Help! Rotten Stringers!

Hey all,

I've made a mess.

I've read the other posts, and not found the answer I wanted. Probably for good reason.

I have a 1993 sea ray 180 (18'), with a rotton stringer. It looks as though it goes right under the motor mount as well. I can't hoist the engine out, and was curious as to weather there were any other options other than wood replacement. The origional wood seems to be 1/2 at most, and I would much rather dry it out, treat it w/ epoxy, and then jam pack it with epoxy filler of some kind. 3m and west systems have structural filler that is incredibly stong (i've bought some to play with and test as it has fiberglass strands in it), but I don't really trust it. Why? Because there is a reason there was wood there in the first place. It just seems that in todays age of technology, there should be something injectable that should do the trick. I've gutted the rot out from above, and it went clear down to the hull in places. If pictures would help, let me know and i will procure some.

I am not yanking the engine. I want it to work well... but jeez... yank the engine?

 

Rotten Stringers

Personally, i like wooden engine bed laminated with fiberglass because of the vibration damping qualities. It absorbs engine resonance that would otherwise be amplified by the hull. But wood decays over time.

The engine bed is highly reinforced and should not be taken lightly. All that engine mass will rip off when the boat heaves or slam a big wave.

Injectables will not work. It has a very low density.

I suggest ripping apart the engine bed stringers and replacing the wood with high density pvc core in the range of 200kg/m3 and laminating it with 4 to 5 layers of glass. Add extra layer of glass on areas where you have to embedd stainless steel plates or bolt SS brackets.

 

Not what you want to hear

bhd,
I know this not what you want to hear but, here goes.. Yank the motor!. Many years ago I didn't know how the epoxy (west systems) worked, so when my pal showed up with his 23 wellcraft with a soft stringer we went to town on it. Mixed a big batch of resin / hardner poured right in the bolt holes filled it up. Well.... the smoke from the epoxy reaction cleared after awhile and that was the weakest, crappiest repair ever! My pal insisted that the new lag bolts for the motor mounts really bit good and were tight, so down to the lake he went the following weekend. Needless to say the mount was loose. He ran it for the season, basically with the engine moving around.Did a nice job on the driveshaft / dampner too. That winter we YANKED THE MOTOR and cut the tops off both stringers and left the fiberglass on each side. Then we carved out all the mushhh. Then a little die grinder to clean up inside once the space was dry . Laminated a bunch of marine plywood to the thickness of the space left open (we actually called west systems tech line) We used epoxy with 406 to make a glue to set the new stringer section. We used the same mixture to glue all the plys together. Glassed over the top with biax fiberglass and sanded it smooth for the motor mounts. To this day that repair in still rock solid, the boat is unfortunatly falling apart around it. See, won't you feel better what you slam the first wave and not worry about that motor rolling past you!

Good luck
Capt. Chris

 

The mount feels solid as heck though, even though i am diging mush righ out of the middle of it. There is a bracket coming off of the stringer itself, which might explain why it is still solid. I will definitely do some more deconstruction/investigation, and then take some pics for everyone to look at.

Thanks for the comments so far guys.

 

Another thing,... I've alrady scooped the mush out. Its tunneled out very well.

Can i not mix epoxy with fiber strands or other filler, to a sizable amount, fill the cavities back up with the mixture, vacuum bag, and then use more expoxy and mat to relaminate the top of the channel? Anything would be stonger than the mush, and this would prevent a lot of work in disassembly. Why do companies sell STRUCTURAL FILLER if you can't use it?

Thanks again ya'll. I don't want to do this twice, and i couldn't possible let someone pay me for these problems.

 

bhd,
You can use west system 406 to thicken the epoxy, but in moderation.They also have a high density filler (I think it is 403?) . Fillers all have different properties, some for laminating, bonding, fillets, fairing and so on. Check west systems web site for more info , they even sell very good how-to manuals for the different products they make. As for filling huge voids with epoxy, just be careful. I don't understand how you would vacuum bag this repair, thats not really the right apllication for that process. They usually use it for laminating and molding. Good luck
Chris

 

http://briefcase.yahoo.com/dkidoliver

the jpeg named boatexplain.jpg is a brief overview. If someone tells me a safe way to "Pour" the wood in from above : ) I will send them a nautical present worth ~30. or just send them the cash. Seriously though, take a look at it... tell me your thoughts.

The wood was roughtly 6 inches deep, and 1/2 wide. How structural can this be?

Also, can I laminate many pieces of wood together to fill the void? I can fill the void from for and aft of the motormount without removing the engine. (the mount is actually built off of the stringer a bit.

I hate to ghetto it, but just assume that's what i'm going to do.

 

bhd,
Try EZ-Poly structural filler - permanently bonds to and seals most anything. http://ez-poly.net it's a two part polyurethane that can be poured into hard to get to places like yours no odor, safe can be used if surface wet, dry gravel/wood can be added to it 50% to make it go further fantastic stuff.

 

BHD, Seacast makes a pourable epoxy filler for this type of repairs. Check them out at www.transomrepair.com

 

The ez polly seems like a nice route to go. Seacast is going to be over 200 bux, and they haven't responded to my questions very well. I just wanted to get an idea for how easily it poured, and no response. They doo seem a bit more established then expolly though.

Thanks for the info guys. I really appreciate it.

 

BHD, Just read an interesting thread on this forum about Seacast, you should look it up. Its not epoxy after all, though I have seen it used with good results. Don

 

This might help

BHD, you can add glass to EZ-Poly to increase strength, it will pour and fill, density (specific gravity) is about 1.6 (like hardwood), impervious to fuels, salt water, rot, etc, try some out, might save a lot of hassle. PMB

 

I shot them an email and haven't heard back yet. They don't seem to have purchasing prices on their web site. I'm just about done disassembling the boat in the damaged area. The whole right rear area was soaked down the the sole. I've almost gotten all the foam out.

Where should one purchase the self expanding foam. Are there any good websites on how to calculate the amount needed?

For internal structure, is marine grade plywood absolutely necessary? Should I treat it with some type of water sealant as well?

I've heard good things about the newer MAS series of epoxies. Does anyone have experience with it?

Thanks so much for the replies so far. This has been very helpful.

~Dave

 

HRM... just noticed that PMB and GCA have only posted once, and both are from San Diego. I wonder why they signed up just to reply to my post? ; )

Sales Guys?

 

Anyone have anymore advice on this? If I really should replace w/ wood?

c'mon... such a bit forum, so little feedback!