Anyone have designs/ideas for a hush box?

[March]

I agree with the comments above: at 5 mph, the sound should be far from bothersome. The human ear has the ability to "adjust" to background noises--how often do you pay attention to or even notice the sound of your engine while you're on the highway? Only when something goes wrong.

That is the reason why blocking the sound is not a good idea, to begin with. Your ear is tuned to the sound of a healthy engine. If there are hiccups, you'll catch them instantly.

As for the plastic baffles under the captain's seat, they wouldn't do you much good--except for, psychologically, of course. Just like the idea of egg cartons people used to "insulate phonically" amateurish recording studios with. A blanket (rather than a plastic foil) draped over the seat may absorb some of the higher frequencies, if you happen to lay down on the floor of the cockpit, but it won't do you much good otherwise.

Some people like to play loud music in the cockpit while motoring around, but I find the droning of a healthy engine quite pleasant. Wouldn't want to NOT hear it.

[Russ]

My boat came with a plastic panel that fills in the space under the helm seat from the motor well. It provides a little noise reduction as well as prevent stuff from falling out of the cockpit into the motor well.

As mentioned above, at low RPMs, most of the noise is from vibration throughout the boat. Not much you can do about that.

--Russ

[kevinnem]

i have no idea how practical it is , but would a set of large solar panels, battery and electric motor work?

even if it is out-of-budget, I wouldn't mind a discussion on the amount of power they use, and thrust they generate, and compare to gas. as 1 hp is like 750 watts, I think that it will be a no starter, but interesting non the less, ... how much hp to hit say , 4 or 5 mph?

secondly , sound works in a way that most people don't quite realise. namely the nature of sound is such that the perceived volume is highly correlated with the pleasantness of the sound, IE songs on the the radio you like, are always to quite, and songs you hate are always to loud.
also the sound level is highly dominated by the single loudest sound, .. there is little need to try to make everything more quite, rather, identify the loudest sound and deal with it.

[Russ]

i have no idea how practical it is , but would a set of large solar panels, battery and electric motor work?

even if it is out-of-budget, I wouldn't mind a discussion on the amount of power they use, and thrust they generate, and compare to gas. as 1 hp is like 750 watts, I think that it will be a no starter, but interesting non the less, ... how much hp to hit say , 4 or 5 mph?

750 watts of solar panels is a lot of surface area. Solar panels never achieve full capacity unless the sun hits them 90 degrees without any obstructions or clouds. So 5hp is a lot of panels.

We take for granted just how much energy is in a gallon of gasoline.

Our boats all use solar power for propulsion. Sails which are powered by wind created by solar energy.

[NiceAft]

Our boats all use solar power for propulsion. Sails which are powered by wind created by solar energy.

Getting a bit high brow here aren't we professor.

Ray

[captronr]

We had an old old outboard that all the foam sound insulation under the cowl had disintegrated from. It was LOUD. We found at NAPA/Autozone some 12" square rubber panels with adhesive backing. They were HEAVY and about 1/8" thick. Put several layers on the inside of the cowl and it cut the noise in half.

If there isn't room inside the cowel, a couple stuck under the captain's seat might help as well.

Ron

[Three Gypsies]

On our X we found that 3 5gal army surplus gas jugs fit in the perfectly in the space under the helm seat . This prevents the sound from traveling forward .
The engine is hardly heard by anyone , except the driver . I noticed the stereo can be played at a normal level and all can enjoy it ,,, except the driver .
The gas jugs must divert the sound upwards , so as to annoy the driver ,, but Hondas are very quiet engines so its not that bad .

[dlandersson]

lol

Our boats all use solar power for propulsion. Sails which are powered by wind created by solar energy.

Getting a bit high brow here aren't we professor.

Ray

[DaveC426913]

I don't understand. That four stroke motor is extremely quiet,

Well, that's relative. If we're cruising on a canal for six hours a day, even a quiet motor can be enough to disturb the peace and quiet we're hoping for.

Don't worry about any engine noise, after a short while, you won't even notice it.

Thing is, we're trying to listen to the world. Birdies, wind in the trees, serenity, etc.

I hâve à Honda Bf 50 and i cannot hear it at the bow when on low rpm. Maybe there is some kind of problem with your motor.

That's great. But how do you drive from way up there?? Maybe the only thing wrong with my motor is that the steering column is about 20 feet too short!

9/10 times when I'm casting off with guests they ask quite worriedly if I'm gonna start the engine before I untie…

Agreed. It's quite quiet at dead-low idle. But 5mph is cruising speed, and 6 hours is a long time.

Closing the hole under the seat (I have a Sunbrella panel for that)

As do I. I will experiment with that.

a big empty plastic storage tote placed under the rear (hinged) seat achieved some significant engine-noise suppression.

You're right, a cooler isn't a bad thing to have in the 'pit when cruising anyway.

I guess I was assuming that a significant portion of the sound would come over the helm, rather than under it. That may be a flawed assumption.

Additional soundproofing inside the cowl seems to have a significant effect

I suspect that the cowling already has as much soundproofing material as will fit.

OK, you guys have convinced me that it may be less of a problem than I suspected. Come launch, I will go do some experiments with an optimistic mind, and see how I can bring it down without building a high-density foam-lined plywood box around my entire outboard. :

[DaveC426913]

Our boats all use solar power for propulsion. Sails which are powered by wind created by solar energy.

But solar energy is merely a byproduct from the interaction of the four fundamental forces: strong, weak, electromagnetic and gravitational. So our boats are actually powered by the Big Bang.

[Russ]

Our boats all use solar power for propulsion. Sails which are powered by wind created by solar energy.

Getting a bit high brow here aren't we professor.

Ray

LOL

The point is that with all our great technology, sails are very efficient means of propulsion. Photo voltaic has a long way to go to push our boats.

[NiceAft]

Russ,
What's in the drinking water in Montana
Are you going to night school

Ray

[Boblee]

[quoteAgreed. It's quite quiet at dead-low idle. But 5mph is cruising speed, and 6 hours is a long time.
][/quote]
5mph (8kph) is max 1500rpm and thats going against current and wind, if no current or wind IMHO you should be doing a little over 1000rpm?, these boats are extremely efficient at low speeds and the honda motors are one of the quietest and most economical at low revs, much quieter than the etec.
At that speed you will/should not be creating any bow wave at all and will be very surprised if it stops you hearing any other sounds.

[seahouse]

Our boats all use solar power for propulsion. Sails which are powered by wind created by solar energy.

Agree, and if you accept that premise, then you might accept that when you fire up the motor you are also using “solar” energy... because the energy that went into growing the plants that decayed into petroleum ooze also originated from the sun at some point in time.

Of course it's the larger time lag that makes the difference to that viewpoint in the eyes of an environmentalist.

Technically, anything that uses heat from the top few hundred feet of the surface of the earth (the approx. depth of penetration of solar energy on land) can be correctly termed solar as well, and not “geothermal” as it is so often incorrectly called by those who market such systems (and sometimes by others who should know better). They are really “ground source heat pumps”.

Geothermal heat (way deeper, and way hotter, like geysers etc) on the other hand, results from the earth's radioactive decay – which is a separate and distinct energy source from solar.

- B.

[seahouse]

Ooo... but I digressed...

My full enclosure included (but it was available separately too) a canvas piece that fills the space under the seat, which reduces what would be straight-line noises from the engine, which is probably the cheapest and easiest way to get some sound reduction at any speed.

They don't leave much room for foam under the engine cowling to keep the overall engine size to a minimum (I couldn't find any room at all to store the pull cord for my E-tec under there, and the foam was so thin that removing a patch would get me nowhere). So a quieter motor with more foam might also be physically larger in size, a trade-off that might differ among manufacturers.

But I would think that on a nice slow casual canal cruise, as suggested, that a foam cover placed over the cowl that didn't block any openings might do the job, (unless you were in a heat wave ).

Direct Injection motors (yours?) make more noise because the fuel pressure is an order of magnitude, or more, higher, so the heavier pump and injectors cause “fuel hammer” as the valves open and close so fast. The other noises are the result of multiple flame fronts inside the cylinder during combustion. It's a price you pay for more bang for your fuel buck, and all the other efficiency benefits.

Together they make a rattling marbles sound that's similar to the sound that a conventional engine makes right before a hole gets burned through the top of the piston, which, if that's what makes the sound less pleasant for you (like it did me at first), needn't.

- B.