OK Here's the deal I have my Hurricane to the point that it is transitioning from a boat to a airplane with a pusher prop in the tail. I see several aerodynamic modifications that would greatly increase the stability but I'm not sure about the legality of these mods in the mono class. Now at top speed it is behaving like a tail heavy pusher prop flying wing design and I don't know what I can get by with as to wings and fins.

ED,

Here in NAMBA land, Any surface in contact with the water in terms of "FIRST CONTACT" defines a mono.
What a few have gotten away with to stabilize their monos is a Flat plate that is ABOVE ride surfaces of the actual hull, yet to retain being a legal MONO, indexs water above hulls "Primary" planing surface.

Like a CAVITATION plate of an outboard, Some fast MONO users have attached a plate that is fixed above and behind prop so they can use the roostertail as a secondary riding surface.

The water that go's skyward off the prop in defected off a plate mounted above and behind prop. The pressure put upon this plate act's as another ride surface giving increased down force to the hull while at full speed. Somewhat like trimtabs but using the waste water off the props rooster tail and therefor causing ZERO drag while giving increased down force ;D

The boats using them run FASTER ... FLATTER and under greater attitude control than those without.

Hmmm Interesting Scott
I was playing with the idea of some longer trim tabs and a shorter stinger but the secondary plate sounds extremely interesting.
The prop design I'm working on creates much less of a roostertail than the Voodoo 70/16-2 that I was running which turned out to be the best all round choice for my boat from the available off the shelf props.
On the aerodynamic end this week I'm going to try a old model airplane horz. and vert. stabalizer mounted above the pipe above the cg of the boat and also try it mounted as far to the rear as possible, I feel that the rear location will be better.. I've had some success by moving the cg fwd and bringing stinger angle up to level position. Also using two smaller fuel tanks located to maintain cg through the run,this is getting much more critical as speeds increase. I think that it may come down to a wing and vert. stabilizers similar to those used on unlimited hydro's and a more foward cg than normal. I don't want to put a set of Indy car wings on a mono but

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I ran a single wing on my full size v-drive drag boat mounted generally above the flywheel area and just hich enough to clear the engine, after that it wasn't quite as high a pucker factor at top end. Ed

??? Problem areas with using Aerodynamic stabilizers like fins or wings is that there ability to work right requires them to be located in "Clean Air"

Monos with there typical OPEN engine bay cause a LOT of turbulence across and behind the top area of hull. Adding a full coverage cowl calms down most high speed monos ..

You will also find as you start getting really fast with monos the bottom design needs to change to allow boat to settle in deeper even tho traveling faster. A sharper keel will run deeper in the water than a rounded one, Full length strakes also cause more total hull lift than those boats that have NO strakes on back 1/3 of hull.

The better HIGH SPEED mono design IMO :-\ is one using a rounded keel on @ the forward half, then smoothly transitioned to a sharp keel for last 1/3rd of boat. Strakes that STOP at 1/2 to 2/3rd boats length.

This allows boat to run with a tad more boat "In The Water" which adds a BUNCH to the stability at speed.

Scott

Sometimes adding weight will made a boat faster. At the speeds we are running now some boats are just to light. You just are not going to make enough down force to counter act the lift so the boat will be stable.
Jimmy

Thanks for the input
The cowl / hatch is the first thing I played with. I could tell a big difference with / without it . This weekend I'll raise the rear end about 1 1/2 " from the normall position,that will begin to change the angle of attack of the airfoiled hatch a considerable amount. It was lifting enough to pull the hold down magnets loose. I solved that problem by adding some low profile spoilers at the 30% point or the thickest part of the Clark Y airfoil section but as expected they induced a lot of drag and tu rbulance. If any of you remember our old Ford "J" race car project from the 60's this is what I expect the basic design of the hatch to look like when finished. I'm going slow and testing instead of shotgunning the project with a complete redesign. I just finished adding a 1 1/2 " extension to the rudder standoff and will try that tomorrow if the lake here at the house is in good shape to run on. Dang this retirement is turning into WORK :o

The added rudder standoff extension didn't make any noticable in stability or handling so I went back to the old extension.
I shortened the stinger 1/2 inch and that DID make a noticable difference.
Shortened rudder 1/2 inch and picked up a little speed with no change in handling.
Also made some aerodynamic changes to create more downforce centered just fwd. of the CG, It's now to the point that the hatch needs no hold downs and without the hatch you can depend on the boat blowing over.
Moved the CG fwd. about a inch and running stinger parallel with the ride surface. Boat can now stay airborn 2-3 ft off of a wave and still land safely.
Lots More to do

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Sounds like your well on your way in finding more " Air time "

In no time we shall call you ... Eddy "Air Time" Sidders ;D

Hi Scott
Ran Boatmobile yesterday,no problem off top of rollers now, as it was any roller would cause helluve spinout .Now WOT around course and seems plenty fast. Added a little more cup to prop tips. Now I have to get a GPS, Police radared it at 62 in heat trim but we know about police radar LOL. Airtime Ed