Re: 1977 Cobalt 19BR Floor Rebuild/Engine Replacement
why is the transom assumed bad if the motor mount is?
Why if a collapsed motor mount is a known problem you're trying to address, why not post a pix of the mounts, bilge area and the keyhole.
Don't think of
assumed as the popular u & me definition, it's to err on the side of caution & to prevent costly rework later.
IF you need to redo a motor mount, its somewhat likely you'll need to pull the motor, IF you want the motor to stay where it is supposed to stay: bolted to the m/m & attached to the outdrive thru the keyhole in the transom
Now the motors out, it will never be easier to pull the outdrive & give it some much needed attention. Most boats that suffer from neglect, rot & poor maintenance in 1 area, also usually suffer from neglect & poor maintenance in other areas.
You now have unrestricted access to the mostly bare transom and can closely examine the keyhole. There is no downside to taking some core samples @1.5" deep w/ a 3/8" drill bit from the INSIDE. Wet, dark wood shavings are
NOT good, dry light are
GOOD. Around both sides, top & bottom near the keyhole, and near other thru hull attachments (U-bolts, ladder/swim platform etc). On a 19' boat, 10 samples isn't too many.
Use tape to mark 1.5" drill bit:
Once you put it all back together,
YOU'LL KNOW it's as good or
better then it ever was. No question it'll provide years of safe & reliable service.
Let's compare that to a less involved rehab, still done to maximize safety & reliability (but doesn't include any transom work, which for me makes safe & reliable suspect):
You fix everything that looks like it needs to be done, so probably remove the motor, put leave the outdrive installed, fix the m/m and a piece of a stringer or 2. They are usually in contact with the m/m (transom is too, as JIg said), as they were likely built in contact before any glass work originally, which is 1 reason they rot too. Replace the deck you removed to gain access the m/m & stringers. And put the boat back in service....
Perhaps 1 of the stringers has damage that wasn't easily (if at all) found. Maybe there was 1 thru bolt (ladder maybe) that was allowing water to infiltrate your transom. Encased in fiberglass, that moisture will eventually lead to rot. And you'll be right back where you started, taking the motor out, the outdrive off, all the exterior stuff bolted to or thru the transom, the deck (all again, for the 2nd time) and the transom, some portion of m/m, and stringers. Plus removing the entire interior again.
Will it be in 1 season, 2, 3, 5?
No way to KNOW, but it will involve redoing much of the work you're considering now, and more. Add that to the expense of doing it the 1st time, and you've spent MORE then if you'd done more the 1st time.
And you can now safely tell any & all 'welcome aboard' a safe & reliable boat.
Nobody is suggesting to take a sawzall to your boat & removing EVERYTHING w/out doing due diligence 1st. But you do need to be aware that it MAY be much more involved, much more expensive & more time consuming then you thought/planned.
. Don't put your boat through that.
