Hi Sailorman Ed,
Sounds like the same issue as I had with a newly purchased catamaran
about a year ago. The boat (a 38ft Maxim) came equipped with a couple of Yanmar
SD20 saildrives, and the boots were coming off. I daresay that different makes of catamaran
may have different arrangements for seating the saildrives, but mine are mounted on the top edge of a fiberglass
tube (about 10 inches in diameter) which is an integral part of the hull
, and which flares out to about 12 inches wide where the shaft of the saildrive
exits below the bottom of the boat.
In my case I felt that one of the reasons that the boots were coming off was that the area of the boot actually glued to the bottom of the boat was minimal, and hence I had 2 wooden inserts made up (from 2 inch thick wood) for each saildrive
which were glued into the shaft either side of the saildrive, and flush with the bottom of the hull
. If you do this, take care that sufficient space is left to extract the saildrive upwards if you ever need to do this. The wooden inserts, once faired with the bottom of the hull, then provided a significantly increased surface area to which the new boots could be glued.
I would recommend new boots, and gluing these down after the surface to be glued has been thoroughly cleaned, and if necessary filled and faired to make it even.
The other maintenance
things I did at the same time were to clean the saildrive up inside the tube as far as I could, and have it painted with a suitable anti corrosion paint
(the sail drives are alloy so a special paint
is required), and (if you raw water cooling
system draws in sea water
through the saildrive) to thoroughly clean out the water
intake to ensure that there is plenty of cooling
water being drawn up into the cooling system.
Best of luck with your repairs