Michael replied:

Hi Peter, Try Zemco brand of trip computer, they have been around for 25 years making the things, very reliable, i bought one in 1980 , 28 function. A company in North sydney sells them. If i can remember the business name , i will reply again. Hope this helps. Michael

Member - David replied:

Also, you may pick up a cheap ex-rally HALDA..or a TERRA_TRIPA bad days sailing sure beats a good day at work