Three-Point Hydro Spray?

Three-Point Hydro Spray?

Posted by Glen Witt on Aug 1st 2014

I recently received a question from a gentleman who built our Glen-L Tiny Titan 8-foot hydroplane.  He was experiencing what he thought was too much spray coming over the sides, and therefore decided to modify the design of Tiny Titan by adding strips of 1 ½-inch wide aluminum along the outside bottoms of both sponsons. He was quite happy with the results and reported them back to me.

Herein follows my response to him; I hope you find it enlightening:

Glad to see you have solved your problem. However, you may be using an aspirin to fix a broken wrist (so to speak); you’ve eliminated the spray but not the source of the problem.

A three-point hydro powered with the proper motor, the right prop, height and tilt adjustment, along with proper weight distribution should not have excessive spray leaving the sponson.

Bow On View

The sponsons at speed are planing on their aft end; they are not going through the water but they are skimming over the top, supported and lifted by the air rushing through the tunnel between the sponsons.

The third point at the transom should also ride loosely on the water, and in racing hydros the prop is virtually supporting the aft end.

When accelerating, the bow of the hydro will rise and the driver must throw his weight forward to force the bow down and get the boat on plane. As the boat picks up speed, the driver should shift his weight aft; one should be able to feel speed improve when the weight distribution is correct and the boat skims over the water, instead of ploughing through it.

Our Tiny Titan test model was built per the plans and weighed 74 pounds. Powered by a 14-HP outboard turning a two-blade 7 ½ x 10 prop, a calibrated speedometer registered 33 mph with 5 gallons of gas and a 175 lb. driver aboard.

Your solution to your spray problem may work to your satisfaction, but as the designer and test driver of the prototype I know it shouldn’t be necessary. I had a lot of fun with the little hydro and as shown in the photo there was minimal spray from the sponsons at speed.

As an aside; this design was featured on the front cover of Popular Mechanics and over the years hundreds (probably thousands) have been built. It is a well-proven design.