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  #1   IP: 205.188.116.136
Old 01-14-2005, 02:15 PM
Sailwood Sailwood is offline
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Prop size

I have no clue as to what pitch my prop is, but it is only a 10" dia. 2 blade. I have a Columbia 29 (1965) that won't back up for beans. In fact, it appears to walk more to port than it reverses. I am aware of the 3 blade prop from Indigo but am leary of the increased drag it would produce. Now, is prop selection, at least in part, a function of the vessel size? What would be appropriate in this case? Can one have too much diameter? (space restrictions aside) What would be the proper pitch for a 12" 2 bladed prop for this boat?

Doug
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  #2   IP: 205.188.116.134
Old 01-15-2005, 11:53 AM
dtinder dtinder is offline
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prop size

A general rule is turn the largest diameter wheel you can-----and still maintain 20% TIP CLEARANCE with the hull or aperature as the case may be. Usually props can be "bent" up to 2" plus or minus in pitch to accomodate your needs in staying within the power curve for best efficiency. Generally, 1" of diam change will add or subtract approx 200 rpms---whereas a 1" pitch change will produce approx 100 rpms change.

Dave in sunny Ft Myers
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  #3   IP: 206.48.20.86
Old 01-16-2005, 08:33 PM
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Don Moyer Don Moyer is offline
 
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Doug,

To piggy-back just a bit on Dave's response, if you pursue a 12" fixed two-blade prop, either a 7" or a 6" pitch should work well for you. The 7" pitch will perform nicely in calm wind and sea conditions, while the 6" pitch will have a slight edge in powering into heavier seas.

Also, I wouldn't give up too quickly on the Indigo prop. For its excellent performance, it is reported to have a rather modest amount of drag while sailing. In any case, it's rather difficult to reduce drag too much in a fixed blade prop, since the same design perimeters that provide good performance (especially in forward), also tend to produce drag. This is the reason avid racers usually go to a folding prop.

Best regards,

Don Moyer
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  #4   IP: 68.75.50.40
Old 01-17-2005, 07:27 PM
Jim Booth Jim Booth is offline
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timely post

I was browsing the internet and saw a couple testimonials on the Indigo prop. One sounded almost ecstatic about the improved performance in reverse, even in a crosswind. We've stayed at the dock a couple times because we couldn't back out controllably. We are novices though... I also saw a site that said Moyer Marine recommended a CDI prop. Was that an error? It sounds now like the Indigo prop might be the way to go. I fiddled with the reversing gear quite a bit last summer trying to fine tune its action. I'm thinking the Indigo might be a way to get improved action all around. Don would you care to comment on the relationship between the touchy reversing gear and a prop change to Indigo? I don't think I'm ready to tackle changing the slotted nut to yours with more slots yet.
Thanks,
Jim
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  #5   IP: 206.48.20.86
Old 01-18-2005, 02:47 PM
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Don Moyer Don Moyer is offline
 
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Jim,

The reference you saw regarding our recommendation of the CDI prop is quite old, and (more importantly) it predates the excellent prop developed and sold by Indigo Electronics. Each of the props has a group of loyal users, but I would have to say (as you have discovered) that there is considerably more enthusiasm for the Indigo prop in recent years than for the CDI.

I'm not quite sure what you mean by your question regarding the relationship between your touchy reversing gear and the Indigo prop. Since the Indigo prop will undoubtedly allow you to reach a higher point on the power curve (which is a very good thing), you might discover that your forward clutch adjustment might slip at these higher outputs if it is a bit on the loose side at present.

On the other hand, at power settings below maximum available, you might find the increased efficiency of the Indigo prop to be a benefit in that it will convert more of your available power to thrust before reaching the point where your reversing gear starts to slip. I recommend that you check with Tom Stevens from Indigo on this second point. I could well be stretching my understanding of his test data. Tom's number is: (800) 428-8569.


Best regards,

Don Moyer
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  #6   IP: 68.72.93.41
Old 02-21-2005, 11:54 PM
Jim Booth Jim Booth is offline
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Don,
I guess I got involved in other stuff and forgot about this thread. By touchy reversing gear I meant it seemed I could find a notch where it wouldn't slip in forward, but maybe neutral wasn't really neutral. Or I could get neutral more correct, but then it wasn't quite right at one or the other end of the shifter range. I have your excellent manual and think I'm doing the adjustment right, but I haven't found the magic combination of adjusting collar and cable lengths to make it work smoothly and be reliably in neutral with the shifter in the detent. While I have your attention, since my throttle/shift lever needs replacing anyway, will a modern single lever control work with the A4 and its reversing gear? There's also a new product called PowerTiller (powertiller.com) that puts the controls at the end of the tiller. Have you seen that one?

Thanks,
Jim
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  #7   IP: 38.118.52.121
Old 02-22-2005, 06:51 AM
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Don Moyer Don Moyer is offline
 
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Jim,

Perhaps one of our other subscribers knows of a "more modern" cable system for the Atomic 4. However, until you go through a logical sequence to insure a good internal adjustment of your reversing gear itself, I don't believe the solution to your problem lies in a more sophisticated cable system, and certainly not the "PowerTiller", which according their website
is designed for an outboard.

Achieving a proper adjustment of your reversing gear is not a balancing act between the internal adjustments of the reversing gear and the boat's cable system, but a step-wise process as follows:

IMPORTANT NOTE: Since the condition of your boat's cable system appears to be somehow confusing the internal adjustments of your reversing gear, I suggest that you disconnect the cable at the shifting lever on the engine and make the following adjustments by working the shifting lever on the engine.

1) Adjust the forward clutch assembly so that when locked in the forward detent, it will not slip at your highest power settings, but at the same time, not be needlessly tight (to where it takes a weightlifter to place the shifting lever in and out of forward). It's convenient to be in the water when making this adjustment, so that you can check for slippage by pulling on the dock lines.

2) Without ever touching the forward adjusting collar again, adjust the reverse brake band adjusting nut so that you have a comfortable neutral range between forward and the place where you begin to engage reverse. Since you have a shifting lever on the side of your cockpit, you should have plenty of travel to achieve a comfortably wide neutral zone, and still be able to reach reverse before running out of cable travel.

3) Place the reversing gear into the forward detent, still using the shifting lever on the engine.

4) Place the large turnbuckle over the engine shifting lever and align the holes in the turnbuckle and shifting lever, while someone moves the shifting lever in the cockpit to the forward limit of its travel. The hole in the turnbuckle should only move a short distance beyond the hole in the shifting lever (approximately 1/2"). If there is too much cable travel beyond the point where the forward detent is reached, you may run out of cable travel when engaging reverse. Adjust the large turnbuckle on the end of the cable as necessary to achieve the above relationship between the cable and the shifting lever on the engine.

Best regards,

Don Moyer
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  #8   IP: 136.182.2.221
Old 04-29-2005, 06:04 PM
Jim Booth Jim Booth is offline
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I was going to hold off on my prop update until I got the rest of my adjustments done according to your fantastic instructions, but I won't get to that for a while. I bought a new shift lever assembly that I need to put in first. We launched Tuesday with our new Indigo prop. There's definitely a lot less vibration in the tiller and throughout the boat. The engine sounds like it isn't working as hard. I now know I need to tighten the forward gizmo a notch since it would slip if I tried to go above about 5kts. My son was happy with the way it backed up. He said he had more control over it. Actually, he said something like, "Hey I can steer in reverse!" I post another update when I get the other jobs done.

Thanks for this forum and all the great advice.

Jim Booth
Columbia 8.7
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  #9   IP: 65.242.82.227
Old 05-06-2005, 02:55 PM
Mike Deveney Mike Deveney is offline
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Prop Size

I installed the Indigo prop on our Sabre 28 at the beginning of last season. I found it to be all it is advertised to be. Higher up on the power curve than my 12-7 two blade, better control in reverse and I have not noticed any difference in drag under sail. I'm statisfied.
Mike
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