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  1. #1
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    Apr 2019
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    Kansas
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    Rotten balsa wood in inner hull of Monark v16 bass boat need help

    I have a 1982 Monark v16 boat that when I went to replace the plywood floor I noticed an inner liner of the hull. It's like it's delaminating I thought from the hull but realized in between was rotten end grain balsa wood. I cut most all the inner hull out and the wood is like wet mud. Question is, is there a fix by way of reinforcing the inner hull in a different fashion? The outer hull looks great. Thanks for any suggestions!

  2. Member crank68's Avatar
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    Mar 2011
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    Kenly, NC
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    17,416
    #2
    May need some pics...
    BULLET 20 XRD/250 Merc Sport XS
    www.ncboatguy.com

  3. Member
    Join Date
    May 2015
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    Kiln Mississippi
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    #3
    I usually add a lot of hull support like adding extra boards to the trailer, also I will pick up the boats off the trailer and lay 12" wide strips of 3/4" plywood under the boat on the bunk boards before any cutting is done inside. Adding a hook to your hull while repairing it is easy to do. You can look at my 171SC Champion restoration post to see me replacing areas of end grain balsa with Coosa Bluewater 26 panels. Cores do not add spine like stringers, cut and replace small areas at a time then tie all together with a continuous cap of glass. Smaller repairs makes it easier to support. The old V16 McFast hull set some propeller boat speed records in the past. My go to capping glass fabric is 1708S-Glass.

  4. Member
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    Apr 2019
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    Kansas
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    #4
    Thanks for the advice, I really do appreciate it! Just a couple of things, this boat only has one stringer, down the center of the hull and not the full length of the boat. About 3' back from the bow and about 3' forward of the transom. All of the surface inside, topside of hull had the balsa core with fiberglass laid over it. I have already cut most of that out where I can get to. The top cap of boat is still in place so I'm having to work around the console, cooler and live well and storage etc. I really don't want to have to take the top hull half off if I don't absolutely need to. If I use coosa board where I can and also a couple of extra smaller stringers would that be a good idea? Just how necessary was that balsa core needed to make the hull strength sufficiently strong when the factory built it?

  5. Member
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    May 2015
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    Kiln Mississippi
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    #5
    It would be a stretch to try and advise you without some pictures. Core usage in boat building has its pros and cons with much debate. The balsa cores I see here are always dry rotted if not rotten from water. Coosa is a stiff material and if I'm understanding you correctly you will need a core that is scrim & cut like H-80. H-80 it the core material I'm currently using to rebuild a Hells Bay Waterman that took a piling punch through to the aft 1/3 of the boat. Coosa went back in as the new transom (it was broke in 6 places) but H-80 was used due to conformability to for original hull shape. The density of the core foam is important since no hard edges can be created against the outer skin. That causes cracks. What ever you use, before you start re-laminating, check the planing area of your hull with a very straight edge for hooks. You don't want to mold in a hook, your weight, the vessel's weight, lack of interior structure, sitting on a trailer, can deform the original skin. That is why the very first thing I do is split the boat. Stringer systems are much better to me than just a core. Today a laminated hollow stringer system is popular with a higher density foam injected inside and no core material is used in the skins. Replacing stringers in bass boats you will see the pros cut huge sections of the top cap out for access to the rotten stringers then repair the gelcoat when finished. Unless you have a personal attachment or just want that hull design, used hulls are cheaper than what your facing. The materials alone are very expensive. After I finish my 171SC I will have to roll it over and blueprint the hull, I doubt me crawling around in the boat while it sits on the trailer, repairing & replacing the original inner structure, even with the experience I have, the boat will still have hooks of some sort. Without the cap on I can easily rotate the bottom side up and rest all the weight on the recently replaced inner structure floor. A very nice & large flat spot will exist to rest it on with even weight distribution. I use old, small boat trailers with 10" - 12" tires to get the hull as low as possible to blueprint. It makes it easy to work on and I just roll that job out of the way for curing time. To try and answer your last question, in the late 70's & early 80's manufacturers were trying a lot of things and balsa sandwiches was a big one. Most of the "sandwiches" had less fabric & resin due to relying on the core for hull integrity. I believe Cajun Bass Boats pushed the balsa hard back then. Hydra-Sports had it right with the Kevlar over balsa. Without core integrity and the original mold to place your hull in for repair my personal opinion is to "Punt". Please don't shoot the messenger, if you brought me your boat to fix and it was constructed as you describe here, I would not touch it. Too much effort to end product ratio. I hope this helps to give you out.