Tuff Boat on Long Island

**XstreamVking** · 08-09-2015, 05:37 PM

Very good explanation, just like I was back in college.....

**Dirk Pitt** · 08-09-2015, 05:41 PM

Originally Posted by Jimboat

Haha...sorry for sounding like a professor. (I got carried away)!

I was not in any mean trying to be disrepectful, I really was under the impression all these years that we were faster in salt, and I completly appriciate being corrected, the rubber ducky experiment was just levity, I hope you got that.....

**Jimboat** · 08-09-2015, 05:47 PM

Originally Posted by Dirk Pitt

I was not in any mean trying to be disrepectful, I really was under the impression all these years that we were faster in salt, and I completly appriciate being corrected, the rubber ducky experiment was just levity, I hope you got that.....

No problem. haha.

**Dirk Pitt** · 08-09-2015, 05:50 PM

but I did find this which looks like it confirms your observation
R = C x ((rho x V^2)/2) x A

where:

R = resistance in pounds
C = coefficient of skin friction
rho = density of water in slugs per cubic foot
V = velocity in feet/sec
A = wetted area in sq. ft.

Using this as a basis for some "hoodoo math", one can test to see whether a hull will have more or less frictional drag in fresh water than in salt. To keep things reasonable here, we will assume that the coefficient of skin friction will be constant at 0.995, and velocity is constant at 33.77 ft/sec (20 knots).

In salt water,

rho = 1.99
A = 100

therefore R = 0.995 x ((1.99 x 33.77^2)/2) x 100 = 112903.7

In fresh water, which is 2.34% less dense than salt,

rho = 1.94
A = 102.4 (wetted surface increases due to more of the hull being submerged in the less-dense fluid)

therefore R = 0.995 x ((1.94 x 33.77^2)/2) x 102.4 = 112708.5

**vnemous** · 08-09-2015, 06:04 PM

All I know is in the real world my super with the 250 on it was 4 mph slower in lake george than the barnegat bay JMO

**Dirk Pitt** · 08-09-2015, 06:34 PM

Originally Posted by vnemous

All I know is in the real world my super with the 250 on it was 4 mph slower in lake george than the barnegat bay JMO

altitude? and then theres density altitude............Ill let Jimboat explain that if he would be kind enough

**baja200merk** · 08-09-2015, 07:02 PM

The northerners that run in salt at sea level should not compare the northern high altitude fresh water lakes. Even though the newer engines account and adjust for barometric pressure which helps minimize power loss compared to a carb motor there is still a loss

**AZMIDLYF** · 08-09-2015, 07:17 PM

Originally Posted by baja200merk

The northerners that run in salt at sea level should not compare the northern high altitude fresh water lakes. Even though the newer engines account and adjust for barometric pressure which helps minimize power loss compared to a carb motor there is still a loss

What type of system do the new motors use?

**XstreamVking** · 08-09-2015, 07:29 PM

My boats always run faster in a lite chop, like you see in salt water. Flat fresh water wont aerate the bottom like a lil chop does. jm 2cts

**RBT** · 08-09-2015, 07:33 PM

Wow this thread has really taken off, what's gonna happen when winter comes around.

firstly, charleyN. There is a big difference between vacuum bagging and infusion. While I get that both have a bag, the process is very different as are the results and the lamination schedule has to be designed accordingly. All tuff's were bagged, the latest have been infused. Since the 106.4 boat. I have been infusing since 2007. I wouldn't vacuum bag ever again.

We have humidity here, those Great Lakes have a huge effect on us. Our actual altitude is 730 feet above sea level, I suspect this has more effect than salt does. But if I were a betting man, I'd say that it would go faster in gsb then here. Like I said before tuff #1 has run over 100 mph since inception. Over a decade ago and it was the heaviest of them all. The basic lamination of all tuff is the same, sometimes advanced composites are substituted. The 106 boat is standard layup schedule on,y substituting glass for Kevlar. Same mass, same orientation.
And for speeds, 225 ficht 87 mph. Old boat, over a decade this way, 300 Yamaha 93 mph. Turd of a motor compared to a merc. These are the old boats, most of the owners don't care about putting up a number. Fact is they are fast.

**davemvegas** · 08-09-2015, 07:35 PM

Originally Posted by AZMIDLYF

What type of system do the new motors use?

map sensor.

**Dirk Pitt** · 08-09-2015, 07:37 PM

Originally Posted by davemvegas

map sensor.

do they control the air fuel mixture throughout the power band?

**Dirk Pitt** · 08-09-2015, 07:40 PM

Originally Posted by RBT

Wow this thread has really taken off, what's gonna happen when winter comes around.

firstly, charleyN. There is a big difference between vacuum bagging and infusion. While I get that both have a bag, the process is very different as are the results and the lamination schedule has to be designed accordingly. All tuff's were bagged, the latest have been infused. Since the 106.4 boat. I have been infusing since 2007. I wouldn't vacuum bag ever again.

We have humidity here, those Great Lakes have a huge effect on us. Our actual altitude is 730 feet above sea level, I suspect this has more effect than salt does. But if I were a betting man, I'd say that it would go faster in gsb then here. Like I said before tuff #1 has run over 100 mph since inception. Over a decade ago and it was the heaviest of them all. The basic lamination of all tuff is the same, sometimes advanced composites are substituted. The 106 boat is standard layup schedule on,y substituting glass for Kevlar. Same mass, same orientation.
And for speeds, 225 ficht 87 mph. Old boat, over a decade this way, 300 Yamaha 93 mph. Turd of a motor compared to a merc. These are the old boats, most of the owners don't care about putting up a number. Fact is they are fast.

when the winter comes we will have to de rig it and re rig with 2 motors, ah but which motors

that should keep us busy speculating

**RBT** · 08-09-2015, 07:46 PM

May I suggest turbo Hondas?

**powerabout** · 08-09-2015, 07:46 PM

Originally Posted by Dirk Pitt

do they control the air fuel mixture throughout the power band?

map sensor checks the load from rpm and moves the VE table in the pack constantly
Engine really needs a humidity sensor to cover all bases then it has air density covered
Engines can use the MAP sensor just when you turn it on before cranking to get an air density
( I am talking aftermarket here as I am no expert on E-tecs)