Hatch boxes and welding preparation

The dagger board is still stuck this morning but we installed supports from inside to be able to control its movement once the boat will be raised.  There isn’t much more to do but hope that everything goes well when the marina guys are here with the travel lift (at $125/hour).

One of the problematic points in the rust department is around the forward starboard hatch. 

It is right on deck and must be constantly soaked in saltwater because from inside, we can see something leaked.  The rust in one of the corners turned to a big gaping hole when we put the pick and hammer to it last year.  We had then closed it up temporarily with foam and epoxy  but the time has come to figure out what’s happening in there.  After the removal of the overheard panel, we can see that most of the vertical portion of the hatch box is rusted through.  The culprit is the same as the salon windows:  The hatch was screwed right into the wood frame, which was used as backing.  At least half the metal between the hatch and the frame is gone.  An idea pops up, and that’s a good thing because that state of affairs would normally be pretty discouraging:  Jean-Pierre the welder has in his shop the capability to do laser cutting from a computer file.  JF has been waiting for a long time to experiment with this technique, which is very precise and offers limitless possibilities.  Using Rhino3D and AutoCAD, it is relatively easy to draw a hatch box, have it cut and fabricated at the shop, possibly out of stainless steel and to insert in into the precut deck.  Since JF can draw the plan and the cutting file, as well as the cut-out in the deck, the cost might actually be reasonable.  Moreover, the wood frame, even though it suffered some water damage, is salvageable.  After sanding and varnishing, it could potentially be reinstalled.  This time though, the hatch will be bolted through.  The wood frame will be routed out to leave space for the nuts and so it’s easily removable for inspection.  Mmm… Interesting.  

The first hour after lunch is dedicated to the design of a new hatch box on Rhino:  Because the measures have to be taken off the deck and hatch quite precisely, it’s better to do this at the boat on the laptop.  In parallel to this, we realize that a mushroom vent is installed a few inches behind that hatch, probably due to the fact that this room was originally a second head.

 No need for this anymore, since it’s liable to receive a lot of spray too.  We’ll remove it at the same time.  Jean-Pierre had suggested to cut any patches with radii around, to relieve structural stress.  We ask the question on the Westlawn forum, the Yacht Design school where JF is studying.  The answer is given by Dave Gerr, the school director:  Affirmative;  Sharp corners would increase local stress threefold over the overall plate stress.  Ouch!

Then, more prepping for the welder’s visit.  We pull off insulation from under two spots that rusted through the deck, which received temporary patches last year.  It took only one hour, much less than we thought.  We’re starting to dig this metal boat thing.