Forgive my ignorance but are there any general rules when it comes to motor sailing ? should it be jib first/ only. Mainsail only etc, which conditions favour which sail configurations ?. Any ideas would be very gratefully received,
Rules for motor sailing? Not really, apart from the upside down cone which despite being prescribed is used by hardly anyone.
Main only can be when motoring nearly into the wind or you had it up anyway when the wind dropped - best to avoid the thing flogging by sheeting it tight or even a tad to windward if there is no true wind.
Jib only tends to be when it has roller furling and laziness or some other reason makes it easy to unroll and add a bit to the motor or you're going downwind and you don't want the boom/gybe scenario - again you don't want it flogging but it needs some wind to stop that. Both and motor when there's a bit of a breeze but you want to go faster. So it's entirely up to you what you do - you can even main, genoa and spinnaker + donk, if you want!
My personal recommendation is to not bother with the motor at all and enjoy the peace.
I see you have a trailerable Sportina, so I guess you have an outboard rather than an inboard. An inboard diesel can be left ticking over very economically at fairly low revs when the wind is light and you need to add a knot or so to your speed, but owners of boats with outboards rarely do this because outboards are generally noisier and less economical.
A common motor-sailing scenario is when you are hard on the wind and you need to get a bit closer to the wind and minimise leeway to make your course, or when you need a bit of help punching into a head sea. This is generally not the most pleasant part of sailing, so in these circumstances a bit of engine noise is a small price to pay for getting there quicker.
It can also be worth keeping a bit of main up sheeted in hard even when there is little or no wind and you are motoring, as it can damp the rolling. We have on occasion kept a scrap of genoa up or the triple-reefed main for this purpopse, but It may make the sail slat and bang and put strain on the gear though, so you have to suck that one and see.
The Sportina should be fast and close winded, so I doubt if there will be many other times when you will feel compelled to motor sail any great distance, but if you do then I agree with Marisca - pretty much anything that works for your boat goes; just be careful not to get a rope round the prop if you are doing fancy sailing stuff with the engine in gear.
FWIW, when cruising & unable to make a point or a narrow passage under sail in a head wind, I use the engine. If it is likely that I will be able to free off & sail again shortly then the main will stay up, but the genny will be rolled away to stop it flapping & slowing me down. I wouldn't normally use engine & sails down wind as the sails will be backed by the forward motion unless the wind is strong enough to provide a decent speed - in which case, why waste fuel in the engine?
