CDI vs Idigo

[MikeB.330]

I have an A4 powered Pearson Vanguard and am currently using the indigo 3 blade prop. At 1800 rpm she will cruise along at almost 6kts. 2000 rpm will get you to hull speed 6.5kts +-. Max rpm seems to be aound 2400 although with a clean prop I may be able to hit 2600. As far as cruising goes the prop is just fine. I don't like how slow the boat is to take off or back down. After backing out of the slip or starting from a stand still it takes a ton of throttle to get the boat moving. Yes the bottom is clean. Reverse kinda sucks as well for the same reason. It takes a lot of rpm (like 2200-2400) to get the boat stopped.

OK now the question. how does the CDI prop compare to the Indigo.
According to the CDI website the prop should act like my old (13x9) prop at lower rpm but let the engine turn up for cruising power.

What have you tried, what works and what was a waste of money. I had the Indigo installed when the Moyer Marine A4 was installed. 80 hours later and I'm still not in love with this prop.

thanks


Mike

[Don Moyer]

Mike,

While you're waiting for others to check in regarding reverse, etc., I would only point out (as a motorhead) that your performance in forward is arguably as good as it gets, which is important since that's presumably where you spend 98% of your time.

Reverse mode, as you probably know, has a built in 1.27 to one gear reduction, which means that it's fairly normal to have to really hit the engine rather hard to get the boat stopped and/or begin to make seaway in reverse.

Regards,

Don

[MikeB.330]

Understood Don.

I'm interested in how the variable pitch prop works. My understanding is that it would feel more like a larger prop at low rpm (like my 13x9 did) but the pitch would flatten out at higher rpms. The peak rpm should stay about the same at 2400 rpm.

If I didn't know how hard it was on the A4 I would go back to the oversized 13x9. In the long run 1200 peak rpm will not make for a happy engine.


Mike

[Don Moyer]

I believe you're talking about the "Vari-Pitch" prop manufactured by CDI. This is a plastic prop whose blades tend to flex a small amount at higher RPM, losing a bit of pitch in the process. My recollection is that the manufacturer claims the prop (originally a 12 X 7) will flex to approximately a 12 X 6 at high power settings.

Don

[MikeB.330]

That's the one, any real life stories?

[Jim Booth]

I have the Indigo also so can't comment on the CDI. I do notice when shifting to reverse that it's important to get full engagement in idle and to hold the shift lever firmly before applying throttle. Once it's snugly in reverse a burst of power is all it takes to get me out of the slip with enough speed to steer. My shift lever lays almost horizontal when in reverse so I use my foot to hold it in reverse. Otherwise, reverse tends to slip and I'd need a lot more throttle to move the boat. My 'other captains' sometimes forget and end up using lots of rpm to get going. I think they don't hear the motor, so I instruct them to listen for the reverse gear noise. If it isn't making a racket, it isn't in reverse.

Jim Booth
Columbia 8.7

[baileyem]

I have a 1966 Pearson Coaster with A4 and an Indigo prop. I have been so dissatisfied with the performance of the Indigo prop that I replaced it with my old 2- bladed prop.

The prop may work well on other boats, but it sure dosen't on a Coaster. I believe that the problem is with the full keel that is rather thick just ahead of the prop. The prop is set close to the keel and is surrounded by the rudder in a rather small opening, and there is no room to extend the shaft aft.

I could never get more than 1700rpms before the prop began to cavitate. The more I pushed the rpms toward 1700 the quicker the cavitation began. This was especially a problem when bucking a rough sea and a head wind, as cavitation often began at 1500 rpms or less.

I can turn 1500 to 1600 rpms with my 2 bladed prop, but I am considering trying a prop from Performance Propellers, because I would like to run my A4 at the recommended rpm.

Any comments?

Mike

[Don Moyer]

Mike,

Your prop could indeed be cavitating, but before spending money on a new prop, I would question whether your prop is really cavitating or whether the forward clutch is slipping. The two conditions are quite similar, and we get quite a few reports where a slipping clutch is mistaken for cavitation.

An easy way to at least get an idea of which condition you have is to evaluate how difficult it is to engage forward. If you can move your shifting lever into the forward detent without too much effort, you should definitely adjust the forward clutch assembly before buying a new prop.

By way of a bit more explanation; the Indigo prop frequently allows an engine to turn up to a higher point on the RPM/power curve than other props, which sets the stage for a clutch to slip which did not slip previously (at lower maximum available power).

Don

[baileyem]

Thanks, Don, I will definitely try a clutch adjustment before writing off the Indigo prop completely. It will have to wait until May, but I will post the results at that time.
Mike

[Don Moyer]

Mike,

If you'd rather not wait until spring, you can get a pretty good sneak preview of whether or not your clutch is likely to slip by simply checking how much resistance you encounter when engaging and disengaging forward (without ever starting the engine).

Don

[MikeB.330]

My Clutch is NOT slipping at all. The prop just doesn't have the bit the two blade prop did. I mean, it does in a way but you have really spin it up. It takes much longer to get the boat moving. I know my Pearson Vanguard isn't the lightest thing around. It's a full keel deal just like the Coaster. I think that's my biggest complaint about the Indigo prop. The larger two blade got the boat going much faster.

I may try the CDI prop this spring and E-Bay the Indio unit


Mike

[Don Moyer]

Mike,

With two Mikes reporting on Indigo props, I have to be careful to remember which one I'm talking to. To the Mike with the Vanguard who is cruising along at 1800 RPM and 6 knots, please let us know how you like the CDI prop.

Don

[Jeff in TO]

Hi there,

I'm also interested in hearing back from anyone who's tried both the CDI and Indigo props. I'm looking to upgrade this spring.

My boat came with a twin blade 11x7 installed.. No complaints about forward cruising power or speed, my complaint is the lack of thrust in Reverse.. (A-4, Direct drive)

I have satisfied myself that there is good engagement of the reverse gear, tied to the dock there is lots of thrust, but to actually use it to make the boat move backwards takes lots of revolutions, and makes lots of prop-walk before there is any steerage. If there is any kind of wind from behind, backing out of the slip without the stern walking into it sideways is next to impossible.

Same with using reverse when docking - I have to approach soo slowley in order to get the boat to stop.

The benefits listed in Indigo's website seem geared more to 'better forward performance' with some indications of improved reverse, but I do not see them using improved reverse as a big selling point, although it is mentioned as an added benefit.

On CDI's site, they say much more about their product yielding improved performance in reverse, and their prop is less $$.

Having said that, it's hard to compare and judge the products based upon the marketing information from their websites.

I guess I'm leaning towards the CDI based on their "sales pitch" (sorry - that's really bad - ha ha) but if there is someone who has experienced both props on the same boat could speak up here about their experience it would be a huge help!


Happy Sailing,

Jeff

[Jesse Delanoy]

We put the Indigo prop on our Catalina 30 about three years ago. It improved our performance in reverse dramatically.

[Jeff in TO]

Originally Posted by Jesse Delanoy

We put the Indigo prop on our Catalina 30 about three years ago. It improved our performance in reverse dramatically.

Good info, Jesse. Any idea what size/pitch propeller was on there previously?

[sewalker]

Hello Don,

I have a 1977 P-28 and also have a problem like Mike with the engine reaching a maximum RPM of 1800 and feeling like the original 2 blade prop is cavitating. I have adjusted the forward clutch. It now feels like it needs a definite effort to engage and when it is engaged you are unable to move the prop at all (tried it when it was hauled this fall but unsure of how much effort this would really require).
The engine rpms will not increase above 1800 when it is engaged. If the clutch were slipping, wouldn't the rpms be able to continue to rise as you gave the engine more throttle?

Thanks,
Stan

[Don Moyer]

Stan,

It is true that if your power is limited to 1800 RPM (not all that unreasonable, depending on what size prop you're using) your forward clutch assembly is no doubt not slipping. It is also very normal to require a fair amount of force to engage the latching mechanism of the forward clutch assembly when it's set properly.

Don

[ahld]

Hi Don,
This thread brings up an interesting (to me at least) question. When determining the proper pitch for a given engine/hull combo it's customary to set pitch to target WOT rpm at the engine's power peak.

If an A-4 puts out 30 bhp @ 3000rpm, and in this case WOT rpm is 2400, isn't this boat "over-pitched"? With all the associated issues such as poor low speed acceleration, overloading the engine, low top speed etc?

A-4's seem to be one marine engine where its acceptable to be 100's of rpm below the peak power/operating rpm. Please explain the reasoning. Thanks!

Dave

[Don Moyer]

The shortest answer to your question is that for direct drive engines it's virtually impossible to design a prop small enough in terms of diameter and pitch that will allow the engine to reach 3000 RPM at wide open throttle and still have enough efficiency remaining to move the boat at acceptable speeds at any RPM much below full throttle.

The Indigo three-blade 10 X 7.2 is a very nice compromise. This prop allows for 2500 to 2700 RPM at wide open throttle which is close to the highest point in the torque curve (which means best efficiency for the engine) and will still allow good power and speed at Universal's recommended maximum continuous cruising power setting of 2000 RPM.

I think it's a reasonable analogy to consider the power available in a three-speed automobile. For argument's sake, let's say that your low gear will allow maximum red-line RPM at wide open throttle in negotiating a certain slope in the road. In this gear full power of the engine is available. Second gear will cause the RPM to peak out at a somewhat lower RPM on the power curve and the engine will only develop enough power to negotiate a gentler slope. RPM in high gear will peak out still lower and the engine will usually have only enough power available to drive on a rather flat road. The question is, which gear ratio would you chose if you had to select only one of the three? Most people would probably settle for second gear. They would sacrifice some power on hills or heavy headwinds but retain more power for hills and headwinds than high gear would provide.

Don

[Jim Booth]

We replaced the 12x7 with indigo after our first year of boat ownership, mainly because of reversing issues, but it was actually probably mostly our inexperience with an inboard. When tested first time my son said, "cool, I can steer in reverse" as he did figure 8's. Forward is as claimed by indigo - less vibration in tiller and boat, smoother operation, feels like the A4 is loafing, etc. Stopping seems fine. A couple times the few second burst of reverse actually reversed direction instead of just stopping the boat. That looked pretty sillly! Prop walk is much reduced also with three blades.

Jim

[jlroberts]

Mike, did you ever solve the problem or get better results from the Indigo? I have a 69 Pearson Coaster also (#115) that was new to me this season and I was considering the Indigo prop mostly for increasing steerage and control while backing and docking. I currently have the two blade prop that came with the boat. It performs well otherwise with a good forward top speed. I notice a lot of the people who are happy with the Indigo seem to have boats without full keels. I would like any opinions. Thanks.

[msauntry]

Those of us with Pearson full keel boats tend to have a rather thick deadwood right in front of the prop. The Indigo guys did their own testing on a Triton and found the 13x8 two blade prop did outperform their own prop on this particular design. The larger diameter lets the prop get well out into clear water. The Indigo prop, especially in reverse, is struggling to get water flow around this thick deadwood.

I had a 13x8 two blade on my Pearson Alberg 35 and found that it could not spin anywhere near full rpms. Maybe it was fine for the Triton but not the Alberg 35. I've had the Indigo prop on for about three years and am happy with its forward performance. I'm getting better rpms and its pretty smooth. I find its acceleration seems just fine. Reverse isn't that impressive but it never was and never will be. Max speed is 6.2 and I should be up around 6.5, so there's still room for improvement.

I plan on doing two things:
1. Repitch the 13x8 to a 13x6 and try it again.
2. Fair out my deadwood so water can get past it a little easier.

The Indigo prop is just fine, especially if you do a lot of motoring. I had this on for a trip to the USVI and back with about 180 miles of ICW and liked its performance. I think there might be a better prop out there for my particular boat, but I just haven't found it yet. I think with our deadwood issues, many of us could benefit from the larger diameter props.

I'm curious what other FULL-KEELED A4 owners have used prop-wise and what max speeds they've been able to get.

Thanks,
Micah

[jhwelch]

My Bristol 29 is full-keeled and the propeller is in an aperture so it's size
is 8x10 (yes, that is what is stamped on it) and I manage to putt
along at 5.2 knots. With a bit of help from a sail my boat will get
up to 6 knots.

-jonathan

[sv_leeway]

My C&C Corvette (31') is a full-keel/centreboard, with an 11x8 two-blade prop in the aperture. Reverse is terrible, with very little stopping power and severe prop walk. In forward I can get close to 6 knots, but the cavitation is quite noisy at anything over about 4.5. We usually motor at about 5.

I've not thought seriously about changing the prop, and have just gotten used to coming into the slip nice and slow, and to being prepared for anything when backing out.

Rob

[msauntry]

Rob and Jonathan,
I imagine you'd both benefit from the Indigo prop. I seem to recall C&Cs having a tip clearance problem where water from the prop "slaps" the hull, but that might have been another model than the Corvette. It was often mistaken for cavitation which made me think of it. I'd think an 11x8 would be about right though, so I'm surprised you're not getting better performance with that. I've been pretty happy with the Indigo prop and can cruise all day at 5.2-5.4 knots and burn about 3/4 gallon per hour, so it must be close to ideal to get that performance. I'm just hoping to get to hull speed (~6.5) with a two blade prop. My Alberg 35 is probably at the size limit for what an A4 can push.