Why put the prop so far behind the transom?

[007clint]

The offshore v-hulls (and others) put the prop and rudder way behind the transom. Also, on Sport Hydros, IMPBA allows the strut on the back of the transom but restricts how far the prop can be out ("A strut width no greater than 9/16 inch wide may be mounted either under the hull or on the transom with the farthest end of the drive dog, as measured from the transom not extending out more than 3 inches."

NAMBA requires the strut to be under the boat and "The propeller drive dog may be one drive dog length behind the transom of the boat." - Why? If it doesn't make a difference they wouldn't be putting these requirements in a rule.

I have heard for one experienced racer that with the same set-up on a sport hydro and the strut under the boat (and therefore the propeller closer to the transom) is 2-4mph slower. Any agree or disagree?

Why were the NAMBA and IMPBA rules put in? Can anyone shine some light on this?

 

[Jerry Muro]

The offshore v-hulls (and others) put the prop and rudder way behind the transom. Also, on Sport Hydros, IMPBA allows the strut on the back of the transom but restricts how far the prop can be out ("A strut width no greater than 9/16 inch wide may be mounted either under the hull or on the transom with the farthest end of the drive dog, as measured from the transom not extending out more than 3 inches."
NAMBA requires the strut to be under the boat and "The propeller drive dog may be one drive dog length behind the transom of the boat." - Why? If it doesn't make a difference they wouldn't be putting these requirements in a rule.

I have heard for one experienced racer that with the same set-up on a sport hydro and the strut under the boat (and therefore the propeller closer to the transom) is 2-4mph slower. Any agree or disagree?

Why were the NAMBA and IMPBA rules put in? Can anyone shine some light on this?

Bad request this was a nasty discussion in the past.

 

[007clint]

Bad request this was a nasty discussion in the past.

:unsure: OK - so let's stick with boat performance and stay away from the politics!! Does it matter on a sport hydro (or scale) where you put the prop?

 

[SayMikey]

Bad request this was a nasty discussion in the past.

:unsure: OK - so let's stick with boat performance and stay away from the politics!! Does it matter on a sport hydro (or scale) where you put the prop?

It makes a ton of difference,in sport 40 for instance my drive dog is 1/4 or more back from the strut end. And as mandated the strut may not extend beyond the transom. I can see 4 mph easy by running it this way. On a scale you must keep it under the boat<drive dog unless the real boat stuck out. You better have a pic of the real deal if your going to a national event. My words come via IMPBA as im now the TECHNICAL DIRECTOR. Mike Schindler

 

[Jerry Wyss]

Bad request this was a nasty discussion in the past.

:unsure: OK - so let's stick with boat performance and stay away from the politics!! Does it matter on a sport hydro (or scale) where you put the prop?

If you don't race, you don't have to worry about any of it