Knotmeter or GPS

[Chuckbear]

Most quality wind instruments that will give true wind will accept speed and heading input from different sources including a GPS

 

[Ross]

I don't know when they made the change to the paddle wheel but I have seen a few boats with a spinner next to the keel. Those were faired so as to not collect weeds and were not sensitive to minor fouling. The spinners are very much like the spinners on a patent log.

 

[Mike B]

Ross, I had a 1991 Benny with a paddle wheel so I know they've been around at least that long. Back then Raymarine didn't fit the thru hull with a flap so it was pretty exciting when you pulled the paddle to clean it or have the boat hauled. It's amazing how much water gushes in through a 1 1/2" hole.

 

[larryw]

I used to struggle to keep that tiny wheel free of weeds, worms, general sea-crap, but one day just took the wheel out, put the blank in, and never replaced it. That was five years ago, and if I need to know the speed I look at the GPS. The wind speed indicates apparent and I can make my own judgements about other things. The sailing here in SoCal is deep ocean, not much to run into. A little fog. Radar does that. Navigage mostly by eyeball and plotter, but all we really have to do is keep the dirt on one side or the other, depending on direction.

 

[sailingdog]

Bill—

According to everyone I've spoken with at Raymarine, their ST40/50/60/60+ uses STW, not SOG. This might not be the case with the latest ST70...but I think it still uses STW, not SOG.

The true wind can "technically" be calculated with either.

True wind using the SOG gives the actual true wind and is quite handy

relative true wind (not apparent) is used with the STW. It gives results close to the actual true wind but subtracts out the contribution of current and lee-way.

My Raymarine uses the SOG to calculate true wind as I believe any system with access to GPS data will. In the event the GPS goes down or is not present then it falls back to STW version.

FWIW

 

[Mike B]

Raymarine definately uses STW to determine true wind. You only have to have the speed paddle foul up and you'll get a big fat zero on the true wind display.

 

[Bill Roosa]

Raymarine true wind

Mine dose not work that way. My true wind works fine wo the knotmeter.

Parhaps it is a set up item you can force the unit to use.

 

[Chuckbear]

Bill—

According to everyone I've spoken with at Raymarine, their ST40/50/60/60+ uses STW, not SOG. This might not be the case with the latest ST70...but I think it still uses STW, not SOG.

Raymarine uses its propitiatory Seatalk to integrate its instruments so should not be used as a measure of how other manufacturers instrument will integrate with other systems. To say all wind instruments must be connected to a speed transducer because Raymarine does is not correct.

 

[Chuckbear]

Mine dose not work that way. My true wind works fine wo the knotmeter.

Parhaps it is a set up item you can force the unit to use.

Bill, If your system is integrated with a NMEA connection somewhere in the mix and connected to your plotter/GPS it is very possible it is taking speed and heading info for the wind indicator from that source. Not all Raymarine techs you talk to always know what they are talking about. Most are looking at a response from a computer screen to answer your questions. I am a certified Raymarine tech and I have dealt with them many, many times.