Guest john Posted February 17, 2006 Report Posted February 17, 2006 hi forum, new to boat fishing! i went out fishing for the first time with my new gps the other day. after anchoring up for a few minutes i noticed my gps was saying that i was still traveling at 0.3 of a knot i checked the plotter screen but the anchor didn't appear to be slipping . any ideas Quote
plaicemat Posted February 17, 2006 Report Posted February 17, 2006 At 0.3 of a knot, you probably wouldn't notice the anchor dragging. Try letting out more warp and see if this cures the problem. Do you have sufficient chain between the anchor and the warp? Usually, if a gps say's you're moving, you are! Quote
Newboy Posted February 17, 2006 Report Posted February 17, 2006 0.3 knot is very slow movement, maybe the anchor is slipping very very slowly. Either that or the calculation from the gps is out slightly, rounding up or down errors. Quote
blueboatdriver Posted February 17, 2006 Report Posted February 17, 2006 I shouldn't worry about it. As your GPS is not 100% accurate and your position probably jumps very slightly all the time. Your GPS receiver is just timing your position between these small jumps; hence it thinks you are moving and records your speed thus. IMHO Quote
Fugazi Posted February 17, 2006 Report Posted February 17, 2006 John, It depends, if you check that the numbers are showing movement in one definite direction i.e. west then you Quote
TomBettle Posted February 17, 2006 Report Posted February 17, 2006 Blueboatdriver is about right with that one. Even tide up on the pontoon the GPS may record very slight movement. This is caused by the boat rocking slightly or pulling on the ropes in the wind. The same will apply at anchor, your boat will rarely be completely stationary. Wind, wave action, movement in general will all cause some movement and sometimes register movement on the plotter. If I am concerened my cnhor may be slipping, I zoom right in on the plotter and mark a waypoint where I am at that moment. With the plotter zoomed in, any movement in the boat is easily shown up. Side to side movement on the plotter is down to the wind and not a lot you can do about it apart from take it into account when anchoring. If you appear to be getting further and further away from the waypoint in a downtide direction then your anchor is slipping. Any sense in the above? I doubt it, but I know what I mean! Quote
Paul D Posted February 17, 2006 Report Posted February 17, 2006 Gordon H has it spot on I think. If the GPS is showing the movement and it is always in the same direction then you are moving If the direction jumps around all the time ( mine does this ) then it is just the vagaries of wind moving the boat or the noise within the position calculation made by the GPS ( as BlueboatDriver states ) With WAAS on you will get up to 3 m accuracy. With WAAS off you will get something like 24 metre accuracy. Quote
Maverick Martin Posted February 17, 2006 Report Posted February 17, 2006 hi forum, new to boat fishing! i went out fishing for the first time with my new gps the other day. after anchoring up for a few minutes i noticed my gps was saying that i was still traveling at 0.3 of a knot i checked the plotter screen but the anchor didn't appear to be slipping . any ideas The main point here is you appear to have checked your plot line and found that your anchor was not dragging. So that would indicate the answer given by Simon (blueboatdriver) and Gordon H are correct. These electronic bits of kit are brilliant but when your stationary are not 100% . Take for example when you first move off from a stationary position, it may take a couple or three seconds for your gps to calculate your heading and give you the correct info but once you are moving they are pretty much spot on BTW John why not register in the forum, it costs you nothing and gives you more access to the site. Martin Quote
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