PIR's on boats

[catalac08]

Hi All
Thinking about a wireless alarm system with strobe + sounder for boat, actuated by a PIR to be placed in the cabin. This is designed as a shed or garage alarm and battery operated. Is there anything about a boat that is so different that makes this use of a PIR not a good idea? Although the mooring is in sheltered creek there is sometime wash from passing boats.
Thinking about false alarms really. Obviously need to get top quality batteries for the PIR and the strobe/alarm.
Any thoughts on this also wonder about possibility of passing craft electronics actuating the alarm; thinking about the time I operated my car key fob in a car park and another car (different make) also flipped its locks!

 

[rob2]

Interaction with other electronics is probably not too likely. To be honest, I'm surprised it doesn't happen more often, though. When I last bought a lock I was told there were tens of thousands of differs, so it's just coincidence that I got key no 9? Just cause there are so many possibles doesn't mean they'll set up to make more than ten of them.

As to a PIR, you'll have to be meticulously tidy and make sure all lockers are latched shut and nothing can swing or roll. Its just as likely that stormy weather will cause the odd trigger rather than wash from passing traffic. I remember a friend's car alarm frequently triggering from having the roof open in Summer, too. Still, if it doesn't work too well, you can always fit it in the garage/shed/caravan instead!

Rob

 

[nickd]

PIR stands for passive infra red, as far as I understand it detects an intruder by the sudden appearance of heat where previously there was none. So movement of the boat caused by whatever means is unlikely to set off a PIR unless you have heat source within the boat which is, for instance, dangling so that it could move diffrently relative to the fixed objects around it.
cheers

 

[tillergirl]

I have a wireless system at home. PIRs should work fine but spiders in PIRs might be a problem. They are the prime cause of my neighbour's false alarms - he is wired. Pet proof ones might be best (not because of the spiders!) but because they would probably be best at ignoring things swaying slightly with the motion of the boat (although I take ned's point about heat). If you get a system that can ring you, you not only get a warning that it has gone off but can reset the system. My domestic system allows me to ring the alarm and listen in to the house (never found that particularly exciting) but it would be very useful to etermine false alarms. The expense has of course gone up from the basic DIY system if you have this.

 

[rob2]

Probably a good idea to leave the curtains closed to prevent sunny hot spots from flitting around in front of the PIR, then.

Rob.

 

[bammylovechops]

Hi All
Thinking about a wireless alarm system with strobe + sounder for boat, actuated by a PIR to be placed in the cabin. This is designed as a shed or garage alarm and battery operated. Is there anything about a boat that is so different that makes this use of a PIR not a good idea? Although the mooring is in sheltered creek there is sometime wash from passing boats.
Thinking about false alarms really. Obviously need to get top quality batteries for the PIR and the strobe/alarm.
Any thoughts on this also wonder about possibility of passing craft electronics actuating the alarm; thinking about the time I operated my car key fob in a car park and another car (different make) also flipped its locks!

You could try speaking to Trevor at:

http://alarmmyboat.co.uk/default.html

He supplied all the stuff for my S28, although I did not fit it myself.

 

[Seajet]

I think the 'infra red' aspect is a bit of a red herring; these sensors work by dividing their 'view' into segments, then noticing changes - movement -between these.

Heat probably isn't a great worry, but beware a lot - the majority - of these shed type alarms work on a trembler type sytem, if the alarm body itself is moved; that would obviously be no good on a boat.

 

[Gin]

Hi All
Thinking about a wireless alarm system with strobe + sounder for boat, actuated by a PIR to be placed in the cabin. This is designed as a shed or garage alarm and battery operated. Is there anything about a boat that is so different that makes this use of a PIR not a good idea? Although the mooring is in sheltered creek there is sometime wash from passing boats.
Thinking about false alarms really. Obviously need to get top quality batteries for the PIR and the strobe/alarm.
Any thoughts on this also wonder about possibility of passing craft electronics actuating the alarm; thinking about the time I operated my car key fob in a car park and another car (different make) also flipped its locks!

I had a system installed 4 years ago- perhaps technology has improved- initially I got false alarms from the PIR element of the system but once the unit was changed to a 'triple technology' type, which as I understood required two out of the three internal systems to confirm an activation all false alarms stopped

 

[dsw]

i got one off ebay £140 which calls me if set off and after 3years no problems at all and its i.r with opp contact switch,
also you can call and listen.
pm me if you want their phone number.

 

[Robin]

We had PIR household type alarms on both our last two boats over 15 years and they are fine, in fact Force 4 used to sell a 'marine' one (same but double the price). Our last one was a bulkhead mounted main unit with a keyring 'zapper' on/off but it also had an extension alarm which could be mounted elsewhere but was no waterproof. We had the second alarm in the same cabin and the noise of both together was unbelievable and better able to chase a burglar away than to attract attention from outsiders who largely just ignore alarms anyway. The second alarm simply plugged into the main unit, but would go off if unplugged.

We also added a 'shed' alarm with a pull pin trigger to the main hatch. The unit was clipped onto a bracket on the companionway and the cord to the pin hooked onto a loop of line on the washboards, set as a hair trigger to go off if the washboards moved more than half an inch but allowed the hatch to be slid back to disarm it if you knew it was there. We also had a flashing red LED mounted to shine a red beam across the companionway that was visible at night through our smoked perspex washboards, looked very good but was a dummy, mounted in a small box with a visible keyswitch. The LED was from Halfords, the box and keyswitch from a scrap box in a chandlers. We also had 'Alarm Fitted' stickers on the washboards, proper ones that looked the part, from Maplins I think.

This info is no use to anyone with evil intent as our boat is now sold and gone to pastures new..

 

[Elessar]

I have a wireless system at home. PIRs should work fine but spiders in PIRs might be a problem. They are the prime cause of my neighbour's false alarms - he is wired. Pet proof ones might be best (not because of the spiders!) but because they would probably be best at ignoring things swaying slightly with the motion of the boat (although I take ned's point about heat). If you get a system that can ring you, you not only get a warning that it has gone off but can reset the system. My domestic system allows me to ring the alarm and listen in to the house (never found that particularly exciting) but it would be very useful to etermine false alarms. The expense has of course gone up from the basic DIY system if you have this.

Pet proof alarms don't ignore movement.

The way a PIR works is it measures the level of infrared the sensor can see. The lens in front of the sensor looks at patches or blobs and directs them to the sensor.
If you walk across the device, the IR the sensor sees goes up and down as you go in and out of the blobs.

You can set the number of up-downs needed before the alarm is triggered on a good sensor. Putting it to 3 will reduce sensitivity and reduce false alarms. The sun going in or out for example is a one way increase or decrease in IR, so will not trigger an alarm. A tree breaking the sun light intermittently however could trigger an alarm.

The pet alarms simply have no blobs at ground level allowing the animal to walk beneath it. For that reason they are best mounted lower down the wall than a normal sensor, so they "look" around like a lighthouse if you like.

BTW the blob system is why a normal pattern device is more sensitive if you walk across the area of coverage rather than walking towards the sensor, as the blobs are elongated like a torch beam if you shine it on the floor away from you. A pet sensor is virtually blind to movement towards the sensor.