ScottB

Ambitious aren't we. Just don'r break it before Marathon

BRUCE SEROFF

I better not break another ...itll be a short season

rtaylor

Thanks Guys for the insight. I was thinking less about what was in the water and more about how much of the prop was out of the water(surface drive concept where the upper half of the propeller stroke only adds resistance), but I see the point.

Randy

HebertNecessity

Just put a pulse drive on, Nothing to break and you can move the X dim with the trim switch!

JO - PANTERABOATS

Hey Guys,

I will try to give you a few examples of some of my past experience so that you may relate to this matter a little better.

On a "full pleasure" 28 I normally mount the drive at 17 to 17 1/2 with a Bravo 1 drive ( approximately 6 inches with the drive fully tucked in). If I go any higher what happens is that the drive when trimmed out will not have enough leverage to trim the boats hull out of the water which ends up adding more wetted surface and adding slip.Out in the ocean in bumpy to rough water it is not as noticeable since you are trying to keep the boat flying level and close to the water.Remember if you are flying you are not going anywhere.You need the prop to be pushing water to go fast. Also by setting the drive higher the slip increases and even though you turn RPM and pitch you are not giving the best forward thrust out of your prop.

When I build a race boat with no cabin or cockpit liner with a much lighter race lamination and lets say a 10 inch notch transom this allows me to go approximately 3 inches higher on my X dimension.One reason is that the drive will not have to carry as much bow weight due to the cabin weight leverage,second the notch transom gives the propeller cleaner water when coming of the hull bottom since the drive is sitting 10 inches further back.
This is basically the same as having an extension box, or the new ITS system.On race boats we play around with fuel tank placement sometimes or add lead plates near the bow if needed in rough water.This all comes into play with a boats optimum performance.

If you look at the pictures of Bruces 28 and Alberts just purchased 1995 28 3 man bolster I had advertisied here compared to lets say to the Black F1-71 race boat I raced 2 years ago you will see that the dash placement and where the driver,throttleman,and sometimes navigator are sitting much further back.This makes a big diffrence on drive height, slip, and how the boat will perform.On Alberts 1995 boat I believe I pushed the 90 gallon gas tank 3 feet forward than where it would be underneath a full pleasure cockpit.On Bruces 28 I set it forward 42 inches I believe.When you have 500-600 pounds of added fuel this also comes into play.In ideal conditions lets say 2 foot chop you will see how the boat tends to run faster due to the hulls less wetted surface and a chop allowing the transom to squat a bit more allowing more bite and less slip.

Now on Steves 28 6 man bolster the forward passengers are sitting almost like in a full pleasure version 28 with no notch transom ( full bottom ) and the fuel tank slid forward to increase rough water handling.Now you have a diffrent set up to work with.This is the reason that all the new Panteras I deliver now are fully rigged here since I know how I set it up from the get go.Placement of the Fuel tank,Batteries,trim pumps, also come into play on the boats balance.

If you set the drive to low you increase more drag and reduce your acceleration.So you need to find a happy medium point.

2 examples:

On the black F1-71 race boat I set the drive at 21 since I figuered I would go high and work my way down.This boat had a 10 inch notch transom,light lay up,fuel tank moved forward (80 gallons) and 2 person crew sitting in the center with a lowered center of gravity.On flat water in the bay I put on a 26 pitch Bravo 1 4 blade labbed.My Father and I turn it on the limiter immediately at 5350 RPM and show 72-73 MPH.Boat runs flat and not much bow lift when trimmed.I then go and put on a 1 inch spacer dropping me to 20 on my X dimension and run it same day, same conditions, almost same amount of fuel and show on the Gaffrig 78-79 MPH with the same prop and same RPM.Besides picking up 6-7 more MPH I notice that the prop is not on the limiter so fast even though eventually it hits it and that the boat is now carrying alot more of the hull out of the water when trimmed and my acceleration has also increased.What happens is that my slip went down,the drive had more leverage when trimmed,and the boats drive was still high enough to the point that I was not adding drag and reducing speed and acceleration.Would the boat gone faster with lets says 1/2 inch lower X maybe?

One more example:

In 1994 I built a 28 to race in B- class at the time powered with triple 2.5 Mercury outboards.I am almost certain I was turning 24 pitch Mercury choppers at 7600 RPM with a 1:87 gear ratio. The boat GPS at Lake X in fresh water 84 MPH with 3 of us and 1/2 tank of fuel.Mercury tech ask me what would you like to try first.I say lets pick the motors up one notch on the bracket approximately 3/4 of an inch.We decide to just raise the outer 2 engines and leave the center engine alone to give us more push in the water.Within an hour we drop the boat back in and now go to a set of 26 pitch Mercury choppers and immediately I see alot more acceleartion in the mid range,top speed on GPS increases to 89-90 MPH and the boat handles just as good.What happens is we got some drag out of the water which in turn increased acceleration, top speed and handled the same.On this boat I was not concerned with trim leverage since I had 3 motors instead of 1
to carry the boats hull out of the water.I can practically air the entire hull out of the water with triple outboards.The motors were also mounted on a 20 inch setback bracket.

I hope this gives you an idea on how critical X- dimension is on a boat when you are going after the optimum performance.It takes alot of trial and error when you get into a race boat with weight being moved around.

The full pleasure versions we have delivered so many over the last 29 years that we have them down just about as perfect as you can expect it to perform.

I want to see every Pantera whether rigged by us or not to perform the best it can do.

Regards,

JO

JO - PANTERABOATS

One last note:

3,4,and now 5 blade props now come into play.Like Mike Carter states Diameter,Pitch,Blade thickness are just a few other examples that can be used to gain performance and reduce slip.

I have attached a few pictures of the (2) 28 That I gave you examples of.

It is Mid Night and still here at my Factory answering this topic.

I got to get some sleep now.

Regards,

JO

JO - PANTERABOATS

Here is F1-71 28.

BRUCE SEROFF

Hey Jo...thanks for taking the time. I know exactly how it feels ...burning the midnight oil. Im sure we will eventually get this issue ironed out, and will only help everyone looking for optimum performance. As soon as you get into Alberts boat, check where the propshaft is. Maybe it will help me get set up before i come down..I know we discussed this issue a million times and it sounds very logical. I hope it works.

See ya soon

rtaylor

Jo and Others,

Thanks so much for the insight. I can't wait to order a Pantera in the next year to 2. Jo, I know that originally you guys focused on outboards. How popular are they nowadays? All of my experience is with outboards and I'm not sure if it would be time to try an I/O. How would a twin 300 setup work?

Randy