Since then I have done the following:

1.  Removed the bilge pump as I had not previously noticed that it was wired with standard crimp connectors with no shrink tube or other waterproofing and the connectors were in the water.  After I removed the pump and disconnected the wires and made sure the power and ground wires were not in the water or touching anything, I tried again with same result, everything on the dash and PP fired up but the 60A breaker immediately tripped when I turned the key to start.

2.  Checked the battery and found only 7.8V across the terminals with both connectors removed.  It is the battery I got with the boat 4 years ago so got a new one and installed it.  Same result, 60A breaker immediately tripped when I turned the key to the start position.

3.  Read as many posts here and on planetnautique as I could find about electrical problems and have removed all 3 of the engine grounds and cleaned all the contacts.  Nothing seemed really bad but I know grounds can be problematic.  I removed the 60A breaker and, unfortunately, the plastic housing broke while I was trying to remove it so I've ordered a new one from nautiqueparts.com and hope to have it by the weekend so can't try it again until I get the new breaker.

4.  I pulled the dashboard and checked all the grounds I can find to all the instruments and everything seems OK there, too.  It appears that the dash grounds all go into the harness that goes from the back of the dashboard down under the floor and into the main harness that then is grounded to one of the 3 big round points I found on the engine block?

5.  I put a socket wrench on the engine lower pulley and I can turn the engine over.  I had the battery disconnected.

So, if you've read this far...😊, is there anything else I should be looking at once I get the new 60A breaker if it doesn't work?  I've read on here and planetnautique that a couple pf people have had problems with the 60A breaker and just replacing it solved the problem.  Although I'd be happy if it does, that doesn't sound like a satisfying solution as something is causing the breaker to trip.

Any help for a newbie will be greatly appreciated and I will definitely post the results and what does solve my problem..😊

Thanks, Ken   (for those who might wonder at my username, I had a NH vanity plate in the late 90s.  I wanted it to be FLAT H20 but NH only allowed 6 characters so I asked for FLT H20 but they wouldn't give me the space and it came out FLTH20...😊)

The starter on your 98 draws at least a few hundred amps initially

You also should mention whether this is a carbureted or fuel injected engine, most likely a Ford or maybe a stray Chevy 

The new 20A & 60A breakers will only be delivered Saturday earliest so won't be able to check anything live again until I get them.  I will remove all the connections on the starter solenoid and clean them beforehand.  I checked and they are all tight but will remove and clean anyway.  I'll also check the connections on the NSS.

I'll post again after I get the new parts and test.  Again, thanks very much for your assistance.

1. New battery (old one was dead)

2. Cleaned all terminals and connectors for the three engine block grounds

3. Cleaned all terminals and connectors on the starter relay

4. Cleaned the battery cable ends on both the positive and negative cables at the battery and starter relay (for the positive) and the battery and engine ground point for the negative

5. Replaced the 20A ignition breaker in the dashboard

6. Replaced the 60A breaker at the back of the engine near the ECU

I think the last one, the 60A breaker was probably the real culprit although I know dirty/corroded connectors can cause lots of problems.

Thanks for your help with the starter circuit info.  Tomorrow should be out on the water again...😊

Glad it's fixed.