Deck Delamination / Core Problems

[commanderpete]

No specific answers, but here is an example of a core job from underneath on a San Juan.

http://personal.monad.net/~catamount/Quasar/part1.html

[mrgnstrn]

If you are going to attempt the "under-side" repair, you might want to look into vacuum bagging.
West-System has a $3 manual on the basics of vaccuum bagging, which might be worth looking at.
The basic principle is that you put in your epoxy, stick on the core, cover the whole thing with some polyethylene sheet sealed at the edges, and draw a vaccuum on the inside. That way air pressure (~14.7 psia at sea level) pins the core to the ceiling evenly. And presumably better then trying to hold it in place with braces, etc. With a really good vaccuum pump, you can probably get almost all of that 14.7 psid, but even a moderate one will let you get at least 10 psid. For the whole underside of the forepeak, that would add up to.....~2000 square inches, and ~ 10 lbs per sq-inch diffential pressure (psid), maybe 20,000 lbs of clamping force evenly over the whole area. Sure to squeeze out any excess air bubbles and excess epoxy. And since you can vary the vacuum, if you feel like you are going to squish the core, you can reduce the vaccum, say to 5 psid.
Ebay can hook you up with a vaccuum pump for ~$75.
When I replace #3's core, I plan on first trying the vaccuum bag technique.
Some numbers to remember:
29 inches Hg vaccuum ~=~ 14.7 psid
is almost a perfect vaccuum.
10 psid ~=~ 1440 lbs clamping force per square foot.
Let me know how it goes!

[ElBeethoven]

So I have yet another question (BIG surprise there):

On #120, the core in coachroof over the v-berth is SHOT on the starboard side, the ENTIRE starboard side, including down and around the portlight. Or at least, the vertical walls around the portlight are compressible if there is, in fact, no core there. I have reread this entire thread, the more recent thread about recore we had going, searched the web, read the articles suggested, scanned my books, etc., and I cannot find ANYTHING about what to do if the VERTICAL faces of the coachroof are soft.

So what IS in the vertical walls? How would one go about repairing it if it IS rotten? Fill it with epoxy a little at a time? Without slicing off the whole coachroof, how could one be certain that bottom "joint" is void-free where new core (or whatever) meets the deck?

Anybody?

P.S. At least it was "encouraging" to find several cases of coachroof recore from the OUTSIDE, as I had planned on going in from the cabin. I've definitely changed my mind on that one. :-)

[ebb]

Vertical sides are hollow. Check out what the rebuilders are doing.

[Bill]

See the first post in this thread. It has a link to Bill Sandifer's article on recoring an Ariel -- including the coachroof. And, more info on deck recoring.

[mrgnstrn]

What is the thickness of the core in the forepeak?
I want to buy materials from the supplier without having to make a 2.5hr round trip for one measurement.
I am sure that if I had time to scour the website, I would find it; but alas I am at work.

Thanks!,

[Mike Goodwin]

I guess you mean the deck core on the foredeck. #45 was average of 1/2" , thinner near the rails .

[mrgnstrn]

Yes....the foredeck.
And Thanks!

[ElBeethoven]

Ok I have completely lost the forest among the trees. Would someone just please TELL ME from where and what kind of balsa I need to get so that I can finish this budget of mine and decide if I want to tackle this lovely deck recore project!?!??! I've been bouncing around the web for six hours, and I swear I don't know a bit more than when I started except of course that there are 8 million different kinds of balsa core.

And theoretically, we're talking about total square footage that would approximate both side decks in toto. How much epoxy would that take? Two gallons? Three? Twelve?

Can I just use 3/8 marine plywood double coated with thinned epoxy? Now THAT sounds like the way to go (which I'm sure it isn't).

A very frustrated,

J.

[commanderpete]

There have been many threads on Tim's Triton site about core jobs.

At least one thread spoke about materials needed. It's a bit imprecise, naturally, but may give a rough idea. The sq. footage on a Triton deck might be 1/3 more?


http://www.triton381.com/forum/viewt...ght=balsa+core

[Mike Goodwin]

Using ply or balsa is going backwards , closed cell is the way to go.
How much epoxy do you need , how much beer can you drink , couldn't tell you either one without seeing you or the boat.
You got plenty of time to get the epoxy, it will take more than an hour or 2 to open up them decks .
Just do it !

[Mike Goodwin]

When you core the decks , you use thickened epoxy , not thinned . No voids!

[c_amos]

When you core the decks , you use thickened epoxy , not thinned . No voids!

Don't you mean the other way around? When working where I might encounter a void, I have been flowing thinned. Ground out tiny bubbles repairing circuit cards years ago, sure don't want any lurking in any part of my hull.



Jeremy,

Would like to see some more broad views of your boat, many times others will see something they have had an issue with (good or bad) that can be helpful. Really, most of us just like to look at these boats

As I understand your posts, on calculating the costs, you are trying to get a rough idea of what you are getting into. I understand and admire your rational approach.

My experience has been that it will be very difficult to accurately estimate the cost, but that the material and labor prove a good investment. I believe the more important basis for the decision must be based on something not so easily expressed on a balance sheet.

Neither the heart nor the eye are the guide that Hollywood make them out to be in life. Boats may well be the exception to this rule.

IMHO.

[Mike Goodwin]

Thin epoxy is a sealer only!
You want to bed the core in thick epoxy , thinned stuff can run out where you can't see it. Lay done a layer of "P-nut butter" and push the core into it so that you get an ooze all around , then you know there are no voids . Plus thickened epoxy is stronger than pure resin and thinning epoxy weakens it even further . Been doing this s**t for 40 years now and learned a thing or two.
I'm becoming one of the old timers and all I really wanted to be was be an old rummy! What are you if you drink Bushmils?

[Bill]

Using ply or balsa is going backwards, closed cell is the way to go.

Do you have any product suggestions?