do I really need a log?

[morgandlm]

An interesting debate. I also would not remove my through hull log. In fact I go to a fair bit of bother keeping it working and accurate. However, I suppose it is probably the least useful and the most trouble of the basic instrumentation set-up of compass, depth and speed. I do like the near instantaneous info about speed and the double check of distance covered through the water when plotting positions etc. I do still plot fixes on the chart and I do still use a compass for fixes because I'm sad and like the intellectual exercise ... but I also use a GPS.

I recently sailed a Sweden 42 on "Blind Week" out of Southampton. This boat had a fully integrated electronics, plotter/radar package with amazing instrumentation and was superb to use. However, we still kept an hourly log and maintained a plot on paper charts too. I assume some of the data being integrated included input from a paddle wheel log since speed through the water was available. It was quite sobering doing a "what if the electronics go tits up exercise?" when navigating up the east coast of Alderney. I do worry about these boats with a fabulous plotter in front of the helmsman but no other fall-back navigation being done.

Would I fit another paddle wheel transducer? Probably not. I would however fit another instrument that gave speed through the water if someone would invent an effective, economic bit of kit that did not involve spinning drogues or paddle wheels.
Morgan

[whipper_snapper]

Those who think they are pretty good at estimating speed through the water, so that's alright then, are either deluding themselves or don't understand basic nav! No-one can estimate distance run over a few hours with anything like the accuracy of a decent log. Without that you can't generate an EP.

So if your GPS fails, then you need a log to do any half serious offshore nav. That's not to say 'you must have a log', frankly the chance of total GPS failure on the average boat with multiple units including handhelds seems very remote. But don't kid yourself that if that does happen you can guess distance run in open water over long periods. You can't.

Personally, I am prepared to sail without a log and rely on GPS, in those circumstances what I really miss, is the ability to accurately estimate tide/current.

[Refueler]

[If the GPS failed, then I wouldn't know exactly how fast I was going - not really a problem as I'm rarely in a hurry.]

Distance "Run" is very usefull

How would you know distance run if you have no log, GPS failed ? Unless you are religious about plotting position on charts ?

Personally I like having a log.... I sailed for years without on present boat and then finally bit the bullet and fitted it. I use it more than the GPS SOG in fact. At intervals comparing to GPS SOG to see what error I have ... so I can just look at far easier to read screen and know reasonably how fast I'm really going.

[maxi77]

if you were restricted to just ONE instrument, the log is the key essential. Without knowing how far you have run, you can't know where you are; and if you don't know where you are....

All other instruments, and I mean that, ALL others can be substituted by skills and experience. A log and a chart; no more for the bare essentials.

Go ahead and rely on the complete infallibility of your GPS, so long as your family and the insurance company are happy, too.

Perhaps the mags ought to undertake some research into how many times a GPS has failed, how many times the signal has disappeared, in order to give some weight to the arguments for/against the need for backup kit.

I fear the reality today is that so much in the world depends on GPS that the failure of the sattelite signal is highly unlikely and even if it did it is likely that knowing where you were would then be one of the lessor of your problems.

I do agree that whilst modern retail electronics are very reliable they are not perfect. Even so despite having 5 different GPS receivers (sad I know) I still have a towed log and a sextant available

[Refueler]

...........Would I fit another paddle wheel transducer? Probably not. I would however fit another instrument that gave speed through the water if someone would invent an effective, economic bit of kit that did not involve spinning drogues or paddle wheels.
Morgan

There are plenty of Pitot and other log systems that mount to the transom ... no need to drill through bottom of boat ... no need to have fountain of water when log removed ... it just clips into a bracket on outside of transom. In fact you can have a double job - Fishfinder and speed ...

Back to paddle-wheel log. Mines been fitted for over 2 years and never needed to be pulled to clean. When I lift out for winter - I find the paddle wheel clean. It's a standard black plastic affair ... Echopilot Duo.

[Manuel]

carrswood - you surprise me. If you are keen on sail trimming then you want to know the speed through the water, not over the ground. It doesn't matter what the exact speed is, but it is much easier to watch the effect of sail trimming on the log than on the GPS. My paddle wheel was broken by the yard two years ago and I have not replaced it. I have three independent GPSs with independent supplies so my risk is of the system going down locally to me. But I was navigating long before GPS and I am completely happy that I would arrive safely despite the entire GPS system collapsing whereupon I would be looking for a review of my nav needs, along with all other mariners and airmen!

The most likely scenario is war, with SA switched on with a deliberately massive and unpredictable inaccuracy. I think that Uncle Sam might give some warning and it is not a game he would be allowed to play more than once.

[dmh]

I agree with most of the forum, keeping the paddle clean is a pain in the butt and with GPS it is usually not needed for navigation. I keep a Walker log on board just in case the GPS goes down, pity they are not made any more as I think the best insurance policy against GPS failure is a paper chart, Walker log and compass.

[LONG_KEELER]

Those who think they are pretty good at estimating speed through the water, so that's alright then, are either deluding themselves or don't understand basic nav! No-one can estimate distance run over a few hours with anything like the accuracy of a decent log. Without that you can't generate an EP.

So if your GPS fails, then you need a log to do any half serious offshore nav. That's not to say 'you must have a log', frankly the chance of total GPS failure on the average boat with multiple units including handhelds seems very remote. But don't kid yourself that if that does happen you can guess distance run in open water over long periods. You can't.

Personally, I am prepared to sail without a log and rely on GPS, in those circumstances what I really miss, is the ability to accurately estimate tide/current.

It's a pity that you have not learned the skill in how to judge speed when at sea. I think you will find it very satisfying if you decide to do so.

[whipper_snapper]

It's a pity that you have not learned the skill in how to judge speed when at sea. I think you will find it very satisfying if you decide to do so.

I can judge speed pretty well! I cannot judge distance run in typical variable conditions over several hours or days. The old time navigators could make pretty good guesstimates, and there are some amazing feats of navigation recorded that relied on this skill, but these were people who spent their lives navigating in this way or with crude instruments. With all due respect, I doubt that you are that good.

Of course, anyone who attempts to learn this skill by comparison with a GPS SOG readout will never achieve a useful accuracy.

[Barnac1e]

Back to paddle-wheel log. Mines been fitted for over 2 years and never needed to be pulled to clean. When I lift out for winter - I find the paddle wheel clean. It's a standard black plastic affair ... Echopilot Duo.

Baltic waters must be very different to others - perhaps somewhat brackish, thereby not being conducive to supporting either salt or fresh water flora and fauna that are responsible for most underwater fouling.

I know that when I kept a boat in Whitby harbour the high tide saltwater and the low tide freshwater flow from the river Esk had a similar effect of inhibiting the very different varieties of growth by the regular change of salinity. The result was similar to yours - little or no fouling.

I now have a mooring in an Italian lagoon marina (very slightly brackish) and the mussel growth is phenomenal, particularly this year. Of course, warm water helps but twice this year I have had to immerse myself into rather dubious marina water to scrape off the monster shellfish colony that have grown on my propeller, just to depart my berth.

I gave up with a paddle-wheel log impeller long ago, which had to be withdrawn and replaced every trip, and now use GPS exclusively.