Hull Vibration and Resonance Good IDEAS

[Bduncan]

A friend of mine gave me a great idea. Even when your prop etc is balanced you may notice your boat will still have some vibration and resonance throuhout the hull. You can clearly feel this when you run the motor with the top off out of the water. I cut a few small squares of DYNAMAT (used to stop vibration and resonance in interior panels of cars in stereo installation) in various places in the hull. I have done it in my Spartan and Revolt and it seems to make a significant difference.

They makes various thicknesses of DYNAMAT and DYNAMAT like products. I bet it would great for a new build.

http://www.dynamatstore.com/index.php?l=product_list&c=28

[siberianhusky]

Water does the same thing for free!
Not good to run the motor without a load, when it's under load and on the water, the water dampens everything quite nicely.

[iamandrew]

I just made some washers made out of a bike puncher repair kit, seems fine to mee :)

[RandyatBBY]

Look at the prop on the bench and while you run it if the prop spins out of round you know it it out of ballance

[tlandauer]

Water does the same thing for free!
Not good to run the motor without a load, when it's under load and on the water, the water dampens everything quite nicely.

[RandyatBBY]

Water does the same thing for free!
Not good to run the motor without a load, when it's under load and on the water, the water dampens everything quite nicely.

Yes you do not want to go to full throttle just a short burst to check balance on prop.

[Bduncan]

Guys, the aforementioned comments and advice are pretty obvious. No I don't go full throttle when boat is out of the water. How do you know what your boat does in the water. My props are are perfectly balanced. I noticed since I put the dynamat screws take significantly longer to come loose. That's enough proof for me. It works. Take it or leave it. Cost 10 bucks

[siberianhusky]

Something must be out of balance or out of true, you can hear the water slapping the hulls over any other noise on my boats, also never have issues with fasteners comming loose on my electric boats.
The water in this vid of one of mine is as loud as the boat.

http://www.youtube.com/watch?v=Q0sUPu5M76g

Pretty clear what is happening on the water, no resonance there.

[properchopper]

I used some heavy-duty Dynamat back in 2006 on my H&M Drifter S. Helped some. I've found that some drivelines are noisier than others, particularly in cats, regardless of attempts to perfectly balance the components.

[Bduncan]

Thanks for a legitimate response

[JimClark]

Just because people disagree with your great idea no need to get defensive and snippy. You asked for opinions. We have no idea as to what your expierence level is. New people come on here all the time and wonder why their boat vibrates on the bench

[properchopper]

I've also found that fairly long, straight drivelines are noiser than shorter ones and those with a fair degree of bend, particularly in applications minus teflon. I do remember that my first Drifter S with the buzzing driveline had me going nuts trying to cure it. When a driveline converts power to noise, that noise is wasted energy that could be otherwise used to spin the prop. My current Drifter S uses a wire drive which is so quiet you can hear the prop pounding on the surface.

Here's a boat with a buzzing driveline - listen at 2:04 - 2:06 , 2:26 - 2:27 , 2:46

http://www.youtube.com/watch?v=N0ixeztr-wE

Here's the Drifter with the wire drive :

http://www.youtube.com/watch?v=dOPTQrj-0RM

[iridebikes247]

Probably helps especially with plastic hulls. I have an older boat made of plastic and it used to make a ton of noise on the stand. Water and load really do help the flex shaft find a way to shut up lol. I run MHZ oilers in some of my boats now and use chainsaw oil, can't hear the boat run anything less than 1/2 throttle its almost strange to me. Your idea is cool for scale boats especially or boats that use a transmission or anything like that. I fill the flex in my boat with oil and stand it on the transom and really let everything flow in makes for such a smooth driveline but sucks cleaning the oil if spilled. Thanks for the tip bud

[tlandauer]

The Dynamat absorbs the sound just like a recording studio has absorbing panels on the wall to absord unwanted sound waves. The resonance can occur in a specific RPM range and each hull is different. If one doesn't like that , then other than using sound absorbing material the only other way is to change that natural resonance threshold.
I agree with Siberianhusky that if fasteners are routinely shaken loose, there is something out of balance. A prop can be perfectly balanced, but what about the drive dog, collet? I personally have no means to balance the flex cable with the prop ATTACHED and connected to the motor via the collect/coupler.
This IS my argument on there other thread regarding the ills of WOT on the bench.http://forums.offshoreelectrics.com/...T-on-the-bench
Post # 4 and # 18, I am not talking about motor load, just the possibility of what happened in post #18.

[JimClark]

How does the shaft line up?