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Smoke Alarms & Engine Rooms


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We are trying to work out the optimum position for smoke and CO alarms on our (new to us) boat. 

 

We have ascertained that it is impossible to fit them according to all the manufacturers instructions on this boat and so we need to come to a compromise that will compromise our safety as little as possible 

 

We are supposed to site the alarm at least 3m from any potential source of CO. The ONLY place that fits that description is in the bathroom and you are not supposed t site them in a bathroom as the steam will affect them. 

 

You are not supposed to site them in a place where there is "dead air" like corners for example and they must be at least 300mm from a light. 

 

Wel we have a diesel stove towards the fbow. an LPG cooker not far behind that backing onto the bedroom wall. beyond the bedroom is the bathroom and then the engine room with batteries and a Webasto central heating unit. Next up is a trad back cabin with an Epping in it. 

 

I have decided to site a dual smoke and CO alarm somewhere in the front of the boat. I can put it towards the front of the cabin to get it as far from the sources of CO as possible. 

 

I wanted to put a smoke alarm towards the back of the boat so that anyone sleeping in the back cabin will also have the protection of an alarm.  The nature f the back cabin is that you are either going to thwack your head on it as you walk through (if it is centrally placed on the ceiling) or it is going to be in dead air. I wondered about putting it in the engine room but I can imagine the general fumes from warm oil etc that you get with a JP2 might be sufficient to trigger the alarm if it is in there. 

 

Does anyone have any experience of siting a smoke alarm in an engine room at all? 

 

finding a suitable place on this boat for these alarms is proving a problem as there are lights everywhere!

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1 minute ago, roland elsdon said:

It seems intuitive to put a co2 detector somewhere near your head when you are asleep, as the first daily goal is to wake up alive. Thats my rational for placement.

I think you mean a CO detector ;) 

 

I would never sleep with it blinking it's little green light every so many seconds through the night above my head - just outside the door will be fine 

 

I can do that by putting it next to the cooker! 

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11 minutes ago, cheshire~rose said:

 

Does anyone have any experience of siting a smoke alarm in an engine room at all? 

 

Yes I've got one in my engine room. It didn't require a lot of experience, I just stuck it under the deck (cruiser stern). Just an early warning system. I've got a water level alarm in the bilges of the engine room too

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I use a couple of rate of rise alarms, one at each end which being temperature operated and not bothered by smoke etc from the engine, wood burner or stove, though I also have a toast proof smoke detector above the bed.  For CO alarms I have 2 on the wall one near the bed, the other near my chair.  The problem of having an alarm close to a CO source is it may alarm when you top up the stove etc, but so far no problem.  If it had I would move it a bit further away.

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14 hours ago, cheshire~rose said:

I think you mean a CO detector ;) 

 

I would never sleep with it blinking it's little green light every so many seconds through the night above my head - just outside the door will be fine 

 

I can do that by putting it next to the cooker! 

I recently installed a second CO alarm in the bedroom for the "not waking up dead" reason and to meet the BSS recommendations. This had a very annoying white indicator that flashes every minute, or so. It now has a bit of tape over the light that is transparent enough to see the flash in the dark and know that the alarm is still doing its thing, but not so much as to be obtrusive. Tape kept clear of the sensor grill for obvious reasons!

 

Jen

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1 hour ago, OldGoat said:

We always have top windows open and don't keep any flame / fire alight at night...... 

Until that fire that you thought was out continues to smoulder quietly, filling the area with CO...

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In addition to alarms elsewhere in the boat, I’ve put a CO alarm on the bulkhead by the engine room door into the bedroom, at head height, so more or less clear of the ceiling/deckhead, and an ionising smoke alarm on the ceiling forward of the door into the electric cupboard. The door has a vent grill at the top, so hopefully early combustion products of an electric fire would trigger the alarm.

 

The CO alarm has a digital display, so handy for glancing at when the batteries are on charge to see if hydrogen is finding its way out of the battery box.

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2 hours ago, OldGoat said:

We always have top windows open and don't keep any flame / fire alight at night...... 

No fridge? I know they aren't SUPPOSED to emit flames, but that's just the point - they have been known to catch light after an electrical fault.

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41 minutes ago, Athy said:

No fridge? I know they aren't SUPPOSED to emit flames, but that's just the point - they have been known to catch light after an electrical fault.

Good heavens no - I have a Batts fridge born out of the finest product manufactured in glorious Bognor Regis and fettled  by Maurice himself. 

What could possibly go wrong??

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7 hours ago, OldGoat said:

We always have top windows open and don't keep any flame / fire alight at night...... 

There was a case last year of a boater getting CO poisoning from the boat next door. The CO entering her boat.

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If you site it in the "wrong" position it will go off too often, and the risk is that people will then take the battery out instead of moving the alarm.

 

Hydrogen sulphide from a dying or overcharging lead acid battery will trip them easier than CO will - I think it was @Alan de Enfield that had that happen.

 

My primary cabin one sits between the stove and the cooker, about 1m from each, and only unnecessarily alarms once every few months.  I'd rather have the occasional false alarm than miss a real one ...

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On 10/07/2019 at 13:20, cheshire~rose said:

Thanks folks - it seems that the general oily diesely haze from a traditional engine may not trigger a false alarm after all. We might prop it on the top of the day tank for a trip just to make sure before we start drilling holes!

I've had alarms in my workshop as a mater of course. The 'oily haze' there makes most Trad Engine rooms look like operating theaters. I do check the units regularily (spray can) & replace if obviosly filthy but thus far havn't had one fail on test.     

 

Quickly adds- or at any other time!         

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On 10/07/2019 at 12:33, BruceinSanity said:

 

 

The CO alarm has a digital display, so handy for glancing at when the batteries are on charge to see if hydrogen is finding its way out of the battery box.

 

Do CO alarms detect hydrogen gas? I didn't realise. What else do they detect - apart from CO ?

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2 hours ago, blackrose said:

 

Do CO alarms detect hydrogen gas? I didn't realise. What else do they detect - apart from CO ?

AIUI, they detect any reducing gas, that is one that binds to oxygen as CO -> CO2 or H2 -> H2O. A typical arrangement is a Wheatstone bridge (remember them?) with three resistors and a piece of platinum wire of equal resistance in the four arms. Platinum has the property of changing resistance in the presence of a reducing gas, thus unbalancing the bridge, causing a current to flow across it and triggering the alarm.

  • Greenie 1
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On 10/07/2019 at 19:08, TheBiscuits said:

 

Hydrogen sulphide from a dying or overcharging lead acid battery will trip them easier than CO will - I think it was @Alan de Enfield that had that happen.

 

 

 

That happened to me two years ago. We arrived at the marina in February for one of our monthly winter visits and I could hear the alarm going off as I walked up from the car and then noticed the rotten eggs smell as I got nearer. 

 

I replaced the leisure batteries (which I knew we're on borrowed time), added a second CO alarm (at pillow height near the bed) and have since never left the battery charger switched on whilst not on the boat. We do have 200W of solar which keeps the leisure batteries topped up throughout the winter.

 

I also remove the batteries from both smoke alarms and both CO alarms when we go home as it would be very annoying if anyone happened to be on either of the neighbouring boats when an alarm started its low battery warning beeping. On the other hand, if an alarm sounded in anger it is highly unlikely anyone would be near enough to hear it in time (or at all) as our marina is sparsely populated, to say the least, most of the time. No-one was around when my CO alarm sounded.

 

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We prefer the alarms with a "hush" function so that a false alarm can be silenced without removing the battery - although those we have just bought have a sealed 10 year battery so it can't be removed. 

 

Having done all the careful calculations about where to site the one at the front of the cabin we agreed on the best place and fitted it.

 

It never occurred to us that it is almost directly above the chair that Dave sits on. I have some electonic help to remind him when he is filling the cabin with a fug ?

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I dont have a smoke or co alarm in the engine bay. But I do have  an automatic fire extinguisher in there.

 

Placing the co alarms inside the boat didnt cost me much time . There is a shelf near the bed head and another shelf near the main seating.

 

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2 hours ago, MartynG said:

Placing the co alarms inside the boat didnt cost me much time . There is a shelf near the bed head and another shelf near the main seating.

Just a thought - isn’t there a risk that a shelf might be an area of “dead air” and thus increase the response time?

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4 hours ago, Lily Rose said:

We do have 200W of solar which keeps the leisure batteries topped up throughout the winter.

We do this too, very successfully until this year. My health issues meant we didn’t set off cruising in April as usual and SA has been sat on her mooring all this time. All well and dandy except the solar only charges the domestic bank and it only occurred to me to check the start battery at the start of this month.

 

It was down to 12.5v and 24 hours with the shoreline charger on only lifted it to 12.6v, so I guess it’s goosed. It’s 9 years old so I’m not too upset at having to replace it. I don’t want to start faffing around with VSRs and the like, I guess I could just put a jump lead between its positive post and one on the leisures, removing it before boating. 

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