Please excuse my terminology and somewhat blunt approach to asking for help but here goes.

I've a 16/2 in my canal boat that was marinised for the boat and it had run very sweet for the last 10 years ( about 2000 hours on it) Recently cruising along the canal I noted smoke coming from the crankcase breather and a distinct 'knock' - never heard before. On advice from the people who put the engine in the boat i got access to the engine via the crankcase 'door' and under one cylinder these were pieces of metal, small  - on showing this to the installer they suggested it was the big end shell bearing.

On that side I can introduce same 'knock' by grabbing the bottom of the conrod and feeling some movement which i assume means the big end 'shell bearing' has failed. i suspect the smoke was the bearing heating up during its failure. I may be to blame for this as I had not completely filled the engine to the top mark on the dipstck   -I assume therefore the bearing has run dry and hot hence the smoke and bearing failure ?

The same engineer suggested unbolting the conrod and checking for wear/damage with a view to replacing the bearing. Now I have seen there are different thicknesses of replacement bearings shells to ( I assume) account for wear such as I may have. He suggested this should be an easy thing to do and check... he's experienced I am not

My questions to the enlightened is ..... is is a relatively simple thing to unbolt the conrod via the open side of the crankcase. Then is it a matter of checking the surface as well as measurements of the shaft the conrod bearing clamps to. If there is not real wear replace the shell bearing with like for like .... if there is wear replacing the shell bearing with one to compensate for the wear?

Obviously if the crankshaft surface is damaged too badly i expect that it is the crankshaft out to have it build up and turned back to spec?

Sorry if my questions are basic and contain incorrect assumptions and or terminology. I'm struggling to get anyone to take the work on and I may have to get my own spanners out .... hence the questions ?

Any observations/experience or feedback gratefully received

Nev