I have a question for the knowledgeable up here, I have some questions about setting up twins on the 25'. I know most people set twins up on 26"-28" centers, sometimes 24" center to center minimum - to 30" center to center is common. You see more set close together than you do apart but I have read up here and told by some of you guys that you will get the cleanest water for the props if you set the motors center of the center panels (middle hull steep). This would set the motors at 50" centers apart. I looked back at some pictures, and the early 21' race boats had motors spaced far apart with the little low power (55hp) homelites but most of the latter 21'race hulls had the (mercury 110hp) motors very close together. I am wandering if they found to have better performance running them close together. I know that people say the closer the more speed you gain and less blow out when turning. Most of the go fast guys run them close together as possible for several reasons but know the vdr may behave differently. The turning may be the biggest issue with the wide spread due to the 25' rolls so much, I would think it could cause a bad blow out issue on this hull. Also I have heard that too close together may cause water to be stole from prop to prop and counters could cavitate if too close. The engine height will vary depending a pond where I place them, and far as now I figured on setting the bracket mounting tab at 31" above the hull bottom so that it would take a single 30" leg motor with the AV plate slightly above the keel. So with me running twins (25"legs) that would work out if I did the 28" centers but if I run them out apart further the mounting tab would need to rase the motors an additional 3" or so to compensate for the deadrise. You don't see many outboards today spread apart far except for cat hulls and such so I am guessing there is a reason. Also one other question, How much toe in do the motors need? I have read that at the standard 28" apart they need 1/4" of tow in for counter rotators. If spread further apart would this change? What would work best 1/8" or 1/4" or? I assume there is a lot of trial and error here but like to have a good starting point. Bushwacker, and any of you other engineers or experienced guys in performance twin set up help!
Here is a few pic's to show the spacing on the twin outboards on the 21' race hulls which as very very similar contour to the bottom of the 25's as shown by another member before up here that graphed the bottoms on a cad computer program and compared them.
These two are close together:
These two are further apart:
