74 Ozark tri hull..what have I gotten myself into..

[roweboat]

Hi everybody.. noob here.
Just bought a 74 Ozark tri hull.. I new it had issues, but wow!
It started when I noticed a bolt head in the bottom of the ski locker and decided to pull it out.. the song lyric came to mind "and up through the ground came a bubblin crude".. had to cut the bottom out of the ski locker to get all the water/muck out. Then decided to see why the floor felt soft.. Long story short, the entire stringer/bulkhead system is one large
drainage system and each "compartment" between bulkheads drains into the main stringers on either side of the ski locker.
Once I got all the completely rotten plywood, dirt, muck, mouse nests, etc cleaned out of each section I was able to get an idea of how it all worked. The only thing I can't figure out is the drainage for the forward storage compartments in the bow, I even poured some water in but was unable to track it.
All of the plywood deck was wet from the cockpit aft and all that was left was the fiberglass skin.
Here are a few picks so you can get a better idea what I'm up against.



I've never done fiberglass work before. I'm not sure exactly how tackle the new deck.. I've read plenty of threads on the subject and feel I can do it, just not the best way to do it. Here is what I'm thinking.. the sidewalls come all the way to the existing glass deck (I left a few inches when I cut out the compartments) and I have the rotten plywood removed. Is it best to try to slide the new deck under the existing skin on the edges? or build some shaped blocks to fit under there and just run the edge of the new deck right up to the interior side walls? If I go under, I have no way to attach the deck to the hull, if I go above, I can attach to the interior side wall... or do I let it float at the edge and not attach to the interior side walls but just caulk the joint? I don't know how the interior side walls come apart, they are not part of the cap, so even if pulling the cap was an option (it's not) it would not solve the problem.
I just have so many ideas/options swirling around in my head it is hard to get them written down coherently..
Any input would be appreciated.. hope I made sense with all this.

37 years old and even with all that muck and water and poor draining etc, she still stayed afloat. I think she's earned a new lease on life..

 

[Woodonglass]

Re: 74 Ozark tri hull..what have I gotten myself into..

Have you core sampled the stringers and transom? Before you redeck her it would be a good idea to confirm that they are not rotten.

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

Have you core sampled the stringers and transom? Before you redeck her it would be a good idea to confirm that they are not rotten.

Hi woodonglass,,
Thanks for checking in on me. I have read a lot of your posts and threads. Here is what I have found.
The stingers are all hollow fiberglass. Then they laid the plywood deck on, then they glassed the deck.. but only on the top, the deck plywood was totally raw underneath! In my
pics, you can see where I have cut open the areas between the stringers/bulkheads to remove the wet rotten plywood, however, you can also see the stringers are still covered by the plywood and top layer of glass. After reading your post, I went out and used a 1 1/4 inch hole saw directly on top of the starboard fore/aft stringer near the bulkhead that the forward engine mounts to. the plywood on top of the stringers is wet, but the glass under (top of actual stringer) is ok (except for the 1/4 hole I just put in it with my saw and will plug before decking).. This was a great suggestion by you as I was just thinking I could deck over what was left there.. now I see it ALL has to come off to expose the fiberglass stringers. I will check the transom in the morning for sure.
I'm guessing I need to check it from the inside but how high from the deck level and how many probing holes?
Tomorrow I will also attempt to remove all of the remaining glass/wood so I have nothing left but stringers/bulkheads then get more pictures.
Thank you so much for the help!!

 

[Woodonglass]

Re: 74 Ozark tri hull..what have I gotten myself into..

Use a 1/4" drill bit. Put some tape on it for a depth guage @ about 1". Drill from inside the boat and down as low as you can Port and Starboard then up about 4". Check the shavings and report back what you find.

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

Use a 1/4" drill bit. Put some tape on it for a depth guage @ about 1". Drill from inside the boat and down as low as you can Port and Starboard then up about 4". Check the shavings and report back what you find.

Ok! Will do. Thank you again! Here is a drawing (rough) of how it appears to work with the hollow stingers and shows all the drainage holes I've uncovered.
I will report back tomorrow!

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

Well, the transom is wet :facepalm:
The deeper I get the more outta my comfort zone I get.

With it being just me, no help, should I cut the back of the cap, perhaps a foot or so around the corner and onto the side? That way I could work on the transom..I don't think I can get the whole cap off by myself.
I guess really, I have nothing to loose. It's not seaworthy as it sits.

Can I pull the outdrive but leave the engine in?

The rear of the boat is not flat..it has a cool curved shape:


I started with a 1/4" bit, then used a hole saw to remove the glass, exposing the plywood sponge..

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

OK, I cut the cap off the transom around the corner at the forward edge of the vent box. The area on either side of the engine/outdrive mount is filled with foam, which has been chewed up to make mouse nesting. The inner glass has delaminated from the wood.
One thing I don't understand is that the outer skin has no wood and the inner skin is what looks like 1/4" ply with a fiberglass skin on it but the only place there is solid wood is the square area where the outdrive attaches... so , what is supporting that engine/drive connection? Guess I'll find out when I get all that nasty foam out of there..
The wood that is visible at the top (left side of pic) is a 1x2 for screwing the cap to hull.
I'll get some more pics when I get the foam cleaned out of the cavity.

 

[Woodonglass]

Re: 74 Ozark tri hull..what have I gotten myself into..

Looking good!!! You really need to pull the motor and the outdrive to do this right.

 

[glnbnz]

Re: 74 Ozark tri hull..what have I gotten myself into..

Wow does that bring back memories!! So close to looking like my 73 yet so far as yours is an I/O and mine is an outboard. Sounds like you are heading in the right direction.

I am signed on so that I can follow along!

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

Looking good!!! You really need to pull the motor and the outdrive to do this right.

Thanks Wood,,
drilled a 1/4 test hole directly under the engine.. wet there as well. So I have resigned myself to the fact that the drive and engine need to come out. Still have water leaching into the keel so decided perhaps I can lift the cap and look under the bow, maybe there is some saturated foam in there??
Got the cap loose all the way around but it wont budge in the front, they glassed it to the deck under the cockpit so I will have to get a cutting disc and attempt to do some surgery before I can raise it. I will get some 1x4s and use them to bridge the beam in several places.. My thoughts of boating by labor day are still solid.... just not THIS labor day..ha

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

Wow does that bring back memories!! So close to looking like my 73 yet so far as yours is an I/O and mine is an outboard. Sounds like you are heading in the right direction.

I am signed on so that I can follow along!

Hi Glenn! Yes, I read your entire thread! Gave me hope.. Yours look so nice sitting in the water in your sig pic.
I do have a question.. how does the cap come off? I have it loose all the way around but it appears it is glassed to the
deck under the cockpit area on both sides.. was thinking I may have to just cut it.. also, how did you get the deck out from under the interior side walls?
I'm just south of St Louis, maybe when I get it done we can pull it up there to IL and meet up at the lake.
I will probably be picking your brain more on this,, its my first time and I have no idea what I'm doing..I appreciate any and all help I can get!

 

[glnbnz]

Re: 74 Ozark tri hull..what have I gotten myself into..

Hi Glenn! Yes, I read your entire thread! Gave me hope.. Yours look so nice sitting in the water in your sig pic.
I do have a question.. how does the cap come off? I have it loose all the way around but it appears it is glassed to the
deck under the cockpit area on both sides.. was thinking I may have to just cut it.. also, how did you get the deck out from under the interior side walls?
I'm just south of St Louis, maybe when I get it done we can pull it up there to IL and meet up at the lake.
I will probably be picking your brain more on this,, its my first time and I have no idea what I'm doing..I appreciate any and all help I can get!

Ah yes the Ozark boat design can be a difficult one to understand. I will tell you what I did but I know that some would not recommend it, but I wasn't looking for show quality but something that is serviceable. My transom is fine so I decided to keep the cap on. To this day I am not 100% sure how the cap comes off. I do see (I think in one of your pictures) that you have cap off over the transom. So I believe that you can work on your transom area without interference from the cap.

Now for the issue of what I did around the edges of the deck. I cut out the deck up to where there was dry wood and then butted the new wood up to that. I know that is not how most of the people on here would have done that, but I noticed in a tri haul the fiberglass in that area is really solid.

Please ask me any questions and I will try my hardest to answer them.

Yes maybe we can meet up at the lake sometime in the future.

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

Ah yes the Ozark boat design can be a difficult one to understand. I will tell you what I did but I know that some would not recommend it, but I wasn't looking for show quality but something that is serviceable. My transom is fine so I decided to keep the cap on. To this day I am not 100% sure how the cap comes off. I do see (I think in one of your pictures) that you have cap off over the transom. So I believe that you can work on your transom area without interference from the cap.

Now for the issue of what I did around the edges of the deck. I cut out the deck up to where there was dry wood and then butted the new wood up to that. I know that is not how most of the people on here would have done that, but I noticed in a tri haul the fiberglass in that area is really solid.

Please ask me any questions and I will try my hardest to answer them.

Yes maybe we can meet up at the lake sometime in the future.

Unfortunately my deck was wet all the way to the walls and all that is left at the edges is the thin layer of fiberglass. Had it been dry, I too would have done what you did. It appears that the interior side walls are glassed to the hull at the rear and possibly the front under the cockpit area. I will somehow have to access that deck portion between the interior wall and the outer hull either by figuring out how to remove the wall, or cutting several inches off the bottom and repairing that later.
The cap seems to be the biggest hurdle right now and I have to be careful in the deconstruction of the boat so I can get it back together without too much effort.
Sure appreciate all the help and look forward to the day when we can meet up at the lake!

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

Ok, just a quick update.. Finally got all the parts needed to get the engine running to check it out. I wanted make sure it was a viable motor before proceeding. Other than a tune up and minor adjustments, it seems to run fine so now I can proceed to making preparations to pull the outdrive and engine.
It appears that the inner side wall, which is about 4-5 inches in from the outer hull, has had this cavity filled with foam. The inner side wall intersects the deck right where the hull curves so I'm not sure how they supported the deck at the hull side, unless they just let it rest on the hull and tabbed the top.. either way, I have my work cut out for me. I still have yet to determine how the cap is attached under the helm area. I hate to just go cutting away only to find out it wasn't necessary. The forward part of the original deck from the helm forward appears dry and solid.
There is a step up into the bow area and I am wondering if I could just cut an access hole in the floor up there in the bow for inspection then install a hatch cover to seal it,,this way it could be opened to vent the hull. If I did this, I could probably get away with leaving the cap on and not creating more work for myself..hmm..
I'll update more when I get the outdrive/motor removed and I can actually proceed with tearing things apart.

 

[glnbnz]

Re: 74 Ozark tri hull..what have I gotten myself into..

Good to hear from you. Yes I feel that boat projects start with the motor. So that is a good course of action to take.

Looking forward to seeing more progress now that you feel good about the motor

 

[roweboat]

Re: 74 Ozark tri hull..what have I gotten myself into..

Ok, the outdrive was remove a few days ago and today I pulled the engine, transom plate, bell housing, and gimbal housing. I built a stand to hold the engine and the outdrive using a pair of furniture dollies connected with 2x4s so I have 8 wheels supporting it all.



In looking at the keyhole, the edges of the plywood transom appear to be delaminating and looks like they didn't even bother to fiberglass the edges.




The 2 bolts that bolt through the transom plate into the gimbal housing were severely eaten away from water and one of them snapped leaving about 2 inches sticking out of the back of the gimbal housing. The two studs that are on the gimbal housing and protrude through the transom and plate are also severely eaten up, so this will have to be taken to the boat shop for repair.
Now I can start cutting away at the inside fiberglass to expose the plywood and start removing it.
The only thing that worries me about this project is the time it will take to get finished means I have to retain in memory how it all goes back together..