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Construction question on an O’Day 272

ct272

.
Dec 22, 2020
3
O'Day 272 Westport
Hi, I recently had to replace the thru-hull connector for the bilge pump in my 1987 O‘Day 272. While the connector was removed I had the opportunity to see both the outer fiberglass hull and the inner cabin liner.

I had expected to find some type of insulation material between the two pieces but I was surprised that the gap between the two walls was empty.

I am a new owner so I don‘t know what I was supposed to find there. Does anyone know where there is supposed to be balsa coring or some equivalent material in the O‘Day 272. Any thoughts are appreciated.

Thanks
 

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Oct 22, 2014
15,712
CAL 35 Cruiser moored EVERETT WA
This space between the liner and the hull is normal. The inner liner is a shell that contacts the hull in various places. These contacts are designed to maintain the hull in the designed shape. To stiffen the hull.

The thru hull is designed to be fit to the outer hull. The better designed thru hulls have a backing plate attached to the inside of the hull. Here is info on how it can be designed.
 
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Ward H

.
Nov 7, 2011
3,076
Catalina 30 Mk II Barnegat, NJ
Yep, as John says, it’s common to find a space like that between a liner and the outer hull. And the nut holding the thru hull in place is designed to be against the inside of the hull, not against the liner. From your photo that appears to be the case.
If the nut is against the liner you have to be careful not to tighten the nut to the point the hull or line flexes in. To prevent this you can fill the gap with a spacer or thickened epoxy.

The better designed thru hulls have a backing plate attached to the inside of the hull. Here is info on how it can be designed.
I don't think this pertains to your question or your above the water line thru hull. That link is for below the water line thru hulls with seacock valves which will be stressed when opening and closing the seacocks.
 
Jan 1, 2006
5,953
Slickcraft 26 Greenport, NY
Just to clarify a little, the liner is not part of the hull. It is essentially cabin furniture which does serve to stiffen the hull. The hull would be quite flexible without the deck, bulkheads and liner. Wooden cabin furniture serves the same on older boats. But due to the labor of joinery is more expensive to build.
 
Jan 7, 2011
2,766
Oday 322 East Chicago, IN
This space between the liner and the hull is normal. The inner liner is a shell that contacts the hull in various places. These contacts are designed to maintain the hull in the designed shape. To stiffen the hull.

The thru hull is designed to be fit to the outer hull. The better designed thru hulls have a backing plate attached to the inside of the hull. Here is info on how it can be designed.
The photo the OP posted is an above-the-waterline thru hull.

I am in the middle of replacing all 8 of mine (Various sizes).

Greg