GPS failure and the sextant.

[Neil_Y]

Obviously a modern gps antenna is waterproof
That's the point they are of course water proof from the factory but there are many experiences of this failing to be true after a couple of years sat in a drawer for hand helds.

Highly unlikely that all the ships batteries will fail at the same time. That ls what happens been there done that, so spare leads don't help, spare battery higher up is a good idea, charged but isolated.

Jumper-leads from the batteries to the GPS and other equipment are quick and cheap to make up. Have a selection of ends to suit and stow it away in the chart table where it hopefully will never be needed.

All true about clouds visibility etc and using sextant, but it can also give accurate distance off, vertical/horizontal angles to fix your position when you get to land. If you're Ocean crossing one poor fix is quite useful. Even if you just get latitude.

These days probably the best bet in many places is a good vhf with mast head antenna and separate battery, you will get maybe 20miles range and you might find another boat/ship listening. I've spoken to a few boats I couldn't see when days out of a harbour but close to a shipping route.

 

[jwilson]

Would it have turned sight reduction tables to papier maché,as happened to Shackleton,M.Richey,etc.?

Event 1 - Water absolutely everywhere, mixed with diesel. Books mostly survived, albeit very ragged, some charts did not. Ended up making landfall engineless with a torn scrap of chart.

Event 2 - water washing around saloon floor and up inside side linings where the neatly installed electric/electronics were fitted and stored. No damage to books.

I know a sextant is the piece of string to "belt, braces and a piece of string", but as others have said, it has more than one use in traditional navigation.

 

[jerrytug]

Thanks for that..I'm thinking about book stowage and how vulnerable they could be. I'm studying my Ocean Theory,and altering my bookshelves etc to be more suitable for blue water,cheers Jerry.

 

[Deleted member 36384]

Thanks for that..I'm thinking about book stowage and how vulnerable they could be. I'm studying my Ocean Theory,and altering my bookshelves etc to be more suitable for blue water,cheers Jerry.

Paper is a common blockage of pumps in the various sinking stories I have read.

 

[jerrytug]

Paper is a common blockage of pumps in the various sinking stories I have read.

Yes indeed,and when did you last hear of a foundering because a GPS72H blocked the pump suction? ;-)

 

[lustyd]

Surely if books survive so well we should all throw them overboard and use the bookshelf to store a spare GPS and batteries?

I'm all for astro as an intellectual exercise but where do you stop with the backups? Do you carry a spare sextant? Do you carry 3 watches (2 are useless in a vote!), at least one of which is a mechanical one? Do you carry spare tables? Do you know how to calculate new tables "just in case".

Would it, perhaps, be more prudent to just know where on the earth you are at all times so that you know the direction to travel for the closest land? Then just sail carefully forward until something that isn't blue is in front of you and follow it until you find port.

I would suggest it probably more prudent (and cheaper) for long distance cruising to carry a globe and china graph Pencil and mark your position daily in order to keep an idea of where the closest land mass is!

 

[snowleopard]

I once had a total electrical failure on a Cowes-St Malo race. It turned out to be a corroded fuse holder. No electronics of any kind, just the compass. We found the Channel Light Vessel by DR but the weather thickened (sea level have, vis ~2 miles, sun visible) and we found ourselves to the West of Jersey with no fix. I got out the sextant and got a position line running NW-SE so was able to transfer that and ride it down into the St Malo approaches.

 

[Roberto]

but I hope the hat hasn't survived.

I had a spare one as backup, of course

 

[jordanbasset]

I once had a total electrical failure on a Cowes-St Malo race. It turned out to be a corroded fuse holder. No electronics of any kind, just the compass. We found the Channel Light Vessel by DR but the weather thickened (sea level have, vis ~2 miles, sun visible) and we found ourselves to the West of Jersey with no fix. I got out the sextant and got a position line running NW-SE so was able to transfer that and ride it down into the St Malo approaches.

Good to have a back up. Mine was not so bad, just a dodgy aerial in the fixed GPS. So got hand held GPS out and had a fix in seconds. To be fair if the batteries were flat and the spare batteries flat and I had no way of charging them, then there would of been an issue. Equally if the cloud was not so fortuitous in your case you would not have been able to make a sighting. Just a question of working out the probabilities and what works for you.

 

[Neil_Y]

I think we'll see more calls for help when lost, as the generation that grew up on DR, aerobeacons, horizontal angles and distance off calcs (as well as when sextants were the only way when crossing oceans) fade away.

 

[jerrytug]

I think we'll see more calls for help when lost, as the generation that grew up on DR, aerobeacons, horizontal angles and distance off calcs (as well as when sextants were the only way when crossing oceans) fade away.

Do you? Why,when GPS is so much easier to use and all vessels carry it? Why,when so many yachtsmen including me are keen on mastering astro? I reckon it's the exact opposite,the human race is always looking for new ways to navigate. We have been since we swung out of the trees (quite recent in my familly) and the various techniques add to previous discoveries, rather than displace them. In a lot of ways,the over-romanticised old generation knew feck all,and for every Viking who made it with his cross staff and prayers to Odin,10 sank!

 

[capnsensible]

Thanks everyone for all the interesting replies, seems like its not only me who has had failures!

As lustyd mentions, how far do you go with 'backups' ?? Must say that whenever Ive done an Atlantic passage Ive mostly used gps, but my oppos incident with the engine and my two experiences with melted batteries wrecking handhelds has kind of prompted this post.

Once, out of curiosity, I turned off gps and ran for the last 10 days to Antigua by astro. It very nicely turned up in the right place and when we put gps back on our observed position was a bit under 7 miles off. I was happy with that.

Good luck to anyone who gives it a go!

 

[capnsensible]

Yes. You arent really analysing the risks in a rational way and your comments do smack of a mind made up.

P.S. Do you sail a long keeler? Heavy? Gaff rig maybe? Baggywrinkle?

Sorry Im not analysing risks at all. I am reporting the failures Ive seen and asking if anyone else has had these problems.

I own a Moody 33 and a Sunodyssey 36.2.

 

[KellysEye]

>deck will be bucking like a bronco, or/and there will be 99% cloud cover, so whats the point these days".

On an Atlantic crossing you get used to the boat's motion and it isn't a problem. Also over the Alantic there are lots of clear night and days so getting enough positions is not a problem. We used a sextant for fun as others do.

On the handheld GPS front we carried two, one was kept in the grab bag with a dozen spare batteries.