21 EC Engine Box Sound Protection

[captnmunro]

Has anyone tried to reline the engine box with 1" rather than 1/2" sound barrier. Does it make an improvement?

 

[rt11002003]

A lot of the noise resonates thru bilge cavity. I suggest putting sound suppressing material under the engine, don't block the hole. I'd also explore lining the cavity running to the cabin though it may be impossible to access that area. It's been more than two years since I owned a R21EC and I've forgotten a lot.

I'd also try a material called "Soundown". The spelling may be wrong. I've heard good things about it.

No matter what you do, an engine box setup is going to be noiser than having the engine below deck, all other things equal.

gene

 

[tlkenyon]

Carpeted the pilot house (R-21 Classic) making sure to have carpet on all (but small) aft-facing surfaces at floor level. Beneath the door, there is a nearly open area to the engine. Covering that w/ carpet did a lot of good, especially as it does not involve water drainage in any way.

 

[billb]

We are new owners of a slightly used 2012 21 EC. We live on Gambier Island in Howe Sound, just north of Vancouver and we use our boat often. Engine noise was a concern, but it really isn't any worse than our previous V8 powered boat. However, when looking over the Yanmar engine installation in the 21EC, I noticed that the cabin heater hoses attached at the forward end of the engine are in contact with the upper surface of the engine box when the box is closed. It is clear that there has been rubbing - the hoses are shiny and the engine box insulation is pressed upward. The engine is mounted on rubber and it moves a lot while running so I am sure that vibration is being transferred to the engine box which probably has acoustic properties similar to a base drum. I plan to rework the hose positions slightly, moving them downward so that they don't touch the engine box. In doing so, the bend radius at the engine fittings is increased, and we don't want to 'kink' the hoses. If it is possible to do this, I expect the noise may be reduced a little, and life of the hoses will certainly be improved. I've searched this site for similar comments, but none found. Has anyone else noticed this interference?

Thanks
Bill

 

[SGIDAVE]

Hello Bill,

I see this is your first post....Welcome to the forum!

On my 2013 21EC the motor box insulation was falling off the top in the aft half of the box such that the exhaust mixing elbow was touching the insulation. There was a rust stain there. There was no sealant around the screw holes attaching the cup holder on the aft end of the motor box; water had saturated the insulation on the top and back of the box causing premature detachment.

I don't think my heater hoses rub on the top of the box in my boat. I recently replace ALL of the motorbox insulation with Soundown barrier insulation. I used 1 1/2" thick on the top and forward ends; 1" thick on the rest. No rubbing of hoses, etc now. I detailed that project here (viewtopic.php?f=5&t=4335).

Realize the engine "vibrates" on its rubber mounts at idle but much less so once RPMs are increased to cruising speed. Nonetheless, adjusting the 'bend' in the hoses to eliminate contact with the motorbox would be a good thing. Is the motorbox insulation sagging where it contacts the heater hoses?

As others have suggested, adding insulation (like Styrofoam? or something that wont absorb water) to the hull, under engine, pilot house floor, etc might help reduce the resonance of the engine sound which becomes so prominent in the pilothouse at 3000+ rpm. I like to cruise at 22-2600 as this seems to give best speed/noise ratio. But, I'm a new owner and still learning about the boat.

For instance, I learned about "prop walk" the other day and actually practiced backing up and using prop walk to "back and fill" while on the water a couple days ago. For this size boat, the 21s have a HUGE rudder and turn very responsively.

Let us know how it works out for you,

/david

 

[billb]

Hi Dave,
Thanks for the welcome and the response to my posting.

I did read your posting about the way you re-insulated the motor box. You also identified the cup holder screw holes as the sourceof moisture ingress. I plan to take a look at those screws on our boat.

Assuming that your 2013 R21 has Yanmar power, I would be interested in your comments if you look at the heater hoses at the upper forward end of the engine. I can learn to live with the noise - we can carry on a comfortable conversation in the cabin. I'd prefer not to have slow damage to the hoses over time, but I don't want to tighten the bend radius of the hoses too much and restrict flow. In the end, it may be best to leave things alone, and just check the condition of the hoses periodically.

Thanks again,
Bill

 

[SGIDAVE]

Hi Dave,

Assuming that your 2013 R21 has Yanmar power, I would be interested in your comments if you look at the heater hoses at the upper forward end of the engine....I'd prefer not to have slow damage to the hoses over time, but I don't want to tighten the bend radius of the hoses too much and restrict flow. In the end, it may be best to leave things alone, and just check the condition of the hoses periodically.

Thanks again,
Bill

Hello Bill,

Sorry for the delayed response. My heater hoses touch the top of the motor box. I don't see any 'shiny' (worn) area on the hoses in my boat. Mine is the Yanmar engine.

If you look below, this is a listing pic from a new 2013 R21-EC. You can clearly see 'shiny' areas on the heater hose as it bends to go under the deck to the pilot house heater core. I believe this is the area touching the inside of the motorbox as you have described. This is another example of the hose-touching-motorbox insulation situation you mention. This makes your boat, my boat, and this one listed below, so likely many have this situation.

Like you, I wouldn't want to tighten the radius more and risk kinking the hoses. I'm a new owner but have looked at most (all?) R21-related posts on Tugnuts and C-brats and have not heard of any leaks in the bend-area of the heater hoses. They usually leak from where they are fitted to the heater core. If it becomes an issue, maybe installing an elbow would allow lowering the whole hose pathway more effectively than simply pulling them lower. I will watch mine for now.

Fair Winds,

/david