1980 cobia gulfstream

[logan944t]

Re: 1980 cobia gulfstream

Im trying to plan the layout of the floor with storage and the joints of the floor to the walls.

Is there a plastic version of door jambs for boats? It would be like the fittings around the gas tank ports--- a plastic flange material that I could cut to size and have a decent joint for the hatchs to close to--as well as providing a decent joint for the floor to cap connection.

 

[logan944t]

Re: 1980 cobia gulfstream

Spent about 2 hours cutting away bits to gain access to the bulkheads under the console and outer stringers. Got most of the tops of the stringers cut off. Some sections still had wood (wet) and other sections only had a black mess.

Ive decided to replace the wooden stringers with foam ( 8 lb) since I dont want to do this again.

 

[logan944t]

Re: 1980 cobia gulfstream

Ok I would like some opinions and advice.


The transom has soft wood at the very bottom where the drain plug goes. Holes Ive drilled 3" above the drain plug hole are solid and the cutout for the sterndrive is solid. Holes drilled right and left of the drain plug are solid at about 2" away.


The transom itself is 2" thick in a "T" shape and about 1.75" thick lower transom port and starboard.


Do I repair just the rot? Or remove the whole transom and put in a new one?

 

[marioc]

Re: 1980 cobia gulfstream

Have you seen any of Frisco's threads on his repair...?

I guess being where you are, you can pretty much work on this through the winter...outside?

I'll be doing the same in about a month or two!

Mario

 

[logan944t]

Re: 1980 cobia gulfstream

I guess being where you are, you can pretty much work on this through the winter...outside?

We get a few days of freeze warnings -- but not many. Its tough, but Ill try to muddle through .

 

[zopperman]

Re: 1980 cobia gulfstream

Ok I would like some opinions and advice.


The transom has soft wood at the very bottom where the drain plug goes. Holes Ive drilled 3" above the drain plug hole are solid and the cutout for the sterndrive is solid. Holes drilled right and left of the drain plug are solid at about 2" away.


The transom itself is 2" thick in a "T" shape and about 1.75" thick lower transom port and starboard.


Do I repair just the rot? Or remove the whole transom and put in a new one?

If you're doing the MERC conversion (Which, IMO, since you want to keep the boat, you should) then you need to make a new transom anyway.

 

[logan944t]

Re: 1980 cobia gulfstream

If you're doing the MERC conversion (Which, IMO, since you want to keep the boat, you should) then you need to make a new transom anyway.

No, sorry for the confusion -- Ive read a lot of the threads on here WRT an OB conversion and decided to go with an O/B and a bracket.


For me, the ease of maintenance and the easy ability to repower is what sealed the deal. The idea of a huge hole in my transom and relying on a rubber seal to maintain watertight integrity....gives me the creeps. Just seems too flimsy to me --even tho I know millions of boats use that set-up.

I would feel comfortable with an inboard--seems like less of a chance for a leak as well.

 

[zopperman]

Re: 1980 cobia gulfstream

well, woah there.. lot to consider. in that case though, I would DEFINITELY replace the whole transom.
read up on weldzilla's thread and captainkickback's thread... both undertook conversions...
the boat will handle very differently..
ARMSTRONG makes brackets (bolt on)

 

[logan944t]

Re: 1980 cobia gulfstream

Both of those threads are inspirational.



Worked about 3 hours on the stringers today. Getting even just the loose rot out was taking way too long so I cut the stringer on one side vertically and peeled the flap down. This way I was able to work a lot faser and remove whatever wet wood was left as well.

The wood that was just wet --but not rotted-- was a nice yellow color --close grained......just something I would have loved to make some furniture out of.


Im considering repairing the whole transom. I would have to cut the cap above the transom since I dont want to remove the cap. This way I could be sure of the condition of the wood and make the transom all one thickness--2". I would follow weldzilla's example and install an aluminum backing plate for the swim platform and bolt aluminum kneeboards from the old stringers where the engine is mounted now-- to the aluminum backing plate. This way the kneeboards support the bracket and engine.

 

[logan944t]

Re: 1980 cobia gulfstream

Spent another 3 hours cutting access to under the console ( glad I did-- only one piece of unrotted wood left), cutting the stringers apart, scoring the flotation foam that is left outboard, and trying to wet-vac more water out of the stringers. Also removed all the wiring aft of the console.


Costs so far:


1) 400$ for boat transport.

2) 100$ in 2x6's and 2x4's for the Gantry and the cradles.

3) 70$ on 2-ton hoist.

4) 50$ on sawzall blades, grinder discs, respirator, goggles.

 

[logan944t]

Re: 1980 cobia gulfstream

The fuel tanks ( 70 x 2 ) have a tag on them that indicates they have been installed since 1979. Im preetty sure they are filled with gunk.

Is there a way that I can rehab them to reuse them?

I would prefer poly tanks --but they are close to 300x 2 and if I can have servicable tanks then I dont want to spend the cash.

 

[logan944t]

Re: 1980 cobia gulfstream




Before ( about 1980)







After ( 2011)



Spent about 3 hours removing more of the flotation foam. The last 6' towards the transom was dripping wet-- and it hasnt rained here in 4 or 5 days.








Easiest way I found to remove the foam is in big chunks. To do so, I scored the foam with a sawzall and a 5" blade. Using a 4' crowbar I dug down to the hull and then slid the crowbar along the hull--prying as I went to force the foam to break along the score cuts.


The outboard stringers are decidedly less stiff without the foam.The sides of the hull are also a more flimsy.

 

[logan944t]

Re: 1980 cobia gulfstream

Would there be any benefit ( stiffer, less weight) to building a transom that was constructed more like a house wall ? That is, an outer sheet of 3/4 ply then "studs" ( 1" wood or even 5052 aluminum channel) , then an inner sheet of 3/4 ply instead of a solid 2" transom like I have now?

 

[logan944t]

Re: 1980 cobia gulfstream

Spent about 3 hours working on the final touchs to the gantry,




and then pulled the (2) 70 gal aluminum fuel tanks,





which were foamed in at the factory





and preventing water from draining. Had to use a crowbar hammered under the tanks to break the foam's grip on the tanks.

Tommorrow should be pulling the 305.

 

[oops!]

Re: 1980 cobia gulfstream

Would there be any benefit ( stiffer, less weight) to building a transom that was constructed more like a house wall ? That is, an outer sheet of 3/4 ply then "studs" ( 1" wood or even 5052 aluminum channel) , then an inner sheet of 3/4 ply instead of a solid 2" transom like I have now?

nope....no benefit....in fact detrimental.....it needs to be solid core.....anti crush

as far as the foam stopping the water from flowing to the bilge......any water in a foamed area is not supposed to be there......it is either from condensation, a thru hull penetration, or a thru deck penetration

 

[logan944t]

Re: 1980 cobia gulfstream

as far as the foam stopping the water from flowing to the bilge......any water in a foamed area is not supposed to be there......it is either from condensation, a thru hull penetration, or a thru deck penetration

How about a thru cap penetration? One of the previous owners drilled a hole for wires on the console ( cb I think) and never caulked it in. So the rainwater would pool against the console--drain by the wires and eventually find its way into the forward space between the console and the cabin bulkhead. There is a drain hole in the bulkhead but the foam filled it in.

After I get this mess cleaned up Im gonna fill it with water to make sure the hull is watertight--thank you for the suggestion Oops.

 

[logan944t]

Re: 1980 cobia gulfstream




Spent about 4 hours getting the engine out. Had to grind off the heads of 8 bolts ( 6 on the front tilt bracket and the 2 big ones that mount the front of the stringer drive) that a PO had rounded off before me.

I mounted the gantry




on 2 furniture movers I bought from lowes ( 22$ and change) that were rated at 900 pds. I was able to hoist the engine ( 2-ton chain hoist from harbor frieght 80$) to clear the stern and then move the gantry back and lower the engine on a 3rd furniture mover.


After poking around a bit with the engine gone I ran into this


which is not that much of a surprise.






Empty engine bay!! Now the rehab can begin!

 

[zopperman]

Re: 1980 cobia gulfstream

Nice delamination!!!

 

[logan944t]

Re: 1980 cobia gulfstream

Spent about 3 hours on boat today-- cutting stringers near transom and planning new stringers and how to cut the inner transom glass. Looking at my earlier demo work Ive learned to be more precise with the cutting tools.

Tomorrow will be the big step -- cutting the transom. To me, it feels like stepping off a cliff.

I also want to open up the stringers that were under the motor to make sure they are solid.

Im gonna be all up in tyvek fashion tomorrow!

 

[logan944t]

Re: 1980 cobia gulfstream

Rained buckets last night and I was hoping that it would stop today. I was able to get the cap above the transom cut



and with the help of my son completely off.










This is a closeup of the cap thats still on the boat.






It is soaked wood. So Im thinking that I will be cutting off more of the cap and eliminating the wet wood.


Unfortunately, altho my plans included removing the inner transom today, Mother nature had other ideas and since I have an aversion to standing in water, holding a wet sawzall and getting rained on....thats it until it stops raining.