I am not a hardcore speedsailer, but I wanted to get basic speed and tracking on the iphone and wasn't sure what the best software is to use on the water that can map your session in googlemaps and know top/avgs speeds and distance travelled.

Whats everyone using out there?

I don't suppose you can set the speed for knots?

Cyclemeter GPS cycling computer?

Around $5 paid app? Not that I am complaining, just want to make sure it's the right one.

Great thanks. I'll give it a go.

This is yesterdays downwinder session, from my 'Boattracker' App,
the other screen option shows distance, av speed, top speed, time. knots, km, miles are all options.

As for phones non waterproof absolutley not..but for $80 you buy an amazing water tight housing good enough for underwater photos! Then you can slip that into a water proof pouch and there you have it.

Can call for help on trips like this is you need, or for a 'ready' for pick up upon landing...no brainer for me..a purpose built GPS cant help you if you get stuck.
Ive also got 'find my phone' activated..so built in Epirb! if required!

Havent had a chance to look at other Apps yet, but i know there are some great mountain bike Apps that have really detailed info, that I'm sure woudl work for sailing also...

This trip was around 26km, top speed 26knots in a decent lumpy swell!