Factors Affecting Speed on the water....

[OliverM5]

I'm Fairly new to the boating thing (used to drag racing, etc) and wanted to know the effect of the following factors when considering top speed (23' Scarab with 710 hp blown motor);
1) Weight - How does every 100 pounds added effect top speed?
2) Air Temp - How does every 10 degrees increase effect top speed?
3) Water conditions - Does smooth glass or slight chop give you best top speed?
What do you think I should be running with this power setup? Hull weighs about 3740 with motor.......

[jackpunx]

I'm Fairly new to the boating thing (used to drag racing, etc) and wanted to know the effect of the following factors when considering top speed (23' Scarab with 710 hp blown motor);
1) Weight - How does every 100 pounds added effect top speed?
2) Temp - How does every 10 degrees increase effect top speed?
3) Water conditions - Does smooth glass or slight chop give you best top speed?
What do you think I should be running with this power setup? Hull weighs about 3740 with motor.......
Wieght.. it depends on where it is in the boat.. the further up to the front of the boat.. (stereo in bow) it will decrease the boats performance
Temp---10MPH
Water conditions --- Smooth water sux.. need a little bit of chop to break it up... 6"-1' maybe a little more in your boat..
Welcome :D

[Tom Brown]

I'm Fairly new to the boating thing (used to drag racing, etc) and wanted to know the effect of the following factors when considering top speed (23' Scarab with 710 hp blown motor);
1) Weight - How does every 100 pounds added effect top speed?
2) Temp - How does every 10 degrees increase effect top speed?
3) Water conditions - Does smooth glass or slight chop give you best top speed?
Let's see....
1) Every 100 lbs of additional weight will slow the boat down
2) Every 10 degrees increase in ambient temperature will reduce the engine's ability to produce power
3) The less water in contact with the boat, the less friction so... a high frequency, low chop will yield the best top speed.
What do you think I should be running with this power setup? Hull weighs about 3740 with motor.......
... a decent power and ground wire from your two new Oddesy 1800s to your amps.
Did I get it right? :confused:

[OliverM5]

Wieght.. it depends on where it is in the boat.. the further up to the front of the boat.. (stereo in bow) it will decrease the boats performance
Temp---10MPH
Water conditions --- Smooth water sux.. need a little bit of chop to break it up... 6"-1' maybe a little more in your boat..
Welcome :D
So 10 degrees increase in air temp reduces speed by 10 mph?
If I ran 75-80 mph top speed with 650 extra pounds in the cockpit and 123 degree weather in smoother water, what will i run without the weight in 90 degree weather?

[Big Warlock]

I have that same boat. I have a modified 454 that puts out 550 hp. The boat does 70 mph. I would guess you would be able to go 80 mph tops. And the hull isn't made for much faster than that.
The speed to air temp is not an exact ratio. There is a curve and I don't know it off hand. But initially you will lose more power then slowly lose less as temp increases. Not an exact degree for mph though.
Don't take fat people with you and you should be fine on weight. There is a ratio about that as well. The fatter they are the more ice chests they want to load in your boat. Find yourself a couple of anorexic (sp?) babes that like salad and drink vodka. Your speed will increase substantially and the speed will stick very close to the bell curve measuring your popularity.
Last time I made the fat people comment, they asked me to leave my own boat!!! Biatches!!!!

[OliverM5]

I have that same boat. I have a modified 454 that puts out 550 hp. The boat does 70 mph. I would guess you would be able to go 80 mph tops. And the hull isn't made for much faster than that.
The speed to air temp is not an exact ratio. There is a curve and I don't know it off hand. But initially you will lose more power then slowly lose less as temp increases. Not an exact degree for mph though.
Don't take fat people with you and you should be fine on weight. There is a ratio about that as well. The fatter they are the more ice chests they want to load in your boat. Find yourself a couple of anorexic (sp?) babes that like salad and drink vodka. Your speed will increase substantially and the speed will stick very close to the bell curve measuring your popularity.
Last time I made the fat people comment, they asked me to leave my own boat!!! Biatches!!!!
The last owner had it up to 92 on GPS....it was a hairy ride!

[Tom Brown]

The last owner had it up to 92 on GPS....it was a hairy ride!
That translates to about 60 mph. .... not bad. :cool:

[Creator]

If you're new to boating I would recommend not running 92mph in that boat right off the bat. Keep her in the 70's until you get use to it. 92 on the water is really fast and if your not familiar with how boats act it can be deadly. Be cautious and ease into it. Enjoy.

[OliverM5]

If you're new to boating I would recommend not running 92mph in that boat right off the bat. Keep her in the 70's until you get use to it. 92 on the water is really fast and if your not familiar with how boats act it can be deadly. Be cautious and ease into it. Enjoy.
This is my second boat and my third season of boating.....I am just getting comfy with the 70's and know that its no joke on the water.....thanks for the heads up.....

[JB in so cal]

:confused: In my boat, I keep my anchors in the very-most forward compartment in the bow. 3 anchors=probably over 100 pounds. Am I affecting performance. I've got a friend with the same boat and he can grind out a few more MPH than me.

[Kilrtoy]

It will not effect anything
but im sure it will affect something.....
Im just teasing

[JB in so cal]

It will not effect anything
but im sure it will affect something.....
Im just teasing
Boy, tough crowd.
Their has to be a better way of getting they're.

[HocusPocus]

air temp-water temp=average temp
[weight]+boat color=topspeed
mmmm......
if id known there was gonna be a test... i would have studied more.

[JB in so cal]

air temp-water temp=average temp
[weight]+boat color=topspeed
mmmm......
if id known there was gonna be a test... i would have studied more.
If a DCB is heading west at 120 mph and a blown Howard is heading east at 120 mph, the ambient temp is 116 degrees, how long before a fight will break out at Moabi? :220v:

[Kilrtoy]

If a DCB is heading west at 120 mph and a blown Howard is heading east at 120 mph, the ambient temp is 116 degrees, how long before a fight will break out at Moabi? :220v:
Does the howard have a drain plug in it ...should be the first question... :) .

[TheLurker]

Wondering about top speed, Is this a good time to bring up through hull exhaust or not? :D
Comments Kilr or Jordy?

[Kilrtoy]

Wondering about top speed, Is this a good time to bring up through hull exhaust or not? :D
Comments Kilr or Jordy?
thru hull
2-5MPH
thru hull & over the transom
5-10MPH
Thru hull/over the transom and thru the hub
15MPH PLUS....

[JB in so cal]

:confused: In my boat, I keep my anchors in the very-most forward compartment in the bow. 3 anchors=probably over 100 pounds. Am I affecting performance. I've got a friend with the same boat and he can grind out a few more MPH than me.
I just find it hard to believe that a 28 foot boat is going to run slower with 100 pounds of iron in the bow :confused:

[locogringo]

It will not effect anything
but im sure it will affect something.....
Im just teasing
You mean I'm just teasing, right?

[Phat Matt]

I just find it hard to believe that a 28 foot boat is going to run slower with 100 pounds of iron in the bow :confused:
Another reason not to keep it in the bow is that it is going to bouce around A LOT more and could cause damage. Keep them in the stern if you can.

[ratso]

You mean I'm just teasing, right?
lmao... :D

[Kilrtoy]

You mean I'm just teasing, right?
JES, JEW R wright

[Phat Matt]

JES, JEW R wright
Why do you have to bring religion into this? :D

[LHC30Victory]

If a DCB is heading west at 120 mph and a blown Howard is heading east at 120 mph, the ambient temp is 116 degrees, how long before a fight will break out at Moabi? :220v:
Now THAT'S funny :D

[JB in so cal]

Now THAT'S funny :D
just tryin' to help.
I guess I'm gonna go look for a boating-related site to try and find an answer to my boating related question :rolleyes:

[JB in so cal]

Another reason not to keep it in the bow is that it is going to bouce around A LOT more and could cause damage. Keep them in the stern if you can.
I hear you on this, but the compartment I have them in is padded and carpeted - it is THE anchor locker for the boat. I just don't know if it's slowin' me down, or not.

[Phat Matt]

I hear you on this, but the compartment I have them in is padded and carpeted - it is THE anchor locker for the boat. I just don't know if it's slowin' me down, or not.
Cool. It was my public service announcement for the night. With your boat though, I bet it helps you plane out faster. :D

[ECeptor]

This site does not have temperature corrections, but can let you calculate the affect of weight and power.
http://www.go-fast.com/boat_speed_predictions.htm
You just need a power, weight, speed data point to start from.