Structural Importance of Liner?

AaronD

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Aug 10, 2014
537
Catalina 22 9874 Newberg, OR / Olympia, WA
As I was cutting more holes in my interior liner the other day (mounting a couple electrical components), I had a curious wondering: What areas (if any) of the liner are important to the structural integrity of the boat?

The simple answer might be that none of it is required, and you could cut out the entire liner without compromising anything. But that can't be quite true - the upper chainplates are often bolted to the liner (as recommended in the C-22 Association manual and other sources). Or if not the chainplates themselves, a least the bulkheads to which the chainplates are bolted. So in that case, the liner seems to be serving some structural purpose, doesn’t it?

I've seen lots of modifications that cut out chunks of the liner, adding doors or drawers to create new storage lockers. E.g.:
--https://stingysailor.com/2014/09/06/under-v-berth-storage-solution-2/
--http://www.catalina27.org/Fleet4/boatleeboards.jpg

Does anyone know just how much is too much? Are there sections of liner we shouldn't mess with? I don't have any immediate plans to cut out big areas, but it seemed like a sensible question to think about while many of us in northern climates are focused on winter projects.
 
Jul 20, 2005
2,422
Whitby 55 Kemah, Tx
If you are talking deck liner, then not much of it is structural if at all. If you are talking hull liner then yes (think hull as skin and liner as bones), it is structural and provides support to the hull, but it is common to cut holes in it for wiring and hoses, so small holes are ok.
 
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Mar 20, 2015
2,255
C&C 30 Mk1 Silver Harbour, Lake Winnipeg
The hull liner provides the structural stiffness to the hull, so when I modified the galley on my New Style C22, I made sure the corners of the rectangular hole I made for the new drawer where rounded. (to minimize the risk of cracks starting at the corner due to a sharp 90)
I also built the drawer in a box, which is bolted and screwed into both original and new bulkheads on the port side.
I also made the drawer just big enough to do the job without cutting too close to the port/starboardedges of the panel, which leaves a big frame of fibreglass around it.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
If you are talking deck liner, then not much of it is structural if at all. If you are talking hull liner then yes (think hull as skin and liner as bones), it is structural and provides support to the hull, but it is common to cut holes in it for wiring and hoses, so small holes are ok.
I agree... The overhead liner is not generally very structural, but the "pan" or hull liner is very structural... dont cut into any of the corners as they are what primarily creates the stiffness in the boat.. a few smallish holes in the flat surfaces are ok, and round holes are better than square holes, but that doesnt mean a square hole will cause a failure, but under extreme prolonged stress it would fail sooner..
 
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Nov 19, 2008
2,129
Catalina C-22 MK-II Parrish, FL
The hull liner was a Frank Butler invention that the other manufactures copied. It greatly stiffens the hull, and it's required to remain intact as-per our class association rules. The deck/cabin and the interior liner is also structurally important. They too are bonded together and have various coring materials bonded between them. Stand on the deck or the cabin top on a C-22 and you will not have any movement. Also, unlike many lesser quality boats, the interior liner is easy to wipe clean unlike some manufactures that simply glue carpet to the interiors of the cabin. I had Ken Lange, owner of International Marine, sitting in our C-22 and he was looking at the quality of the fit and finish to the interior of the C-22 and was very impressed.

Don
 
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AaronD

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Aug 10, 2014
537
Catalina 22 9874 Newberg, OR / Olympia, WA
Thanks. That's exactly what I was wanting to learn. Big doors and easy access to extra storage areas sounds nice, but I'll shy away from cutting big holes (and just keep stuffing the hard-to-reach space with extra orange PFDs, storm sails, and such).