R21 EC Engine Compartment Soundproofing

[Shangie]

Hello Ranger Tugs- We are thoroughly enjoying our new to us 2013 Ranger Tugs 21 EC and making improvements to make the boat even more enjoyable. The engine is very noisy underway and we see the cover has some insulation and or soundproofing but may want to upgrade materials if there is a superior product We can't decide on an upgrade material until we know what was factory so we can make comparisons. We are looking at a product that is very expensive compared to some but if it helps absorb sound it would be worth it. QUIET BARRIER™ HD SOUNDPROOFING COMPOSITE is what we are looking at but don't want to purchase that if what you already put in is comparable. Also, because we have no idea of what the factory soundproofing and/ or insulation is, we don't know it's average lifespan so we can replace as part of routine maintenance.. We bought the boat at 168 miles in January and have doubled those hours in only four months time! Thanks for any help.

 

[lproulx]

Welcome to the 21ec fraternity. I spent a lot of money and effort to quiet my 21ec down, with modest success. My father worked in the field of occupational health noise reduction, and I absorbed some of his knowledge along the way.

Noise is energy transmitted from a moving object, be it a loudspeaker cone, violin string, or whatever. It can set a receiving object (our ear drums) to vibrating. I have a Volvo engine in my 21ec. I imagine the Yanmar probably makes similar noise. The first step in keeping things quiet is to mount the engine on rubber "feet" that will reduce the amount of vibration transmitted to the hull. The factory did that. We can't improve on it. My Volvo seems to vibrate more than I would hope for. Diesel engines have very high compression, and their power pulses are sharper, more abrupt than gas engines. Sad to say (because I like diesels) gas outboards are much quieter. At certain speeds, the engine vibration sets all sorts of things to shaking and rattling. There's not much that can be done about that. Basically, the whole boat vibrates.

Higher frequency noise can be absorbed by enclosing the engine in a box with sound absorbing lining. The factory lining seems to be just foam rubber with a foil facing. It is almost useless. A company in Salem, Mass sells a sophisticated lining material, with a heavy vinyl layer sandwiched between two foam layers. The idea is that the sound from the engine will try to make the heavy vinyl (they used to use sheet lead!) to vibrating, but it is so heavy that it just absorbs the sound energy and doesn't vibrate much, thereby not transmitting the sound to the outside. It works very well for higher frequency sounds, but can't do much about the low frequency noise from the engine. I spent several hundred dollars on their product, and I would say it helped some, but not whole lot. Company's name is Sound Down.

I have come to just live with the little diesel's noise. There are certain RPM "sweet spots" where I find the vibration reduced and the noise less bothersome. I try to cruise there.

I would suggest and hope, that you can get used to the noise. I think you may be disappointed by putting much time, money or effort into reducing it.

Larry

 

[Captain Nice]

An excellent post Larry. I have the Volvo engine as well. My assessment of the factory motor box lining is that it is primarily for heat reflection and insulation. I have added additional vents in the box with no appreciable increase in engine noise in the cockpit. I suspect the OP's noise complaint is in the cabin. There is a lot of open space between the "house" assembly and hull/cockpit tub (look behind the fridge, inside the port cabinet and feel under the door sill). I have stuffed these areas with closed-cell foam, but can't say it helped much. Unfortunately, the engine's proximity and cabin's interior hard surfaces of vision glass and bare fiberglass are just not conducive to reducing vibration and engine noise. Part of the "charm".

CN

 

[Shangie]

Thank you Larry and CN- All good information. The sound only bothers me when we are over 2500 RPMs. I had her wound up to around 3000 at times while cruising this weekend to get back to starting destination in a more timely manner and I notice I am only bothered when we get the RPMs up. Otherwise it sounds more like a putter putt to me and really doesn't bother me in the cabin s long as the door is closed. Am having a discussion with a company called Sound Cow over noise reduction because I think if we could achieve a 15- 20 percent decibel reduction at higher RPMs it could be worth it. They have a sound dampening product for marine engine boxes that absorbs sound but I do not want to spend $350.00 just to get barely noticeable noise reduction. Perhaps I could PM each of you with the product we are considering for some review?

 

[Captain Nice]

Happy to.
We never run with the door closed due to our warm climate. I will experiment with that, from a noise perspective, next time we're out.

CN

 

[Shangie]

CN, We bought the boat with a fan already wired into the cabin and it really helps with heat dissipation underway, especially when we open the windows. I also always keep the screens in the overhead and v-berth hatches because even that wee bit of dark material helps cut sun. I also bought some window cling film from an automotive supply and cut it round to fit in the portholes to cut sun and heat and give privacy at the marina since we sit low in the water. During the day it still lets in a little light.

 

[Shangie]

Thank you for all the feedback. I used the information to formulate appropriate questions to ask the companies that provide soundproofing materials and it was agreed there would be little improvement. Again, overall, the noise is no issue until I get the rpms way up, which seldom happens since we enjoy traveling at 5-6 knots. The noise at higher rpms does not even disturb my husband at all so I think it is a matter of perspective. I was just not used to the 'putt a putt' noise since we formerly had a sailboat with a small horsepower four stroke. Also, I was unfairly comparing the noise with kayaking experiences which are generally quiet unless taken on heavily used lakes.. The good news for me is that we boated so much this season that I grew fond of the constant rhythm of the engine telling me it was doing well, even at higher rpms. .

 

[baz]

Ear muffs maybe!
Ear plugs maybe!
Loud music maybe!

Polystyrene can absorb noise quite well as I've used that to lessen the noise of a cluttering printer at times. Make a box out of Polystyrene and place that over the engine box...cheap and can be discarded if it does not work to lesson the noise for you... With this you must somehow provide air to the inside box and then for the engine to breathe.

Good luck.

 

[Shangie]

Barry, What I have discovered, after spending considerable hours motoring Puget Sound this past spring/summer, is that the noise does not bother me any more while in the cockpit. Part of the disturbance I was trying to 'fix' was a mixture of unfair comparison to the quietness of sailing and kayaking. The other was my lifelong fear of any engine revving louder than a typical car which I ascribe to a father's hyper aggression and scary antics at dangerous highway speeds that traumatized all his children.. Doing the majority of the skippering this season made me comfortable with the "louder than my car engine's noise" as I maneuvered the boat, changing rpms to suit sea conditions and therefor increasing or decreasing engine sound. The knowledge gained from piloting made me calm when someone else took the helm. I love the responsiveness of this boat and immensely enjoy the large open cockpit for connection with all that is occurring on the water. We are finishing up a Sunbrella bow cover project for the boat and hope to build a hard top this winter. She's a keeper!