2005 crestliner pro angler 1650 50hp tldi nissan. Have a 11 pitch wot about 5200, at 25 mph, also have a 13 pitch wot 4800 rpm 29 mph. These are figures with two people in the boat, add two more adults and can't get on plane with the 13 pitch. It seems perhaps I should get a 12 pitch? or...