two blade would do the job.)
OTOH, they do offer a money-back guarantee on the product. Worse comes to worse, you would be out of pocket for two haul-outs... the second one to put your prexisting prop back on.
Note that "extending" the shaft to allow more prop diameter gets into potential balance and shaft support problems, and conflict with the rudder.
Putting the prop wash too close to the rudder blade will cause steering mal-forces that may reveal why the original proportions were designed the way they were.
Food for thought.
Loren
paul culver
Member III
I'm considering a prop replacement myself but you mentioned a haul out to get it done. I've seen divers replacing props on other boat makes. Do Ericsons require haul out?
Well, I could be a wise guy and ask if you have the push-button hull lifting option on yours..
But like ANY boat with an inboard, you have to do several things to change out a prop. There's the cotter on the castle nut, the nut to remove, and the prop and key to remove and not drop either to the murky depths.
All do-able for an experienced diver and a bit o' luck.
The real problem is that when you change the size and type of prop you will need an accurate measurement of the tip clearance... and then you might run into installation problems with the taper, keyway, and etc. that could not be forseen. There is also a chance that the old prop will require a puller and some "persuasion" to make it let go of the shaft. The later problem is harder to do when the worker is working in neutral buoyancy with limited visibility.
Expressing my conservative outlook, it would seem like one would want some time to get up close and personal with the installation of a different prop and resolve any install challenges at nose level, out of the water.
Let us know what you decide, and how the install works out.
Best wishes,
Loren
But like ANY boat with an inboard, you have to do several things to change out a prop. There's the cotter on the castle nut, the nut to remove, and the prop and key to remove and not drop either to the murky depths.
All do-able for an experienced diver and a bit o' luck.
The real problem is that when you change the size and type of prop you will need an accurate measurement of the tip clearance... and then you might run into installation problems with the taper, keyway, and etc. that could not be forseen. There is also a chance that the old prop will require a puller and some "persuasion" to make it let go of the shaft. The later problem is harder to do when the worker is working in neutral buoyancy with limited visibility.
Expressing my conservative outlook, it would seem like one would want some time to get up close and personal with the installation of a different prop and resolve any install challenges at nose level, out of the water.
Let us know what you decide, and how the install works out.
Best wishes,
Loren
jmoses
Member III
CDI Prop
Emerald,
I put one on back in 2000 nd have not looked back since.
My 1972 E-35 with A-4 was woefully proped when I bought it and the gent gave me three other props saying he couldn't get it right. Well, I read up on the CDI, talked with the folks and bought one. It has made a world of difference as the engine hits Revs, actually backs down now, and the engine temp actually registers now (~100 degrees F).
Only complaint? The prop is composite so you can't use regular bottom paint on it as the chemicals will attack it. I use a special transducer paint, but it doesn't last as long as good old copper paint.
John H. Moses
Emerald,
I put one on back in 2000 nd have not looked back since.
My 1972 E-35 with A-4 was woefully proped when I bought it and the gent gave me three other props saying he couldn't get it right. Well, I read up on the CDI, talked with the folks and bought one. It has made a world of difference as the engine hits Revs, actually backs down now, and the engine temp actually registers now (~100 degrees F).
Only complaint? The prop is composite so you can't use regular bottom paint on it as the chemicals will attack it. I use a special transducer paint, but it doesn't last as long as good old copper paint.
John H. Moses
Hi Everyone,
thanks for the responses
John,
Your input is, of course, of particular interest since it is hands-on. I think I will have to talk to them and do some more research. Any particular places you suggest I look to supplement information on the CDI prop?
Thanks
.
thanks for the responses
John,
Your input is, of course, of particular interest since it is hands-on. I think I will have to talk to them and do some more research. Any particular places you suggest I look to supplement information on the CDI prop?
Thanks
.
Last edited:
Cory B
Sustaining Member
CDI Prop
I too used a CDI Prop on our previous boat with an Atomic4. It was a noted improvement in every respect over the old 3Blade we had on the boat. Eventually the CDI got replaced by a 2 blade feathering MaxProp, which was better yet.
A few thoughts about the CDI Prop:
1) As noted above, stuff grows on them, and its not as easy to clean as a metal prop.
2) For better or worse, even though its a two blade, it probably has pretty close to the same surface area of a 3 blade.
3) Wanna repitch it? Forget it! (I thought it was pitched a tad too much for our boat).
4) The not-so-ordinary attachment method is actually pretty slick.
Good luck,
Cory
I too used a CDI Prop on our previous boat with an Atomic4. It was a noted improvement in every respect over the old 3Blade we had on the boat. Eventually the CDI got replaced by a 2 blade feathering MaxProp, which was better yet.
A few thoughts about the CDI Prop:
1) As noted above, stuff grows on them, and its not as easy to clean as a metal prop.
2) For better or worse, even though its a two blade, it probably has pretty close to the same surface area of a 3 blade.
3) Wanna repitch it? Forget it! (I thought it was pitched a tad too much for our boat).
4) The not-so-ordinary attachment method is actually pretty slick.
Good luck,
Cory
Which end is which?
"I spoke with CDI direct.....might as well go to the horse's mouth and not the other end."
I'm a techie... so I tend to be very leery of speaking with anyone in sales or marketing.
Q: How can you tell when a salesperson is lying?
A: You can hear him (or her) speaking.
The problem is that you learn more from the victims... uhhh, *customers*... than you can learn from those with an agenda.
All right, so I no longer have my Ericson 25-- but I loved it while I had it. I also am comfortable surrounded by others here, but I now sail an old Catalina 30 with the two-blade prop, so I am especially interested in this discussion.
I have been advised that, for non-folding props, the two-blade is better since it can be lined up "behind the keel" to cut down on drag. Since I'll do damn near anything to "stay on the rag" rather than start up the motor, this seems a good point.
I was told, by a diesel salescritter at the Beta Marine booth during "Not-So-Strictly Sail" (so named 'cuz they included Trawlers) in St Petersburg, that my prop is designed for the revs the A-4 produces and that I'd need to re-prop for a diesel. Tempting as it is to convert to a diesel, I'd rather not spend money on such a conversion until I'm desperate. (I'd rather buy a rebuildable A-4, do the rebuild, then drop it in...)
(laughs)
Q: How can you tell if a programmer is going to tell you that the project will take longer to complete?
A: He (or she) walks into your office (or cubicle) and starts to speak.
Q: How can you tell when a politician is lying?
A: Using "politician" and "lying" is a redundancy.
and, finally, from the Reagan years:
Q: How can you tell Ronnie is lying?
A: You can see Nancy's lips move.
So, as you can see, I'm leery about assuming that a vendor is going to be completely candid and let you know where they fall short; after all, no matter what field you are in, Poleshuck's Law will apply.
"I spoke with CDI direct.....might as well go to the horse's mouth and not the other end."
I'm a techie... so I tend to be very leery of speaking with anyone in sales or marketing.
Q: How can you tell when a salesperson is lying?
A: You can hear him (or her) speaking.
The problem is that you learn more from the victims... uhhh, *customers*... than you can learn from those with an agenda.
All right, so I no longer have my Ericson 25-- but I loved it while I had it. I also am comfortable surrounded by others here, but I now sail an old Catalina 30 with the two-blade prop, so I am especially interested in this discussion.
I have been advised that, for non-folding props, the two-blade is better since it can be lined up "behind the keel" to cut down on drag. Since I'll do damn near anything to "stay on the rag" rather than start up the motor, this seems a good point.
I was told, by a diesel salescritter at the Beta Marine booth during "Not-So-Strictly Sail" (so named 'cuz they included Trawlers) in St Petersburg, that my prop is designed for the revs the A-4 produces and that I'd need to re-prop for a diesel. Tempting as it is to convert to a diesel, I'd rather not spend money on such a conversion until I'm desperate. (I'd rather buy a rebuildable A-4, do the rebuild, then drop it in...)
(laughs)
Q: How can you tell if a programmer is going to tell you that the project will take longer to complete?
A: He (or she) walks into your office (or cubicle) and starts to speak.
Q: How can you tell when a politician is lying?
A: Using "politician" and "lying" is a redundancy.
and, finally, from the Reagan years:
Q: How can you tell Ronnie is lying?
A: You can see Nancy's lips move.
So, as you can see, I'm leery about assuming that a vendor is going to be completely candid and let you know where they fall short; after all, no matter what field you are in, Poleshuck's Law will apply.
Tom Metzger
Sustaining Partner
Poleshuck's Law
John - Being a young newbie, I, and Google, are having a problem learning much about Poleshuck's Law.
Please educate us.
John - Being a young newbie, I, and Google, are having a problem learning much about Poleshuck's Law.
Please educate us.
junk to me
I put one on my Coronado 34 with an A4, and couldn't get it off fast enough. As soon as I put it in reverse to back out of the yard, I noticed a lack of power. With the conventional two blade, I could turn 3000 rpm but only needed 2200 to get 6 knots, with the CDI I had to turn 3000 to get 5.5 knots in flat water. I put it in hoping to get rid of some prop walk, but didn't use it enough to notice a difference. My diver took it off after a week or two.
I'm glad to see others had a better experience.
Don Wigle
Wiggle Room
E38 #8
I put one on my Coronado 34 with an A4, and couldn't get it off fast enough. As soon as I put it in reverse to back out of the yard, I noticed a lack of power. With the conventional two blade, I could turn 3000 rpm but only needed 2200 to get 6 knots, with the CDI I had to turn 3000 to get 5.5 knots in flat water. I put it in hoping to get rid of some prop walk, but didn't use it enough to notice a difference. My diver took it off after a week or two.
I'm glad to see others had a better experience.
Don Wigle
Wiggle Room
E38 #8
Poleshuck's Law of Competition
I've repeated this to others and had to explain it on the Linux-390 Mailing list:
http://www.google.com/search?as_q=&...as_dt=i&as_sitesearch=&as_rights=&safe=images
"Sure we're not doing everything right, but then, no one else is,
either. That's why we're still in business."
Mind you, I did re-phrase it without the expletives that Rick Poleshuck originally used.
Then there's Romancheck's Sixth Law: "Laugh at yourself: Why should everyone else have all the fun?"
I've repeated this to others and had to explain it on the Linux-390 Mailing list:
http://www.google.com/search?as_q=&...as_dt=i&as_sitesearch=&as_rights=&safe=images
"Sure we're not doing everything right, but then, no one else is,
either. That's why we're still in business."
Mind you, I did re-phrase it without the expletives that Rick Poleshuck originally used.
Then there's Romancheck's Sixth Law: "Laugh at yourself: Why should everyone else have all the fun?"
Tom Metzger
Sustaining Partner
Yeah, but...
I saw that, but that is a statement, not a law.
A law predicts behavior.
I saw that, but that is a statement, not a law.
A law predicts behavior.
Hey John and Tom,
Is it almost time to re-run the "Light Bulb Thread" again? Please?
And, to thinly grasp at the topic du jure... anyone know of any use of a four blade prop on our small diesel limited-diameter prop clearance installations in order to maximise blade area?
Loren
Is it almost time to re-run the "Light Bulb Thread" again? Please?
And, to thinly grasp at the topic du jure... anyone know of any use of a four blade prop on our small diesel limited-diameter prop clearance installations in order to maximise blade area?
Loren
Hi Loren,
Here's the link you are looking for:
http://www.michiganwheel.com/MIWheel/products/inboard/mich_prop_pwr2.htm
now, somewhere in the back of my grey matter, I remember someone telling me about a one blade prop.... serious here
Oh, yes, please, lightbulb time (must be winter with a lack of sailing affecting the brain remains)
.
Here's the link you are looking for:
http://www.michiganwheel.com/MIWheel/products/inboard/mich_prop_pwr2.htm
now, somewhere in the back of my grey matter, I remember someone telling me about a one blade prop.... serious here
Oh, yes, please, lightbulb time (must be winter with a lack of sailing affecting the brain remains)
.
jmoses
Member III
Sales call Vs. Techie Call
The key to talking to anyone in a corpoartion that sells gizmos/produts/software is to get another techie on the line.
I am a respected marine surveyor, licensed engineer and captain and can smell B.S. a mile away. I talk with hundreds of folks a year on gear, equipment and problems with such items and the approach is to get another engineer or non-sales rep on the line. Never call a help line that's for sure. I keep asking until I get the right person on the line, after all "A squeeky wheel gets the oil"
Also, no product is 100% applicable for 100% of the applications. All I said is the the CDI prop has worked well for my 1972 E-35 with A-4.....not on anything else.
John Moses
The key to talking to anyone in a corpoartion that sells gizmos/produts/software is to get another techie on the line.
I am a respected marine surveyor, licensed engineer and captain and can smell B.S. a mile away. I talk with hundreds of folks a year on gear, equipment and problems with such items and the approach is to get another engineer or non-sales rep on the line. Never call a help line that's for sure. I keep asking until I get the right person on the line, after all "A squeeky wheel gets the oil"
Also, no product is 100% applicable for 100% of the applications. All I said is the the CDI prop has worked well for my 1972 E-35 with A-4.....not on anything else.
John Moses
Engineering still includes Art
"Also, no product is 100% applicable for 100% of the applications." - John Moses
A lot of *real* engineering is a study of compromises between theory and practice. The better the engineer, IMHO, the more he (or she) will accept reality as the final judge of success.
To the best of my knowledge (perhaps I'm out of my depth, here) the shape of a hull is a study in compromises as well-- along with a *lot* of "Art". What does each hull form do best? I think we'll agree that all hull shapes are equal when it comes to marine growth (like barnacles) but, when clean, they have differing strengths. The question, of course, is what compromises did the designer make for your hull?
Add to this the fact that Pauli/Heisenberg effects are at play when it comes to propellers, too.
AFAIK there is no one perfect hullform for *all* purposes, so, it stands to reason, there's no one perfect propellor for *all* hullforms...
Now is the time for me to quote myself:
"Nothing gives you a sense of authority faster than a big hammer."
"Innovation starts from the bottom and progresses until an executive discovers it... who will then f**k it up."
"Also, no product is 100% applicable for 100% of the applications." - John Moses
A lot of *real* engineering is a study of compromises between theory and practice. The better the engineer, IMHO, the more he (or she) will accept reality as the final judge of success.
To the best of my knowledge (perhaps I'm out of my depth, here) the shape of a hull is a study in compromises as well-- along with a *lot* of "Art". What does each hull form do best? I think we'll agree that all hull shapes are equal when it comes to marine growth (like barnacles) but, when clean, they have differing strengths. The question, of course, is what compromises did the designer make for your hull?
Add to this the fact that Pauli/Heisenberg effects are at play when it comes to propellers, too.
AFAIK there is no one perfect hullform for *all* purposes, so, it stands to reason, there's no one perfect propellor for *all* hullforms...
Now is the time for me to quote myself:
"Nothing gives you a sense of authority faster than a big hammer."
"Innovation starts from the bottom and progresses until an executive discovers it... who will then f**k it up."
John,
now that you've lived with it awhile, what is your opinion on the way the composit/plastic material they make these out of is holding up? I understand that environment, use, care etc. all add in to this equation, but would you hazard a life span? Is it showing that it is "wearing" somehow? No worse than a bronze one? Think you ever hit anything with it?
Thanks, just trying to get a feel for some of the "lived with it, been there done that" without the first hand experience. Wonder how the difference in revs between the A4 and the Yanmar 3GM30 and the difference in hull shape between our boats all ads up.
Thanks
.
now that you've lived with it awhile, what is your opinion on the way the composit/plastic material they make these out of is holding up? I understand that environment, use, care etc. all add in to this equation, but would you hazard a life span? Is it showing that it is "wearing" somehow? No worse than a bronze one? Think you ever hit anything with it?
Thanks, just trying to get a feel for some of the "lived with it, been there done that" without the first hand experience. Wonder how the difference in revs between the A4 and the Yanmar 3GM30 and the difference in hull shape between our boats all ads up.
Thanks
.