Waterproof Battery-powered Siren

[Johnoe]

Good evening,

I'm currently researching the feasibility of a university project i'm working on and wanted to ask some advice from you guys.

The project would involve the use of a siren which could be heard up to a radius of 1km (in a rural or light suburban environment) and would normally be part of a submerged system. The siren would sound when removed from the water but obviously the system would need to be waterproof.
The system would also need to be battery powered.

Is this broadly feasible? I'm not too concerned about the switch mechanism or anything more about whether a submersible siren system would be able to create the required volume.

Thanks in advance

[Daniel]

Are you looking for a mechanical or an electronic siren? There are many waterproof speakers available, but a mechanical siren would require a sealed motor and a corrosion-proof rotor and stator. Is this some sort of diver alert device, or is it a car alarm for your submarine?

[Johnoe]

Yeah, it's an alert device. Think Tsunamis.

It has to be fairly loud, around a 1km radius of warning

[Daniel]

Is your plan to place the device underwater and have it sound when the ocean draws back before the tsunami wave strikes? In this case, it would seem that a remote sensor would be more efficient.

[Nelso90]

I would say a remote sensor would be a more feasible idea, as you would be able to put a HUGE warning device (Like a T-135, or a T-128) in the middle of your population center, and then warn them more directly, it would also be more cost effective, as the motor and stator, or speaker driver assembly would not have to be a sealed unit. It would also be less prone to damage by boat strikes, or people running over it (I assume the sensor would be placed at a public beach or waterfront).

[Justin]

Yeah, it's an alert device. Think Tsunamis.

G'day mate, welcome to the forums.

So we're talking a device that is supposed to warn of an incoming tsunami, if I understand your project correctly? It sounds like you wanted some sort of buoy to act as the trigger? Would you be able to tell us more?

Nelso has the right idea with the use of a dedicated warning siren in the centre of town as that would make sure that it could be heard, and in turn, alert the most amount of people (or become an array of sirens for larger or more densly populated (think ambient noise) areas).

The way that our tsunami warning system for Australia and New Zealand is set up is monitoring the ground for seismic activity underwater and if there is a substantial anomaly, the alarm is raised at the warning centre for evaluation and if need be: public alerts.

[Johnoe]

Hi all, thanks for the replies.

I've been looking at the concept a bit more today.

Basically the idea is to have a device which attaches to buoy underwater. When the tide recedes prior to the tsunami the device is exposed to the air and a warning siren activates.
The idea is that it can be used in very remote areas; it could have, say, a five year working life and require no maintenance or or external power.

Remote sensing and seismic versions exist but these assume an existing level of infrastructure that my target area doesn't have. The concept is literally a box that could be attached to a buoy and forgotten about unless the drawdown occurs in which case the siren will sound.

So, after some research i've been looking at having a compressed air reservoir which is released through some kind of waterproof airhorn (as used by some divers).

Any feedback would be greatly appreciated.

[Charlie Davidson]

You could add a solar panel and good set of batteries as your power source.

If you wanted it to notify someone (or something) in a remote location, you could add a radio encoder on the device to send a signal out to notify an EMA, activate an alarm or even have a system of sirens that it would activate.

It really depends if you want the device to be all-in-one or if you want some kind of remote activation. I think my ideas would be too complicated though

Anyways, that's my two cents. Hopefully I've provided you with some useful information.

[Johnoe]

Thanks for the reply.

I considered a a solar panel or tidal power system but I think i'm going to just use a sealed battery source. The system standby power consumption would be very low so a single battery should be feasible.

I'd like to keep the system as self-contained as possible, things like wireless transmitters or receivers all require extra power sources and infrastructure that is not necessarily available in the areas i'm looking at.

[Daniel]

One thing to consider is that while the ocean typically draws back before a tsunami wave rolls in, it doesn't always do this, particularly if the earthquake epicenter is close to shore.