If you use something different for sound signals
Send us pictures of what you use and we will include them here.
Sound signals are required to bring attention to a flag signal and sometimes must accompany a signal. In earlier years - and still in some parts of the country - Signal cannon were used. Nowadays, particularly in Northern Ireland, we have problems using signal cannon. First the firearms licence holder must be present when they are fired - so if that is the Club Hon Sec he/she needs to be on the Committee Boat and secondly boat owners do not want the mess and smell that a signal cannon makes. Certainly in my Club we nearly always use electrically powered air horns of one type or other.
Evolution of a signal horn (or 2 or 3)
We started using a car type air horn - this was a simple box to hold the compressor and a button to press for the sound.
There wasn’t even a relay in these first versions. The power came by clipping the crocodile clips on to the battery of whatever committee boat or RIB you were using.
This produced around 116 Db
The horns are a bit vulnerable to damage and the crocodile clips were/are a bit awkward to use. Moisture got in - down through the tube holes.
In order to get a louder noise the next version (Bertha 2) used two sets of car air horns with two compressors.
This version did use relays as the button was a low current type and the power came from a sealed motor bike type battery mounted internally. The switch changed from one to two sets of horns.
Produced around 118 Db and the 7.2 Amp hour battery would last for a five day championship and more.
The second picture is a picture of Bertha 2’s internals - two compressors and two relays and a small 12 volt battery.
This version generally worked well - it was louder, good sensitive push button and no leads to connect. There were however several problems with this design:
We made the mistake of passing the air tubes down through the top of the box. Rain also uses this route and we had problems with moisture on the relays and switch. As not much space the tubes kinked inside the box.
The push-button microswitch was too sensitive - we had a couple of sounds at the wrong time just because the finger was hovering too close to the button. The plastic horns on the top of the unit are very vulnerable to damage. A bit awkward unscrewing the lid every time you need to charge the battery.
Horn Mark 1
Horn Mark 2 - Bertha 2
Horn Mark 3 - Big Bertha
For the F18 World Championship we had to find a louder horn again as the start line would be over 430 metres long. I did a lot of research to find a louder horn and came up with a diaphragm horn (No compressor) that produced 120 Db. (The Db scale is logarithmic so an increase of 10 would have doubled the noise!) The horn was a Fiamm Vega Dual (Fiamm part no 920335) 475mm long.
I built a simple box to hold the battery, an on off switch and a horn button. The horns were clipped on to the starting mast about three metres above the deck, the cable ran back over the sailcover and down to the box.
The horns could be heard at the other end of a 430 metre starting line. Especially good to hear it on the ARO’s tape - first via radio and then by air. (Yes it was a redress hearing)
Had the same problem with the horn button being very sensitive so was prone to sounding a toot if your finger hovered too near to the button.
So we had problems with several of these - the button was too sensitive - leading to sounds at the wrong time, unscrewing the lid to charge the batteries was a pain. So with these problems in mind we set about rebuilding these systems over the winter.
Rebuild - Big Bertha
Next to be rebuilt was Bertha 2. We went for a box that completely enclosed the horns to avoid damage (one season on they are still intact). We deliberately used two different types of horn which gives a discordant note. We used copper pipes where possible to avoid the kinking problem.
New Build - Ice Bertha
We decided to build another unit like the Mark 1 but this time include its own battery - so no fiddling about with crocodile clips. It is a single compressor, two horn system and will be used for events where the start line is not so long, or for finishing. We also had in mind using it in a RIB for our Winter Dinghy Series - The Ice breaker. Again we followed a similar format - Positive action momentary horn switch, horns enclosed in a framework to prevent accidental damage. This is a smaller format horn/battery box which can work well from a RIB.
We now know a lot more about the batteries and their performance - we were even considering adding a cheaper chinese volt meter to monitor charge. A fully charged battery is around 12.7 Volts, a discharged on around 12.2 volts so we could add on a $2 volt meter and just charge it when it gets to a certain level. We used 7.2 Amp Hour sealed batteries and these do not need charged during a week long event.
First to be rebuilt was Big Bertha - The Battery Box was lower in height (more stable on deck), horn button replaced by a momentary, on/off switch. This had a much more positive action to prevent misfires. Access to the works is through the sliding bottom only. This was to make it more waterproof and we added a socket to plug in a remote switch - this is only used for giving sound signals at the finish line but means the line sighter can make the sound signals.
Rebuild - Bertha 2
Each horn set is switched on or off independently and there is only one horn button - again a positive action momentary switch to prevent misfires. So we can fire one horn or the other or both. We have also included the facility of a remote button for finishes.
All air tubes going to the horns from the compressors go out through the side wall of the battery box - as much protection from rain as we can give. Again access is only from the bottom.
These sliding bottoms allow a certain amount of air circulation in the battery box without letting in rain and are quick and easy to use to get at a battery to charge it.
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