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Materials for a Re-Core?

Have questions about fiberglass, gel-coat, or core repairs well as composite questions?
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VultureNo2
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Re: Materials for a Re-Core?

Post: # 3482Post VultureNo2 »

Thanks Chet. I did have the link already and plan on calling them. Only concern is distance and if shipping from there to here will add to the cost. Maybe a road trip in the 94 awd ext Astro van for the stuff is an order. Bill
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Re: Materials for a Re-Core?

Post: # 3531Post JETMORE »

balsa and epoxy gets my vote, 2nd best is balsa and vinylester. go to u.s. composites online and epoxy is clsoe to half the cost of big name epoxys and similar properties. for major impacts, balsa has far more strength (safer) than any foam or honeycomb. compression, shear, and tensile, balsa is the stuff, and its cheap. to be honest, being as this is your first, use the same core, because you really need to talk to a naval engineer to switch core. it isnt as easy as just changing the core because the properties of core are different. you can even now purchase various densities in balsa through genetic modification. use douglass fir, okoume is good also. the argument i always hear from the "foam" guys is that upon SMALLER impacts, the foam is not destroyed and can be repaire, whereas, the balsa may be destroyed and you may not even know it. good point, but upon LARGE impact, the balsa will better protect you and the boat. in light of the slamming loads one encounters in a small fast boat, balsa is the way to go. don't believe the bill of goods that foam is the way to go in everyones eyes. many high end boat builders use balsa still. i will say, that in a "production line" boat build where not everyone is watched as closely as they should be, it probably is nice to know that the core cannot rot, as it is foam, even if not properly sealed. but, you are doing the work yourself, and this is not an assembly line. gougeon brothers, who make west system epoxy and even higher end pro set products for outfits like nasa love the use of balsa as it will not rot if encapsulated properly. it may seem like overkill but gougeon as data showing that 7 coats of neat (unthickened) epoxy over wood repels moisture almost absolutely. the data emphatically shows that to do this, you do not thin the epoxy but rather heat the wood to about 100 degrees. the pores open of the wood, and then the epoxy goes into the pores. another "radical" idea that works extremely well, that most internet weekend builders don't mention, is the use of plywood for a core. now, ply is heavy, so it is ideal to only use it in the rear of the boat, like paul allison used to do. that's right, Allison used to d othis back in the old days. the ply is even better than balsa, and the beating the last 4 feet of the hull take are ideal for ply, then go to endgrain for the remaider of the hull. doug fir, or any of the lloyds registry bs1088 ply is good stuff that will outlive the the fiberglass if encapsulated correctly. vinylester is a far better moisture barrier than poly, so, at least, use this. final point, leave an openeing in the floor under the bow for better ventilation.
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Re: Materials for a Re-Core?

Post: # 3532Post Hippie459MN »

Very very well said and another excellent post. I have never heard of plywood being a good core material though myself but I am also just learning about all of this rebuilding boats stuff. So maybe my plywood core would have been ok for a season or two. :D

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Re: Materials for a Re-Core?

Post: # 3536Post ccrick »

I,ve seen ply core in a few manufaturers. Strong as hell when done right. I'm a beleiver in composites. My experience in boats goes way back to wooden chris crafts. I went to kindergarden a mile from the famous chris craft plant in Algonac. Lived on the north cannel of the St. Clair river. Through the 80s, I worked at a marina and did a lot of hull work. Replanking a bottom of a chis craft connie is quite a job. All the glass boats used wood and even if the layup was good it was still destiny. I remember the engines would break loose from the strigers in the old formula's, sea rays and welllcrafts due to rot. Lake St. Clair is a rough lake and a lot of 40'+ boats. Think about strength on those boats as there clipping along at 30 and hitting the wake of the 50 footer going the other way. Hmmm, and they have foam cores and way more square feet of surfaces and surface loads, A different situation-cruisin along and you look in front of you and theres a log floating and you clip it on the port side. Get the boat out of the water and its cracked and splintered to the core. I know which ones going to be easyer to fix. Don't get me wrong, bulsa is a great core material and is stronger than foam. It depends on a lot of rocket science. I know I'll break before my boat does. I did use ply for my floor and stringers. I like ply because it's so darn strong. To repair rotten stringers we would laminate marine ply. Worked great. Just my opinion on the ongoing discussion wood or composite. The boat held up this many years and the core was rotten. I wonder how many years of life I added to it now!
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Re: Materials for a Re-Core?

Post: # 3539Post VultureNo2 »

Thanks everyone for your input. Bill
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Re: Materials for a Re-Core?

Post: # 8469Post upper decker »

GREAT Thread, Thanks to all who have posted on this thread, the info here is second to none. Great talk of materials Randy very informative, :up: :boating:
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