Riva Florida runabouts and Riva Super Florida runabout boats

riding bow high for the best control

Riva built this luxury runabout in Lake Como, Italy in wood and plywood from 1953 to 1968. The factory records indicate that 711 runabouts were made over this time frame.

A Super Florida Riva is a longer hull with 2” more beam than a Florida Riva model.  The hull was made bigger along with the new name to perform and ride better with a more powerful V-8 engine that became available as time progressed from the 1953 beginning of boat production.

These runabout boats all had a deeper forefoot than the typical Chris Craft of that time, while at the transom, the bottom was all but flat, as was the Chris Craft runabout.

This gives a better riding across the water experience at low speeds but these Riva need to get that sharp vee in the bow area out of the part of the hull that is in contact with the water as any speed increases. Why? What steers a boat should be the rudder. If a wave or wake at an angle catches the vee up front, that area can become a larger “rudder” than the boat’s metal rudder and the runabout will “bow steer” and the helmsman can not correct or over-come this redirection by the smaller area metal rudder that is attached to the steering wheel.

This vee forward is deeper than a Chris Craft

almost flat bottom at the stern

How to do prevent this action? Simple, balance and power the runabout such that the vee splits the waves and wakes at low speeds and weight balance, adjust the shaft down angle, and power to make the boat ride bow proud, or bow high, at speed. Without a power trim in a fixed shaft inboard, these three items are very important.

What happens as power causes the speed to go up? One must change one or all of these three design goals to work at the new, higher speed.

Over-power a straight shaft inboard and the flat transom stern area give more lift to the transom area of the runabout. Lift the transom and the bow gets pushed down at the same time. The lift of one pushes down the angle of the other.

The down angle of the inboard’s shaft also provides lift to the back of the boat. More lift from the almost flat bottom stern and down angle of the shaft causes the runabout bow to want to submarine and bow steer.

The fix?

1)      Change one or all of the three things to work together at the new speed to make for a safe riding / handling boat again.

2)      Have power trim on the drive to allow the helmsman to adjust amount of lift at the stern area of the boat. That is why I/Os (sterndrives) have power trim and that feature makes them more complicated.

What does this all mean? The runabout was set-up to perform well for an expected top speed: put in a souped up engine and that set-up will not perform well at the new top speed.

A good side view of how the vee goes to flat as the hull bottom moves aft

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