Tuff Boat on Long Island

[2.5-21]

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[Dirk Pitt]

The blue G2 powered boat ran 94 according to the gps pic in his thread and the yellow (non-infused) boat ran 93 I believe. I don't know how much heavier or the weight difference between any of them to be honest...

I dont remember seeing a picture with the blue tuff going 94mph, I was in it at 89mph
if the boat dosent go close to 100mph it will be on the next plane to china, but I will be totally honest with all the numbers, soon the cool weather will be here,by then I will have zeroed in on the right prop,and other things, a good prop and i have seen this many times is good for in some instances 4 to 5 mph,

[dnelson964]

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[Dirk Pitt]

Bingo 2.5. It all starts with the true total weight.

A lot of folks over the years have said that all the Tuff 21's are different custom layups. Tuff has been building this model for at least a full decade for general consumption and I'm sure that they have built at least (24) hulls in that time frame. Can Tuff 21 weights differ by more than 150-200lbs over two dozen hulls built? I tend to doubt it but I am not a boat builder. I think a bit of the speed that the Tuff's achieve are based on running in freshwater and zero humidity up North. I'm sure that there are folks on this board that can comment, but the combo of freshwater and no moist air is probably worth 3-4mph in top end. Now you are more apples to apples.

106mph 300XS Tuff in Canada is a 102mph Tuff in Long Island is a 100mph Tuff in Miami.

like I noted before we crawling aroung it yesterday really for the first time, P&G had it all week, but there seems to be a lot of carbon fiber in this boat, so is it a std layup boat?, did he run out of material and had some other stuff laying around and said "hey Jr. throw that stuff on the shelve over here"? we"ll see, but Ill get the information that Tuff provided to John McKight and then compare notes, the variable is going to be the rigging like Greg said, i do have all the pictures of the build of my boat ie the infusion process

[dubber]

I dont remember seeing a picture with the blue tuff going 94mph, I was in it at 89mph ,

Right here in this thread - second post. There was some discussion on it as well.

http://www.screamandfly.com/showthre...ith-250-H-O-G2

[Dirk Pitt]

Right here in this thread - second post. There was some discussion on it as well.

http://www.screamandfly.com/showthre...ith-250-H-O-G2

ok yes its possible,it only 2 0r 3

[Dirk Pitt]

Bingo 2.5. It all starts with the true total weight.

A lot of folks over the years have said that all the Tuff 21's are different custom layups. Tuff has been building this model for at least a full decade for general consumption and I'm sure that they have built at least (24) hulls in that time frame. Can Tuff 21 weights differ by more than 150-200lbs over two dozen hulls built? I tend to doubt it but I am not a boat builder. I think a bit of the speed that the Tuff's achieve are based on running in freshwater and zero humidity up North. I'm sure that there are folks on this board that can comment, but the combo of freshwater and no moist air is probably worth 3-4mph in top end. Now you are more apples to apples.

106mph 300XS Tuff in Canada is a 102mph Tuff in Long Island is a 100mph Tuff in Miami.

boats run faster in salt water than fresh .salt water is more dense because it has more mass (both water and salt) than an equal volume of fresh water (where there's no salt)...how much more dense depends on the amount of salt (salinity)....but I guess that can be debated too, I guess the true test is to take 2 rubber duckies and set up 2 bath tubs one with salt one without, and see which one is faster

[99fxst99]

One can not infuse without a vacuum bag.

No,but one can vacuum bag without infusion. I am guessing he meant this (vacuum bag only) is not what is being done.

[baja200merk]

a good prop and i have seen this many times is good for in some instances 4 to 5 mph,

We picked up 4mph the other night moving my buddy's motor up 1/4" ran 110.7 fastest box stock 87 octane Ficht in the world.

[Jimboat]

boats run faster in salt water than fresh .salt water is moredense because it has more mass (both water and salt) than an equalvolume of fresh water

Actually....

Salt vs. freshwater is more complex than we'd initially think.

Salt water is slightly more dense than fresh water. Lift and drag are, among other things, both related to the density of the water. So more density = more lift, and also more drag.

So, the answer isn't going to be obvious. More density means more drag (less speed). But also, more density means more Lift which can mean less wetted surface, causing less drag (more speed). So the net result is very dependent on the hull design and the speed at which we're testing the hull.

AND...even more complicated, the net result also depends on how much of the total lift is coming from the wetted surfaces (hydrodynamic lift from vee surfaces and pad), since many high-performance hull also contribute significant aerodynamic lift.

AND...the water density has an effect on the drag of the lower unit too...more dense salt water causes more drag on lower unit. (Sometimes this can make as much or more difference as the other contributors!)

The water density issue is much easier to visualize if you consider fresh water vs. MUCH more dense "mud". More density (mud) might be considered to give faster speed result, right (because of more lift)? But no, due to MUCH higher drag in "mud", the net result is MUCH slower speeds! (Makes more sense, right?) Same is true for fresh vs. salt water.

AND...just to make it all completely confusing, the thrust efficiency of the propeller in (more dense) salt water vs. fresh water changes the results too!

ALSO, type of boat hull makes a difference. For example, a displacement boat (e.g.: sailing, or displacement speed powerboat hulls) has more buoyancy in salt water due tohigher density. (That's why we float better when swimming in salt water than we do in fresh water). So for boats getting mostly buoyancy lift, the answer is different than for boats getting most of their lift from planing lift (such as high performance vee hulls).

The bottom line for THIS specific example....fresh water is going to be very slightly faster(< +0.5mph), assuming everything else is also the same (temperature of water, temp of air, atmospheric pressure, relative humidity, boat weight, fuel load, passenger payload, water conditions, etc.)

[XstreamVking]

I concur professor. This is how I have always heard it described.....Real world, I have not seen any difference.

[LittleCharger]

Bingo 2.5. It all starts with the true total weight.

A lot of folks over the years have said that all the Tuff 21's are different custom layups. Tuff has been building this model for at least a full decade for general consumption and I'm sure that they have built at least (24) hulls in that time frame. Can Tuff 21 weights differ by more than 150-200lbs over two dozen hulls built? I tend to doubt it but I am not a boat builder. I think a bit of the speed that the Tuff's achieve are based on running in freshwater and zero humidity up North. I'm sure that there are folks on this board that can comment, but the combo of freshwater and no moist air is probably worth 3-4mph in top end. Now you are more apples to apples.

106mph 300XS Tuff in Canada is a 102mph Tuff in Long Island is a 100mph Tuff in Miami.

Humidity is roughly the same in Ontario as Long Island. I wish we had zero humidity.

[Dirk Pitt]

Actually....

Salt vs. freshwater is more complex than we'd initially think.

Salt water is slightly more dense than fresh water. Lift and drag are, among other things,are both related to the density of the water. So more density = more lift, alsomore drag.

So, the answer isn't going to be obvious. More density means more drag (less speed). But also, more density means more Lift which can mean less wetted surface, causing less drag (more speed). So the net result is very dependent on the hull design and the speed at which we're testing the hull.

AND...even more complicated, the net result also depends on how much of the total lift is coming from the wetted surfaces (hydrodynamic lift from vee surfaces and pad), since many high-performance hull also contribute significant aerodynamic lift.

AND...the water density has an effect on the drag of the lower unit too...more dense salt water causes more drag on lower unit. (Sometimes this can make as much difference as the other contributors!)

The water density issue is much easier to visualize if you consider fresh water vs. MUCH more dense "mud". More density (mud) might be considered to give faster speed result, right (because of more lift)? But no, due to MUCH higher drag in "mud", the net result is MUCH slower speeds! (Makes more sense, right?) Same is true for fresh vs. salt water.

AND...just to make it all completely confusing, the thrust efficiency of the propeller in (more dense) salt water vs. fresh water changes the results too!

ALSO, type of boat hull makes a difference. For example, a displacement boat (e.g.: sailing, or displacement speed powerboat hulls) has more buoyancy in salt water due tohigher density. (That's why we float better when swimming in salt water than we do in fresh water). So for boats getting mostly buoyancy lift, the answer is different than for boats getting most of their lift from planing lift (such as high performance vee hulls).

The bottom line for THIS specific example....fresh water is going to be very slightly faster(< +0.5mph), assuming everything else is also the same (temperature of water, temp of air, atmospheric pressure, relative humidity).

0k I was half right, but an extremly scientific explaination, really thank you for taking the time for that explaination,I hope my memory affords me to recite it verbatim,but I still think the rubber duckys in a controlled enviroment might produce different results

[Dirk Pitt]

I spoke to john Mcknight he said that he was told the boat constructed as is weighed approximently 1100lbs, he was just unsure if that weight was with or without interior, so it appears Greg could be right on the money

[Jimboat]

I concur professor. This is how I have always heard it described.....Real world, I have not seen any difference.

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