Hull design questions
 

I have been boating for 20 years but I have owned only runabouts (young kids & watersports). My questions are regarding step hulls vs. traditional non-step V. With all of the spin outs and rollovers recently, is this a phenomenon mainly associated to the step hulls? Do non-step hulls spin out? My boat has 22.5 degree deadrise and runs just south of 60. Is it possible for a runabout to spin? I have a 496 BIII and trim tabs. Forgive my ignorance on the subject. I've had a passion for performance boats for 20 yrs. but one isn't practical for me right now. Thanks for any insight as I'm always looking to learn.

Yes, you can spin out a non-stepped hull. (Ask me how I know that.) I spun my 20' Checkmate out with only a moderately tight turn, but I ran the outboard motor way up on a jack plate, so that didn't help. However, my current 22' Progression would appear to take a miracle to spin out and the motor is mounted even higher up. The big difference? Twenty vs. Twenty four degress of deadrise and very sharp lifting strakes on the Progression.

Generally speaking though, it's a lot tougher to do with a non-stepped hull than with a stepped hull - especially some of the early ones. Driver skill has something to do with it in all cases, but when you "lubricate" the bottom by aerating it, the likelyhood goes up.

I take it that the sharper V and lift strakes then dig into the water preventing a spin-out?

Michael

You can spin out a non step hull... put the trim in and tabs down and turn hard at speed. the bow will bury, stern will lift up and fly around on you.

It is easier to spin step hulls because they run loose and turn flatter. Steering at speed in my boat at times feels like the rear end is moving around causing you to point a different direction. It is just different.... a step hull can flip easier as well because it can slide through a turn and 'catch' causing the roll.

Probably the bigger factor is speed. Step bottom boats run faster. It used to take a pretty big chunk of change to buy a boat that could run even over 70. Now boats in the 90's seem commonplace. It used to be you couldn't buy a boat that went 200. Now anyone with the dough can buy well past their ability.

To a point, yes. But as has already been said, if I tucked the motor in all the way and buried the tabs, I might be able to get it to come around by looseing the stern. With zero tab and the motor tucked in though, mine will turn so hard it will scare you.

As a general rule it is much easier to spin a stepped hull boat or a cat but the hydrodynamics are the same for any application. Let me say if you put more drag on the front of the boat than the back by lowering your tabs and raising the stern or by pulling back on the throttles during a turn causing the bow to drop the momentum of the rear of the boat ( where the majority of the weight is located ) will cause it to try and pass the front spinning out. When I took the Tres Martin driving course back early in the spring he told me the vast majority of spin outs are caused by drivers suddenly pulling back on the throttles during a turn causing the weight of the boat to surge forward making the center of gravity of the boat move forward causing the spin.