chainplate calculations for a jordan drogue

[asdf777]

Thanks! I'm hoping to put chainplates on the blue strip, but the hull to deck joint may interfere - the bolts are sticking out quite a bit, at least an inch. The only opening to this hull area is through lazarette, and access may be problematic.



The only other consideration is using these chainplates for anchoring from the stern.

The hull thickness (top sides) is 1/8" - 3/16". Most likely 3/16" the way I remember it.

G10 seems like an excellent suggestion! I'm thinking 1/4" thick, 2" wider as you said.

So would 316 SS 1.5" x 3/8" x 12" be better than 2" x 1/4" x 12?

How about grade 2 titanium? SS 316 or grade 2 Ti? I'd be curious to play with titanium, but grade 5 is not practical cost wise.

Thank you!
Gleb

[Stumble]

Why not 2"x3/8x12? Here bigger is always going to be better. And frankly the extra weight and cost would be minimal.

While G2 titanium is fine, you would need to resize the mess of it. G5 is substantially stronger, so much so that you can go much smaller and keep the same strength. So small in fact that when the company I used to work for has a set of chainplates redesigned for G5 everyone (including the engineer) decided they looked to small and put in bigger ones. They were probably fine, but it just looked wrong.

Give Allied Titanium a call. For a couple of 12" straps with no bends I would be suprized if G5 would really be that expensive. And at roughly four times stronger than 316, you could go silly small, if we assume a design load of 18,000lbs, in G5 you would need about .15 square inches of working metal total (ie the area to the side of the bolts). I would also recommend G5 bolts, just to prevent a dissimilar metal issue. But not required.

[asdf777]

Here is a follow up. I got titanium chainplates - really cool stuff!



My shackle pin seems slightly less than 0.5" and AT made a hole slightly larger (0.520") to account for tolerance, etc., so in the end, there is almost a millimeter of free play.





Is there any shock load to worry about or it's too small? Do you think there is a way to calculate it?

Thanks,
Gleb

[benz]

Hi Gleb,

I wouldn't worry about a shockload from the hole being slightly big. But I'm glad to see you decided on chainplates instead of the cleats, since the big issue with cleats is not with them but with leading the bridle (or dockline) for that matter, over the rail with no chafe. Many drogues and parachute anchors have been lost due to chafe, so the ability to lead a bridle fairly to your drogue is of great importance.
Ben