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Malibu Skier Stringer Help!!!


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Hey everyone, I have a question regarding stringers in my Malibu Skier and I've been getting a ton of mixed reviews as to how to fix. Last weekend a friend and I removed the engine from the boat. While hoisting engine we noticed the lags for the engine mounts just pulled right out. Meaning rotten wood.  We also removed the floor and can tell the stringers are rotten too. Now our idea to tackle this beast is to grind and remove top of stringer and scrape out the wood, leaving the fiberglass mold intact. 

Now here's the issue, I've had 5 people tell me 5 different ways of repairing. My usual boat Mechanic says use pressure treated wood and glass over, which I read doesn't work well because nothing adheres to the wood. In fact everyone says not to go that route. Another guy said to use seacast and pour in the fiberglass "form". I looked on youtube and it looks like it'll work. Any suggestions on that product? I know it's super pricey but also won't rot. Another boat place says they fill the stringers with foam, then glass over which doesn't seem to be strong structurally and I doubt it'll help with the Eni email mount. My buddy told me to install a piece of 2x6 mohagany for stringer and 4x4 mahogany for the engine mount, epoxy around and glass over. Which seems fine but also stated that's it is heavy. Last but not least another a guy told me to cut strips of marine plywood and epoxy them together set in place of stringer then glass over. Basically make the stringer of several strips of plywood. As its easier to shape. I'm really worried about the integrity of the engine mount stringer and how to do it. Any info or suggestions would be great, just seems like everyone does it different......thanks!!!!!

We pulled the engine due to noticing that the engine was only resting on 3 mounts and the other popped off due to the lack of wood in stringer and vibration of the engine or so I'm told. That caused my engine to be out of alignment and screwed up my drive shaft and bearing in strut under boat is gone. So fixing this is a must, to prevent further damage. I'm no professional but I was told this is the place to ask these questions. 

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I used a product at the time called Penske Board. It is stronger than wood, and lighter. It is a fiberstrand foam board. Don't let the foam part fool you. This stuff is strong and durable.... but it is expensive.... and it comes in 4x8 sheets (I layered my together). 

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  • 3 weeks later...

I have done this job on a1975 Century Arabian. Like others stated, pressure treated is a no go. The quality of the wood and the water content make it so no adhesive will properly bond. 

I found a lumber company that sold premium wood, lowes/Home Depot will not sell the quality of lumber you need. You are after real Douglas fir and mahogany. Both have good strength to weight ratios and superior rot resistance. You should use your old stringers as a template if there is enough left to shape the replacements. When ready to install permanently, grind the fiberglass on the hull where the stringers will be and clean with acetone. Make sure to wear proper ppe. It is a messy job. Once clean mix some epoxy with silica thickener to the consistency of peanut butter and apply to the hull. Bed in your stringers (note- don't encapsulate your stringers first. The epoxy will bond well with the bear clean wood) let that sit 24 hours, once done you want to use fiberglass cloth, thick stuff like 24 oz to go over your new stringer. Couple of points here. The cloth does not like to bend. I would use 3 pieces of cloth per stringer (one on each side and one over the top - for the top you may find it easier to use two pieces of 12 oz cloth as it will contour better). When doing the side, grind/acetone 8" from each side of the stringer and mix up two batches of epoxy one with silica and one without. Apply the thickened epoxy on the hull side stringer to make a radius for the cloth like ")" then place the 24 oz cloth in position try to be as close to the top of the stringer and 8" inches on the hull. Use your regular epoxy to saturate the mat and let cure - 24 hours. Once each side is in place do the top. 

Couple of notes with epoxy - it is great stuff but hazardous. Cover all skin, double layer nitrile gloves (they always tear at the worst time) and use a real mask with filters ( the silica is not good to breath) some people develop a sensitivity to epoxy over time which looks like a nasty rash. Epoxy without thickener will run like water and get everywhere so plan accordingly. 

After all done, paint with a good quality bilge paint and it will look awesome. Don't worry about the inevitable imperfections, runs and sags - I have seen worse from professional boat manufacturers. Also don't worry about weight here, better to overbuild. Last point to consider is hull flex. Without the stringer the hull itself can flex and twist make sure you are properly supported. 




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  • 1 month later...

Hey everyone it's been awhile since I've logged on here. But as of now we decided to go with the solid wood stringer. We purchased 2 2x8 douglas fir KD and shaped the stringers the best we could. I've read a few places that it's not recommended that the stringers sit off the hull 1/4" anyone have any input on that. When we set them in we had trouble shaping near the bow and getting the angle to work. Unfortunately the whole stringer was rotten so there was no template to work off of. 

Now I'm at a standstill. The stingers are ready to be bedded but I'm unsure of the material. Epoxy seems to be the way to go but it's pricey. And I'm unsure if I bed the stringers and make my fillets with epoxy and cabosil will I have to do the whole project in epoxy including the tabbing and encapsulating the stringers. Also would the deck need to be epoxy based too.

I've read some forums and asked a few local shops. Everyone seems to have their own methods of doing it which has left me confused and no real direction. Another thing is fiberglass. Some say tab and wrap stingers in chopped mat then roving over. Some say tab in 6 oz fabric then 1708 bi axel or roving over that. So I don't know how much I'll need depending on who's advice I go with. I like the 6 oz tab idea seems to be a more common approach. Sorry everyone if this seems all over the place my brain is dead with all this reading lol. Any input is greatly appreciated thanks

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I have done more stringer/epoxy work than I care to think about building a little runabout, restoring a couple of old 60s era closed bows and restoring  a 1975 Arabian   I'll post pics in another post.  Ther are several ways to do this and everyone uses their own technique.  I have always had good luck with Epoxy.  It is more expensive than Fiberglass but it will bond better in this situation and it will be more forgiving.  You will need a lot of it and I would recommend West systems with the pumps that come with it.

to answers your questions:You want to bed the stringers in epoxy thickened with silica. Mix to the consistency of peanut butter. no chopped Matt - the epoxy won't saturate well and it won't give you the strength your after. 6 oz is too thin.  Biaxial is always good. 

Not sure where you live, but if your anywhere near Massachusetts I would be happy to help. If not feel free to pm me and I will give you my cell number and can answer your questions in more detail. 

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