nb Innisfree

FWIW when fitting out Innisfree I finished up with about 14 holes in the hull for skin fittings, about 2" if memory serves me right, bi-metal hole saw in 6mm steel, tried slow speed with plenty of lube but got bored (bored ha ha) after the first two so experimented with a long side handle higher speed no lube and loads of pressure, it worked a treat, very tiring but quick, same holesaw and it's as sharp now as it was then (2004) drilling through quickly before heat could build up helped. At first I made up a special threaded rod and spring with a nut to apply the pressure evenly but by the time I'd set it up I could drill straight through manually. I would drill a pilot hole first then slowly and carefully start with the hole saw, once it was biting evenly I attacked with full speed and pressure, knack was to carefully keep drill at 90 deg to metal. I'm not suggesting anyone tries my method but for me it worked very well and saved a lot of time., took me less than a minute to bang it through before I was knackered! ETA: Only downside was it made my mains JCB 550 watt drill smoke! It survived but gave up.the ghost after a few months, heavier duty one would have been better.

Seems to me the doodlebug detector coil needs replacing, either that or upgrade to a mysteron system.