Alternative to marvelous Buccaneer 24

I would have thought in the local area of compression some Sglass would be more appropriate.

 

Mixing glass and carbon is probably only going to work if the layup is engineered by an expert.

They have drastically different responses to the same amount of deflection. The carbon loads up much more for the same deflection. This property is quantified as the modulus of elasticity. High modulus material feels stiffer. Carbon is at the top for high modulus, glass is near the bottom.

 

Gary
Always admire what you do.
Question as am only on phone and pic a bit small but is that cedar core in foils?
Was core failure/compression a factor in prior fail point did you notice?
Cheers
Craig and the Ezifold team.

 

That's the part i needed to know, thanks Gary

 

Thanks, that's an excellent explanation !

 

My boats get a tough life moored in tidal areas and therefore spend an amount of daily time sitting on the hard - and when it blows savagely, the wing masts develop frightening power - and if the boat is abeam the wind, it will angrily turn into it when the tide begins to lift it. That puts large and jolting loads on the poor foils (there are packer skids lashed beneath) ... and I think Groucho's foils had already been damaged and weakened before they broke on the last trip. And yes, I think the core collapsed before the carbon let go.
I use a mixture of oregon, sometime kauri, sometime red cedar for the core planking, (the thickest areas are in oregon) then grind out hollow areas where the loads are highest for the carbon layers.

 

Gary
Thanks for that.
Reason I asked is we have incorporated lifting foils on our Buc test mule redesign, in talking with the guys in Auz on purple haze they have foils engineered by VPLP and I was somewhat surprised the core is timber ( don't quote me on that as I can't get back far enough in messages to find the lay up) anyway our convention given our test program is to go with non cored carbon to the high load areas as it seems you are now doing but the engineers can fea that. In talking with the guys in Auz in the race scene the foil compromise area in the ones that have let go would seem it could be core crush as the primary fail point followed by materials critical failure to follow. I firmly believe we learn more from what didn't work with our engineering than we ever do from what works especially when pushing boundarys.
I'm in Auckland late this month and would be great to catch up with you if you were around would like to know more about Mirandas performance differences etc.
Regards
Craig and the Ezifold team boats get a tough life moored in tidal areas and therefore spend an amount of daily time sitting on the hard - and when it blows savagely, the wing masts develop frightening power - and if the boat is abeam the wind, it will angrily turn into it when the tide begins to lift it. That puts large and jolting loads on the poor foils (there are packer skids lashed beneath) ... and I think Groucho's foils had already been damaged and weakened before they broke on the last trip. And yes, I think the core collapsed before the carbon let go.
I use a mixture of oregon, sometime kauri, sometime red cedar for the core planking, (the thickest areas are in oregon) then grind out hollow areas where the loads are highest for the carbon layers.[/QUOTE]

 

I'd skip the cedar, fir/oregon is a lot tougher especially if you can find tight grain samples from higher/colder elevations.

 

A place I used to work used a technique with foam cored foils whereby after the foil was shaped, the thickest part of the foil was routed out each side for the staggered uni's each side.
Before laminating though the foil was cut into sections. The front and rear were cut off and then cut again fore and aft, a double bias was glued in and then re-assmbled, this made finishing the trailing edge a lot easier. The thickest part of the cord was cut into 3 and then re-assembled with the double bias to help prevent crush. The whole board was then glassed in DB, then the staggered uni's down the cord starting full length and tapering off, and finally a covering strip of DB, on larger boards the Db went all over with another double up on the leading edge. Never had a failure in the 4 years I was there.

 

Reuben
Bit of thread hijack, we use similar method then I beam section as per (1st pic) then backfill trailing edge epoxy mix each side then recess board edges and kevlar (2nd pic) makes for a bullet proof rudder or daggerboard, am unsure how it would hold up in the lifting foil build though.
Quite tempted to run the numbers for (something like the AC guys did with titanium inserts replaced with) solid carbon skin to skin laminates between I beams of carbon in highest stress areas as per last sketch.
Cheers
Craig and the Ezifold team

QUOTE=redreuben;725786]A place I used to work used a technique with foam cored foils whereby after the foil was shaped, the thickest part of the foil was routed out each side for the staggered uni's each side.
Before laminating though the foil was cut into sections. The front and rear were cut off and then cut again fore and aft, a double bias was glued in and then re-assmbled, this made finishing the trailing edge a lot easier. The thickest part of the cord was cut into 3 and then re-assembled with the double bias to help prevent crush. The whole board was then glassed in DB, then the staggered uni's down the cord starting full length and tapering off, and finally a covering strip of DB, on larger boards the Db went all over with another double up on the leading edge. Never had a failure in the 4 years I was there.[/QUOTE]

 

core material

Since I am about to build several foils, I have been experimenting with available core material. I built my past foils with foam and various combinations of wood/carbon/glass, but this time I am trying to improve my product. I have never completely trusted the carbon/foam central beams, and have repaired several broken one from builders, so I am looking for alternatives and suggestions. Wood has the advantage of stiffness, but some of the plastics from my local building supply (trim and other products) seem pretty adaptable also. I have been using my shop press to do some "destructive" testing, and I will report what I find. So far, a PVC trim board looks promising to use as a core with a carbon wrapping. It is less crushable than all but the hardest wood, it is about the same weight, and of course it is not affected by moisture. The carbon carries the load anyway, so the difference in stiffness from wood cores doesn't seem to make much difference. The PVC is also readily available, and cheap
B

 

Bruce
Design laminates with care after 30 years at it often the core is the primary failure point over looked in the failure analysis no matter what the core is or how much of it isn't left between laminates. A locally made set has 5mm core between solid carbon, they are failing and core compression's where primary fail point is, I'll find the photos the guys sent us for comment and email you Bruce.
Cheers
Craig and the Ezifold team

 

Many boat shops use a pvc core of around 70-80k because thats what they have in stock for hulls and decks, reality is foam density for foils should be closer to double that. imho

 

Michael, for some reason replying to your boatdesign message regarding 3 Devils, is blocked - so I'm replying here.
The original 3 Devils I've now decided is too mean; it's just a purist racing tube and living aboard would be complete hell. So I've redone the main hull with a little more volume. Because I've learned from Sid that that boat is also too cramped and hellish for anyone down below. Alright for one person if you want to sleep - or sit with your head out the hatch - but that is about all.
So new 3 Devils would allow two/three crew ... but one on deck sailing while the others sleep.
Your building in veneers/epoxy would be fine - but 9mm is quite a thick laminate - but would be probably more suited to your near offshore waters.
I'll do some more re-thought drawings (of complete boat, including rig). Meanwhile here is a recent 3 Devils effort - which still looks over-the-top in terms of masochism to me. Send me your email address. Mine is: coxcreek@slingshot.co.nz
cheers
Gary

 

Gary, thanks so much and sorry about the email.
i forgot to update my email at these forums.
But it's updated now.
Too mean ?!? Bro i'm as spartan as an apache.
i'm only looking for a pilot like cockpit with a sliding canopy of plexiglass and foot peddle rudder controls and i'm good to go.
If the cockpit seat can fold down into a cot, well thats all frosting.