engine noise mitigation

[schubvet]

After many years we are finally switching to a trawler but when we took a ride in a 43 ft Californian with twin Cat 3802s the noise in the salon was so loud conversation was imposible.
Any sugestions on what trawler (38-44 ft) would be the quietist. My wife said it would be impossible to even read with the engine noise of the older Californian
I guess all those years of sailing have spoiled her.

[Lepke]

Proper soundproofing can tame most of the noise. Newer, more expensive boats will usually have better noise control. But there will always be some. My salon is over 2 Detroits. The engineroom has custom soundproofing. At max continuous rpm you can have a normal conversation.

[Cheechako]

It can be vibration, exhaust, or basic block noise.
-The vibration reflects through the hull and is very hard to get rid of. There are exotic mount materials used for large machinery that could help.
-Exhaust noise ought to be easier to prevent with the right mufflers etc.
-Basic combustion/block noise is engine room soundproofing.

[Simi 60]

It astounds me how noisy some breeds of engines are.
Some boats we hear droning miles out and wonder how the owners could put up with it.
Others you don't hear when they are right next to you.

[a64pilot]

If it has twin Cat 3802’s, it’s not what I think of as a Trawler.

A lot of boats with bigger, more powerful motors are intentionally made to have a loud exhaust note, to sound big and powerful.
I don’t know that boat at all, but a lot of older less expensively made boats are like that, very, very noisy inside, you have to be on a flybridge to stand it.

My ideal of a Trawler has a single 6 cyl engine, nothing is as smooth as an in-line 6. Most people are surprised to find that a 6 is smoother than a V8.

[denverd0n]

Ditto a64 and Cheeckako. I would add, were they running at high RPMs? A lot of engines will be unbearably noisy when run at a high rate, but perfectly livable at a more modest speed.


So, look for a trawler with a single six-cylinder, and don't try to push it past hull speed. No, it won't be as fast as twin 3208s running wide open, but it will be far quieter and get you there just as reliably. Then make sure that it is well tuned, balanced, and everything is aligned correctly. That will take care of most of the other noises.


If exhaust noise is an issue, that's usually easy to identify. Vibration is the one that can be hard to pin down. Could be engine vibration, shaft vibration, prop vibration, transmission, who knows? Good engine mounts can make a big difference, but you also need to try to get rid of the source of the vibration. If everything is running properly, aligned properly, balanced properly, there should be very little vibration to begin with.


You might also want to toodle over to trawlerforum.com, where you will find more trawler specific discussions. Good luck!

[Terra Nova]

Originally Posted by schubvet

...twin Cat 3802s...years of sailing have spoiled her.

Twin Caterpillar 3208's have about 10X the horsepower of your sailboat.

And Californians (not true trawlers) were entry level boats built to a price point.

Look at more modestly powered Grand Banks.

[NewMoon]

Our Nordic Tug 37 (39 counting the swim step hull extension) is very pleasantly quiet, even in the pilothouse, standing right above the Cummins inline 6 diesel. Reasonably economical as well - about 4 nm/gal at 7.25 knots.

[mvAlegria]

Hi,
A trawler is usually a full displacement hull with most often one engine ( sometimes a small come home auxiliary engine), Large trawlers 60+feet may have twins. These boats go slow (6-9knots), they go far on a tank full ( 2500 mile for ours) and their engine(s) run at low RPMs and consequently are quieter. Th Krogen 54 we had and lived on for 6 years and cruised from West Coast to the Med and back was quiet. In theory ( architect's calculation) it needed around 50 hp to reach hull speed . In actuality the engine ran at 3/4 power for hull speed and about 50% for "fast" cruising speed.The engine was probably rated for continuous use at around 200hp.

So if you want relatively quiet ride, get a traditional trawler. The moment you start planning the power needed goes exponentially up, as does the fuel consumption and the noise.

I now have a semi deplacement 34 foot Beneteau "fast" Trawler. It's somewhat of a hybrid boat, does go a little faster and is acceptably quiet with the new very quiet Cummins QB6 engine. I still mostly use it close to or just above hull speed.

Hope this helps.

[schubvet]

Thanks to all of you for the feedback. The noise was at a speed of only 8knts.
It is going to be an inline 6 and more of a displacement hull. I sure as don't need to get up on a plane and such gallons of fuel per hour.