Fun With Air Trumpets

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cbigma

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Location
Danversport, MA
I’m not a social tooter.

That doesn’t mean I’m an anti-social tooter, it just means that I’m not one to announce my every transit of the harbor with a blast of my horn. I only use my horn when I need to get someone’s attention –immediately.

When stonebuster started the thread on “pilothouse trumpet horns” over on the All Parker Boats section, it got me thinking. Why don’t they make powerful air horns that are loud, long-lasting and reliable? And why do they all seem to stop at 120 decibels?

I did some digging on the Web and bought this single trumpet horn rated for 120 DB at 300hz at Hamilton Marine for about $120. About the same as what I paid for my last two sets of electric horns that only lasted a season.

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It came with a cute little air compressor, but somehow even 120 db didn’t seem quite loud enough for me.

So I Googled around a bit and discovered that the more air pressure you put into these horns, the louder they get.

I did a little experimenting and found that I could actually blow into the trumpet and get it as loud as the little aquarium-pump compressor they give you. The harder I blew, the louder it got! When I realized how annoyed the Admiral became with this experiment, I kept at it until I nearly split my cheeks. I had the dog howling, and the cat running for cover. I stopped only when she had that Lorena Bobbit look in her eye. :shock:

The little air compressor that came with the horn was only rated for 10 psi , . If you get 120 db for 10 psi,,, what would happen at 20 psi. 30 psi? But I’m getting ahead of myself……. 8)

First I had to find a place to mount this single 17” trumpet in a way that would prevent it from gargling salt water whenever we left the harbor. I butchered the old SS brackets from the last set of electric twin trumpets that died, and rigged the horn with a downward angle, using the bolts for the Raydome mount. (I –did- check afterward, and the trumpet is clearly “under the radar” and contains no electrical components.)

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I also replaced the clear flexible aquarium tubing that came with the horn because the OEM tubing walls were too soft and thick and I wanted to crank up the pressure. I wanted a more rigid tubing, so I didnt lose anything to tubing expansion I substituted polyethylene tubing with a thinner wall. It is not as flexible, but was thinner walled for the same OD, giving me greater volume and higher pressure capacity.

I ran the tubing down through the same cable outlet as the Radar feed. I then ran the tubing through the conduit above the stbd windshield, then down along the window frame and through the dash. Finally out the bottom by the helm onto the deck.

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Now for the air power. What to use to crank the volume up a bit? A bigger compressor? A SCUBA tank? Something that could give short bursts of low volume air in excess of 50 psi, without too much weight or electrical components. Hmm………

A foot-operated bicycle pump should do it. This one, a Bell air-stomper foot pump is rated to 120 psi, and cost about $14 at your nearest sporting goods or bicycle store.

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There was hardly any traffic out there today, surprising for a clear spring day, but the wind was brisk. I wanted to get a few miles offshore for the trial. I had no way of measuring the intensity of the sound, or any clue as to what I should expect. I foolishly stood up on the bow and challenged my son to “step on it”. Don’t try this at home.

Now I know why they all stop at around 120 decibels. I did experience pain and I still have a ringing in my ears. There is an air gauge on the pump and we were up somewhere around 40 -50 psi with a single stomp. I have no idea at what psi the diaphragm in this horn will rupture. I do know that replacements are available.

Be careful. Tampering with these horns could result in permanent hearing loss.

John
 
John... That is awesome!
A foot pump... who would have thought!?

BTW - When I had my Coast Guard VSC inspection the other day, my Ongaro horns failed me. :( The port side horn failed to work, though the stbd side worked like a charm.

Now I have to figure out how to take the non-working horn apart and repair it.

I like your solution, but I hope your leg is up to giving fog signals. :D
 
Indeed genius!

I can only imagine your boat sounding like a baying donkey, as you pump the foot pump... :shock: :D
 
The foot pump is fun, and yes, a very loud Donkey would be a good description :mrgreen:, but Kevin is right. We'll be plugging in a variety of air sources over the summer to find just the right one.

The next air source we'll try will be a two-stage regulator on a SCUBA tank with a trigger valve. That way I can also experiment with just how much pressure the diaphragm will take before it ruptures, and just how loud is TOO LOUD. :shock:

I think that the reason all retail horns cap off at 120 decibels is that the threshold of pain for the human ear is somewhere around 130 decibels.
Its not that they can't make a little compressor that cranks out more than 10 psi, it's that they don't -want- to. :roll:
 
Megabyte":1r0a8uiu said:
John... That is awesome!
A foot pump... who would have thought!?

BTW - When I had my Coast Guard VSC inspection the other day, my Ongaro horns failed me. :( The port side horn failed to work, though the stbd side worked like a charm.

Now I have to figure out how to take the non-working horn apart and repair it.

I like your solution, but I hope your leg is up to giving fog signals. :D
Megabyte, The horns that failed were the "new" all stainless inside and out with the 5 year guareentee? (that I just installed Saturday) Cbigma, Are those air horns all stainless on the inside too? Very ingenious and I like where you mounted them. If you need more loudness (to shatter glass or eardrums) you could always mount another on the other side and have duals. :lol:
 
stonebuster":38w4n4ai said:
Megabyte, The horns that failed were the "new" all stainless inside and out with the 5 year guareentee? (that I just installed Saturday)

Yes sir they are... and I did tell the inspector the story about recommending them to other owners. :(
If I can't free up that one horn, I'll be calling Ongaro to either get repair guidance... or a replacement set.
 
stonebuster":3vgwt1bo said:
Cbigma, Are those air horns all stainless on the inside too?

Stonebuster....Nary a speck O' stainless anywhere to be found on this horn. All brass (chrome plated on the outside probably just plain old brass on the inside) with a lexan diaphragm.

That's it. No other parts in it... just a diaphragm, some compressed air, and a brass trumpet. Like the groaners offshore.
 
esfishdoc":3gtz4f68 said:
Hmmmm.... I'm thinking a canister of compressed air with actuator switch.... mutiple toots.... fill up at home....

Good Stuff!

Hmm... like one of those hand-held blaster horns you see at football games etc.....with the little can of (what used to be freon) air.? I wonder how much pressure they contain? Hmmm..... I'll give it a try this weekend! :lol:

Thanks Richard! :D

I'm having more fun with this horn than I should be allowed to. 8)

It's probably illegal.

You can bet there is some local ordinance about how loud a boat trumpet can be....... :roll:


I'll found out soon! :mrgreen:
 
Megabyte, I'd be interested in how Ongaro handles your situation. The literature that comes with them leads you to believe they will replace for free. Keep us posted.
 
Megabyte":3av0a1n5 said:
stonebuster":3av0a1n5 said:
Megabyte, The horns that failed were the "new" all stainless inside and out with the 5 year guareentee? (that I just installed Saturday)

Yes sir they are... and I did tell the inspector the story about recommending them to other owners. :(
If I can't free up that one horn, I'll be calling Ongaro to either get repair guidance... or a replacement set.
Megabyte, My Ongaros are still holding up, but how was your problem resolved? Did Ongaro honor their warrantee?
 
I shot some PB Blaster into the horn and then stuffed a paper towel in... left it for a week... followed up with some WD40, and it started working again.

Haven't used the horn in weeks, so I guess I should check em to make sure.
 
Megabyte":1lu26gaf said:
I shot some PB Blaster into the horn and then stuffed a paper towel in... left it for a week....

PB Blaster? ...... PB? ....... Peanut Butter? :shock:

You put Peanut Butter in your Ongaro Air Horns? :shock:

No -wonder- your horns don't work....! Sheesh!

You need some "slide" in there too... like some Jelly or Bananas.

Any 4 year old could tell you that! :mrgreen:

C'Mon Kevin...get with the program! 8) 8)
 
I have a hand held "back up" horn that you can recharge with a bicycle pump. It is the same size as compressed air horns that are about the size of a coke can.
It is so loud that I can't stand to use it unless I duck into the cabin and hold the horn ouside thu a port or hatch.
I think the critical test would be if someone can hear the horn over the noise of their outboard and a least a hundred feet way.

Skipper Hub
 
Try these! You might need a little more than a foot pump unless you store it in a tank. I have a Nathan train horn on my F350 and it is an absolute blast!! I am finally tired of the horn on my Parker and will be getting one of these soon. I will post the project. Everything will be stainless and brass so no rust or corrosion. 5 Gallon Stainless tank with manual or powered pump and use the same switch as factory.
 

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maxout":1ixmk5g3 said:
I will post the project.

Aww Aww Awwsome!

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