I think the DCA may be interested in a modification I have made to my Heron.

My boat is eight years old, and since buoyancy bags do not last for ever, I began to consider how to proceed. Class rules now permit built-in tanks, and I was interested to note that a rectangular hatch is optionally available in the stern deck, giving access to the rear tank. Any member of the DCA is naturally interested in dry carrying capacity, so of course I planned to include this option.

The modification I have made to otherwise standard specifications is that the hatch cover is made with a Perspex top surface, through which it is possible to see clearly a chart mounted on a sub-frame. This new arrangement has been in use and on test during the course of a week’s day-sailing on the River Blackwater, and so far it has proved useful and snag-free.

Given the idea, construction is quite straightforward, in the main. Having already completed the stern deck and hatchway, the frame of the hatch cover is built of four lengths of 1” by ½” softwood, with halved joints at the corners, To this is added a 3/16” ply flange, which carries self-adhesive rubber sealing strip below, and the Perspex top. My flange was constructed from four strips with mitred corners (like a picture frame), though a single piece of ply could be used, with the centre cut out later.

The third stage of construction is to add, to the lower surface of the softwood frame, a piece of ply which is to support the chart. This piece of ply is the same width as the frame, but is 2” less than the fore and aft dimension, so, when fastened to three sides of the frame, there remains a 1½” gap through which the folded chart can be slid into position.

Stage four is to add a crossbeam, about ½” by I”, below the chart table. It has two ⅜” holes at the centre, to receive shock cord (and a safety line) to hold the cover in position.

The structure is now almost complete. After checking for a 1/16” of clearance all round, the cover can be varnished, and the Perspex (I used the 2 mm thick kind, which has proved strong enough for a 14” square window area) is attached and sealed with Bostick, which needs to be applied more generously than usual. All that remains is to add the rubber strip under the flange, and fit the shock cord and retaining cord.

The size of the ‘chart table’ may be dictated by the existing structure of the boat, but I would advise making it as large as is feasible, if only to minimise the amount of folding and refolding of the chart.

Be prepared to have to raise the rudder, to give clearance for the tiller: the Perspex will be nearly ½” above the general level of the stern deck. And lastly, if anyone knows how to make a tiller out of Perspex, I’d like to know!