Nothcing The Transom At The Botton
 

Has Anyone Notched The Transom At The Bottom To Get A More Stable Ride At High Speed On Older Hulls.
I Here Someone Is Doing This In Long Island Ny Any Input
Rich Cuny

i dont think it will make the ride more stable if anything it mite make it worse if the boat wasnt desighined for it . i now of one boat builder that put a notch in the transom of a 35 foot boat then after running the boat they stoped doing it , your going to loose the last 1 foot of running surface ,,

i would think you should try extension box's to put the prop's in cleaner water and you mite gain a few mph .

just my thought's

mike

From a purely engineering point of view, generally speaking, the notch does very little to change stability. What it does do, is change the hydrodynamic flow of the water behind the boat, allowing for higher X-dimensions (prop shaft heights), which in turn reduces drag, and allows use of modern hi-perf props.

This can be especially useful in bravo boats.

Thats exactly what a notch is ,,,a built in extension box !!!!!
On some boats it works and on some it dont !!

What boat is it that your looking to do this ????

Raybo In Lindenhurst LI Has Been Doing This On Alot Of Older 21 Superboats For Better Handling At High Speeds And Yes It Does Work

Notches do work, of course: Reggie has been using them for years and everyone knows -- seriously -- that his boats win.

There is a significant body of hydrodynamic science that backs up the concept of notches.

As you go faster, the boat needs less bottom to support the weight of the boat. Therefore, the faster you go, the part of the boat in the water gets smaller and smaller, shorter and shorter, closer and closer to the transom.

The center of lift on a planing bottom is very close to the leading edge: the pressure is highest (pushes up with the most force) within an inch or so of where the bottom hits water, and the pressure then decreases rapidly, and then gradually diminishes to almost nothing at the transom. This is true no matter how short the bottom is.

When the boat is going fast enough, the center of gravity is in front of the point where the hull enters the water. Obviously this does not work, so the bow drops. This leads to porpoising: the bow lifts, drops, lifts, ...

By adding a notch, you are moving the transom forward just for this high speed domain. You can get the forward edge of the wetted surface forward of the CG, then you've got a stable boat again.

Everything Reggie does on bottom design is very well rooted in hydrodynamic science.

So the closer you make your boat's bottom mimic a Fountain, the better off you are.

Hope Reggie paid you for that advertisement............He wasn't the first to notch a transom or add a pad!! :party-smiley-004:

I will let it go at that......................

It certainly works better than notching them at the top:party-smiley-004:

Bill Farmer comes to mind :rolleyes:

Might be true, but he does it better than anyone else.

the formula I own 1995 336SR1 has a notched transom, 336 was launched in 1993, notch added in 1995. it still has deep bravos and I understand the notch added a couple mph, my boat won powerboat mag offshore boat of the year in 95
but I am told this boat really performes with shortie drives ( for reasons mentioned by appsyscons and carcrash)

someday I will try imcos shorties and higher pitch props on 1.5 drives instead of my 1.36 drives

Ramb

In 1995, your boat was likely set up with Mirage props. With the -2" lowers and Bravo 1 props, your speed should jump at both cruise and top end. Where would Formula set your X today? It might be more than +2". I also agree that you will like the 1.5 ratio.

He didn't say Reggie invented them. Just stated Fountain uses them.

Reggie doesn't notch transoms... he just extends the back above the running waterline so he can sell a 27 foot boat as a 35. next we will hear how the beak is aerodynamically designed and wind tunnel tested to provide a precise amount of aerodynamic bow lift.

Sorry........I should have just left it alone........:rolleyes:

That's awesome how that works out. Good looks and functionality.:drink:

It's funny how Reggie's big power race boats have 90% of the beak removed... must hurt performance rather than help around the race course.

Its funny that u don't know allot about fountain race boats !!!:rolleyes:

The reason why the beak is almost gone ,,is because they are 39-40 feet ,,out of a 42 foot mold and then cut down !!

To fit the race deck !!!

:ernaehrung004:

Also ,,i actually think that Excalibur on there 32 had the first notch ?! ( 1980'ish )
And that was also used by reggie to built a Fountain ,,just like my Aero-Tek !

Raybo is following the exact dimensions we put into the 21 Shadow after George re-designed the 21 Challenger. It worked in 1979....and it works today.

That hull will still run rings around anything made today.

T2x

anyone got any pics????????

Here is one that was put in a friend of mines boat ,,38 cig !!

Thanks for the info, tough guy.

:eek: Why do u call me tough guy ??? Just try to help !!

Gary has just filled the notch back in with an underwater muffler box! Should see soon on how it runs, and how quiet it is. Should be as quiet as a church mouse.

:eek: WHHAAAAATTTTT???????????:eek:

http://s126.photobucket.com/albums/p...2275275033.jpg

Bad pic but this is the 1984 Wellcraft Excalibur 27. Is this the transom notch you guys are talking about?
Erik