The mizzen staysail is very nice; most times the forward staysail will work as mizzen staysail too. The secret weapon of a ketch is a mizzen spinnaker
(see my avatar which is actually our bigger brother Beowulf).
But, before playing with all that, it's more important to find out about what sailplans work on your specific boat. Do the following tests:
Start with just the main on a reach. Is the boat balanced? Our boat is perfectly balanced with just the main, but our mizzen is 70% of the surface of the main, while yours is closer to 30%. So your main mast
might be further aft compared to ours, giving you less or no balance on just the main.
When it is balanced, try sailing upwind, incl. tacking. If you can do that, you will want a heavy mainsail
with 3 reefs
for use in storms, skipping trysails, but check your rigging
(I'll come to that).
Next is mizzen + jib. You really should be able to find a balance here, use full mizzen and furl jib as needed. Measure/mark the jib in that furled size as you might want one made like that!
Next is all hoisted. Under full sails, see how the jib does and try furling
it to the size of the previous test. Many ketches use jibs/genua's that are too big, maybe your perfect everyday use working jib is the size that balances the mizzen without the main. That is what we have as our only jib (but we have a spare one).
Now try these three combinations reefed. You need more wind for that to check upwind behavior. Change jib for staysail for reefs
1, 2 and even 3 if you have that many. Is the staysail too big for all reefed down config? you'll need a smaller one! We have a hank-on staysail that can be reefed!!
A mizzen spinnaker
might have trouble with your main backstay. The Sundeers have no backstays
(roached main and mizzen can't pass backstays) so I can't advise. Also, the gap between the end of the main boom and the mizzen mast determines possibilities. But at least a reacher (free hoisted with furler) should be possible. This will be the light-wind sail there and the main staysail can be used as mizzen staysail for medium wind broad reaching.
It all depends on where you will sail too. Don't bother with spinnakers or reachers when you will spent your time in the Caribbean
. Use them means loose them here ;-)
About the rigging
and the capshrouds in particular. Many, many ketches are designed to share the load over both masts. This assumes you will always use the mizzen so that part of the load is taken by the mizzen capshrouds, many times 30% for mizzen, 70% for main. When they take a 30% safety
margin you would just get away with only using the main in high winds but you really need to upgrade the main capshrouds (and thus lowers). A good way of achieving that is using same diameter wire but switching to dyform. Same norseman terminals can be used, just different cones. Rigging books
tell you how to calculate that. When using just the main in high-wind situations, your main capshrouds must be sized to handle the full load! This load is equal to the "pull masthead to waterline" test (you don't need to do that really because it can be calculated but it is done for new designs!).
Ask me anything you need, I studied this a lot, incl. rig tuning. (ask to be allowed to help when changing your standing rigging, most riggers are okay with that and you learn a lot. I did swages, norseman and full tuning. The rigger even ordered me to buy and study a specific book ;-) )