In theory they are no problem - split anodes are coming in on new designs of saildrives, but they are designed for the job and don't use the adaptor plate you will have to buy to use them. They have never caught on here, perhaps because they are so expensive if purchased in the UK (note they have dropped the price dramatically in the US). Also the standard Yanmar anode is relatively cheap, seems to last longer than Volvo - a bit bigger than the old single piece Volvo - and not difficult to change. If I had a Yanmar, don't think I would bother.