Author Topic: Crack On Inner Transom Surface - C-500 (Read 5627 times)

featherbowler · « **on:** September 03, 2019, 04:33:40 PM »

Hello to All!

I had leaking into the drain plug well of my 1981 C-500 (1984 Evinrude 115 HP engine) and found that the mounting bolts for the engine bracket were loose enough to turn by hand using just a socket, no wrench. While tightening to a suggested 45 foot-pounds of torque using a torque wrench, I heard a 'pop', and stopped the work. Upon inspection, both of the lower, 'inside the boat' washers (rectangle-shaped, roughly 15/8" by 2"), had recessed slightly in the black fiberglass (?) coating they rest against. There is no cracking of any sort on the outside that I can see, and a check of the upper bolts showed that those were torque to no more than 15 lbs. of torque. I'm loathe to check the applied torque of the lowers (by stepping-up the lbs. of torque in increments) until I get things figured out. I'm concerned about dry rot in the transom, of course.

How much trouble I'm I looking at, and how should I proceed?

Thanks!

featherbowler · « **Reply #1 on:** September 03, 2019, 04:41:47 PM »

I think that the washer has sunk to about its own thickness, especially along the two lower edges. The white 'line' that extends vertically from the '9 o'clock' position is part of the cracking.

As a note, I called the factory a few years back, and they said that they had no record of my style of C-500 being made, and yet I have seen a couple while doing Google searches. The back bench was switched out for 'cafe' - style front/rear seating, so as to make way for the ski rope attachment pole. Were these boats 'factory specials'?

Thanks again.

Plugcheck · « **Reply #2 on:** September 03, 2019, 05:38:09 PM »

Sounds and looks like a rotten transom. If it's that bad up high, it's likely worse farther down. If there is no visible cracking in the outside fiberglas, that is good. Best way to further check the transom is with a drill, but don't go all the way through, about 3/4" deep will do. If it pulls good chips you're ok, otherwise mushy is bad.

Hyperacme · « **Reply #3 on:** September 03, 2019, 08:09:36 PM »

Welcome to the forum Featherblower !

Would guess the caulk / sealant on your motor bolts failed and allowed water in, wood is rotted and washers and bolts are crushing it.
Water will soak down and is most likely rotted below bolt holes
My speedo tube hold down screw holes were not sealed or not sealed well, water got in and rotted wood down and over to hull drain hole. Hard to see in picture (speedo1) but I removed the wet, rotted wood with just my fingers.

There a CVX16 rebuild thread here, to give you an idea of what's involved ..
http://www.classicglastron.com/phpbb/viewtopic.php?f=34&t=6642&sid=c90435cac54d2c6f3632443e3d5b778f

There are better / newer methods of rebuilding it also, which I can link to if you like ...

Your hull / stringer / transom will be the same as the CVX16 in the rebuild thread.
Some just put plates on and hope to get a few more years out of boat.
Depend how much you like the boat, if worth fixing right or put a band aid on and hope for the best ..

Hyperacme · « **Reply #4 on:** September 03, 2019, 08:30:56 PM »

Yellow Metric / C500 ..
Could you post or PM me your HIN ? It is on the right side of stern, just below rub rail ..
And more pictures of your C500 .. please ..

Heard one story that six ( 6 ) were made for a promotion in Canada.
Another story .. They were a splash ( copy ) of the C500 by a company in South America ( Brazil ? ) ..
But with five ( 5 ) in North America .. That didn't sound true.

All seem to have early to mid 70's CV style seats.
Metric / C500 are kind of rare, only made for two years, and your yellow one is very rare ..
I've seen five now .. Unless yours is one of the boats I'm posting with a new reg. number.

Yellow Metric / C500 #1

Hyperacme · « **Reply #5 on:** September 03, 2019, 08:34:50 PM »

Yellow Metric / C500 #2

Hyperacme · « **Reply #6 on:** September 03, 2019, 08:38:18 PM »

Yellow Metric / C500 #3

Hyperacme · « **Reply #7 on:** September 03, 2019, 08:41:57 PM »

Yellow Metric / C500 #4

So the guy from Brazil .. who never posted a picture of his .. and now you .. make 6 yellow Metric / C500's known by me.

featherbowler · « **Reply #8 on:** September 03, 2019, 08:45:33 PM »

Thanks Plugcheck and Hyperacme, for your swift replies. The two bolts heads are about 8 inches above the floor inside the boat. About how far above the floor should I drill, and would a 1/8 inch drill be appropriate? I'm assuming that I will fill the test hole with plastic wood or something after drilling.

Yes, it would be nice to have the links to the newer methods to repair the transoms. The boat is in pretty good shape, and I would like to repair it correctly. It's in Houghton Lake, Mi., and I'll need to bring it down to Detroit where I live so I can work on it. I've never done this type of project before, but I did install a new heater core in my wife's '93 Buick Regal, inventing a new tool (and some 'choice' words) in the process to get the job done! So I'd feel somewhat confident in taking the task on. Many of the members here have posted excellent guides that I've gone over when I've been in a 'boat stuff' frame of mind, so I know that I'm in the best place to get guidance to do the job right. My kudos to all the members for creating such a great resource.

On my way to the 'back forty' to get that VIN number right now.

I hope that blue CVX in the photo wasn't yours, Hyperacme. That's the definition of "It's gonna' be a long day..." ....

Hyperacme · « **Reply #9 on:** September 03, 2019, 09:09:59 PM »

They made molds of transom and stringers and poured composite.

Ron's CVX16 project ..
http://forum.cgoamn.com/index.php?topic=6488.msg94136#msg94136

C500 Spy Pics ..
http://forum.cgoamn.com/index.php?topic=7551.0

Just using composite board would be OK as well ..

Let the fun begin ..
http://forum.cgoamn.com/index.php?topic=8054.0

And even wood is fine if done right, with materials from some place like Express Composites.
Who can answer all your glass / resin / etc. questions.
https://www.expresscomposites.com/

Hyperacme · « **Reply #10 on:** September 03, 2019, 09:13:38 PM »

OH YA .. CVX with motor hanging off the back is Trent's CVX.
Said he was only going about 50 mph when it ripped off the stern …

Hyperacme · « **Reply #11 on:** September 03, 2019, 09:32:05 PM »

Thank you ..
I have another HIN from a yellow Metric / C500.
There built about a month apart from each other ?

GCV17686M81F 1981 C500 Yellow

Plugcheck · « **Reply #12 on:** September 03, 2019, 10:31:05 PM »

Trent's transom in his CV took a beating at the meet this year as well. As for checking the wood in a boat(especially stringers), I prefer to use a 3/8" bit, but that's just me. I suppose an 1/8" bit would still reveal the chewey nugget center of rotten wood. Sometimes the rot caused by water leaks around the mounting holes only extends a short distance from the hole. In this case maybe a larger washer or brace would buy some time. Me? I'd fix it before the outside shows stress cracks(winter project) which then becomes a larger project.

featherbowler · « **Reply #13 on:** September 03, 2019, 10:48:28 PM »

I'll use a 3/8ths per your suggestion, Plugcheck, perhaps two inches below one of the bolts, unless you suggest otherwise.

Hyperacme, thanks for the info you sent me. I'm trying to post some more photos, but the internet up here is a tad slow at the moment ....

Hyperacme · « **Reply #14 on:** September 03, 2019, 10:57:19 PM »

Pictures off your phone are huge ..
Take's some time to upload .. and can fail if loading a few at a time.
You could email them to me and I'll resize and post ..
My address should be in my profile .. click on my user name.

featherbowler · « **Reply #15 on:** September 03, 2019, 11:20:09 PM »

More photos ...

featherbowler · « **Reply #16 on:** September 03, 2019, 11:28:33 PM »

Hey, that resizing stuff works! ...

featherbowler · « **Reply #17 on:** September 03, 2019, 11:34:14 PM »

And finally ...

dorelse · « **Reply #18 on:** September 04, 2019, 09:59:13 AM »

Those yellow ones are so cool. Definitely a nice boat & worth saving!

Hyperacme · « **Reply #19 on:** September 04, 2019, 10:18:33 AM »

WOW ! Some one took very good care of your boat !
Some years G/C offered extra cost color option, but nothing listed in for the C500 in 1981 P.I.G.
Some late 70's G/C's had gold and yellow as a color choose and the 1981 CV27 yellow looks like your yellow.
Such a weird (in a very cool way) boat !

Is the motor a 1981 ?