Deck core - The heated debate yet again

[Dymaxion]

I'll stay out of the main debate, injection fixes. But for those who have removed/replaced deck skin, what's the recommended tool? Anyone used a small router, like a laminate trimmer, to cut around largish sections and then pry off the deck section. Getting ready to re-bed the toerail and several of the through bolts leak into the cabin. Tx

[OS2Dude]

If it is just the area around the toerail bolts, I'd core each hole separately. Is there a large area of deck that is damaged that would require a core replacement?

I'd use a Dremel if I was to need to remove a large section. It will take several cutoff wheels (Depending on the size of the area to be removed) but the seam will be smaller when you have to reattach. If you go this way, do like a plastic surgeon and look for existing seams/edges/differences in deck texture or color in which you can 'hide' the future repairs to the gelcoat.

[Dymaxion]

Tx OS2, no idea how far the wet/rot extends around each bolt yet, but I do have a set of hole saws!

[neilpride]

Originally Posted by chowdan

I have no problems removing chainplates as it is not a major task.

Removing the top layer, chiseling out and replacing rotted core then re-glassing in the top layer is a major task. Working over 70 hours a week on average(at times over 90 hours) means I have very little time as I am starting my own business while working a full-time salary position.

I don't think I could make this surgery with a single 2 day weekend, and I even doubt that I could make the drill & fill method fix in a single 2 day weekend either. I haven't worked with fiberglass all that much so this will be a first for me(i have fixed dings and dents and such on surfboards growing up, but nothing of this scale or importance).

Take few hours if you have the plates out, determine the area in question, use a pen and mark the perimeter of the plate slot, use a dremel and cut the top deck skin, sand the perimeter to bare fg, dig out the rotten core portion , clean and sand the inner fg skin , acetone etc.. wet out the cavity with some fresh epoxy , mix a mixture of west with some silica and some 404. spread the mixture with a thick consistency, work with a putty knife and cast the mixture nice where the plate fit, wait until the epoxy start to gel and epoxy glue the top portion , then to finish you need to aply some glass to the joints , ground smooth and finish with LPU or whatever you are
satisfied....

The other faster option is with the plates out , dig out the rotten core from the deck chainplate slot, try to sand and clean well the cavity and fill it with a epoxy misture, and reinstall the plates when the epoxy is hard and dry.
Cheers.

[dmalcol1]

If damaged area is just the area around the bolts 3/8" drill with bent nail of appropriate length should clean up area nicely.

[cruisersfarm]

Originally Posted by chowdan

Have you gone through the post I linked? I would highly recommend it as it has been written by John Cherubini II, who's father designed the Hunter 25.

John Cherubini the second, has a respectable background within the building field, and that includes restorations of these plastic classics. I have a hard time hearing something from someone who has been in the boat building industry for 40+ years and finding a reason to not believe it.

I don't care who advocates taking a shortcut.

You're wasting your time, money and the boat making an inadequate repair.

Garbage in = garbage out. There is no free lunch fixing delamination.

Use a dremel (not a bent nail or allen wrench) to de core around any holes. Try the nail/allen wrench method first and report your findings.

To cut off large sections of glass to get at rotten core, use anything that makes a shallow cut. I like using a circular saw because I don't like waiting around for things. Set it at proper depth and zip down your cut in seconds.

If the area is tiny, a dremel works.

After you replace the core, try to help yourself in the fairing stage by beveling the glass at all edges of your repair area. using your variable speed buffer/polisher with a sanding disc, taper those glass edges so they are very low rise/run ramps. this will help you later as you reglass and create better joints that you can fair,

[brantleychuck]

Originally Posted by Dymaxion

I'll stay out of the main debate, injection fixes. But for those who have removed/replaced deck skin, what's the recommended tool? Anyone used a small router, like a laminate trimmer, to cut around largish sections and then pry off the deck section. Getting ready to re-bed the toerail and several of the through bolts leak into the cabin. Tx

Use a 4 inch grinder with a metal cutting blade


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[DerekKelsall]

Balsa = compost.

<http://www.yachtsandyachting.com/news/188579/Spectacular-Round-Tortola-Race>
This link came to me today, typical of regular contacts from owners of boats I designed over five decades - though not all winning races! My question to the boating industry is why does balsa and it's problems still feature so often in discussions. I built my Tri Toria in 1965 - we lead the field in the 2000 mile Round Britain race. She was the first foam sandwich of note. A year later I made a rule for myself. Never spec any material which will rot in any part of the structure. Triple Jack (owner built is one of many) Polyester/uni E-glass and PVC foam - the Toria spec and is still good today.

Balsa to have any chance of surviving needs to be buried deep, which should deter its use with thin skins of sandwich anyway. I have never heard a viable reason to choose balsa.

The decks are the worst place for balsa. I know of a few balsa decks which have been totally replaced with foam sandwich.

"Core" is often referred to without naming the material when chalk and cheese applies!! Balsa is still widely promoted. I have been saying this for 40 years - WHY BALSA?

Happy boating,

Derek.

[Nicholson58]

I have posted many times - broken record - on my preferred method. It works well for uys because we have an inner headliner. I take down the head liner, hole say the inner skin, dig out the wet, dry, repair the inner skin, pump the cavity full of epoxy with 3M microballoons (syntactic foam) I use US Composites 635THIN resin only. Pump it in using re-fillable calk tubes. Fill from the low point & vent the high point. This material is totally waterproof forever and has a compressive strength of around 3000 psi - infinitely greater than the usual materials and it bonds better to the skins. Photos Member Galleries - Cruisers & Sailing Photo Gallery Look for the DECK photos. You see the struts used to hold the inner skin repair up. Use heavy film as a release material. I used the same filler to make my new rudder instead of urethane foam or balsa.


As the others have stated, don't waste time with bad repairs. Usually that lets you do it again or worse.

[rognvald]

Epoxy injection only works if the core material has not degraded. It has been my experience that this is usually rare unless the boat is relatively new and the ingress of water has not been significant. I "repaired" the cockpit floor on my first boat with epoxy injection. It was a waste of time since the core was principally degraded. When I removed the skin to do it correctly, it looked like a bunch of Hershey Kisses with rot in between. There is only one way to effect a proper repair: do it properly. Good luck and safe sailing.

[Terra Nova]

OP--instead of focusing on the many reasons you have for doing an amateur repair job (don't have time, $, etc) , while the chainplates are out, see if you can eliminate the core in the area of the chainplates and re-glass with solid glass, not epoxy filler. If you can do this from inside the boat, it could save you a lot of work refinishing the exterior. And you don't need to be hauled out do do this work inside the boat.

[zstine]

To cut the skin, I use a vibrating saw which has a thin blade and since it's not rotating at high speed, the dust is minimal and easily vacuumed while cutting. Last year I repaired my main bulkhead that had rotted in the are of the chain plates. I drilled a 1.5in hole 6 inches below the chainplates and used an Allen wrench and shop vac to remove the wood pulp in a 20 x 16 in area. I stuffed over a yard of fiberglass into the bolting area and then filled the rest of the void with 1in cubes of wood. Started with a few quarts of neat 635 epoxy from us composites. Injecting with 60cc syringes from bottom up plugging holes as I went. The last quart injected in top bolt holes was thickened with 404. Epoxy squirted out from areas 10 inches from injection spot. Used approximately 1 gal of epoxy. When I redrilling the chainplate holes only 3 had small voids, probaby 90% solid. So I basically have g10 bulkhead in the chainplate area.. no issues so far.
For deck around chainplates, the core should be ply not balsa. If you don't need to remove a lot, use a laminate trimmer or router with an undercut bit. Unless it is degraded enough to pick away with a finger, then an Allen wrench will work. Core needs to be like dirt for the Allen wrench method. The laminate trimmer method Will allow you to follow the rectangular hole and remove a 1/2 in depth. Then you can use thick epoxy, support with tape to keep from sagging, and fill the area of core removed.. for the method using an array of holes and epoxy injection, you should see epoxy come out of the next hole before plugging and moving on. If you can't make it squirt out the next hole in you array, then you need to drill the holes closer. This ensures a complete fill and assures you are not getting the Hershey kisses mentioned before. That person did not inject enough epoxy and didn't drill enough holes... oh, and after you fill everything, go back 2 hours later and refill. The epoxy will absorb into the wood core and you need to add more before it hardens so that it can cross link. Keep repeating the fill, wait, fill... it took me 10 hours of this to finish the fill of my bulkhead!