BoatBanter.com - View Single Post - replacing forward cockpit drain hose, valves, ranger 26

In article , DSK
wrote:

wrote:
What to make the spacer of? Are there commercial products available or
are we talking about cutting a chunk of rubber to fit? Are we talking a
bronze dougnut?

Well, this is what I've been doing the last couple years...
haven't seen any down side, nor read anything about it yes
or no: cutting board

Go to K-Mart (or whatever cut-rate retailer is closest) and
buy a large inexpensive plastic cutting board. The plain
cheap ones are about $3 for 2' square. It's tough and won't
rot, it's relatively easy to work, it even takes a thread
fairly well (although I have not used it for strength).

It's not too bad but it's not wonderful either. We pulled the cover off
a sea chest last dry dock and found the big12KHz transducer had
vibrated most of the threads out of the tapped holes in a 50mm thick
block of HDPE. Holes were tapped 3/4" BSW IIRC.

It'd been 4 years between inspections and a hell of a lot of use
between times. Not too bad. We helicoiled it back.

My advice is to use as coarse a thread as possible if you're going to
tap this stuff. Preferably, thru-bolt it to a backing ring of some
kind.

PDW