Nav light bulb

[[3889]]

Chandler wants 8 quid for a single filament twin connector 25w bulb with what seems like an extra long filament, for my nav lights. Car shop does a 21w bulb for £1.
Is there a good reason to pay the extra 700%?
Andy

 

[Guest]

Yes, filament position is critical to get legal nav lights

 

[VicMallows]

The correct answer is that the 'boat' one has a vertical straight filament to give the optimum light characteristics. They are expensive because relatively small production, plus the usual 'yachting rip off'. Make your own decisions!.

Vic

 

[Stemar]

Your chandler will love you? /forums/images/graemlins/blush.gif

It's a specialised marine part which costs more to produce (the extra 'm' in the part number has to be stamped on) ? /forums/images/graemlins/mad.gif

You've got more money than sense?
This one is certainly true - you bought a boat. The chandler is just doing his best to balance the money sense ratio /forums/images/graemlins/tongue.gif

I wonder if one of these would give enough visible angle?

 

[VicS]

I agree with VicMallows and Manoamica

There is no point in having lanterns designed to comply with the regs and then putting bulbs in them do not. A nav light bulb has an axially orientated filament on a specially designed support to ensure the correct angles of visibility. The filament in an automotive bulb is at right angles to that

If you are replacing bulbs so frequently that £8 a time becomes a significant part of your boating budget then you should be looking critically at your electrical system!

 

[Stemar]

If it were the case that the bulb is significantly different, I'd agree, but this sounds like the festoon bulbs my lights use. These have a straight filament going from one end to the other. So do the ones from Halfords. What's the difference? (Genuine question - no sarcastic intent!)

 

[VicS]

I assumed the original question refered to bulbs with a small bayonet cap, which I thought all the 25 watt bulbs are, aplogies if I'm wrong on that count, and my reply was based on that assumption.

I think perhaps that there is not such a big difference when it comes to festoon bulbs but those, sold for nav lights, that I have looked at do appear to have the filament accurately aligned down the centre of the bulb. Often the filament in cheaper bulbs is off centre and/or at a bit of an angle. It should be possible I guess to find one with the filament sufficiently straight but you might get some odd looks if you search through Halfords entire stock looking for straight filaments.

 

[VicMallows]

I've never seen a 25w festoon bulb? .. but agree in principle it should be OK. The LED route is really the way forward ..... Chichester Hbr are gradually replacing nav lights with LEDs. Expensive still though for commercial versions, and still concerns about visibility angle on sailing boats.

Vic

 

[Guest]

Ignore the cheque book sailors .....

Do the sensible thing and keep your wallet happy. Yes it is true that there are bulbs designed for nav-lights where the lens / reflector is cheap and incapable of focusing the light correctly.
Me ? I have the festoon type and loathe paying more than the local Car acc's shop price ..... thats when the bloody things work !!! At present in sore need of TLC ..... previous prat's wiring is cr..p.

25W bulbs ..... blimey - mine are officially stated for 10W max. Taking 3 on at once thats 30W .... add a tricolour or steaming light .... starts to add up even on my tub, but at 25W each .... we start getting serious ........

I can't be sure - but I seem to remember that a commercial ships were only 100W each .... OK special 'Squirrel-Cage' design filaments and tube shaped glass ....

 

[[3889]]

Vic
Its not about cost but value - I enjoy finding ways to thwart the excessive charges of the marine industry.
Also, my nav light bulbs fail fom mechanical shock - normally when I slamdown the anchor locker after dropping its contents on my foot ....again. I suspect the unsupported length of the filament must contribute to this.
Thanks to all for useful replies.
Andy

 

[wooslehunter]

Anyone know where in the IRPCS it specifies bulb power?

Annex 1 section 8 defines precisely the intensity of lights for the visible range required with lots of techno-bumpf.

Rule 22 defines the visibility of lights in terms of visible range.

So it's easy isn't it: look up the range required in rule 22. i.e. masthead light = 6 miles. Then calculate the intensity required from the formula in Annex 1 section 8. This will give you a figure in candellas. i.e. 94 for the UK using K=0.8 as prescribed by the IRPCS. Obviously your friendly motor factor will e able to advise on the output of the bulbs he sells, in candellas.

Bear in mind though that the bulb sits at the end of a long cable fed with a voltage that will vary as the battery discharges so you need to use the minimum battery voltage you're going to see and take into consideration the resistnace of the cables. Also bear in mind that not all of the light produced from the bulb will come through the lens of the nav light so you need to get that from the manufacturers.

One additional gotcha that's often missed out is the luminous transmissivity of seagull poo. This varies according to geographical area, season and type of gull. In fact as the season progresses and the hedgerow fruit comes into season, the dominant factor is actually likeley to be starling poo. Numbers can be obtained form the RYA technical department for seagull poo and the RSPB for starling poo.

Hopefully someone should produce a decent light someday that actually measures its own output and adjusts itself accordingly.

 

[Guest]

<<Anyone know where in the IRPCS it specifies bulb power?
>>

It doesn't as far as I know .... but the light manufacturer states the wattage bulb designed to fit .... my Lazilas cheapos say 10W .....

Unfortunately even they don't estimate Blackberry Poo correction - so that is down to guesstimate factors again..

One day I will get my lights to work ALL the time, instead of just when I bash 'em one !!

As an aside - when will switch panel designers stop using silly fuse holders ..... I have the very nice cosmetic job with the red lens over top of fuse that needs prising out - of course now the red cap doesn't want to stay in .... making the fuse lose contact at slightest twinge !!!!

Must get around to making my own panel .... Maplins here I come ......

 

[snowleopard]

[ QUOTE ]
Anyone know where in the IRPCS it specifies bulb power?

[/ QUOTE ]

the regs specify visibility. for the sake of convenience the ranges are taken to equate to 10w for under 12m, 25w for 12m+

if you are using a bi- or tri- colour lamp you have to have a linear filament to get the correct sectoring but for individual lamps a non-linear filament will give a little more overlap between the separate lamps than strictly allowable but it's much less of a problem.

incidentally i have both 25w 'proper' lights for motoring and 10w lamps with car-type festoon bulbs for sailing. after 100+ nights at sea, none of the marine lamps has yet blown while all the festoons have gone at least twice.

 

[ShipsWoofy]

I am regularly changing festoons, absolutely rubbish life on them IMHO. Luckily they are all at deck height, my tri light uses the expensive ones and has behaved so far.

 

[bluedragon]

Just for information...I e-mailed Aqua Signal in Germany to ask if I could use a 10W vertical filament bulb in my Tri-colour (less than 12m and that's what the deck level nav lights use). Answer is "No"...the bulb is part of the approval, and they know of no 10W tri-colours that meet the regs.

 

[philip_stevens]

Martin,
when I was with P&O Containers (lecky), we had the old copper nav. lights replaced by the more uptodate spec. plastic fittings.

In the old lights, the squirrel cage bulbs were the pear shaped 65cd (candela) bulbs. As you know, cd does not directly equate to Watts - see http://www.theledlight.com/lumens.html.

The new fittings (also in cd) had a helix shaped filament that was only half the length of the squirrel cage bulb, but only the one filament against about 20 or so in the squirrel cage bulb. They also had a special base that could only be fitted in one way.

I know it does not help in this discussion, but it was just an observation.

If you look at http://www.happisburgh.org/lighthouse/technical/ there is a reference to the 500Watt lamp giving out 59,500cd.

All very confusing. /forums/images/graemlins/confused.gif

 

[Piers]

Nav lights - approvals

As you found out, the nav light has to be approved. Furthermore, "the installation of lights on board the vessel shall be to the satisfaction of the appropriate authority of the State whose flag the vessel is entitled to fly." (Annex 1 section 14)

Yes, not only the lights themselves, but the installation on the vessel as well. How many of us have these approvals?

MBM has just looked into this (see this month's news items). Boat manufacturers aren't wanting to comment, and one insurer has stated that if the installation isn't approved the insurance may be invalid....

Interesting!

 

[Mirelle]

You interest me considerably!

We have a pair of copper sidelights, made by Tung Woo in Hong Kong to HK Mardep specs (same as UK) that take a German 24v bulb. I bought a lifetime's supply of these bulbs, anticipating that Tung Woo would give up due to replacement of copper by plastic - they did. The bulbs are marked "90 cd" and the current drain to the step up transformer when these sidelights are in use is 10 amps (at 12 volts)

The filaments are unusual - four vertical filaments supported round a central core.

I find them excellent because I use the sidelights when I am running the engine - when sailing we use the 25watt tricolour.

 

[VicMallows]

Re: You interest me considerably!

Those lamps sound great!; and I can well understand why you want them on that boat of yours. I just aspire sometimes to a nice copper paraffin anchor light, but make do with a cheapo huricane. /forums/images/graemlins/frown.gif