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Board » General Discussion » Wrong Speed VMG

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Posted by trev Posts 4 Registered at 2008-11-09 19:33:09	2008-12-27 00:17:54 - Wrong Speed VMG
	I have set a course in the Sydney/Hobart race with a BS of 20.17KTS and a VMG of 17.10 but when the boat changes to that course the boat is only doing 18.9KTS and a VMG of 15.9. This dosen't look right to me.
Posted by jakob Posts 364 Registered at 2007-09-04 10:05:30	2008-12-27 06:41:22 - Re: Wrong Speed VMG
	Well, I have checked the vmg-predictor and the actual vmg without finding any bugs... Please keep reporting if you see that behaviour in the future. Regards Jakob ...one of the guys behind the game...
Posted by NZL_PaulR Posts 311 Registered at 2008-07-22 12:21:30	2008-12-27 07:00:14 - Re: Wrong Speed VMG
	Perhaps your performance wqas not back up to 100%; hence lower speed until you recovered from lots of tacks or gybes If it breaks, it's not strong enough!
Posted by jakob Posts 364 Registered at 2007-09-04 10:05:30	2008-12-27 07:33:43 - Re: Wrong Speed VMG
	YES, thats most likely the reason. Thanks! ...one of the guys behind the game...
Posted by trev Posts 4 Registered at 2008-11-09 19:33:09	2008-12-27 09:49:36 - Re: Wrong Speed VMG
	Yes I actually think you are right. Looked back about 5 mins after course change and the figures seemed right.
Posted by NZL_PaulR Posts 311 Registered at 2008-07-22 12:21:30	2008-12-27 10:14:47 - Re: Wrong Speed VMG
	And if you are on a steady course, your speed will increase a little more, and a little more and more, whilst still PERF% is 100%. See good hhelming is essential, rather than writing your name in the ocean! LOL If it breaks, it's not strong enough!
Posted by zerl Posts 5 Registered at 2008-11-01 16:45:22	2008-12-29 16:59:44 - Re: Wrong Speed VMG
	I'm curious: does the increase in speed apply to both CC and TWA?
Posted by kalle Posts 413 Registered at 2007-06-01 09:58:04	2008-12-29 17:03:30 - Re: Wrong Speed VMG
	I'm not sure if you misunderstood what Paul meant. When doing a course adjustment you will get lower performance for a certain period (shown in the "Performance" instrument in the client). If you don't do any further adjustments the performance will rise to 100% percent, but if you do another tack etc, it will drop again. Both adjustments using CC and TWA count.
Posted by StuArt Posts 118 Registered at 2008-11-15 22:03:54	2008-12-31 17:37:59 - Re: Wrong Speed VMG
	Hi Kalle, Jacob e.a. I understand the performance decrease and I agree with it But sometimes it seems not to be very realistic - for example when I gype, what can give me in real life a push when well done rather than a disadvantage. So playing with wind shifts could be not wise because of the decrease in performance.
Posted by jakob Posts 364 Registered at 2007-09-04 10:05:30	2008-12-31 19:02:03 - Re: Wrong Speed VMG
	Well, we need to implement a good-enough rule that works for all boats, all conditions and at all times so I am very sure that it sometimes might be a little unrealistic. If you have suggestions on how to model the impact on performance from maneouvers- please just let me know and we will really concider it ...one of the guys behind the game...

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