forward rudder hydroplanes

[moTthediesel]

I have an old Volume IX edition (1927) of the Motor Boating's Ideal series plan book that was given to me years ago by my late father-in-law. In it there are plans for two inboard hydros, both drawn by Charles D. Mower.
The unusual thing about both of them (at least to me!) is that they have their rudders mounted through the keel well forward, between 1/4 and 1/3 the waterline length aft of the bow. The designer makes no mention in the construction notes about this, which makes me think there was nothing remarkable about this at the time.
What was the thinking behind this? Was the idea that the rudder in this position would keep the boat from sliding in turns like the fins fitted to modern hydros and outboard racing utilities? It seems to me that this would make for some spooky steering characteristics; no? I think I remember seeing a Bolger designed sailboat with forward rudder but that sounds a lot less scary than a 40+ mph hydro.
Anybody know anything about this?
moT

[StianM]

I got a old memory off seing something like this on a program about the marine inviroment in Norway.

They had a cat with hydrofoild under eatch keel and it was rudders placed way in front like the weel on a car, but this sustem was computer controled.
the hydrofoils was hydraulic controled and a microprosesor corrected the angle off atack 50 times a second witch made the boat go steady just like there was no wawes.

It must be 15-20 years since now and I have not heard off it since.

[FranklinRatliff]

John Cobb's "Crusader" jet hydroplane used a forward rudder mounted just aft of the front step.

http://www.lesliefield.com/personali...to_gallery.htm

http://www.solarnavigator.net/john_cobb_crusader.htm

[moTthediesel]

Hey, thanks for those links, though they certainly don't make me feel any better about forward rudders
moT

[marshmat]

Show me a WWSR boat other than Spirit of Australia that DIDN't crash. I think this is more a trait of WWSR boats than of forward rudders!
The Bolger boat you refer to is Query, built as a testbed for a number of radical ideas. I wouldn't take her performance as typical of forward rudders.
I can think of one hydrodynamic reason against a bow rudder. The flow off the trailing edge of any control surface is disturbed somewhat from the natural streamlines, and having this disturbance at the front of a vehicle means that the resulting flow irregularities contribute to drag over the entire vehicle. Keeping such disturbances well aft means that whatever they disturb is left behind, rather than under, the boat.

[messabout]

The real deal is a racing single step hydro that resides in Cortez Florida, It has a Curtis OX aircraft engine swinging a big prop of undetermined dimension. The boat was in evidence at a recent gathering of classic boat people. The boat is in the process of restoration. It is sitting on a trailer and the motor runs well as demonstrated during the gathering. The rudder is forward mounted at about 1/4 length aft of the forefoot.

This is an intrigueing old boat. Primitive by our standards. While I'm fascinated by it, I do not wish to ride in it while at speed.

[FranklinRatliff]

Originally Posted by marshmat

Show me a WWSR boat other than Spirit of Australia that DIDN't crash. I think this is more a trait of WWSR boats than of forward rudders!
The Bolger boat you refer to is Query, built as a testbed for a number of radical ideas. I wouldn't take her performance as typical of forward rudders.
I can think of one hydrodynamic reason against a bow rudder. The flow off the trailing edge of any control surface is disturbed somewhat from the natural streamlines, and having this disturbance at the front of a vehicle means that the resulting flow irregularities contribute to drag over the entire vehicle. Keeping such disturbances well aft means that whatever they disturb is left behind, rather than under, the boat.

Lee Taylor's "Hustler", the boat that set the record Warby had to break, didn't crash either.

[Thin water]

I build these little hydroplanes as a hobby. I have not seen the model you are speaking of but most of the runabout type hydroplanes have one or more skegs or keel type structures that look like a rudder but they don't move. They are mounted 1/3 of the way from the transom to the center of the boat. When on plane they are about one third out of the water. Since hydroplanes skip over the surface of the water like a flat rock skipped on a pond they won't turn without the skeg. I made one and did not put the keel on it to see how much slide I could get when turning. It slid fine but took about 1/4 mile to turn it around at 30 mph. I added the keel and it would turn almost like a regular plaining hull. The big three point racing hydros have a fin near the step but they don't move either. They are only mounted on one side since they only turn one way. The real rudder is on the back. There have been many fatalities involving racing hydroplanes that broke off their skeg and slid off the race course, some into the crowd.
JIM