1980 cobia gulfstream

[ezmobee]

Re: 1980 cobia gulfstream

Aw man, that sucks that you've even got wood in your cap!

 

[Gator1996]

Re: 1980 cobia gulfstream

logan. you are really making progress that is a big project. good luck. I look forward to seeing the final product.

 

[Woodonglass]

Re: 1980 cobia gulfstream

I don't think thats wood! Looks more like some kind of foam filler. But...I could be wrong.

 

[logan944t]

Re: 1980 cobia gulfstream

I don't think thats wood! Looks more like some kind of foam filler.

I wish it was. I think it was added as a stiffener along the side. I think I will dig out all the wood and add 8lb foam back in-- its such a small space and the wood couldnt have added much stiffness with the hull right below it.


I did get about a 4" cut on the transom before I had to stop because it started raining again. The cut was high up on the port side about 2" in from the hull-side. Water came leaking out. The thickness at that point is about 3/4" total with about 1/2 " being wood in the center. In the middle of the transom there is a much thicker wooden "T" where the hole for the drive was. Getting the correct depth of cut without cutting the outside layer of glass is gonna be tricky. There is no flat surface to run the circular saw so it has to be cut using either an electric grinder or an air grinder.

 

[GT1000000]

Re: 1980 cobia gulfstream

Great job so far. Sucks about the cap rot...:facepalm:
But in the end you will have a better than factory Product...
Best Regards and Merry Christmas.

 

[logan944t]

Re: 1980 cobia gulfstream

Today was perfect for working outside on the boat-- cloudy and no rain.


Spent about 45 minutes with an air grinder --which was spectacular for cutting right thru the glass and slowing down when it reached the wet wood.



As you can see the outside inner transom skin is completely off. Wet wood and rot are readily apparent.




This area of rot was directly behind a screw.




It took about 30 mins to cut the bolts holding the mounts for the sterndrive. I still have to open up the stringers themselves and see if the 4x4's are rotted. I have a suspicion they are.



This is wasted space. Since the port side had rotted wood in this area I need to cut this out to remove the wood--but I will be putting in shelving with a door for lures and I want to make the whole thing removable to access the wiring and area behind it.






Stupid question ....but what are these holes for? They are on both port and starboard and I thought they were for poles ....but they seem too far apart....unless I need newer bigger poles.

 

[GT1000000]

Re: 1980 cobia gulfstream

View attachment 125993


Stupid question ....but what are these holes for? They are on both port and starboard and I thought they were for poles ....but they seem too far apart....unless I need newer bigger poles.

Part 1= There are no stupid questions! there are only dumb people who don't ask and then they wonder why they screwed up...
Part 2= In conjunction with the three holes just foreward of those big holes, I see what could have been one of those rod holder hook deals, so I would guess that those large holes are where you would put either the rod grip or rod tip into, to keep them from bouncing out of the hangers...something kind of like this... http://images.search.yahoo.com/imag...b=14achkcll&sigi=11q12uovg&.crumb=Zj/DpOkFiUT

 

[logan944t]

Re: 1980 cobia gulfstream

Thanks GT.


I took a look at the transom and the wood that was still attached. It seems to me that my timing is off. I didnt get the boat before it rotted but I didnt get it after all the wood rotted away either.

When I try to take the still "good" wood off the transom it is very difficult. Im using a crowbar and a hammer.

Should I be putting the crowbar in between the wood and the CSM or the CSM and the outer skin? outer skin| CSM| wood| inner skin


Also -- I left a "flange" of fiberglass around the outer edges of the transom but the transom's thickness at the edges is only 3/4". I want to have a full 2" transom all the way to the edges. Should I remove the flange since its gonna be blocking the new wood when I install it? Or is there a trick to this?

 

[GT1000000]

Re: 1980 cobia gulfstream

Thanks GT. You're welcome, sir.


I took a look at the transom and the wood that was still attached. It seems to me that my timing is off. I didnt get the boat before it rotted but I didnt get it after all the wood rotted away either. You need to wait approximately 7-15 more years before you begin this restoration to allow the wood to completely rot...
When I try to take the still "good" wood off the transom it is very difficult. Im using a crowbar and a hammer. You might try a "wonderbar" or you might have to grind the old wood out, until you reach the fiberglass underneath...only to try and keep from damaging the outer skin of the hull, but if you do, that isn't the end of the world, cause you can repair anything fiberglass, just look at OOPS! thread..., here's a link to what a wonderbar is... http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=1CVZQP65SM6JH2N6561D

Should I be putting the crowbar in between the wood and the CSM or the CSM and the outer skin? outer skin| CSM| wood| inner skin, Basically you just want to get down to the first good layer of fiberglass...


Also -- I left a "flange" of fiberglass around the outer edges of the transom but the transom's thickness at the edges is only 3/4". I want to have a full 2" transom all the way to the edges. Should I remove the flange since its gonna be blocking the new wood when I install it? Or is there a trick to this?Here, I would need pics to try and help out, 'cause I'm confused, but it seems to me that this flange is going to be replaced by the new transom and the PB fillet, along with the tabbing and matting...but I am often wrong...:facepalm:

Hope this helps, and I'm sure the more knowledgable guys will be chiming in soon, so don't do anything I have suggested until verified by superior Iboaters...

Have a Merry Christmas and a Happy New Year.

 

[logan944t]

Re: 1980 cobia gulfstream

Ok --sorry for the confusion.

When I cut the inner skin of the transom I left about a 2" flange on the port-starboard and bottom of the transom. This is a pic of the port side flange.






The old transom was only 3/4" or maybe an inch thick and the flange reflects that depth. The transom Im gonna put in will be 2 1/4" thick (3/4 x 3) so the flange that I left will be way to short and just be in the way.





SO I will have to cut then grind a space for the new thicker transom to fit in. I was wanting to save it since the glass itself was so thick.


Got about 2 hours in on her today and I removed most of the old wet, rotted wood.







Most of the layers came off using my patented "logan's 2 crowbar" method. I would get the little bar under the wood a bit--lift--- then ram the big one as far down as I could. Then let the little one down into the larger space--remove the big one -- and ram it down farther. Worked well.


The wood that is left seems to be the top layer of plywood. To remove it Im gonna have to use a sander since prying is putting cracks in the outer transom layer that I dont want. I disturbed an ants nest when I was removing this wood. Thats not a joke-- there were ants living in the transom. If I had another year....I wouldnt have to remove the wood.

 

[GT1000000]

Re: 1980 cobia gulfstream

OK, the pics helped... Yes, that flange will be gone before you replace the transom because the new piece will be tabbed and matted into that area...

NOW, very important!!!...double check that the transom on the boat is or is not curved... I know nothing or less about the mounting requirements of an I/O set up, but I do know some transoms are curved. Yours seems to my inexperienced eyeballs to be curved. I mention this because of what I have read in other forums dealing with this issue. Where the engine connects to the intermediate section, it is usually 2 to 2 and a 1/4 inches in thickness...[ others who know way more will correct me if I am wrong ]...and the edges of it are only approximately 3/4 inches thick, which would indicate the very real possibility of the original transom being curved...
OK, all that being said, once you verify this one way or the other, you need to rebuild it similar to the original setup, especially if it is curved.
If the BIG GUNS don't chime in soon, you might have to post the question in the I/O forum... I do know that PMCCraney in Man vs. Boat is just going through this, so there is a good place to start, also I think friscoboater had to deal with this, too.

Sorry I can't be of much more help regarding this, but we'll get you through it.

 

[logan944t]

Re: 1980 cobia gulfstream

Where the engine connects to the intermediate section, it is usually 2 to 2 and a 1/4 inches in thickness...[ others who know way more will correct me if I am wrong ]...and the edges of it are only approximately 3/4 inches thick, which would indicate the very real possibility of the original transom being curved...

Thats exactly my transom -- but Im pretty sure that it is not curved. I will double check but in any event the I/O is history because this boat is getting an outboard brackett--Im not replacing the I/O.

 

[logan944t]

Re: 1980 cobia gulfstream

Got about 3 hrs in this morning.



First the bad news....





This is the area directly underneath the forward fuel tank. Yesterday I had cleared the foam off and when I stepped on it this morning the glass cracked a bit. So I got out the air grinder and took up a section to find wet, rotted OSB. Im assuming the other aft under fuel tank area is the same. This is freakin me out a bit since Im sure this was built this way to lend strength to the keel. On the up side-- I found where the tube goes that ends in the stern.

 

[logan944t]

Re: 1980 cobia gulfstream

I also got more of the wood removed from the transom.





I also started to remove the layer of wood that is left. The CSM that is next to the wood is .....dry. I dont know how that worked for so many years.






I also tore into the main stringers that the motor was resting on. I originally wasnt gonna touch these --but decided to make sure that they were solid. I wanted to incorporate these into the knees for the OB bracket.





Then I saw this:





Which is really bad news ....but it does free me up to redesign the stringers a bit since Im sure these were designed to hold the weight of the motor --sorta like the hardpoints on an aircraft. I would like to extend the middle stringers to terminate at the transom ( like the outer stringers do) --except since they will be holding the OB bracket ( thru knees) in compression and tension I was wondering if ya'll had any design advice?



One last pic --


That square box thing thats attached to the main stringer.......what is it? It is all fiberglass --hollow and has nothing but dirt and leaves in it. There is one just like it on the other side. The motor did not mount to it-- I was wondering if it was a stabilizer of some sort-- like the "arm" that was on some 70's era ford tranny's whose job is was to dampen vibration?

 

[zopperman]

Re: 1980 cobia gulfstream

Don't forget, Logan, You're making this boat BETTER than the factory and to YOUR SPECS. Don't be disappointed with the new rot, it's just something you can make better.

I have no clue what that box is...

And you're going to do the BRACKET? not just modify the transom?

 

[logan944t]

Re: 1980 cobia gulfstream

And you're going to do the BRACKET? not just modify the transom?

Yep -- 6 or 7 ' swim platform with a single bracket. Im tempted to do a double ......but a mans gotta know his limitations....

Don't be disappointed with the new rot, it's just something you can make better.

I keep tellin myself that.

 

[logan944t]

Re: 1980 cobia gulfstream

Does anyone have pics of transom knees--especially ones of aluminum.

Im designing the transom support and want to see other ways to skin a cat.

 

[zopperman]

Re: 1980 cobia gulfstream

Check out oops!' hull extension thread. He has good knees.

 

[GT1000000]

Re: 1980 cobia gulfstream

One last pic --


View attachment 126149 That square box thing thats attached to the main stringer.......what is it? It is all fiberglass --hollow and has nothing but dirt and leaves in it. There is one just like it on the other side. The motor did not mount to it-- I was wondering if it was a stabilizer of some sort-- like the "arm" that was on some 70's era ford tranny's whose job is was to dampen vibration?

Not sure if this is what you mean, but from the looks of it, my best guess is attached...

 

[logan944t]

Re: 1980 cobia gulfstream

http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053

Saw this at Home Depot today. Was wondering how close to PB this is.



*Edit* Never mind --after looking at the MSDS--it has no fiberglass.