1976 Cobia Tri Hull Transom Destroyed - HELP

[gilligan2032]

I knew my transom was soft and probably needed to be repaired, but didn't realize it was THIS BAD! I was backing my boat down the ramp with the engine lowered (mistake), and the prop caught in sand and caused the engine to rip off and destroy the transom. The wood is incredibly rotted. How should I go about repairing this sucker? THANKS for any advice!!!

Edit... Here is the original full size picture

 

[jbcurt00]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

It is more likely then not, that the soft transom is only 1 problem. Below decks the stringers are also VERY likely to be water damaged (at a minimum) or rotten (more then likely) similar to the transom. Are there ANY, no matter how minor or small an area, soft spots on the deck? You need to closely & thoroughly examine all areas of the boat, in & around all seat boxes, storage compartments, the entire deck (floor), in the bilge if equipped, everywhere below the splashwell and everything that comes into contact w/ the transom.

You'll need to get the motor off, which I'm guessing you had to do anyway, just to get home, after the transom failed.

There are some helpful links in Don's How To thread

And WoodOnGlass has helpful diagrams for "Fabricating Decks, Stringers, and Transoms"

You have a quite a bit of work ahead, once you get the rear 1/2 of the hull stripped of wiring, steering cables, throttle & control cables, electrical fixtures, and all the bits & pieces mounted to the boat.

Read thru the threads listed @Don's list, and read thru a bunch of the resto threads. You will get a good idea of what will be required. Clearly the transom is a major structural element of an OB boat, it can be repaired, but you've got more work to do w/ the torn exterior skin then most.

It is also a good time to take stock in how much you LOVE this boat & it's layout. It will require a lot of time, more then a little money, and a TON of dedication to get it put back together & back in service. If the boat isn't exactly what you want/need or the pending work is too daunting, you would do better to know that now, rather then later.

If the motor & lower unit weren't damaged, in sand it probably wasn't, stripping the Cobia & looking for another project hull in need of a motor, may serve your purposes better. Same for the trailer. Or while you're looking for a different boat, you might sell any & all parts of the Cobia, particularly the motor & trailer, that you can to fund a different boat &/or project.

Welcome to the iboats dry dock, glad the transom was destroyed at the launch instead of while underway!

 

[Woodonglass]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

I am very sorry for your misfortune. Having said that, Your picture will be one of the most referred to pics on this forum for years to come!!! It is a supreme example of one of the most discussed topics here on the forum. It's a shame it had to happen to you but if you you can be assured your problem will undoubtedly help a multitude of others. If you decide to rebuild her, we can and will be here for you to help guid you through every step of the process. It's doable but will be somewhat "Pricey" If the boat is worth it to you and you want to spent the time, money and effort then let us know and we'll help you "Get er Dun!!!!"

 

[gilligan2032]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Should I buy a moisture meter? Where/which one should I get? The deck seems pretty solid amazingly, but obviously my judgement sucks, haha.

How much do you guys think this will cost me? I am a poor grad student, but totally willing to work hard. I only paid 1000 bucks for this boat last October.

I have already put a ton of work into this boat, it is my baby! I will start reading as much as possible, and I'm beyond glad to have you guys for questions. I'll be sure to post lots of pictures along the way.

 

[gilligan2032]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

I have decided to attempt repairing the boat, even if it takes ages and cost lots of money. I love this boat.

The first thing I have done, is build a swingset to hoist the engine off. I figured it was the cheapest way to get it off, and then I can actually use it as a swingset when I'm done.




Then I built an engine stand out of wood.




(That's my girlfriend!)

I bought a harbour freight 2 ton cable puller (come along) for 15 dollars, and was planning on using that to hoist the engine off. I think I will try next weekend. Any tips on doing this? I don't have any experience removing engines, Is is difficult getting the steering rod out?

Thanks guys!

 

[jigngrub]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

OMG Gilligan!!! That was you? That pic has been floating around on iboats here and I was wondering who it actually happened to.

If you really love the boat, a full restoration will be worth it... but it will take quite a bit of time and money which it sounds like you're prepared for.

What size engine is that? It won't be too hard to remove, but you'll need an engine lift ring which is discussed in this thread:

http://forums.iboats.com/johnson-evinrude-outboards/lifting-outboard-motor-286119.html

I'm not sure about the steering rod but you can probably find help for that in the Johnson motors forum too.

 

[eaglejim]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Gilligan,take off the cover on engine and you should see a place near the flywheel to put your hook as far as the steering rod when we did mine there was a lot of pulling and tugging you might want to build an engine stand you can save money using pallets.Built mine out of old pallets and the only thing it cost me was 10.00 for a couple of 2x4's good luck more pics the better these guys are very helpful

 

[jbcurt00]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Welcome back G!

Your 1st posted pix has helped countless others here... So THANKS.

Nice work on the engine lift & stand, my earlier advice stands: Read thru some resto's, Don's list & WOG's Stringers, transom & deck fab details.

Officially welcome to the iboats dry dock.

 

[Bomber Goober]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

As far as the steering rod, judging by graphics it appears to be a 70's Johnson, should be the same as my '74. (1)On the port side remove the nut holding the L-shaped rod on, and remove said rod. (2)On the starboard side there is a nut that is with the cable running through it, remove that nut and just pull and the cable should come out given the steering isn't frozen.(NOTEic is not a '74)

 

[gilligan2032]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Yeah unfortunately, that is my picture!

Thanks for the pointers! It is a 1976 Johnson 70 HP. The boat is a cobia 14ft 1976 trihull.

 

[gilligan2032]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

I got the engine off!!!!!!!! Very satisfying

I used my swingset hoist, harbour freight 2 ton cable puller (come along), and my engine stand to remove and store the engine. The operation went rather smoothly except getting the steering rod out. I had to put a steel bar in there and tap it out with a hammer.

Now I can fully see the damage to the transom, and it doesn't look good. The transom is completely rotted and the outer skin is torn. I have no idea how to go about fixing this, and would GREATLY appreciate some general step wise guidelines on how you guys would go about fixing it. I have been reading the forums to learn fiberglass terminology. Will I have to remove the top of my boat?

 

[gilligan2032]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

 

[River_Lizard]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Clean out everything under the splash-well and see if there's a section of the flooring you can pull up in the back. If there's screws see if you can unscrew them and lift the flooring up. Once you get that done, take a few clear photos and post them up here. Also, take a screw driver and see if you can poke through the stringers towards the transom. (I believe you'll be able to). Then report your findings. The guys might tell you to drill a few holes in the stringers to see what type of shavings come out of the holes.. I'm thinking you won't even need to do that.....you'll probably stick the screwdriver right through where the stringers should have been unless they're engineered stringers (which would amaze me).

 

[eaglejim]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Mine was just as rotten and found out the deck was rotten also but got lucky on the stringers,like you spent a lot of time learning about fiberglass and now that I got transom in I am learning more I am sure that someone will be along to help you fix that transom skin

 

[jbcurt00]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

You'll likely WANT to remove the cap to gain access to the deck & stringers... But you could 'just' remove the splashwell & back portion of the cap, kinda like this:

The fiberglass tears on either side of the motor aren't ideal, but by removing the cap at the transom you'll have an easy time of putting in new 2X 3/4" plywood across the back & you can make the interior & exterior repairs on the fiberglass integral to your plywood install. You will want to do a really good job repairing the cracks w/ multiple layers of CSM & 1708.

 

[jigngrub]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP



By the looks of the size of that splashwell it'll be a lot easier to repair your transom with the cap off or the rear of the cap cut off like JBC posted. It'll take a lot longer and you'll be miserable the whole time to try to repair that damage with the cap/splashwell in place.

... and like others have said, you'll probably find that your boats needs more repairs than just the transom (deck and stringers) and having the cap off for that work will also make the job easier.

 

[Woodonglass]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

The Transom SKIN is more of a cosmetic thing and will not be that big of an issue to fix and you'll never know it happened. First thing to do is to investigate and determine how much restoration is required. If the transom is this bad then there's a very good chance the Stringers will be too. Do you have significant soft spots/areas in your Floor/Deck? If so then you're gunna need to cut the deck out to get to em.

 

[gilligan2032]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Thanks for the tips guys! I will investigate the floor and stringers next weekend and post pics. How difficult is it to remove the cap? Do I need to cut it off? From my reading the forums, it looks like I will need to put supports under the hull to prevent it from warping, correct?

The Transom SKIN is more of a cosmetic thing and will not be that big of an issue to fix and you'll never know it happened. First thing to do is to investigate and determine how much restoration is required. If the transom is this bad then there's a very good chance the Stringers will be too. Do you have significant soft spots/areas in your Floor/Deck? If so then you're gunna need to cut the deck out to get to em.

The deck has zero soft spots, but I don't doubt the stringers are bad. The guy that had it before me replaced the deck and added carpet and claimed the stringers were good, but not sure if I can trust that.

 

[jigngrub]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Thanks for the tips guys! I will investigate the floor and stringers next weekend and post pics. How difficult is it to remove the cap? Do I need to cut it off? From my reading the forums, it looks like I will need to put supports under the hull to prevent it from warping, correct?

The deck has zero soft spots, but I don't doubt the stringers are bad. The guy that had it before me replaced the deck and added carpet and claimed the stringers were good, but not sure if I can trust that.

Take the rubber out of your rub rail and drill out the rivets that are hiding behind the rubber (or they may be screws). The rivets or screws are what's holding your cap on... although a previous owner may have used sealant on it and that could be holding it on to. The back of the cap at the transom usually is held on by sealant and some times has to be cut, but I think you did away with this problem when the transom tore off the boat.

The cap isn't that heavy, just bulky/awkward. Having a couple three people to help take it off after you get it loose will help.

It's better to block up and add additional reinforcement on the outside of your hull or make a cradle for your hull when doing the stringers on a tri hull.


Your deck may be "double decked", new plywood thrown over the old rotten deck and that's why it feels solid... and there's no telling what kind of job the PO did on your stringers, if he even touched them.

Please take pics when tou start taking the boat apart, we love seeing some of the hack jobs previous owners do.

Edited:

This is a good thread for you to read, a boat just about like yours.

http://forums.iboats.com/boat-restoration-building-hull-repair/my-project-74-ebbtide-584261.html

 

[gilligan2032]

Re: 1976 Cobia Tri Hull Transom Destroyed - HELP

Whelp, I have had to put this project on hold for the past year, but I moved and now have a large workshop to begin restoration!

All my picture links died, so I will repost them. This is how my transom was destroyed in the very beginning...

After uncovering the deck, I found that it was LOADED in fungus.

Then I noticed there were two STREET signs that the previous owner had placed to patch the rotten deck.

Also, the deck was slapped on top of another deck... double decked. The deck underneath was totally rotten, and that is where I am currently.

I took the rubrail off and was planning on removing the cap so that I can tear up the rest of the boat, but first I am paranoid about the hull warping. Do I really need to build an entire cradle? Or can I just use straps?