UK-Cherub Forum

Cherub Chat => Tech Chat => Topic started by: roland_trim on May 18, 2009, 10:53:42 AM

Title: Mast step - sleepless night
Post by: roland_trim on May 18, 2009, 10:53:42 AM: Last night I bogged in the mast step. I added some unis to take the load into the bulkheads and then some weave over the lot.

Then I failed to sleep.

When we add the deck on we will add another fillet at the bottom of the mast step/deck intersection. What are the chances of this being a stiffer load path and the core simply crushing and then failing the lot?

The mast stump is a tube, the tube is cut over the intersection of the three bulkheads (4th tail will follow soon from interesection to CB pad) Photos on:
http://www.sailingsource.com/cherub/test/doku.php/tech/bmg/20090518thats_magik (http://www.sailingsource.com/cherub/test/doku.php/tech/bmg/20090518thats_magik)

Any comments appreicated.
Title: Re: Mast step - sleepless night
Post by: ross_burkin on May 18, 2009, 12:28:50 PM: I'm still a bit tired after a heavy weekend so bare with me. Are you worried that instead of the core transfering load from the deck to the hull skin vertically, the fillet between the deck and the top of the bulkhead will just crush the foam downwards?

I'm sure yours is not not going to fail as badly as mine did...
Title: Re: Mast step - sleepless night
Post by: neal_gibson on May 18, 2009, 12:44:58 PM: good effort ross it it go right through the hull as well hope you get it fixed though
Title: Re: Mast step - sleepless night
Post by: JimC on May 18, 2009, 08:37:29 PM: If've done two stumps like that, (one Cherub, one IC) and never had a moment's worry. It would require something truly overwhelming to detach it from those three bulkheads with all that glue area in shear, in which case any failure to the core under the step would be the least of your problems...
Title: Re: Mast step - sleepless night
Post by: roland_trim on May 19, 2009, 09:57:55 AM: Thanks Jim.
Title: Re: Mast step - sleepless night
Post by: phil_kirk on May 19, 2009, 12:18:13 PM: I have done similar to you Roland. Copying the great work of Andy P on the first E-5. That appears to work ok.