• Registered: 2005-03-12
  • Posts: 101

Topic: Instrument Mounting Cutout and Structural Integrity

Like most CO26 I've seen, I have a compass on the port side of the cockpit.  On the starboard side I have a chartplotter and a depth sounder. 

My old compass has been deemed unrepairable so I'm replacing it and I thought I'd take this opportunity to move it to the starboard side also.  This would mean that the port side of the cockpit bulkhead (I don't know what else to call it but I mean the flat, vertical surface to port of the companionway) would now be flat.  This would make crew who want to lean back in the cockpit very happy as they would no longer have the compass bulging into their back.

I'm thinking of cutting a roughly 9" x 12" rectangular hole that would accommodate a panel on which my instruments are mounted.  In other words, I mount my instruments on the panel and then mount the panel on the bulkhead rather than having individually cut-out holes for each instrument in the bulkhead.  My question is this: how much of the part cockpit bulkhead can be safely cut out?  Does this bulkhead support any load at all?

  • From: Montreal
  • Registered: 2005-04-22
  • Posts: 259

Re: Instrument Mounting Cutout and Structural Integrity

I also replaced my aging cloudy old compass with another. 

On the opposite side I installed an opening portlight for more light and air.  While it necessitated a big hole in the bulkhead, it was amply reinforced by heavy bronze frame of the port.

As I recall, the bulkhead was about 1/4" solid fibreglass in that area.

If I understand correctly, you will bond a piece of 3/8 smoked plexiglass over the hole and then install your instruments on the sacrificial panel.  To maximize panel strength in the area, as well as to tidy up the exposed wires and fittings inside the boat, consider adding a frame around the inside of the hole, perhaps 3/4" x 1-1/2" tall.  The frame will strengthen the hole addressing any concern that you had about panel strength and deflection.  Finish the box with an additional teak or plexiglass panel inside the boat.  This inside panel, screwed to the frame, protects the wires, hides the backs of the instruments and greatly strengthens what is now a structural box.

BTW, the Contest 101 is a handsome option and relatively inexpensive option.  It lets light pass to the interior and can be read from both sides.

Have fun!


Christopher

  • From: Petit Rocher NB Canada
  • Registered: 2009-12-15
  • Posts: 55

Re: Instrument Mounting Cutout and Structural Integrity

Good idea to keep the crew comfortable and happy. My solution was to provide a thick stiff piece of foam with a donut hole for the compass. I also use it when sailing solo on auto.

...)))) May the wind fill your sails and the sun shine in your face cool
  • From: Praia da Vitoria, Azores
  • Registered: 2017-07-05
  • Posts: 18

Re: Instrument Mounting Cutout and Structural Integrity

I recently bought a Contest 101 to replace the clouded, half-filled existing compass.  I haven't swapped it in yet but it is supposed to be an exact fit for the old one.  It looks very nice and comes with a cover that will hopefully prevent it from getting damaged from the sun's UV rays again.  Right now the boat is on the hard getting the bottom painted so, it is something I'll do later when back in the water.  Fessalo, I like your idea of a piece of foam with a donut hole!