Ruby, I was very apprehensive about switching to saildrives when we bought our cat. I anticipated more maintenance
and probably more haulouts to change zincs, fluid and seals
After 4 years and several cruises, I'm more comfortable with the sail drives and they do have several advantages: prop thrust vector doesn't angle down so more efficient power; no stuffing box with water
in the bilge
; don't have to align engine and prop shaft. I changed the seals/o-rings in the saildrive
during first haulout myself and it was an easy job. I can only drain about 60% of the transmission oil
from the top without hauling out. I change it about twice a year and the oil
looks clean and no sign of water
so I don't think an annual haulout is necessary just to change saildrive oil.
I think the biggest negative for saildrives is the large rubber grommet that seals
the saildrive to the hull
. I worry about springing leaks
in the rubber even though the condition looks good. I haven't changed grommets yet and I understand it is a big job and engine must be shifted forward. The other big negative is changing the zincs on saildrive. The props must be removed to change the zincs. That isn't a big deal on fixed props, but my folding props must be disassembled in the water... all 30 plus parts
. (The newer saildrives may have an easier zinc change without prop removal)
If I had a choice, I would still prefer conventional shafts over saildrives, but I wouldn't consider saildrives a "deal breaker" if the boat met my other criteria.
I suspect that many cats with conventional shaft drives have engines located under aft bunks also. Saildrives probably give designers a little more flexibility in locating engines since they don't have to allow for the length of the conventional shaft. The saildrive bolts directly to the back of engine and the outdrive leg goes straight down so the engines can be moved further aft.