1991 Formula 242 Stringer & Bulkhead Repairs w/ Many Pics

[tpenfield]

OK, boat restoration fans, here we go . . .

I started pulling things apart today to take a look at the extent of the rotted bulkhead and stringers in my boat. Just to re-cap, I had the engine out over the winter and discovered the structural issues as a result. So, it looks like I should fix things before I put the engine back in the boat.

Of course as nature would have it we have not had much snow this winter, and finally got some this week (Covering the boat). Then this morning it rained, just to make the snow heavier to shovel. Anyway, here is a series of pictures that I took during the the process this afternoon, once it stopped raining.

BTW - this is my first post using the 'PhotoBucket/URL' method of posting pictures . . . hopefully it will work out.

Here is the deck hatch assembly which gives access to the fuel tank and stringer system area . . . It is about 7-8 feet long and also houses the ski locker.



Here is the Deck Hatch Assembly removed . . .



The rear bulkhead and the 'Culprit" areas that were not glassed over properly at the factory (wooops, did I say that ??? ). The plywood has shrunk and cracked over the years, allowing moisture to propagate into the wood. You can see the dry rot extending forward into the port side stringer



The visible rot extends about 2 feet forward along the stringer, but additional inspection with the fuel tank removed will be needed to see if it goes further.



The forward bulkhead is also showing early stages of rot stemming from a fastener hole . . . (darkened area)



A nice crack in the forward portion of the port stringer . . . upon closer inspection, it appears that this is from a piece of fiberglass mat that broke loose from the top part of the stringer right at the visible height step. Most likely from impact stress (I knew I should have slowed down before I hit that wave).




Anyway, The stingers look like they are made of knotty pine . . . I hope it is at least southern yellow pine ?!?!? (probably Doug Fir) They are not fully glassed in, as there is glass at the lower portion tabbing them into the hull and then glass on the top, giving them strength (but not quite enough) . . .but there is no glass in between, just resin coating.

I was not impressed with what I found . . . I wonder if I can take the boat back on the warranty . . .

So, upon initial inspection, it looks like the rear bulkhead is pretty well vaporized . . . dry rot has worked its way forward on the port side and worked its way aft on the starboard side.

Next steps: Remove the fuel tank for a more thorough inspection of the hidden areas and then formulate a repair plan. Anybody need some gasoline ???

 

[Friscoboater]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

I am glad you are using the photobucket method. I hate clicking the little pictures. The rot does not look terrible, but there is some fixing that needs to be done. Are you going to remove the fiberglass deck?

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

I am glad you are using the photobucket method. I hate clicking the little pictures. The rot does not look terrible, but there is some fixing that needs to be done. Are you going to remove the fiberglass deck?

Yes, I was pleased about the limited extent of rot in the stringers, not so much about the construction details.

I do not believe that I can take any more of the cockpit floor out easily. It is all part of the deck assembly . . . a single large piece from what I can tell. So, the deck and hull would have to be separated.

Based on the limited amount of rot (hopefully), I will try to repair it with just the access that I have, once the fuel tank is out.

 

[Friscoboater]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

I thin you are right in there. I think this boat is like my glastron. All the rot was in the back.

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

A quick update . . .

I was able to find a picture of what I believe to be my boat's stringer system in one of the Formula Brochures from the 1990-1992 era. I am pretty sure it is my boat's system as they only made 2 single engine boats at that time (F-206 and F-242), and that is what the picture shows - a single engine layout.

I won't post it here for copyright reasons, but it sure gives me an idea of where things are and what I need to look for. So how cool is that?

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Today, I plan on removing the fuel tank from the boat. It is a 94 gallon tank (as per the certification label), and it has maybe 5-10 gallons in it. My plan is to off-load the remaining fuel (looks like I'll have plenty of lawnmower gas) and then remove the tank.

Question: this will be my first fuel tank removal . . . aluminum tank. Other than the basic dis-assembly of straps, hoses, sender wiring, etc. is there anything that I should be keenly aware of?

I am also wondering how much it is going to weigh . . . it is about 7 feet long and 2 feet wide . . . the certification label says "0.125 gauge" (so I assume that is the thickness of the aluminum). I am figuring around 75-100 lbs, but that is just a guess.

T.I.A.

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

UPDATE: Removed the tank today . . .

After several days of prying and cutting foam it was finally able to break the tank loose from the hull. This boat is starting to wear me out . . .

anyway, here are some pictures of the tank removal . . .

I had to rig up a lifting device to 'pop' the tank, 'cuz even after I removed the foam and cut underneath the tank, it still would not budge.




The tank finally broke loose at the front. Then I had to do the back as well using a similar technique . . .

Then I needed to lift it to get some boards underneath it, so I could 'skid' it up out of the boat. I used my chain hoist.




The opening in the deck was just about the same width as the tank. So as I began to pull the tank out it got 'stuck' because there was still some foam on the sides of the tank. More cutting, etc. I then hooked up the chain hoist to the stern and used that to pull the tank through the tight opening.

Finally some progress . . .




An interesting thing that I found during the removal process was that there was garden hose under the tank in 3 locations. Not quite sure why it was there . . . maybe used to lower the tank into the hull at the factory. . . more probably something that was used to pour the foam in underneath the fuel tank during the manufacturing process. I say that, because the hoses had cutouts in the area underneath the tank and were filled with foam.




I tossed the tank up on the side of the stern for now . . . I will want to strip all of the old foam off of it, check it for any problems and probably re-paint it.



Next steps are to take a closer look at the rot areas. . . .

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

OK. I got to take a look at the bulkhead and stringer 'Rot' areas after the gas tank was removed.

Here are a few pictures of what I found . . .

Here is a look at the rear bulkhead once I got things cleaned up a bit from the gas tank removal




The bulkhead is pretty well destroyed from wet rot . . . notice all of the 'black' wood.



The post side stringer had no real surprises from what I had seen previously . . . Looks like dry rot.



But wouldn't you know it . . . the starboard stringer did have a surprise !!!! Looks like some rot starting its way forward.



I guess at this point, I am wondering what approach to take with the repairs. The stringers have some rot in the aft 1-2 feet of them. The remaining length of the stringers seems to be in good shape. I am wondering if I can repair them rather than replace them ???

The bulkhead is pretty much a replace, so it looks like I will have to cut into the stringers to get a better look at the ends of the bulkhead.

Expert comments welcome and encouraged on this one . . .

 

[Woodonglass]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

I'm thinkin if she's as good as you say she is going forward, then You could cut out the bad and "Sister" in the stringers going to the stern and replace the bulkheads and motor mounts and transom. Shouldn't be a problem.

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

I'm thinkin if she's as good as you say she is going forward, then You could cut out the bad and "Sister" in the stringers going to the stern and replace the bulkheads and motor mounts and transom. Shouldn't be a problem.

I searched this and other forums for a bit of guidance on the process of "sistering" a stringer. It looks like I would install a piece equal to what I cut away from the stringer and "mend" the joint with Ext. Plywood or similar.

A few questions:

- Should I use the same material for the replacement portion of the stringer ?
*** The current stringers are 1/2" Plywood, but they have knots showing, which made me think they were a solid wood at first, like Douglas Fir or something. I thought Marine Ply had all of the knots taken out??? ***

- To mend the joint, I'm assuming that I should use a combination of SS fasteners and epoxy.

- Once mended, I was planning on adding a layer of fiberglass to the stringers for protection and strength. Any advice on doing that?

Thanks much.

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Today, I checked the structure to find where all the rot is located . . . I drilled holes, etc. to see where I could find solid wood versus rot.

The engine compartment uses thru-bolted engine mounts, so there are actually 2 stringers on each side. The inboard stringers, where the engine mounts bolt through are hollow almost all the way back to the transom. The outside stringers have some rot started where they meet the bulkhead.

I did some research and found that borates and ethylene glycol are useful in killing the rot fungus and related 'bugs' So, I drilled some holes in the top of the stringer that leads to the transom and loaded it up with some E.G. I'm hoping that this will stop the deterioration at the stringers and save the transom, because it will be a few weeks until I can open things up to clean them out and do the repairs.

The transom itself looks OK and I have drilled into it in various locations and hit good wood. I will need to do a bit more inspection of the transom, but I'm hoping it is OK.

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Here is my hand at drawing the basic reinforcement structure and highlighting the affected areas: The yellow arrows show the rotted areas and the general direction of progression. It looks like the bulkhead rotted first and shared the joy with its adjointing members. It is time to break up this party.

The biggest challenge in fixing the structure is that the boat is of the 'modern 2-piece design' . . . i. e., it is pretty much a clamshell and does not have a cockpit floor that can be removed seperatley. So, access to the stringers under the cockpit is restricted.



Here is the plan for repairing this mess:

1. Remove about 18" of the 2 main stringers and some of the foam flotation behind them.

2. Remove the rot remains from the bulkhead and the rotted portions of the outside stringers in the engine compartment.

3. Repair the outside stringers with fiberglass and penetrating epoxy.

4. Replace the bulkhead.

5. Open the top of the inboard stringers in the engine compartment and remove rot remains.

6. Load up the inboard stringer cores with fiberglass, then pour in penetrating epoxy.

7. 'Sister joint' in 2 new pieces of the main stringers (as per Woodonglass's recommendation). Refill the chamber behind the stringers with foam.

8. Glass over the main stringers to repair the tear in the fiberglass mat on the port side and to add some strength.

9. Expose early stage rot area in forward bulkhead and apply penetrating epxoy, cover with fiberglass mat.


That's "Plan A" . . . we will see how it goes, and if a "Plan B" is needed.

 

[Woodonglass]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

That sounds like a very logical and "do-able" plan. Here's a drawing of how I sister joints. Just a butt joint with 3/8" or 1/2" plywood 36" (18" to each side of joint) "Sisters" on both sides, epoxied and deck screwed into the stringers. Are you going to glass the stringers in with Poly or Epoxy? I'd recommend poly due to cost and speed. use epoxy to glue the sister joint but then use Poly to coat the wood and apply the glass. Just my 2? worth.

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

I 'temporarily 'busted' the link to my photo (drawing) of the stringer layout. (sorry)

It is now fixed. It seems that photobucket is a bit tempermental about editing photos. I'm learning it is best to delete them and replace it with a new one

 

[oops!]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

i really like the photo bucket links ....

im re reading the thread now...

 

[oops!]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

The inboard stringers, where the engine mounts bolt through are hollow almost all the way back to the transom.
.

thoes are not hollow stringers bud.....they are totally rotten away.

the glass must be cut out, stringer replaced, and the shape re glassed.

your approach with glass fill and epoxy is iffy......the ratios must be corrrect.

use at least 60 or 70% glass to 30 or 40 percent reisn

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

thoes are not hollow stringers bud.....they are totally rotten away.

the glass must be cut out, stringer replaced, and the shape re glassed.

your approach with glass fill and epoxy is iffy......the ratios must be corrrect.

use at least 60 or 70% glass to 30 or 40 percent reisn

Those stringers are hollow now, almost all the way back to the transom. Once upon a time they had 1/2" plywood as the core. Since the outter glass is fairly substantial in that area, I figure that I can stuff 'em and fill them.

 

[Woodonglass]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Stuff em and fill em with What???

 

[tpenfield]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Stuff em and fill em with What???

I could use the Nida Bond stuff or something like that . . . or I may just mix up something on my own. We shall see. There are a few guys over on the OSO forum that have made repairs to similar vintage Formula's, so I have been looking at what they have done etc. Once I cut the engine compartment stringers open I'll have a better idea of the repair.

It seems that the rear bulkhead is a frequent source of problems in Formula's and that ends up spreading into the engine compartment stringers and then eventually into the forward stringers. There is a pretty good thread of a guy with an '86 272 that had just about the same sort of rot situation. The only difference was twin engines, versus my single engine.

So, it is sawzall time this weekend

 

[rickryder]

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

Re: 1991 Formula 242 Stringer & Bulkhead Repairs

That looks like the way my rot started but went a bit futher up the stringers to the helm... I used Nida Bond to repair my motor mount that was somewhat hollow.... Pics of everything are in my thread below