Deckman vs Expedition

[Dockhead]

Originally Posted by Mal Reynolds

. . . Anyway, very happy Expedition user. Now if someone would just solve the true wind problem.

Yes, this is the bastard which limits our ability in everything concerning measuring and understanding sailing performance.


STW data is the root of this problem. As far as I know, a really accurate speed log for sailboats doesn't exist. I've now got an Airmar DX900+ -- not yet used -- which I hope is at least an incremental bit better than previous speed logs. Even if it's not, at least I can use it to directly measure leeway, so that at least I can get a good K factor for the leeway calculation in the H5000.


Another challenge for true wind is the wind instrument itself, although not nearly as daunting as speed logs. We used the tall B&G racing one (at great expense) on my friend's Discovery 67 which we sailed across the Atlantic last year, and that's by far the best I've ever used. On my own boat, I will be changing this year from the ordinary LCJCapteurs one (which was pretty good) to the racing one on an extended pole; we'll see how that works.

[Mal Reynolds]

Originally Posted by Dockhead

Yes, this is the bastard which limits our ability in everything concerning measuring and understanding sailing performance.


STW data is the root of this problem. As far as I know, a really accurate speed log for sailboats doesn't exist. I've now got an Airmar DX900+ -- not yet used -- which I hope is at least an incremental bit better than previous speed logs. Even if it's not, at least I can use it to directly measure leeway, so that at least I can get a good K factor for the leeway calculation in the H5000.


Another challenge for true wind is the wind instrument itself, although not nearly as daunting as speed logs. We used the tall B&G racing one (at great expense) on my friend's Discovery 67 which we sailed across the Atlantic last year, and that's by far the best I've ever used. On my own boat, I will be changing this year from the ordinary LCJCapteurs one (which was pretty good) to the racing one on an extended pole; we'll see how that works.

On the ultrasonic, yes you can sort of get leeway. There are also current effects. Keep the sensor clean or it can stop reading at low speeds. Not great on the autopilot.

With the wind, yes I do think the tall wands that are more sensitive & better software wind sensors help. To me that means B&G/A+T or NKE. I've had wind angle thrown off when runners are cranked on, and when a large mainsail is pressed against spreaders. Too much for me to calibrate out. Not enough advantage unless the boat readily exceeds hull speed surfing down waves. Even if it does, compass mode is fine for me.

While the data is nice to have at night and when below, I swear my next cruising boat is going to have a GPS, compass, VHF, depth sounder, windex and wind vane. Oh, and a leadline and Walker log. I just don't want to spend time fussing over electronics. Too many other things in life to fuss over. Well OK, Starlink too. Oh crap, and an autopilot on the windvane while motoring, and AIS, and...

Let us know how the LJC Capteurs sensor works out please.

[Dockhead]

Originally Posted by Mal Reynolds

On the ultrasonic, yes you can sort of get leeway. There are also current effects. Keep the sensor clean or it can stop reading at low speeds. Not great on the autopilot.

I have had two other ultrasonic speed logs -- the old CS4500, and the updated N2K version. The CS4500 was really pretty good, the later one less so.

The DX900+ is fundamentally different -- it is electromagnetic and not ultrasonic, but most importantly -- it measures the DIRECTION of the water flow, so you don't "sort of get leeway" -- it directly measures leeway as degrees of deviation between direction through the water from the ship's head (not heading). Unfortunately no instruments I know of are capable of displaying this directly measured leeway data (even though there is an N2K PGN for it), but the DX900 has bluetooth and you can get the data via an app. Would be interesting if the wizards from OpenCPN could add it to the instrument dashboard on there.

What Expedition and the B&G H5000 use for leeway is the formula based on speed and heel angle, which is very accurate PROVIDED you have the right coefficient for your particular boat. The DX900+ can be used to generate this number accurately and efficiently, so that your instruments work correctly. You just measure leeway at different speeds an angle of heel and adjust until your instruments correspond to the directly measured leeway. Then you don't really need to look at the leeway data, which is why I think the bluetooth solution is adequate.

I'm not sure what you mean with "current effects". Currents don't affect any of these -- STW and leeway are water-referenced, not ground-referenced, so all currents are irrelevant.

Originally Posted by Mal Reynolds

With the wind, yes I do think the tall wands that are more sensitive & better software wind sensors help. To me that means B&G/A+T or NKE. I've had wind angle thrown off when runners are cranked on, and when a large mainsail is pressed against spreaders. Too much for me to calibrate out. Not enough advantage unless the boat readily exceeds hull speed surfing down waves. Even if it does, compass mode is fine for me.

While the data is nice to have at night and when below, I swear my next cruising boat is going to have a GPS, compass, VHF, depth sounder, windex and wind vane. Oh, and a leadline and Walker log. I just don't want to spend time fussing over electronics. Too many other things in life to fuss over. Well OK, Starlink too. Oh crap, and an autopilot on the windvane while motoring, and AIS, and...

Let us know how the LJC Capteurs sensor works out please.

I really like wind mode on the pilot while running off. I've had very good luck with it on my boat even with previous wind instruments. I don't put on my runners whilst running off; on my rig they are used for tensioning the inner forestay when reaching or beating in strong winds with the staysail up. But even if I had this problem, it could be easily solved by choosing a different nominal wind angle to steer to. You don't care what the pilot says about the wind angle; what you care about is that you've GOT the wind angle you want and the pilot holds it, and you can judge by the windex -- and for goodness sake, the sails -- and fiddle the pilot buttons without even looking at the displayed wind angle. Simples.


Little known fact: B&G pilots (and maybe others too) steer to TRUE wind in wind mode, with the wind abaft the beam. So if you have really crappy true wind data on your network, like most of us do, it's better to switch this off in the setup menu. Pro tip.


I hear you on the windex -- back to basics, right? I've been sailing with the windex alone for long periods these last couple of years while I was having problems with the wind instrument. I grew up sailing with a windex alone for years before I had my first electronic wind instrument, and it works fine. But well calibrated instruments are SO useful; for me they're worth the trouble and expense. Especially if you can get them to give you a somewhat accurate true wind.

But can you believe some modern cruising boats don't even have a windex?! That I can't understand. I often look at the windex before I look at the instruments even when those are working well.

[Mal Reynolds]

Hi Doc,

You are right about the current regarding leeway. Thanks for correcting me.

Also, hadn't run across the Airmar DX900X+, looks interesting.

Pretty sure I read the H5000 Herc will also steer to your optimal downwind polar angle also. Cool ****, but seems like you'd need a crew on deck. My Open 50's optimal downwind angle doesn't change much over anything over 16 knots, so this wouldn't help me. I would just keep it at an angle and bear off in squalls.

Anyway, I can't imagine you wouldn't appreciate Expedition. Adrena is the main competitor. Never used it so can't comment.

[Dockhead]

Originally Posted by Mal Reynolds

Hi Doc,



You are right about the current regarding leeway. Thanks for correcting me.



Also, hadn't run across the Airmar DX900X+, looks interesting.



Pretty sure I read the H5000 Herc will also steer to your optimal downwind polar angle also. Cool ****, but seems like you'd need a crew on deck. My Open 50's optimal downwind angle doesn't change much over anything over 16 knots, so this wouldn't help me. I would just keep it at an angle and bear off in squalls.



Anyway, I can't imagine you wouldn't appreciate Expedition. Adrena is the main competitor. Never used it so can't comment.

Cool, thanks. 16 knots, eh? [emoji44]