Cockpit construction
11-27-2011 | 10:20 PM
#171
Skater Brother
Joined: Aug 2004
Posts: 2,541
Likes: 5
From: Wichita, KS
the pod is the way to go, IMO. but with the different boat builders and teams it will be hard to even come up with guidelines or build specs that everyone agrees on. i wouldn't classify it as a "breakaway" like the drag boats, but more of an individual piece thats glassed in or set in with Plexus (or similar adhesive).
jim's comment on certain builders being hard headed is very much true along with some racers thinking that they have it all figured out.
honestly one of the only way to make a rule for canopy upgrades would be to increase the boat wt# and that weight increase would have to be WITHOUT fuel and ballast.
just to give an idea of what i've tried to explain to some:
if your boat weighs #8800 for a #9500 class wt, that means your short #700 lbs of material. in a traditional laminate that is hand laid-up thats 350 lbs of glass and 350 lbs of resin. about 3 rolls of 24 oz glass and a drum of resin. thats alot of material to leave out and alot of structure that could be used to increase the canopy strenght.
(side note- using a impregnator you could increase the glass ratio to 70%, further increasing the structure strenght)
the common practice is to have the boat as light as possible and make weight using movable ballast. and i'm not against the ballast just if your adding that much maybe its worth looking at the structural integrity of being so light ?????
compare that to a DW 38' that is about #200 lbs under the 10k lb limit for 850 sc for the same size boat. in simple math thats an additional #1000 lbs of laminate. which might be some of the reason the 38DW survived going over 3x with minor cosmectic damage vs how some of the other supercats have faired.
as for the autoclave, steve your saying that equal thickness laminates gain 70% more strenght over a laminate built using an impregnator (70% glass to resin ratio) and bagged at 29 HG of vacuum and post cured, say using a paint booth at 150 degrees F ? also using the same coring materials, of course.
hopefully this tragic accident hits home for those that have shrugged off canopy safety. i've had the chance to met alot of great people within the offshore world and Bob Morgan was one of them. his lost, along with the others is truly saddening and disturbing knowing that improvements could have been made that might have changed the out come.
just in my recent memory we've lost quite a few (catboats):
randy linebach
bob morgan
john tillman
joe gratton
Kevin Graff
Phil Dejana
Mohammad Al Muhairi
Jean-Marc Sanchez
those above are just the few that stick out too me. there has been many close calls and severe injuries in addition. hopefully this time changes will be made. but as history of US baot racing shows its not promising.
jim's comment on certain builders being hard headed is very much true along with some racers thinking that they have it all figured out.
honestly one of the only way to make a rule for canopy upgrades would be to increase the boat wt# and that weight increase would have to be WITHOUT fuel and ballast.
just to give an idea of what i've tried to explain to some:
if your boat weighs #8800 for a #9500 class wt, that means your short #700 lbs of material. in a traditional laminate that is hand laid-up thats 350 lbs of glass and 350 lbs of resin. about 3 rolls of 24 oz glass and a drum of resin. thats alot of material to leave out and alot of structure that could be used to increase the canopy strenght.
(side note- using a impregnator you could increase the glass ratio to 70%, further increasing the structure strenght)
the common practice is to have the boat as light as possible and make weight using movable ballast. and i'm not against the ballast just if your adding that much maybe its worth looking at the structural integrity of being so light ?????
compare that to a DW 38' that is about #200 lbs under the 10k lb limit for 850 sc for the same size boat. in simple math thats an additional #1000 lbs of laminate. which might be some of the reason the 38DW survived going over 3x with minor cosmectic damage vs how some of the other supercats have faired.
as for the autoclave, steve your saying that equal thickness laminates gain 70% more strenght over a laminate built using an impregnator (70% glass to resin ratio) and bagged at 29 HG of vacuum and post cured, say using a paint booth at 150 degrees F ? also using the same coring materials, of course.
hopefully this tragic accident hits home for those that have shrugged off canopy safety. i've had the chance to met alot of great people within the offshore world and Bob Morgan was one of them. his lost, along with the others is truly saddening and disturbing knowing that improvements could have been made that might have changed the out come.
just in my recent memory we've lost quite a few (catboats):
randy linebach
bob morgan
john tillman
joe gratton
Kevin Graff
Phil Dejana
Mohammad Al Muhairi
Jean-Marc Sanchez
those above are just the few that stick out too me. there has been many close calls and severe injuries in addition. hopefully this time changes will be made. but as history of US baot racing shows its not promising.
11-28-2011 | 08:05 AM
#172
Registered
Joined: Feb 2010
Posts: 72
Likes: 0
Look Solving for q, our friendly for holding the boat on the surface BUT Deadly in human contact, Ole "Dynamic Pressure": 200 MPH = 293.2 FPS
OK, we got .5 X 1.94032 (Density of water in the cooler) Times our VERY expensively earned FPS of 293.3 = 284.54 X That $$$ 293.3 again = 83455.582 Pressure in Pounds square foot / 144 = 579.568 PSI Think THICK composite cross-sections and throw those toy hatches in the friggin trash bin!!
In other words we are building a submarine that has to dive to @ 1250 feet or so!!!!
OK, we got .5 X 1.94032 (Density of water in the cooler) Times our VERY expensively earned FPS of 293.3 = 284.54 X That $$$ 293.3 again = 83455.582 Pressure in Pounds square foot / 144 = 579.568 PSI Think THICK composite cross-sections and throw those toy hatches in the friggin trash bin!!
In other words we are building a submarine that has to dive to @ 1250 feet or so!!!!
I'm not sure I understand how you end up with those numbers? 580 PSI is extremely high?
I'll give an example of my own (this is a rough estimation):
Check out: http://en.wikipedia.org/wiki/Drag_%28physics%29
R = ½ρCAv^2
R is the force of drag,
ρ is the density of the fluid,[12]
v is the speed of the object relative to the fluid,
C is the drag coefficient (a dimensionless parameter, e.g. 0.25 to 0.45 for a car)
A is the cross section area
Example: A 200 mph stuff. The water will hit the cockpit from the front
V=200 mph
A= 2*4ft cross section area (a rough estimation of a side by side cockpit)
C=0.5
ρ= The density of water
This will give us a total load of 1510 kN on the front part of the cockpit. This is 154 metric tonnes or 340000 lb. This is also more then the weight of two M1 Abrams tanks…
If the front area is twice the area of the cross section the pressure will be 145 PSI (10 bar) on the front section.
Big numbers!
But there are ways to reduce them!
Also, remember that this is a rough estimation.
No, but you can't just put some fiberglass together randomly. It needs engineering, good materials and testing.
11-28-2011 | 08:22 AM
#173
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Joined: Nov 2003
Posts: 701
Likes: 0
jim i totally agree with you on your statement. both MTI and Mystic are building great products. mti's last few 48's seem alot more advanced and the seem to keep trying to improve. plus mti, i think was the first to install the mask design.
11-28-2011 | 11:11 AM
#174
Skater Brother
Joined: Aug 2004
Posts: 2,541
Likes: 5
From: Wichita, KS
yes i know, i was being facetious.
jim i totally agree with you on your statement. both MTI and Mystic are building great products. mti's last few 48's seem alot more advanced and the seem to keep trying to improve. plus mti, i think was the first to install the mask design.
jim i totally agree with you on your statement. both MTI and Mystic are building great products. mti's last few 48's seem alot more advanced and the seem to keep trying to improve. plus mti, i think was the first to install the mask design.
11-28-2011 | 11:20 AM
#175
Platinum Member
Joined: Apr 2001
Posts: 10,833
Likes: 18
From: Beautiful Fort Lauderdale www.cheetahcat.com
I'm not sure I understand how you end up with those numbers? 580 PSI is extremely high?
I'll give an example of my own (this is a rough estimation):
Check out: http://en.wikipedia.org/wiki/Drag_%28physics%29
R = ½ρCAv^2
R is the force of drag,
ρ is the density of the fluid,[12]
v is the speed of the object relative to the fluid,
C is the drag coefficient (a dimensionless parameter, e.g. 0.25 to 0.45 for a car)
A is the cross section area
Example: A 200 mph stuff. The water will hit the cockpit from the front
V=200 mph
A= 2*4ft cross section area (a rough estimation of a side by side cockpit)
C=0.5
ρ= The density of water
This will give us a total load of 1510 kN on the front part of the cockpit. This is 154 metric tonnes or 340000 lb. This is also more then the weight of two M1 Abrams tanks…
If the front area is twice the area of the cross section the pressure will be 145 PSI (10 bar) on the front section.
Big numbers!
But there are ways to reduce them!
Also, remember that this is a rough estimation.
No, but you can't just put some fiberglass together randomly. It needs engineering, good materials and testing.
I'll give an example of my own (this is a rough estimation):
Check out: http://en.wikipedia.org/wiki/Drag_%28physics%29
R = ½ρCAv^2
R is the force of drag,
ρ is the density of the fluid,[12]
v is the speed of the object relative to the fluid,
C is the drag coefficient (a dimensionless parameter, e.g. 0.25 to 0.45 for a car)
A is the cross section area
Example: A 200 mph stuff. The water will hit the cockpit from the front
V=200 mph
A= 2*4ft cross section area (a rough estimation of a side by side cockpit)
C=0.5
ρ= The density of water
This will give us a total load of 1510 kN on the front part of the cockpit. This is 154 metric tonnes or 340000 lb. This is also more then the weight of two M1 Abrams tanks…
If the front area is twice the area of the cross section the pressure will be 145 PSI (10 bar) on the front section.
Big numbers!
But there are ways to reduce them!
Also, remember that this is a rough estimation.
No, but you can't just put some fiberglass together randomly. It needs engineering, good materials and testing.
11-28-2011 | 11:46 AM
#176
Registered
Joined: Feb 2010
Posts: 72
Likes: 0
Correct. The hydrostatic pressure for a flat section is 144psi at 100MPH.
So if you shape your cockpit like a brick you will see 144 psi at 100 mph.
I haven't seen many brick shaped cockpits so I used a drag coefficient of 0.5 to compensate for a more aerodynamic shape of the cockpit and an estimation of the cross sectional area, etc to get a more correct estimation.
So if you shape your cockpit like a brick you will see 144 psi at 100 mph.
I haven't seen many brick shaped cockpits so I used a drag coefficient of 0.5 to compensate for a more aerodynamic shape of the cockpit and an estimation of the cross sectional area, etc to get a more correct estimation.
11-28-2011 | 12:03 PM
#177
Platinum Member
Joined: Apr 2001
Posts: 10,833
Likes: 18
From: Beautiful Fort Lauderdale www.cheetahcat.com
Correct. The hydrostatic pressure for a flat section is 144psi at 100MPH.
So if you shape your cockpit like a brick you will see 144 psi at 100 mph.
I haven't seen many brick shaped cockpits so I used a drag coefficient of 0.5 to compensate for a more aerodynamic shape of the cockpit and an estimation of the cross sectional area, etc to get a more correct estimation.
So if you shape your cockpit like a brick you will see 144 psi at 100 mph.
I haven't seen many brick shaped cockpits so I used a drag coefficient of 0.5 to compensate for a more aerodynamic shape of the cockpit and an estimation of the cross sectional area, etc to get a more correct estimation.
Last edited by Steve 1; 11-28-2011 at 12:15 PM.
11-28-2011 | 01:11 PM
#179
Platinum Member
Joined: Apr 2001
Posts: 10,833
Likes: 18
From: Beautiful Fort Lauderdale www.cheetahcat.com
The Boat in my Avatar came off calculations both bottom and tunnel, it ran well enough to be National Champion 4 years in a row!
The reason aircraft disintegrate when striking water,it is nearly 800 times dense as the planes designed medium even with aerodynamic shapes . BTW at 144 PSI at 100MPH you are within a pound of me at 143 PSI ! I will put up 150 and 180 MPH.
The reason aircraft disintegrate when striking water,it is nearly 800 times dense as the planes designed medium even with aerodynamic shapes . BTW at 144 PSI at 100MPH you are within a pound of me at 143 PSI ! I will put up 150 and 180 MPH.
Last edited by Steve 1; 11-28-2011 at 03:18 PM.
11-28-2011 | 04:05 PM
#180
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Joined: Nov 2003
Posts: 701
Likes: 0
just curious with all the mathmatical equations going on here, whats the difference between crashing at say 120 mph vs 170 mph.
in layman's term, that is.
point being that maybe runnning boats at supercat speeds vs turbine or unlimited class becomes unsafe and overall speeds need to be looked at safety wise.
maybe sbi and opa need to start enforcing the 150 mph rule so atleast canopy designers have a cap to design too.
in layman's term, that is.
point being that maybe runnning boats at supercat speeds vs turbine or unlimited class becomes unsafe and overall speeds need to be looked at safety wise.
maybe sbi and opa need to start enforcing the 150 mph rule so atleast canopy designers have a cap to design too.
