In the standard layout the outboard is in a well with the propeller next to the rudder . A bigger rudder might interfere with the propeller in this standard setup - see drawing below on Arne's input.
I moved the outboard tc the he stern on an outboard mount and gained manoeuvrability and lots of storage space ( Brompton, dinghy, flotation etc. ). You will need a long or extra long shaft - tohatsu 6 sailpower for instance - I use a 1986 mariner 2 stroke 4hp long shaft which sometimes cavitates in bigger waves or when working the foredeck.
Drawback: you will lose the location for your Hebredian or similar. Other options are available (OGT-ii) and you might not even need the pendulum - vane to tiller might sufficee. So far I only used sheet to tiller selfsteering with good results upwind.
Adding camber and sail area to the sail will turn your boat from a docile little motorsailor into a lively little sailboat. Arne now suggests battens of 3,60 meter - mine are somewhat over 4 meters.
The standard sail hardly ever needed reefing, My current setup ( split junk rig , 5 panels, ~20m², 25% balance) requires reefing by a force 4 and I very often sail with 4 of the 5 available panels using the 5th panel in lighter winds. I recently spend a day with 3 panels upwind on tidal waters in a force 5-6. The camber will make your sailing experience noisier - 6 panels would have been better. Downwind I often reef to 3 panels as she develops a rolling motion with more panels up. Reducing sail downwind does not sacrifice much speed.
Arne's input is very useful for a non-sjr take on a better performing Coromandel and merits close attention.
Arne: a query:
How much would you add to the rudder if you had your way?
Beste groet,
Antoine