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Board » Technical Discussion » Do All Boats Start The Same ?

Posted by A2 Posts 347 Registered at 2009-10-26 00:39:42	2015-01-07 21:16:06 - Do All Boats Start The Same ?
	Since the Free Turn artifact has been 'fixed' it brings to mind another starting issue that occasionally has been discussed in chat relating to the way boats appear on screen at the Gun. In the very beginning some boats seem to get out of the gate sooner than others. So I was wondering if this is indeed the case in fact or simply a lag in the way fleet positions are reported to the client. From careful observation & astute deductive reasoning I am in the camp that believes the former to be the case. Which begs the questions what if anything can be done to get to the front of the queue. Also does the ranking of boats prior to the start of any race indicate the sequence in which the server will execute steering instructions on their behalf ? Granted a single jump advantage early on is rarely decisive by the end of any race but it is a definite psychological boost when reaching the 1st mark or headland down the course. None so blind
Posted by hmm Posts 118 Registered at 2011-11-03 13:35:22	2015-01-08 20:58:49 - Re: Do All Boats Start The Same ?
	The short answer is that all boats start at the same time if they have set a starting command. The sailing engine which takes care moving of the boats has been written by Jakob and Kalle, the original founders of SOL and I can't say I know it thoroughly. This is my best explanation on what happens though. Practically what happens is that the server calculates boat movements one boat at time and when starting there are hundreds of boats starting at the same time. There is no particular order in what the boats are moved, it happens in the order the underlying database SOL uses happens to list them. I suppose databases tend to internally provide data in same order which depends on how it's internal data structures stores the data, it can be related to the order data has been written in the database but not necessarily always so. When the moving happens in sailing engine there is a separate program handling the caches. Every 30 seconds it will take a snapshot of every boat's position and store it to server memory. When SOL clients connect to server for asking the fleet position this snapshot is what they get. This is to prevent the need of every client individually asking from the database the positions of all boats. When this snapshot is taken, it can happen when the sailing engine is in the middle of moving the boats so in the image you can see some boats further than others. In my opinion this explains most of the differences you can see in boat movements just after start. There might be more things affecting the issue (I think the sailing engine has some kind of method where it will detect high load situations and move boats less frequently) but to me the sailing engine is good enough and at least I don't know any way to always get a "front line start".
Posted by Rod Posts 392 Registered at 2010-06-24 22:30:48	2015-01-09 13:50:57 - Re: Do All Boats Start The Same ?
	In the practice races, I have almost always observed that boats starting at the same time, and following the same course, (at presumably the same speed), will maintain the same order until the first rounding, (15 min or so later). This would suggest that the server maintains a list of boats, and moves the boats in the same order, at least until the list is disturbed by different orders being given by the helmsman. If it breaks, it's not strong enough--if it doesn't, it's too heavy.
Posted by Bimmer Posts 447 Registered at 2015-02-23 15:38:27	2016-03-08 08:49:05 - Re: Do All Boats Start The Same ?
	Hi Rod In practice races it is the boats distances to the next waypoint in the actual race that is measured and can be seen on the ranking list, and not the marks we use in PR, so you have to trust your eyes here Bimmer

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