Add frames

I know that my project will end up at 750 frames, so why not start by typing this and then start to model boat , sails , flag, watersurface , etc. But this dont work for me.
As longest I doing my project inside the defaultsetting frame 1 - 250 I dont get any problem. Why?

With framesetting 1 - 746 I made the boat without any problems . When I did sail and flag ( different objects ) from this tutorial everything worked until I came across the frame 250 which blew up the flag and sail . Why?

I want to use my boat as ( Background ) ,with animated sails and flag bobbing on the waves from frame 1 to frame the 741st. Then I add 5-6 fish that jumps up and down from the waves . Fish number one from frame 50 -100 fish two frames 100-150 , etc.

I thought I had tracing the problem. (This have nothing to do with my project, because I can not find this framesetting-window in Add + Force + Wind + Group Vertex + Physics + pinning ) If you go into the Follow Path you can see the settings are 1 - 250 as default (I change to 471)

This is the result from framesetting 1-250 Vimeovideo
I try with 1-741 dont work. Why?

Do you know what problem I making. Tell me
Thanks in advance.

I did a test by simply making a flag with 500 frames. After rendering/animation I press Shift+Cmd+ G and open upp the avi.file with quickTimePlayer and press the playbutton and the animated flag moving/blowing up to frame 100-120. Why not all the way up to frame 500.