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Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

Siren

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britinusa
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USA
5404 Posts

Initially Posted - 01/31/2006 : 10:29:28

I just bought a 12v siren from an alarm company in hope that it might be installed for use as an anchor drag or bilge pump siren.
It's 12v and pulls a max of 500ma.

Plan is to hook it up to our GPS for drag alarm, but could alternatively hook it up to a new to be installed electric bilge pump.

The siren only cost $13 inc shipping so if I don't use it I won't be 'alarmed'

Has anyone hooked up a siren to their GPS (we have the Garmin 192C)
I'm guessing that it might be as simple as connecting it to the alarm cable from the gps and to the power supply.

Any 'gotchas' I should watch for?

You can imagine me pulling the boat around my neighborhood with the GPS drag alarm set to see if the siren sounds

I'll test it to see how loud it is, wouldn't want the sound to cause more concern than the draggin anchor! Perhaps installing an 'off' switch might be a good idea.

Joint Decision. (Sold)
PO C250WB 2005 Sail # 841.

Moved up to C34 Eximius

Updated August 2015

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 01/31/2006 : 10:46:27

In the 70's, my buddy hooked up a 12v siren alarm to his car horn and it was LOUD. It sounded just like a police siren, and coincidently, I was with him the day the police made him disconnect it.

If I were choosing an alarm, I would opt for one that had adjustable volume. A loud siren going off in a quiet anchorage may send all local volunteer firemen racing to the firehouse!

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 01/31/2006 : 11:01:08

I think a loud warning device wired to a bilge water float switch is a good idea. Depending on what conditions you want to alert bystanders to, you might wire it to a separate switch from the automatic bilge pump, so the siren comes on if the pump isn't keeping up. Or, you may want it to come on if there's any bilge water detected by the pump.

In my more paranoid idle moments, I've thought about a bilge water alarm myself. I have lots of pumps and batteries, but those can only postpone a leaking boat sinking, not prevent it. At some point, a human needs to intervene. How would anyone but me standing right there recognize an abnormal situation? Lots of boats pump out some water from time to time, and no one gives it a second thought.

I'd suggest the idea of using a siren as an anchor drag alarm needs more thought... Would this be intended to alert soundly sleeping crew on board? If so, do any of them have weak hearts?

Or notify someone on shore that an unattended boat is moving outside the normal swing of its scope?

For alarms to do any good, someone not only has to notice them, but also know what specific action to take in response.

-- Leon Sisson

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Derek Crawford
Master Marine Consultant

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USA
3323 Posts

Response Posted - 01/31/2006 : 16:40:36

"For alarms to do any good, someone not only has to notice them, but also know what specific action to take in response."
Right on Leon! Just think of all the car alarms that are totally ignored.
Derek

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JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 01/31/2006 : 18:10:00

my boat sails and swings a lot at anchor and also reverses when the tide and wind shift direction. Either of those could be interpreted by your system as an anchor drag. I'd prefer to sleep through that, however. I think a depth alarm would be a better idea. Set it to go off at 10 feet depth. Gives you time to up anchor and move if you are getting into shallow water for whatever reason.

Besides, when at anchor I usually get up at least once in the night to take a look around outside.

Its very good to have heavy ground tackle and good technique for anchoring - when I've felt the anchor dig in with my own two hands and know it is set I can sleep well.

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britinusa
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USA
5404 Posts

Response Posted - 01/31/2006 : 18:48:41

So far, whenever we have been at anchor overnight, the GPS alarm works well in every case except volume! Hence the idea of using the siren.

If it is as loud in the boat as my intrusion alarm in the office, I'll have to tone it down big time (when my office alarm goes off, your only intent is to get the hell out of there!) The siren will run off a 9v battery if required.

Not to worry just about a weak heart on a C250, you have to worry about that bump on your head when the alarm went off!

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 01/31/2006 : 19:08:20

I think a more appropriate warning would be in the form of a buzzer. Radio Shack stocks a pretty good selection of them. That is a marvelous idea BTW. I know that anchoring can be dicey in the keys and I have seen many a boat washed up on Sands Key!

Tom.

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britinusa
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USA
5404 Posts

Response Posted - 01/31/2006 : 20:06:03

Tom, you know our situation!
Sands Key is a favorite hangout.

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 01/31/2006 : 20:11:25

You'll need to see what the rated current supply is on your GPS external alarm lead (wire). If it won't supply the required 500ma at 12V then you will need to run the alarm lead to a relay and feed the siren from the relay.

>"my boat swings a lot at anchor and also reverses when the tide and wind shift direction. Either of those could be interpreted by your system as an anchor drag"

The 'watch circle' on the GPS anchor alarm is adjustable. You set it 2-someodd times your deployed anchor rode length so it only goes off if your anchor has moved. If you sail in a venue with substantial tides it works lots better than depth-based anchor watch.

Edited by - on

Ben - FL
Admiral

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880 Posts

Response Posted - 01/31/2006 : 20:29:36

If I had a siren I would probably have it wired to my OBM in case a second one decided to walk off! All it would need is one of those magnetic window sensors.

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atgep
Master Marine Consultant

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1009 Posts

Response Posted - 01/31/2006 : 22:20:23

Ben, Let's not forget the overheat warning!!!!!!!!!!!!!!!!

I am still working on that issue.

I was looking at something like this.

http://cgi.ebay.com/4821M-Fridge-Freezer-Thermometer-Magnet-Hi-Low-Alarms_W0QQitemZ4436829101QQcategoryZ20644QQrdZ1QQcmdZViewItem

Tom.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 02/01/2006 : 10:21:55

The largest boat at my marina is a new, 40 some odd foot, 6 figure yacht that apparently is equipped with a bilge alarm. Last season, this alarm had a propensity for going off late at night without the owner or marina staff present. This car alarm type alert would go off for hours on end, and very much annoyed those trying to sleep aboard their vessels.

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Ben - FL
Admiral

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880 Posts

Response Posted - 02/01/2006 : 15:23:07

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by atgep
 Ben, Let's not forget the overheat warning!<hr height="1" noshade id="quote"></blockquote id="quote">

Do you mean a "plastic bag over the water intake" alarm?

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britinusa
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USA
5404 Posts

Response Posted - 02/01/2006 : 18:51:36

Regarding the drag alarm setting on our GPS
Yes, setting the radius to twice the length of rode does the trick.
Even in shallow water, if you move beyond the length of rode then you are either dragging or your gps is off.
If in deeper water, then consider reducing the radius by the water depth.

We'll put out 100' of rode and set the alarm to 200' so that even swinging 180 degrees with a tide or wind change the alarm doesn't sound. So far the only time the alarm went off was when I set the radius too low.

It's interesting to review the GPS track on screen after a night at anchor, you can quickly tell where most of the movement was at.

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 02/01/2006 : 19:13:01

Good thing the gps does not measure the rocking the boat does!!!

Edited by - on

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