I have just discovered that the corrosion in the deck backing plate on Avy-J is far more advanced than I thought, and it looks as though it will be necessary to build a new chainplate. The raked transom (raked at about 45 degrees) means that this is not as easy as it might be on a flat transom.
The existing arrangement (shown below) has the transom plate embedded in the hull, connected to the top (deck) backing plate with the transom plate and the deck plate triangulated by two struts of metal. You can get the general idea from the diagram below (not to scale - the plates are not as big as shown relative to the transom height)
The simplest?! solution seems to be to create an external chainplate in one piece running up the transom and folding over the deck, then instead of using two separate backing plates behind the transom and under the deck to make a continuous bent backing plate to mirror the external chainplate and to triangulate that in the same way as the existing arrangement.
Obvious initial questions are:
- How to get the external and internal plates made up with the bend angle correct
- Whether or not it would be acceptable to bed the transom backing plate on top of the current embedded chainplate piece and bolt through
Proposed construction material is 6.9mm A4 stainless (left over from bow roller).
As always, the panel's thoughts are all very welcome.