Hey guys,
I pulled the water tanks out of my boat to clean/sanitize them since they were full of moldy, nasty water. I'm replacing all the hoses and everything so it made sense to pull the tanks too. Once I pulled the center one I noticed what looked like some previous repairs done to an area under the tank. The area appears to be just above the prop-strut but I'm not 100% sure. I assume it didn't leave the factory looking this way, but the glass holding the tank in place looked factory so I'm just not sure.
The tank has a crack in this location, so I'll need to replace it. How would you guys go about correcting this? Grind the glass so it is flush? Grind it down to bring back the channel to move the water in to the bilge? Fill the channel behind the bump with epoxy coated plywood/glass so it doesn't hold water, and then grind down the bump so it is flush?
Suggestions/Recommendations would be much appreciated.
'86 Catalina 36
Work in progress!
You've correctly surmised that this "bump" is the attachment for the prop strut. I unfortunately had to redo the strut last year, so, no, you can't grind down that bump. The bolts holding the strut are just below the surface; indeed, there is an indentation in the hull at that point for the strut, so the bump in fact represents the actual hull shape (on the outside, its just filler that fairs out the cavity). See the drawing in this link:
www.catalina36.org/members/technical/maintenance/replacing-prop-strut
By the way, I spoke with Gerry Douglas about this last year, and he said that if the strut is properly bedded there was no reason to glass over the bolts, but grinding off the glass is not going to solve your problem of the protrusion cracking the tank. Probably need to add some shims to make sure that the bump is not stressing the bottom of the tank. I think another member posted about this a few years ago, so try a search on that.
As to the water accumulation issue: On our boat, the cavity aft of the strut bump was filled with expanded foam (I gather from a prior owner), and after redoing the strutwhen redoing the strut I filled it in again with spray in foam insulation (the stuff you buy in a hardware store in an aeresol can). There will probably still be some water that gathers there, but most of it will be displaced by the foam. More discussions are here:
www.catalina36.org/forum/technical-discussion/water-pooling-aft-drive-shaft-strut
Bottom line is: no, you can't just "Grind it down to bring back the channel to move the water in to the bilge" - no such channel ever existed, because of the hull shape.
Matthew Chachère
s/v ¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY
Perfect! That is exactly the information I was looking for!
Thank you so much for taking the time to answer my question, I really do appreciate it.
Once I get the new tank in hand I'll glass in some additional support for it so I don't have the cracking issue in the future. I'm also going to cut some plywood strips and use some thickened epoxy to fasten them in place, then go over it with a couple layers of glass to seal it up and prevent any water from pooling there.
There is also a spot in the bottom of the aft cockpit locker that also holds water. Most likely drains out when you're out sailing, but might as well fill it in and not have a spot for water to sit.
'86 Catalina 36
Work in progress!