It is often practical to just lift
the rope rode
by hand. If you motor
forward the only weight will be final lift
to get the chain on the gypsy. The maximium weight will be the length of chain between the bottom and the gypsy.
For example with 10mm chain which weighs 2.1 Kg per metre, in 10m of water
the maximum weight, just as the chain reaches the gypsy will be 10 + the distance between the gypsy and water
(say 2m). So 12x2.1= 25.2 kg. You need to make some allowance for the friction and change in direction of pull of the bow roller, but if you can pull say 35-40 kg then a 10m depth
should be OK. This maximium magnitude of pull will only occur right at the end.
All chain rode
has a lot of advantages in chafe resistance and simply in ease of use, eliminating the transition between rope and chain.
Consider the use of hi tensile (G7 or similar) chain. This will have a similar strength to G3-G4 in one size smaller. With one size smaller you can almost double the length for the same weight.