Tidal flow on gps

mad_boater

New member
Joined
14 Oct 2002
Messages
616
Location
staffordshire
Visit site
Any one know which format on the gps shows the direction of the tide in real time. I am about to purchase a new gps this week end.One of the other things I need it to do is to have a loud alarm for the anchor watch. Any sugestions as to format or reciever . My budget is around £500
 

PAULSTEWART

Member
Joined
30 Mar 2005
Messages
240
Visit site
I bought a Lowrance 3300c which runs Navionics and has tidal stream data. For a budget peice of kit I think it is excellant.
As its now been replaced by the 3500, there might be good deals to be had. I'm sure it also has anchor alarm in there somewhere. Good luck!
 

Oldhand

New member
Joined
21 Feb 2002
Messages
1,805
Location
UK, S.Coast
Visit site
A GPS receiver alone cannot show tidal flow direction. To get this information without using a plotter with a tidal flow algorithm, speed over the gorund (SOG) and course over the ground (COG) generated by the GPS has to be compared with vessel heading and speed through the water as the difference between the 2 pairs of parameters, if correctly calibrated, must be the result of tidal flow. Some instrument systems and some PC plotting software will calculate and display "Set" and "Drift" from these parameters, which are your real time tidal flow data. Tidal flow indicated on a plotter is usually mathematically derived from a model and is not real time measured tidal flow.

Please note a GPS system calculates your position with reference to the earth's surface, and by calculating the distance and direction between successive position fixes, the velocity over the ground can be determined and displayed. GPS alone has no way of determining that the velocity over the ground is being influenced by the receiver being situated in a moving mass of water.
 

jfm

Well-known member
Joined
16 May 2001
Messages
23,957
Location
Jersey/Antibes
Visit site
anchor alarm

I dont know of any that have loud alarm for anchor watch but many have a signal wire output that goes +12v when alarm sounds, and you can wire a louder hooter (from Maplin or somewhre) to this wire
 
Top