Composite Vs Aluminium hulls
 

I have a customer that wants to get an extreemly fast offshore vee bottom. I have given him my suggestions, and now I want to show him what a wealth of knowledge this board has to offer. :D
Please be specific, pro's and cons for each.
We are looking at 1200 to 1500 hp,not turbine.
140 to 150 mph max.
Pacific style water, big swells.
Thanks,
pat W

a 39 or a 47 Fountain Super V ( the real super v's not the new super B's) canopy race boats can run at this speed if tall gears are used. I hope he has some experience at running over a 100 in the ocean. Over a 120 is a real hand full. Talking about it and actually doing it is some very serious ****.;)

39 SUTPHEN with a pair of 1500 HP Bandit engines with numberVI dry sumps will run 125 to 130 in almost any water condition. Good Luck

I love Richie, but the 39' Sutphen is too small for this task. The Fountains and Hustlers are not up to the rough water aspect...."Fast won't last"...... Probably will carry more top speed than the following...but what good is that if you're upside down.

Three choices at present......

Apache 45-46 (whatever).....Excellent rough water many available used... probably triple engined........ 125-135

Larry Smith Scarab... Still available new...triple engined 125-135

Cougar 45- Aluminum or composite..... Awesome in rough water but may have too slow a bottom design to move much over 125.

Again this is lethal speed area........ Who is throttling this bad boy? Please don't say "Highly experienced pleasure boater with over 3 years behind the wheel of his Mariah."

T2x

We will be keeping the speed limited by ratio and prop. The customer wants the potential to do that speed. What I am after is the durability of hulls and the different problems occured over time. Why aluminum hulls are no longer used ect.. Why composite hulls delam ect... can a state of the art boat last?
Thanks, pat W

my Phantom with 1300's ran 130 but Shifter said 140 to 150. 125 -130 is miles away from 140 -150 in a V-bottom. 47 Fountain (Popeye) will probly do it with tall gears. Next would be a 42 Outer Limits with say at least 1400's. The rest of the builders are not gonna get you there. My opinion and from experience.:D

My customer has a boat in mind. It is aluminum with a canard that is active via gyro and has a lifting style wing on it that was like Buzzi ran in class 1 in the late 80's. So with that kind of power to weight it should scoot right along. The problem is the hull.. If alu is so good what is bad about it. I know the problems with composit.
Why don't more boat builders use aluminium?
I just want to give him every option before he gets too far into a deal.
pat W:confused:

Aluminum: Keep a rivet gun and a rubber mallet handy!:eek: :eek: The finish is terrible on Aluminum along with the bottom never holding a Blueprinted state. FRP: Today with all the vacuum bagging, epoxy resins and core materials, I personally think you just can't build a better boat with that process. Most builders are really getting it down to a science now, and it should be trusted not to come apart. Just don't demand that they take out alot of the glass to save weight. The vacuum process will save you plenty by removing the excess resin that is not needed. Just my 2 cents. Good Luck with whatever material you choose.

Pat,

For what it's worth I think the comment on Fiber Reinforced Plastics being able to hold their intended shape is the answer to this one. A bottom capable of that speed most stay stable and not take a set on impact.

If you look at the physical properties of the two material options you will generally find that the two are close on tensile strength given various laminate patterns however usually the composite must be thicker, thus the advantage to aluminum in thinner section (Example an airliner skin). But when light weight creates the need for high flexural capability (Flex Modulus) then composites gain the advantage.

In high speed boating the impacts are enormous and in most cases localized on impact. Thus the need for Flexural strength to absorb, flex and return to shape. But remember that a composite is only as good as the manufacturing methodology and adherance to process. Poorly or quickly done the aluminum is more reliable.

Last comment, in most cases FRP is more easily shaped in the complex shapes that a high speed hull requires. Aluminum would require forming that will strech the metal and potentially create residual stresses or lower physical properties in localized areas.

Hope this helps!

Mark

look at it this way aluminum is recycable so after you destroy your boat you still can(no pun intended) get some money out of it.