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Old 20-11-2013, 22:59   #1
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Formosa 46 Balsa Core Deck Thickness

Hey all. I'm in the process of purchasing a 1978 Formosa 46. Does anyone know what thickness the balsa used in the deck is? The decks need to be recored so I'm trying to find out what materials I'm going to need. Also, I'm wondering your opinions on using either balsa or Airex. I am taking this boat cruising (RTW) once the repairs/refit are done, so deck strength is going to be very important. Is the tradeoff between the lower weight of the Airex worth the loss of strength from not using balsa? Oh, and one last thing. Please no "don't buy a boat that needs those kinds of repairs" comments, ok? I'm getting an amazing deal on this boat because I'm willing to do the repairs.
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Old 21-11-2013, 00:24   #2
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Re: Formosa 46 Balsa Core Deck Thickness

I'm not certain about how bad your decks are, but I found a good solution to my bad decks. In the beginning of summer, I cored out numerous holes in my deck and let the decks dry for the next few months. Before the rains returned, I poured penetrating epoxy into these holes. I must have done this 5 or six times and actually used a few gallons of the stuff. I let all of this dry for about a week, then I filled in the cores with penetrating epoxy filler. It has worked great. My deck is no longer soggy and nothing leaks any more. Life is good.

FYI, my boat is a Hudson Force 50. It would be similar to yours.

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Old 24-11-2013, 10:20   #3
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Re: Formosa 46 Balsa Core Deck Thickness

Why would you think you have balsa core in your deck? Have you actually removed some core? Or are you just guessing. I have been to that yard in pertson and I'm pretty sure they used small blocks, say 4" by 4" of mahogany plywood for their deck core. This was common in Taiwan in those days.

You cannot use Airex in a deck. Airex, even if you find it today, does not like heat. There are other foams that you could use. But not Airex.
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Old 24-11-2013, 10:47   #4
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Re: Formosa 46 Balsa Core Deck Thickness

I have a boat that is over 30 YO with balsa core deck and I'm happy with it, since it was done right. I only had to cut out two spots when I started the rebuild. One under a winch and the other under a padeye that had been rotated.

If you decide to go back with balsa just be sure to get the resin down between each block. This is what seals off the rest of the core to water intrusion/wicking, and also gives it better strength.

Also recommend using G10 for backing plates, epoxied to the underside. It adds to the strength of the existing under-skin.
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Old 24-11-2013, 12:26   #5
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Thanks for the tip. As for whether or not they're balsa cored, I really don't know. I
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Old 24-11-2013, 13:35   #6
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Re: Formosa 46 Balsa Core Deck Thickness

The Perfect is the Enemy of the Good

Recoring a deck is a huge and expensive project and will be invisible. If you have the skills, money and patience to bring this boat back to "like new', then it certainly should be on your list but I wouldn't tackle it first. In fairness to you, you might already be working on other stuff.

I've never heard of a boat sinking (or even a cruise delayed) by soggy decks. But while you can circle the globe with soggy decks (many have), many other systems on a newly acquired old boat require attention (rigging, ports engine, seacocks, tanks, steering, sails, wiring, autopilot -- just to name a few )
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Old 24-11-2013, 13:37   #7
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Re: Formosa 46 Balsa Core Deck Thickness

Kev:
Balsa core was very rare on the early Taiwan boats. The core used by almost all the yards was kind of like a mosaic of little square blocks of plywood. Each square about 4" by 4" laid down and trowelled over with a filler material. It was a heavy core and very labor intensive to install. But in those days labor cost was very low. Balsa cored decks came in later at yards like Ta Shing who tried and succeeded in doing a higher quality boat.

I agree with Carl that recoring an entire deck is going to be a gargantuan task. I simply can;t imagine doing it. I'd spot repair where required. Your grp skins on the deck are probably massivly overkill and as Carl says There may be other areas more important to the overall health of your vessel.
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Old 24-11-2013, 13:59   #8
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Re: Formosa 46 Balsa Core Deck Thickness

I would guess it is cheap asian plywood. Possibly squares 3 x 3 or 4 x 4. I assume your 46 has the teak decks and it's likely saturated everywhere.
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Old 24-11-2013, 15:13   #9
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Re: Formosa 46 Balsa Core Deck Thickness

Quote:
Originally Posted by CarlF View Post
[I][B]
I've never heard of a boat sinking (or even a cruise delayed) by soggy decks. But while you can circle the globe with soggy decks (many have), many other systems on a newly acquired old boat require attention (rigging, ports engine, seacocks, tanks, steering, sails, wiring, autopilot -- just to name a few )
Maybe not sink but possibly lose rigging. The problems with soggy decks on sailboats it the loss of strength to hold deck fittings or to even support the mast.

If/when you own the boat I would drill a bunch of probe size holes on the underside and test with a moisture meter just to see how bad it really was before stripping the whole deck off. Even a screwed down teak deck may not be totally gone.
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Old 24-11-2013, 15:35   #10
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Re: Formosa 46 Balsa Core Deck Thickness

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Maybe not sink but possibly lose rigging. The problems with soggy decks on sailboats it the loss of strength to hold deck fittings or to even support the mast.

If/when you own the boat I would drill a bunch of probe size holes on the underside and test with a moisture meter just to see how bad it really was before stripping the whole deck off. Even a screwed down teak deck may not be totally gone.
a big +1 on drilling from the underside to ID wet areas.
If unsure slide the wood out of the drill twist and press it between your thumb and forefinger...water will come out of the wet wood. Sometimes water will come out of the hole!
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Old 24-11-2013, 18:39   #11
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Thanks for the heads up guys. Yes, there are other issues I'm planning on tackling first. Like the rigging. It's ALL getting replaced. Shrouds, stays, chainplates, turnbuckles, halyards, sheets. You name it, I'm replacing it. Then a couple motor mounts are getting replaced. Folllowed by new batteries. And yes, the decks are wet because of the teak. All those screw holes. I'm hoping to have her ready by late summer. Possibly sooner depending on what I decided to upgrade as I'm repairing her while she's up on the hard.
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Old 24-11-2013, 18:56   #12
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Re: Formosa 46 Balsa Core Deck Thickness

There are many threads on wet decks and repairs. We repaired ours by

removing 2-1/2 inch plugs of glass from the inner skin.
dig out the wet balsa. Let it dry
apply new glass to cover the holes.
pump epoxy - microballoon syntactic foam into the cavity.

No insult to the deck; light weight and very strong.

I use US Composites 635 thin resin and add as much balloons as can be pumped. This resin is very slow so there is lots of working time and not much exotherm.
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Old 24-11-2013, 19:00   #13
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Hmmm. I might have to look into that. Def sounds easier than tearing out all the teak and taking a skill saw to my deck.
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Old 24-11-2013, 19:14   #14
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Re: Formosa 46 Balsa Core Deck Thickness

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Originally Posted by Kevin84 View Post
Hmmm. I might have to look into that. Def sounds easier than tearing out all the teak and taking a skill saw to my deck.
You might also find the $200 or so for a moisture meter is a work saver. Use it on the INSIDE with the headliner removed. Fillers on the deck & non-skid may fool the meter if used top-sides. Good tutorial on the web site. Get a pinless analog type. You don't need accessories. Calibrate against places and materials you know to be dry. It will point out the places to start your excavation.

Electrophysics Moisture Meters



Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc. Link to US composites
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Old 24-11-2013, 19:35   #15
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Good info to have. Def need to invest in that.
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