31 January 2013

The crucial duty of the compression post.

A Hunter owner asked me about rebuilding his compression post; and my comments on the Hunter Owners Web in response are probably worth something; so here they are--

http://forums.hunter.sailboatowners.com/showthread.php?p=996161#post996161

And here are some pics that go with it--


This is what Hunter gave H30 owners-- it is NOT a compression post.  This is the view looking through the bilge.  Apparently this corroded object purports to support a piece of mahogany, which supports a piece of aluminum, which supports the plywood sole, which supports a teak block of some kind-- and all of it transmitting the load to precisely the wrong place-- the top of the keel.


Here is my post; and below is how it is supported.




The pic below shows Diana's bilges before I installed the sole (half of it is in place to starboard). Thejoists are all 5/4 mahogany, cut and fit to the hull and bonded with 5200; the post stands on a doubled one abaft the main bulkhead. Note that none of them are in contact with the actual bottom of the hull. The goal was to spread each one's load to as much surface area as possible. Note the limber holes and bilgewater spaces, access for keel bolts, and the central joist having cleats to accommodate the leg of the drop-leafed table (looks like a tripled joist). The part on top of the can that looks like 2/3 of a joist goes in the head compartment.

The electric bilge pump goes in the space farthest aft in this view.  The manual pump's pickup goes in the farthest forward space in the main cabin.

Under each settee is a water tank and a house battery, so all this weight goes here, not to the ends. The red and yellow wires tie the batteries together as one bank.  The orange wire is for the voltmeter.  These will be restrained in fairleads later.

The PVC freshwater manifold (second big space from bottom) connects the two tanks, one under each bunk.  Unfortunately the head sink will feed from only the port one.  There are independent shutoffs, port and starboard.  The valve to the back is the drain, so either tank can be selected to either drain or supply the galley sink.  The black thing is a particle strainer.  Under the galley sink goes a proper cartridge filter.

The hull drain has since been added, under the tanks' drain.  It is removable from inside-- the better to facilitate inspection and maintenance (and to streamline the underbody).

The brown dirt is pretty much bonded into the spilled epoxy and will have to be sanded off and painted in Bilgekote.




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