Inboard engine noise

[LadyJ]

I've seen a lot of forum comments strongly coming down in favour of inboard engines for smaller boats. To see what the benefits were I went out yesterday to test the Jeanneau NC9 which is a lovely looking, well laid out boat. Weather was moderate to rough, 18knots of wind with gusts of 27 and white caps. Boats handled well albeit more slamming than I'd hoped for at cruising speed but not 'uncomfortable' albeit not substantially better than a slightly smaller outboard. What did surprise me was the level of engine noise on the boat, even at idle. The grumble of the single diesel (Volvo 260hp) as soon as the engine came on was irritating and caused the cooker to rattle and the noise was a constant annoyance that caused me to rethink my next step up. I can only imagine a twin engine would be even worse on the noise front.
Is this the same on most inboards or is the NC9 a bad example? I can see me going bigger to a flybridge just to get away from the engine noise but can't see my guests all joining me up top.
Perhaps you just get used to the noise but keen to hear if other feel the same or is there is a set up/model that reduces the annoyance.

 

[Lon nan Gruagach]

I've seen a lot of forum comments strongly coming down in favour of inboard engines for smaller boats. To see what the benefits were I went out yesterday to test the Jeanneau NC9 which is a lovely looking, well laid out boat. Weather was moderate to rough, 18knots of wind with gusts of 27 and white caps. Boats handled well albeit more slamming than I'd hoped for at cruising speed but not 'uncomfortable' albeit not substantially better than a slightly smaller outboard. What did surprise me was the level of engine noise on the boat, even at idle. The grumble of the single diesel (Volvo 160hp) as soon as the engine came on was irritating and caused the cooker to rattle and the noise was a constant annoyance that caused me to rethink my next step up. I can only imagine a twin engine would be even worse on the noise front.
Is this the same on most inboards or is the NC9 a bad example? I can see me going bigger to a flybridge just to get away from the engine noise but can't see my guests all joining me up top.
Perhaps you just get used to the noise but keen to hear if other feel the same or is there is a set up/model that reduces the annoyance.

What sound proofing did the engine compartment have? I am installing QuietLife 23mm and 45mm where it will fit around a 120hp Iveco and, apparently, it makes a massive difference. One thing that worries me in your post is the cooker rattling, implying that the vibration is transfering to the structure,in this case no amount of padding will do, just maybe some gentler engine mounts as well would work.

 

[LadyJ]

One thing that worries me in your post is the cooker rattling, implying that the vibration is transfering to the structure,in this case no amount of padding will do, just maybe some gentler engine mounts as well would work.[/QUOTE]

Thanks, just to clarify the cooker rattle was at start up and initial idle but after the return from the run out that had stopped. Assume once the engine heated up the vibrations were less but no perceivable difference in the overal noise.
I'll look into the sound proofing.

 

[rafiki_]

I think you will find any boat of this size, with an enclosed wheelhouse/saloon, will be noisy with an inboard engine. You have effectively a loudspeaker soundbox, with the engine driving the noise source. There will also be reasonances that will set things off like the cooker, cutlery, crockery etc to rattle. Clearly an outboard engine is isolated from the wheelhouse, and will thus have less impact on interior noise.

 

[Barleycorn]

We have a 210 HP Cummins under the wheelhouse floor and it is very unobtrusive, there is more noise out in the cockpit, especially since I did away with the silencer, but the engine runs a lot better without it. The turbo whistle is noisier than the engine, quite pleasant I think.

 

[Oscar24]

Had a good look over an NC9 at last years Soton show and was very impressed with how light and airy it was. Didn't hear the engine running but thought it had a single D4 260 fitted ?

 

[LadyJ]

Had a good look over an NC9 at last years Soton show and was very impressed with how light and airy it was. Didn't hear the engine running but thought it had a single D4 260 fitted ?

Agree, lovely airy boat. Engine was a 260hp, typo my side.

 

[oldgit]

That low grumble is very reassuring when you are out somewhere and away from shore. Going from petrol to diesel can be a bit unsettling but you soon appreciate the drone of a nice economical diesel sipping fuel in the background.
It is also reassuring to know you really have to do something drastic to stop a diesel running,whereas with a petrol.you merely have to get something/somewhere/anywhere a little bit damp.