Aft cabin hull liner thickness?

[waughoo]

I am trying to organize the boat a bit and would like tk mount my sailing dinghy's mast and boom on the aft cabin hull liner above the head of the bed.  This would require some screws to be strong enough to hold the bracket and the spars.  Has anyone mounted brackets at this location and how long of a screw was suitable to avoid contacting the hull?  Photo for location reference.

[Ron Hill]

Alex : I made a cutout in the forward part of that aft cabin liner.  The thickness is about 1/4" and the depth between the liner & hull is about 2"- 2.5".

Don't know the depth further aft but believe it is probably less?  Hope this helps

A few thoughts

[Stu Jackson]

Alex, I'm not sure what portion of the three sections in your picture you are aiming at.

The upper wood piece is like what is shown in this recent thread:  https://c34.org/bbs/index.php/topic,11093.0.html

The lower section is much like the areas behind the settees in the salon, although there are no storage cubbies there.  I'm guessing there's a similar air space there and is most likely the same thickness as it is in the salon.  Easy to check: tap on it.    If you do use this section, then I'd cut some hand holes and bolt through rather than screw, regardless of how light the gear may be.  Think of bouncing off a wave at the Eastern Entrance.

The big middle section is just hull liner and I wouldn't go anywhere near it directly.  If that's where you want to go, epoxy large wood cleats and mount your stuff to the cleats.

[KWKloeber]

Alex

FUNNY you should mention not contacting the hull.  Yrs ago I drilled a 1" hole to run a power cable behind the C30 liner.  The only problem was -- I NEGLECTED to shorten the pilot bit on the hole saw!!  OOOPS.
Luckily the space behind was just enough that I drilled **only** 1/4 to 1/2 way thru the hull.  Whew, I hate doing gelcoat!! 
Luckily also, it was behind a drawer in the hanging locker so the epoxy repair was hidden.  All that and the space was too tight for what I needed anyway so I found a different route.

Anyway, if you want secure holding a tapping screw into thin (3/16" maybe??) material isn't very secure.  Think about using epoxy/foam-ear-plug screw *anchors*  or well nuts. 
Or mount a board where you need it; epoxy-on teak/mahogany or gorilla-glue-on Starboard (flame treat the surface first) and screw your brackets into that.   
(Well nuts can also be used to secure snap fasteners to a thin liner or coming location.)

[Noah]

Accidentally drilling through the hull is probably the one place you CAN'T get away with covering your mistake bu using a big screw head and finishing washer!

[KWKloeber]

Accidentally drilling through the hull is probably the one place you CAN' get away with covering your mistake bu using a big screw head and finishing washer!

OUTCH!  that hurt.
Although I've seen worse "repairs"/installs -- like a guy who thru bolted (with HUGE hex-head bolts) a boarding ladder to his topsides, right under the rubrail.
*very* nautical-looking.   

[waughoo]

Ken... great solution.  I'll look into those.