Loose or dirty connection somewhere???

Yep agree there is likely to be a loose connection of some sort. Check all connection from battery to starter and any earth connections are not loose.  It could even be a isolation switch fault just by pass it and see what happens.
Best of luck

No worries  its amazing what a bit of salt water can do on connections it does not take long

If you have access put the volt meter on starter when trying to start it to see if its getting full juice as sometimes the starters can get lazy if brushes wearing out. If that is the case then you at least know its the starter and if not its somewhere in the cable or switches.

have you tried another battery tim - its possible to get a bad battery of the shelf - run some jumper leads from the car to the boat and see

Whats the "wiring loom"???

Daggy1 wrote: Whats the "wiring loom"??? Seems like once the power gets to the motor or tilt switch then there is heaps of juice. When out on the water for a couple of hours it starts fine. Seems like overnight a gremlin plays around with something to stop things working the next day. Have tried Outboard Clinics testing, awaiting diagnosis. Cheers

Sounds a bit similar to a problem I had with my Lada Niva years ago, refused to start first thing in the morning but was fine once I got it going, or if I tried later in the day. It was moisture/condensation getting into the electrics overnight. The auto electrician sprayed distributor etc with some stuff that left a waxy coating - no more problems - apart from the fact it was still a Lada

Daggy - I have had exactly the same problem with a mid nintees Yamaha.

As mentioned above, check all the crimps terminals at the end of the earth and +ve cables. Give teh wire a bit of a twist and pull where it enters the connector. They can corrode and not be at all obvious until you suddenly find that they pull out of the connector and drop corrosion gunk all over the floor. The other most likely culprit is the battery isolation switch. They are also a common problem point. Try putting both cables on the same terminal of the switch to take the switch out of the circuit and try starting. If that sorts it, get a new switch and wire it back as it was originally.

Sanandy was right. as was Tobez when he did the service - I bypassed the battery switch and it was all go. So got myself a new switch to install over the weekend. Thanks for your ideas and help.