New to v-drives, loud buzzing noise while cruising

[hcooperrn]

Finally got some time back out on the water, though I was alone so I couldn't get up close and personal with the engine. That said, with the cover off and the FAE on now, I think the noise is definitely coming from under the boat; I'm going to retract my previous thought that I had no cavitation -- if I hit the throttle hard I could hear/feel it spin for a few seconds.

Prop looks good; it's an Acme 1579. Since I was able to hit 40mph at Chatfield (5600 ft elevation); I'm assuming the previous owner was more of a wakeboarder/slalom skier, and that this prop probably won't keep me happy for surfing -- could this be the source of my issues and my noise/vibration at speed, would a slight cavitation at cruising sound/feel like a vibration?

[hcooperrn]

Still no solid conclusion on this one -- I can't isolate the noise coming from the engine, and it may be more of a vibration just creating noise while under way. Honestly, starting to think the engine just isn't Cadillac smooth and that it may be general engine vibration

[IDBoating]

starting to think the engine just isn't Cadillac smooth and that it may be general engine vibration

I doubt it, since your original description in this thread:

a fairly loud buzzing-type sound, not quite sure how to describe it. It isn't quite as harsh as bare gears grinding, yet still very noticeable, not smooth running noises for sure

...doesn't sound like anything normal.

The overall systems on a boat can be surprisingly interactive. For example, I just replaced my steering cable and was really careful about routing it to be as straight as possible, thus minimizing friction in the system. Now, with the new cable, I have this very slight shudder in my steering wheel at top speeds. I'm confident it's turbulence coming off the prop and interacting with the rudder, and with the cable so smooth it's transmitting those little movements up to the wheel.

I bring this up because the sound you're hearing may not be directly engine related, just as my "steering shudder" isn't directly steering related. The engine could be causing something else to rattle. Or the prop shaft could be rubbing on something. Or the propshaft thruhull could have its mating surfaces roughened up and be oscillating. Or your rudder bearings could be loose, allowing the rudder to rattle around from the prop turbulence.

In any case, if your original description was accurate, it sure doesn't sound "normal" to me and I'd keep searching for it.

[hcooperrn]

Good points, thanks, I'll keep looking and listening and checking things.

[IDBoating]

Again... wouldn't hurt to record the sound (there are free smartphone apps) and post it here. Someone may immediately recognize it.

[ChrisSnow]

a spectrum analyser app might also help you locate the offending location this is probably a bit easier than an SPL meter as could narrow down on the sound frequency's you think are appropriate.

[IDBoating]

One of my favorite tools, but who knows what frequencies are of interest and how they relate to locations on the boat? I guess we know RPM, transmission ratio, and v-drive ratio so we know three areas. But if it's "something else" parasitically rattling, its resonant frequency could be anything and unrelated to the stimulus.

[Heff]

Did you ever try out a new prop? I'm 95% sure ours was the prop, which I would've never guessed by looking at it. It had a slight wave in it, and on an outboard I would've never touched it. Everything about this boat feels different than any other I've driven.

If you could borrow a prop to try, it may help you rule that out.

[hcooperrn]

Haven't tried a new prop yet, though I know I need to. After filling up the ballast for the first time, we had some pretty decent cavitation out of the hole, so I know I need to find a better one. Had a bit of shell shock when I saw how much props are for these boats; have to save up a bit.

Anyone know of a place that does loaner/test props in the Denver area?

[Z1Fan]

Haven't tried a new prop yet, though I know I need to. After filling up the ballast for the first time, we had some pretty decent cavitation out of the hole, so I know I need to find a better one. Had a bit of shell shock when I saw how much props are for these boats; have to save up a bit.

Anyone know of a place that does loaner/test props in the Denver area?

Everything about these boats is expensive, but it can be cushioned somewhat by doing alot of the work yourself if your so inclined

[alwayssummer]

I have my old 537 if u want to try it out. It does have a small ding in it. But it never affected performance in my rz2. I can even put it on for you on your way to chatty. However I don't think 40mph would be the best idea right now with all the floating logs in there right now.

[chpthril]

Haven't tried a new prop yet, though I know I need to. After filling up the ballast for the first time, we had some pretty decent cavitation out of the hole, so I know I need to find a better one. Had a bit of shell shock when I saw how much props are for these boats; have to save up a bit.

Anyone know of a place that does loaner/test props in the Denver area?

Dont want to sound like im bragging, but i have yet to take back a prop. With the right info, a solid prop rec can be made. Starts with what prop you have and if your v-drive is a 1:1 or 1.46:1 gear reduction.

Some prop shops will do a demo prop deal, but only when you buy at full retail. This is so they can off set taking a used prop back.

[hcooperrn]

Everything about these boats is expensive, but it can be cushioned somewhat by doing alot of the work yourself if your so inclined

I do all my own work; between student loans and two kids, there's no way I could own a boat like this without the sweat equity. I'm fairly well equipped, I've done full re-powers in I/O's before.

I have my old 537 if u want to try it out. It does have a small ding in it. But it never affected performance in my rz2. I can even put it on for you on your way to chatty. However I don't think 40mph would be the best idea right now with all the floating logs in there right now.

I may take you up on that if the research points in that direction, thanks for the offer! I think that 40mph may have been a bit generous on the part of the speedo, it was definitely fast enough I was worried about drawing too much attention though. And you're right about Chatfield being nasty right now, I won't be going back there for awhile. Jackson is full but clean, that's our normal spot.

Dont want to sound like im bragging, but i have yet to take back a prop. With the right info, a solid prop rec can be made. Starts with what prop you have and if your v-drive is a 1:1 or 1.46:1 gear reduction.

Some prop shops will do a demo prop deal, but only when you buy at full retail. This is so they can off set taking a used prop back.

I'll definitely do some homework first; anyone with experience with props at altitude feel free to chime in -- Currently it has an Acme 1579, and I have the blue Walter V-drive RV-26D, 1.46:1, Velvet Drive trans 10-17-004 1:1

[Z1Fan]

As do I, do most of it myself as well

[hcooperrn]

Just finishing this one off (I hope) -- after being on the water all day yesterday doing several different water sports, I'm fairly certain it is cavitation. It cavitates pretty bad when I start out with a decent load, and when I had the ballast full, I could hear the sound of the cavitation change over into the buzzing noise. On nice smooth water as I get into an easy cruise, it almost completely goes away.

It still may be something else, I just can't isolate anything -- rudder is tight, fins are tight, no change before or after FAE or surf flap. Whenever I can get the funding to try a better prop, if it doesn't come back, I'll dig this thread back up.