Controlled Flex

LOL

 

Richard, filling a void inside a boat with helium can help compensate for the inability to design light weight structures.

 

When the void is large enough, say like the entire hull, will it be unsinkable then?

 

Not likely. If the hull is compromised the helium will escape. Furthermore I suspect it may be difficult to breathe.

Perhaps 99 helium filled red balloons attached to the mast. I concede 99 may not suffice; I didn't do the math.

 

Willkommen im Club Zelter!

I know irony does´nt travel good here..............

 

I have seen a boat, actually more than one, and more than one use inflatable structures filled with pressurized air.


http://www.raiderboat.com/

 

I saw an inflatable where all the air leaked out - quite coincidentally it was no longer a usable boat.

 

That reminds me...have to find a copy of "The Boat That Wouldn't Float" by

Farley Mowat...that was a good book I have not read in a long time....should be a good read again since I now own such a boat myself ...we hopes we patched the leaks but we wont knows until after we barrier coat ....me thinks that much of the leak was simply because the bottom hadn't been painted in years and I let her sit in the bay for almost two months on a hook...Osmosis is a mother...isn't she the Mother of Osiris...and Oshuddup... ??

 

Lindsay Lord continued

I've seen on this and other forums that you've have also worked with Xynole. In those posts you were discussing its superior abrasion resistance but explaining its excessive weight in the context of small boats. Can you comment on its use with Lindsay Lord's design methodology as a structural constituent? Does it have superior structural properties in the LL context relative to Dynel and Vectra? For that matter, have you ever seen any material properties for any of these? say... Modulus, strength or non-linear stress/strain curves or anything of the sort?

Until I read some of your posts, I was expecting to use 50/50 epoxy with the 4 oz material. Fortunately, you've enlightened me about it needing far more epoxy. Unfortunately, Dave Gerr's scantlings (for LL) simply identify the fabric weight required and says nothing about epoxy or total weights. Would you have any insight on realistic fiber to resin ratios? Maybe even with vacuum or better yet... Resin Infusion? Its a little tough to determine how much lighter this technique might be without ratios.

Also, I seem to find very little about the LL technique itself or its use. Although I see it was quite successful on patrol boats, the military is often not very concerned about longevity. Would you happen to have any information on its long term usage? Are there issues with fatigue or creep?

Thank you for your time.

 

Fibre to resin ratio:
50:50 (or better) is achievable in a pro shop with skilled workers using infusion or prepreg.
30:70 is more typical for hand-laid material from unskilled labour. Careful layup and vacuum bagging can get that to 40:60 or so.

 

Yes, I've heard the 50/50 ratio for fiberglass/epoxy, however, I have read some saying this Xynole, Dynel and Vectra require far more... some said that the 4 oz (because of its far lighter density) actually "looks" the size of a 10 oz fiberglass cloth... and thus "takes" epoxy like the 10 oz.

Is this not the case?

 

By weight, yes, you'd probably end up with more resin than ideal with these exotic cloths, if you use the same techniques as for fibreglass. But you don't do open hand layups with Vectra fabric- if you're spending money on this stuff, you do it right, with infusion or a vacuum bag. And you'll certainly make some test pieces before trying anything big, right?

 

ehhrr well not purely nonsense... I had the "pleasure" og having my drawing table close to the test lab once, separated by a thin wall.... hydraulic testing of control panels, lots of tubing... When tested (by accident...) to the breaking limit, some of the tubing straighened out..., I, on the other side of that (thin) wall, concentrating on a drawings part list, with these cursed letter "rulers".... went through the ceiling, wetted my pants... so the internal forces must've been "stiffening/ straighetning the tubing, sort of. Seen the long baloons that kids like? When hard inflated, they too are "stiff"... How to use this stiffness practically in a boat design, is a bit beyond me.... So, I'm not quite disagreeing with you there, Apex...

 

(Filled with helium...)

Then everybody will have this strange way of talking.....
Man, that would've been a ship for the Israelis to board... That movie would've been a sure winner....

Sorry guys, just got carried away, will never happen again, I promise, I think.....

 

Oh certainly I'll do samples using resin infusion. However, I'd like to get some idea how much less the Lindsay Lord system will be over my current fiberglass/epoxy/foam core laminate that I have spec'd out now. If it was only say 5% better, I wouldn't go to the extra cost. I can estimate it if I know the relative density of the fibers to fiberglass.

Would you happen to know
1) the density
2) the long term creep or fatigue of the LL system
3) how Xynole stacks up against Dynel and Vectra