CD-25 Propeller

[journey on]

For reasons previously recounted, I change from a Pro-Pulse propeller (9912) to a Michigan Apollo stainless steel 4-blade.

The plastic prop is 14.5 dia, by 16 pitch. The SS prop (made in Thailand,) is 14 5/8 dia, 16 pitch.

The Apollo vibrated, especially at idle, and I took it to a dealer, who reworked some flaws, the casting wasn't perfect. Tried it this week end, off Oceanside, Ca, and it still vibrated. I tried getting performance numbers, and they seem slightly better than the Pro-Pulse, but there were swells, and I was either surfing or going up the back of a swell (or at 4500, off the top.)

Any comments?

Boris

[Sea Wolf]

Boris-

Here's a comment I made a few days ago about another propeller vibration / torque steering topic:

Sarge:


I had a case of vibration off a really nice stainless prop once that was caused by inadequate clearance between the prop blades and the torque tab.

You have to have at least 3/4"-1" of clearance, or the intensely propelled water off the prop blade will "thump" as it hits the torque tab.

Usually, though, this type of problem works all the time, not just when turning, until you reach higher rpm and the thumping isn't noticeable because of the higher frequency.

They make special torque tabs that are flared back more to accomodate props that need the larger clearances.

Joe.

[Pat Anderson]

Guess I missed the reasons previously recounted - we really like our ProPulse - what problems were you having?

[journey on]

Sea Wolf, where can I find such a trim tab? Your statement seems reasonable, since the dealer said it was in balance.

Pat, when I was coming through Dent Narrows, the prop dit something, so small I didn't even see it, lost three blades. One had a chip out of it, but the other two broke the adjustment tab. So bad we had to shut down the main engine and come through the narrows on the 10 hp. Since we go through a lot of different places, I thought I'd get something stronger. Otherwise the prop was fine. Just don't forget your spare blades, your prop wrench and your spare motor.

Boris

[Sea Wolf]

[Les Lampman]

Boris,

After many, many props on a BF150 on Sea Skipper (Hank Brooks' CD25) we concluded that the best of the bunch was the Power Tech OFS propeller. We also tried many props on Anita Marie (Fred and Robbin's CD25) and came to the same conclusion. I'm at home so I don't have the exact information on the prop but it's a four-bladed stainless prop and 15-pitch. It performed far better than anything else we tried. The CD25 and BF135/150 combo is fussy about props (I've tried a lot that don't work, a few that work ok, and so far only one that works quite well); I don't know why for certain but I'd hazard a guess that it's balancing out the hull characteristics with the engine's power curve and the waterflow coming off the fairly flat bottom. [ I've never tried another large single so this may not apply to other brands; the only other combo for us has been twins.]

I have a lot of understanding regarding hull design, power curves, torque, and all the other good stuff and I usually can prop a boat out pretty quickly; even with that background the CD25 has been a challenge (thank goodness for willing customers!).

[TyBoo]

[Pete in NY]

Hello Les,
I realize it is a busy part of the season, but for the record, coulld you please when you get a chance, post the full specs or part number of the best prop mentioned in your post, that you have discovered and referenced above for the CD25 Honda BF135/150 combination. I and perhaps others might like to reprop to this prop.

Thanks & regards,
Pete in NY

[Les Lampman]

Hi Pete,

I'll look it up when I get into the office tomorrow. I'll warn you in advance that it isn't an inexpensive prop (although I don't recall the exact amount at the moment) but I wouldn't mention it or recommend it if we hadn't tested it and found it to be worth the investment (for some folks).

[Sea Angel]

HI Les,

When I was looking into rigging my CD25 with twin BF90s, I went with the recommendation of the 4 blade 13 1/4"D x 15P , SS HONDA "Turbo" and have been very satisfied, though a bit pricey. I can sure feel them bite into water when called for. I don't know if any of the recommendations have changed in the past 3 yrs.

The only drawback to any setup here was there isn't a counter rotation out there in the 90HP range. Backing into the finger piers to port with a cross current is a handfull; even with the drives tucked in tight. So, as the old saying goes... practice and pracrice some more. Boy, am I glad I added the camera.

[Les Lampman]

[journey on]

Joe (Inland Lake Wolf):
Here's plan A: see if the trouble is in the torque tab by running the engine out of water. If no vibration, at least one knows that its due to the reaction of the water. Next, when the boat is in the water, remove the trim tab, and again if no vibration the problem is solved, and I'll make a new tab. If there is vibration, it's probably due to the anti-cavitation plate, and that problem doesn't have a solution. Does this sound reasonable to you?

Les:
Thanks for the info on an alternate prop. By the way, my engine is counter-rotating. Don't ask why, it just is. Since I have this one (read paid for,) I'm going to try the above. Also, we run the boat heavily loaded for cruising, and I have found that a higher pitch of 16" works for me at the slow speeds we travel. I experimented with the Pro-Pulse, and 15" was too small a pitch, 17" too large and 16" gave the best mileage vs. performance. Remember our boat cruises for 4 mos at a time, and Judy wants to be comfortable.

Thanks, the Southern Boris

[Sea Wolf]

[journey on]

Les,

I need help. When I run the Honda 150 out of water, the vibration is gone. HOWEVER, there is a rattle from the lower unit/propeller. The prop is tight on its shaft, but there is free play in the lower gear case (with the motor not running.) Is this rattle normal with a heavy stainless propeller?

I didn't notice it with the plastic prop, and I've only run it out of the water twice.

Thanks, Boris

[Sea Angel]

Les,
I have a bow thruster and stern thruster.... my wife. She just can't get the hang of skulling that well. She can skull me now and then with justification; but as to the thrust'r..... I'll leave that one alone.