12 v horn problem

[ditchcrawler]

My horn is mounted on top of the engine room pigeon box and has a compressor just inside the box with a short hose running out. Its controlled by a relay as the horn button is at the stern. so the power cables are probably less than 10 feet long

[Tony Brooks]

6 minutes ago, ditchcrawler said:

My horn is mounted on top of the engine room pigeon box and has a compressor just inside the box with a short hose running out. Its controlled by a relay as the horn button is at the stern. so the power cables are probably less than 10 feet long

And the batteries are probably all but below the horn so the man feed to the relay is easy to wire in.

[tehmarks]

12 minutes ago, Tony Brooks said:

In your case the horn mechanism may have seized/stiffened or the contacts burned/got dirty so it no longer works with whatever voltdrop is along the wiring. Although i suspect a new horn will cure your problem some advise that you try twiddling the adjustment screw in the horn but in my experience its rarely a long term fix.

It's a brand new horn. I knew the old one was knackered when I bought the boat. I flashed the cable with a meter at the time and got sound out of the old horn at the horn end of the cable - but the body was cracked so it was pretty poo and I decided to remove it while I was stripping all the other crap like TV antennas and what have you, to replace at some point in the future. Fast forward three months and the cable has developed a bad join somewhere in the middle - quite possibly from a litte incident in Etruria top lock a few days ago. The entire boat is wired in solid core.

 

Electrics are thankfully my forte. If it were a plumbing leak I'd be in trouble...

 

The solution in my case is going to be to run two cores of 10mm and a multicore of something thin in, and rewire all of the 'essentials' at the pointy end. Someone in the past has bodged the water pump and well deck bilge pump wiring for whatever reason too, and I think the easiest thing to do will be to start afresh. 10mm to a forward switch panel feeding the pumps, headlamp and horn, and a couple of cores for relays to control the headlamp and horn from the stern. And a few cores spare for any future stern-switching requirements that might pop up. Job jobbed. 

 

 

[WotEver]

59 minutes ago, tehmarks said:

The solution in my case is going to be to run two cores of 10mm and a multicore of something thin in, and rewire all of the 'essentials' at the pointy end. Someone in the past has bodged the water pump and well deck bilge pump wiring for whatever reason too, and I think the easiest thing to do will be to start afresh. 10mm to a forward switch panel feeding the pumps, headlamp and horn, and a couple of cores for relays to control the headlamp and horn from the stern. And a few cores spare for any future stern-switching requirements that might pop up. Job jobbed. 

If you're going to be running a new feed to the front anyway then why not go for 16mm² or even 25mm² and do a 'proper job'?

[tehmarks]

24V system, expected 10A maximum current draw and penty of diversity (because who goes cruising in torrential rain in the dark while leaving the tap running?) 

[TheBiscuits]

28 minutes ago, tehmarks said:

who goes cruising in torrential rain in the dark while leaving the tap running?

 

... or wants to wash their hands in a tunnel ...

[Tony Brooks]

42 minutes ago, tehmarks said:

24V system, expected 10A maximum current draw and penty of diversity (because who goes cruising in torrential rain in the dark while leaving the tap running?) 

On a traditional horn circuit I would question exactly how much diversity you have. I agree if a load of stuff is fed from a forward distribution box then you will have some but unless you fit a relay plus its boat length activating wire you will still require two cables the length of the boat.

[tehmarks]

Err, yes. Like I said - I'm going to run a pair of 10mm in to a forward fused switch panel, and a multicore of 'something thin' for relay control over the headlamp and horn, with spare cores for any future such requirement. That way I don't have to rip out half the fit-out to troubleshoot some wiring that I already know is pretty shoddy. At some point in the past the water pump has been piggy-backed off the well deck pump and is an awful maze of crap; I'd rather redo it all to an acceptable standard than continue suffering at the hands of someone else's shoddy work.

[cuthound]

4 hours ago, TheBiscuits said:

 

At this point I think you should just buy another horn of lower power instead of rewiring the boat.  It's only because you bought an oversized horn that it needs so much juice, so get a smaller one.

 

 

 

 

When I  bought my boat I found the horn to be pathetic. It fits inside a nice brass "trumpet" and I couldnt source a replacement that was any louder, so I  replaced it with one of these.

 

 

https://suffolkmarinesafety.com/product/ecoblast-foghorn/?utm_source=Google Shopping&utm_campaign=Suffolk Marine Product Feed&utm_medium=cpc&utm_term=8429&gclid=CjwKCAjw2uf2BRBpEiwA31VZj_RX2G4EAhhraC0db9MeI0on7wK3h9dWtvKq4lrwAcCKnVMB3vDgFhoC5hkQAvD_BwE

 

[WotEver]

2 hours ago, tehmarks said:

24V system, expected 10A maximum current draw and penty of diversity (because who goes cruising in torrential rain in the dark while leaving the tap running?) 

About a 1.5V drop then if you never exceed 10A.  The 24V bit was the unknown until you mentioned it.

[tehmarks]

Yes, sorry, now that I have a 24V boat I forget that 12V is very much the norm!

 

Two pumps (one of which only runs when it's bucketing down or the boat is sinking), a headlamp and a horn. I can't see that vastly exceeding 10A in any event, but at least two of those items will only ever be powered when the engine is running anyway. And it should be a relatively easy cable run straight under the port side gunwale until the bulkhead, as long as there aren't any obstructions in the only hidden bit behind the shower...