Is it worth getting a log or should I stick with GPS?

[MissFitz]

I need to buy some instruments for my boat. I was going to just get GPS and a depth sounder, but was looking at the Clipper combined depth & log & wondering if it's worth spending an extra £50 on that. My impression of logs on other people's boats is that they never seem to be very accurate & are always needing cleaning - &, of course, it's another hole in the hull. On the other hand, speed through the water can be very useful for getting sail settings right &, I guess, for when someone turns the GPS off. What do people think? Does everyone still have logs or are you not bothering these days?

 

[RupertW]

All my boats have had logs but I don't race and therefore enjoy rather than need the water speed information. I clean it fairly often and calibrate it now and again but it's never a primary information source as I would have to lose a boat GPS, Navionics on iPad, two phones and an old handheld GPS before I'd be out of info - and I mostly sail line of sight anyway.

 

[ghostlymoron]

Despite the drawbacks you mention, I still like to have a log for speed through the water. I've found the NASA one less satisfactory than Raymarine but ok as long as you change the impeller annually.

 

[Porthandbuoy]

Have a look at this thread.
I fitted one of Cruzpro’s gps to pulse converters to my Clipper duet system. Now my log reads SOG instead of a different speed through the water on each tack.

 

[Stemar]

If you're trying to get the best out of your boat, a GPS doesn't respond quickly enough for you to see what difference a small adjustment of trim makes. My boat, a Snapdragon 24 is renowned for its performance (for all the wrong reasons) once the wind is forward of the beam, so I'm like an Americas Cup trimmer, constantly looking for small gains. The log is useful for that, but I'd probably be more relaxed if I didn't have it!

Unless you're racing, I'd say it's a nice to have, rather than an essential

 

[Minchsailor]

I like having a log as it gives boat speed through the water - which can be very different to SOG. Also, GPS is not infallible (I know some quite senior people in the marine industry are very concerned about the ease of corrupting GPS signals), so a log is useful backup.

On my last boat I had the duet; no problems provided the impeller was changed annually as the plastic tended to get a bit fragile and expose the magnets which corroded.

 

[Slycat]

If you sail in an area where tides are a significant factor the Log speed is very useful as you can compare it to SOG and draw some conclusions about the tide. Where I sail, I use it a lot.

 

[MikeCC]

Also depends on whether you want true wind available. If you do, don't get the Duet as it doesn't have NMEA output. The individual Clipper instruments do though, and there is now a true wind display but of course you need a Clipper wind setup for that.

 

[Topcat47]

If you sail in an area where tides are a significant factor the Log speed is very useful as you can compare it to SOG and draw some conclusions about the tide. Where I sail, I use it a lot.

+1, the log speed is my primary source of information when daysailing. I only bother about the GPS when passage making. Of course the GPS feds the plotter and the radio, which the log does not.

 

[[70521]]

Personally both instruments as they give different bits of information.

 

[RichardS]

Have a look at this thread.
I fitted one of Cruzpro’s gps to pulse converters to my Clipper duet system. Now my log reads SOG instead of a different speed through the water on each tack.

I also have a Cruzpro and it's good piece of kit but it does not give the speed through water that the OP is asking about unless you sail in a current-free area.

Also, when the GPS "turns off", the CruzPro also "turns off" so it's not a back-up system.

Richard

 

[JumbleDuck]

I have a through hull log (old B7G) which generally works reliably for a week or two after launch and then decays gracefully to zero over the next two weeks. A really good belter through big waves can clean it off, but it's really more of a curiosity than a help. Being Olde Skool (ie perverse) I still stream a Walker log, which is fun to watch and, seaweed apart, extremely reliable.

If I was reinstrumenting from scratch I probably wouldn't bother with a through-hull log.

 

[jac]

LOg for me.

I would always remove it when away from the boat and insert when on board and sailing. That way I never have to clean it but do still have the task of pulling it out and replacing it ,

 

[doug748]

I don't bother, but for your sort of racing I would probably shell out the extra 50.
Hold it there though, it's easy to get on the spending escalator and for a smaller boat, that you may not keep forever, it is easy to overdo it. A well sailed boat with nothing will always beat a poorly sailed one no matter what kit they carry.
Here ends my thought for the day :-}

 

[Motor_Sailor]

. . . Hold it there though, it's easy to get on the spending escalator and for a smaller boat, that you may not keep forever, it is easy to overdo it.

It's a Sonata. You go fast in one by keeping your head out of the boat and looking around.

Take a GPS if you think you'll need to know where you are, but a speed log is no use racing.

 

[Dipper]

LOg for me.

I would always remove it when away from the boat and insert when on board and sailing. That way I never have to clean it but do still have the task of pulling it out and replacing it ,

I do the same with my NASA log. When I left it in, I always had to take it out to clean it anyway if I hadn't used my boat frequently. I don't trust their threaded cap so I use an old transducer as a plug (with impeller and cable removed).

 

[bbg]

If you are going to race, a log is rather important.

 

[lw395]

If you are going to race, a log is rather important.

I agree, although it's less critical if you have another boat of the same OD to tune against.
For racing, I found the 1 decimal place resolution of the Nasa log a bit poor compared to B'n'G's 2 decimal places.
When you tweak something and only see speed change from 6.0 to 6.1, that could be a significant boost or just noise.
When you see it go 6.05, 6.06, 6.07 that tells you what you want to know.

 

[Minchsailor]

Personally both instruments as they give different bits of information.

Exactly - see this:

 

[MissFitz]

It's a Sonata. You go fast in one by keeping your head out of the boat and looking around.

I agree 100% if there's anything to look at - but in the race fleet here all I'm going to see is the fast-disappearing transoms of a clutch of J boats & Prima 38s. So I think a log would probably be useful for fine-tuning the sail settings etc.