Navigating without a log

[[3889]]

The kit onboard breaks. It does sometimes. I know this.

As my log did and I've not bothered to replace it. I've nevered sailed a boat with a log more than 90% accurate over a range of conditions. If my GPS breaks I'll use one of the other 5 GPS /Navionics enabled devices always on board, the combined cost of which were less than a replacement log. If GPS is turned off me struggling to navigate will be far down the list of the world's problems.

 

[lw395]

As my log did and I've not bothered to replace it. I've nevered sailed a boat with a log more than 90% accurate over a range of conditions. If my GPS breaks I'll use one of the other 5 GPS /Navionics enabled devices always on board, the combined cost of which were less than a replacement log. If GPS is turned off me struggling to navigate will be far down the list of the world's problems.

I like to have a speed log for sail trim purposes etc.
Navigation-wise, boat going OK is 5.5 or 6 knots, going well is 6 or 7 depending on point of sail. So uncertainty in how far you've gone is easy to understand. So I might not know exactly which suburb of Bournemouth is abeam, but TBH, I've been much more lost inside the M25.

 

[capnsensible]

As my log did and I've not bothered to replace it. I've nevered sailed a boat with a log more than 90% accurate over a range of conditions. If my GPS breaks I'll use one of the other 5 GPS /Navionics enabled devices always on board, the combined cost of which were less than a replacement log. If GPS is turned off me struggling to navigate will be far down the list of the world's problems.

Yeah, kinda standard answer, no disrespect. Trouble is, lots of people dont always sail or even own their own boat. So you dont always have that back up.

Ive sailed 4 different yachts in the past two weeks. Two of them had faulty GPS units. The one Ive been out on all day today had two that didnt work.

Noone had a tablet or whatever. 5 phones, no navigation apps between them.

Bit of a non issue in my pilotage waters. No problem.

Log worked though........

 

[zoidberg]

'He who knows, and knows he knows - he is a wise man. Seek him.
He who knows, and knows not he knows - he is asleep. Wake him.
He who knows not, and knows he knows not - he is a child. Teach him.
He who knows not, and knows not he knows not - he is a fool. Shun him.'

 

[ShinyShoe]

Ive sailed 4 different yachts in the past two weeks. Two of them had faulty GPS units. The one Ive been out on all day today had two that didnt work.

Noone had a tablet or whatever. 5 phones, no navigation apps between them.

Bit of a non issue in my pilotage waters. No problem.

In pilotage waters could none of the 5 phones get enough data to download an app?

I've not used a phone that doesn't have Google maps in years. It needs data to show the map (it will cache it). But if you drop a pin (long press) it shows the location. Click the pin again to get the location as a fully decimal long lat. Not ideal. But as far as I know works with no cached map.

Yeah, kinda standard answer, no disrespect. Trouble is, lots of people dont always sail or even own their own boat. So you dont always have that back up.

Install app on phone before you go. You have at least your phone as backup. (I'd install one that has a GPS style screen (Saildroid for instance) and a charting app.)

If you are piloting by eye, your backup is fine. If you are likely to nav by device, ask one of the crew to install one as a backup... Not expect they pay for one, just the basics of position is enough if you have a paper chart...

Doesn't solve the OP what happens if gps system failed which seems unlikely...

Assuming the journey was in daylight, good weather and no prospect of fog, probably low risk!

I can't imagine a tug speed changes that much if they don't change engine speed (yes tide/wind will be a factor). So a rope, a means to time 28 seconds a means to measure 48 feet (ignore the 3 inches!) and some form of drogue (bucket?) Would probably be reasonable...

If you reduce the time, reduce the distance in the knots proportionally... So measure 7 seconds, make the knots every 12 feet... A boat doing 10knots then only needs 120ft rope...

 

[langstonelayabout]

Some of the participants in this thread should google Marvin Creamer and have their minds totally blown.

Is it safe to google from work?

With a name like Creamer he could be a co-author of a book I was given years ago that was also authored by a chap called 'Erik Shun'. Fascinating pictures...

 

[laika]

Is one of them a plank as per #46? :encouragement:

Don't bring Planck into it. Next thing you know someone will be pointing out that the more accurate your log the less good your position fix

 

[Stemar]

Don't bring Planck into it. Next thing you know someone will be pointing out that the more accurate your log the less good your position fix

I knew there was a reason for not having a log on a small boat

Actually, I've got one, but it wasn't working so I pulled it out to clean it and put it back. A few days later, the locker was full of water. I had a fiddle and it still leaked, so it's lying in the bottom of the locker and the screw lid. which doesn't leak, is on the fitting. I'll probably get round to fitting a new O ring some time.

 

[LadyInBed]

I'll probably get round to fitting a new O ring some time.

Try giving the old one a coat of silicon grease or vaseline first.

 

[capnsensible]

Hiya! I was taught as an apprentice to never re use o rings but also when fitting, to use a lubricant. :encouragement:

 

[Beelzebub]

Hiya! I was taught as an apprentice to never re use o rings but also when fitting, to use a lubricant. :encouragement:

Not advisable with oxygen cylinders-severe risk of spontaneous combustion:encouragement:

 

[DownWest]

Hiya! I was taught as an apprentice to never re use o rings but also when fitting, to use a lubricant. :encouragement:

Obviously you apprentices had a good time..
The only time I relied on a compass and had a Walker log for a five day trip ( no choice as no kit, well before electronics) The log showed the exact point to point distance, despite losing a spinner at one point and I doubt that we tracked that accuratly in the light conditions..

Went out in a boat a few days ago. Depth was usefull in the narrow channel, Log was on zero, so needs a clean. Not over fussed.

 

[capnsensible]

Not advisable with oxygen cylinders-severe risk of spontaneous combustion:encouragement:

And space shuttles.......

Used silicone grease on firefighting and dive gear. And on HP air systems up to 4000psi.

Hydraulics to 3000psi always had enough submarine blood swilling around to use on itself!

 

[maxi77]

Top memory jogger, ta! Had forgotten all about streaming the log on yachts. Ive actually still got a Walker Log on the yacht somewhere but not used it for years.

Had also forgotten setting dived submarine speed to shaft revs.

These posts are really good for those reminders!

Common command 'set revs for X knts'. We also estimated target speed from type and shaft revs

 

[Dutch01527]

Bit of a thread drift but when I was at University I sailed as Chief Officer on small Panamanian registered coastal general cargo boats to supplement my student grant. Usual area of trade was UK, Ireland, France, Holland and Germany.

We were in Fleetwood, Lancs and received our next destination orders - Tripoli in Libya. We had no charts, no sextant, no chronometer, no other navigation equipment except compass, log and radar. I was horrified and told the Arminian Captain that there was no way we could go. He was not phased and sent me down to WH Smith’s on the high street to buy a world atlas and off we went.

Actually the voyage was pretty undramatic. Using radar and dead reckoning we kept Ireland on one side and Wales/England on the other. Avoided running into France, crossed the Biscay and keet Spain/Portugal to port until we reach the Straights of Gibraltar and thereafter keet North Africa to starboard and did not hit any Islands until we heard the voice of Tripoli radio station.

I asked the Captain what we would do if the radar failed and he said go further off shore and time a land fall at about midday so we had good visibility and a good margin of error on our dr positioning. Not to be recommended but it was not as big a deal as I thought it would be.

 

[john_morris_uk]

Bit of a thread drift but when I was at University I sailed as Chief Officer on small Panamanian registered coastal general cargo boats to supplement my student grant. Usual area of trade was UK, Ireland, France, Holland and Germany.

We were in Fleetwood, Lancs and received our next destination orders - Tripoli in Libya. We had no charts, no sextant, no chronometer, no other navigation equipment except compass, log and radar. I was horrified and told the Arminian Captain that there was no way we could go. He was not phased and sent me down to WH Smith’s on the high street to buy a world atlas and off we went.

Actually the voyage was pretty undramatic. Using radar and dead reckoning we kept Ireland on one side and Wales/England on the other. Avoided running into France, crossed the Biscay and keet Spain/Portugal to port until we reach the Straights of Gibraltar and thereafter keet North Africa to starboard and did not hit any Islands until we heard the voice of Tripoli radio station.

I asked the Captain what we would do if the radar failed and he said go further off shore and time a land fall at about midday so we had good visibility and a good margin of error on our dr positioning. Not to be recommended but it was not as big a deal as I thought it would be.

Ouch!

Very illegal and if the authorities had found out, I suspect even the Panamanian Authorities would nowadays suggest a trip to the chandlers to buy a few charts (you don't need many). You don't actually need a sextant and chronometer for such a voyage and I used to sail a day or two out of sight of land on dead reckoning alone before the advent of GPS. (We couldn't afford a Decca)

However, nowadays, knowing where the reporting positions are for the TSA's and where the deep sea buoys are helps a bit. The various reporting authorities would be onto you if you started taking a small coaster through the TSA the wrong way or without reporting at the appropriate places.

(I admit that I crossed Biscay once without a Biscay Chart and only afterwards realised we'd sailed past some large offshore deep sea buoys in the dark.). We'd plotted our position by transposing the longitude on the coastal chart at our latitude...

 

[newtothis]

Ouch!

Very illegal and if the authorities had found out, I suspect even the Panamanian Authorities would nowadays suggest a trip to the chandlers to buy a few charts (you don't need many). You don't actually need a sextant and chronometer for such a voyage and I used to sail a day or two out of sight of land on dead reckoning alone before the advent of GPS. (We couldn't afford a Decca)

However, nowadays, knowing where the reporting positions are for the TSA's and where the deep sea buoys are helps a bit. The various reporting authorities would be onto you if you started taking a small coaster through the TSA the wrong way or without reporting at the appropriate places.

(I admit that I crossed Biscay once without a Biscay Chart and only afterwards realised we'd sailed past some large offshore deep sea buoys in the dark.). We'd plotted our position by transposing the longitude on the coastal chart at our latitude...

Without wishing to make suggestions about Dutch's vintage, it is quite possible that he was doing this at a time when sextants were the only form of navigation. Traffic separation schemes only emerged in the late 60s.
I have a semi-retired colleague who was a merchant mariner in the 1950 and 1960s who relates spending days/weeks of dead reckoning across the Indian Ocean because there was never a clear shot at sun or stars. The idea was to sight Africa before you hit it, then turn to starboard for Suez.

 

[john_morris_uk]

Without wishing to make suggestions about Dutch's vintage, it is quite possible that he was doing this at a time when sextants were the only form of navigation. Traffic separation schemes only emerged in the late 60s.
I have a semi-retired colleague who was a merchant mariner in the 1950 and 1960s who relates spending days/weeks of dead reckoning across the Indian Ocean because there was never a clear shot at sun or stars. The idea was to sight Africa before you hit it, then turn to starboard for Suez.

I quite agree. In my defence I perhaps should have made it clearer that I was comparing then with now... and what we got away with once upon a time to what would happen if a commercial ship was caught trying to leave port without minimum standards being met nowadays. Lots of incidents reported of ships being arrested or not permitted to proceed to sea in current times until things are put right safety and nav wise.

 

[Dutch01527]

Ouch!

Very illegal and if the authorities had found out, I suspect even the Panamanian Authorities would nowadays suggest a trip to the chandlers to buy a few charts (you don't need many). ...

This was c.1985 before GPS was generally available. Believe me the Panamanian authorities at that time did not give a monkeys. No charts available on a Monday afternoon in Fleetwood.

Even on a British ships I trained on ( Bank Line Navigating Officer apprenticeship) we once crossed the Atlantic UK to South America with cloud all the way, so no celestial navigation. Had to rely on dead reckoning. We had a competition and one of the apprentices won predicting land fall within 5 miles. Everyone was within 30 miles. We just used radar to identify a prominent land shape and we knew where we were.

If you think about it, in the 1980’s before GPS, celestial sights were the only way of identifying position offshore, just the same as it was 200 years earlier.

 

[john_morris_uk]

I’m old enough to have been sailing in the 70’s let alone the 80’s. Do you remember RDF and trying to decipher the morse ID and the null as you swung the receiver round with the hand bearing compass on the top?

And I’d get worried for hours after a passage across a bit of the chart that said ‘magnetic anomalies’ until I’d worked up a decent fix off Sun run Sun or known and recognised objects. All too often closing a coast to spot a church spire and then wonder which one it was on the chart.