Material for new deck layup

Ryan · Post by **Ryan** » Thu Aug 18, 2005 12:46 pm

What material do you guys/girls suggest I use to build up a new deck surface on a newly cored deck? The original topskin is useless, and I have to believe there is a better way than layer upon layer of glass cloth. I've seen biax cloth mentioned often, but I have never used it. I've gone through all the old messages on this site and all the books that I have on the subject, and I still can't seem to find a definitive answer. Any suggestions for a newbie? Thanks in advance and thank you Tim for such a good resource.

Post by **Tim** » Thu Aug 18, 2005 12:54 pm

I wouldn't use cloth. Biax would be my choice. There are several weights commonly available; if you've never worked with it, you might want to try some tests first. The heavy 22 or 24 oz. biax (depending on which source you choose) is very strong and builds up thickness quickly. It can be a bear to wet out thoroughly, but with practice it's not a problem. 3 layers of this stuff would be plenty for a top skin, depending on the size of your boat and the span of the decks. Use more layers of a lighter material if you prefer. The 15 oz. biax is easier to wet out.

If you want to try out the biax, buy the minimum amount of 4" tape that you can from your chosen source, and try it somewhere. It acts the same as the full-size stuff, so you'll get an idea what you're in for. Personally, I would recommend using the heavier material with the stitched mat attached to the back.

You might consider laying one layer of 10 oz. cloth over your final layer of biax to help soak up excess resin (almost guaranteed with hand layup and the heavy biax) and to provide a smoother finished surface that will be easier to sand and fair later.

Good luck!

Ryan · Post by **Ryan** » Thu Aug 18, 2005 1:30 pm

Tim

thanks for the quick reply. Do you have any specific source of biax that you can reccomend? This job is on a Hughes 25', so the decks aren't too large. Thanks again for the help!

Post by **Tim** » Thu Aug 18, 2005 1:37 pm

Try Jamestown Distributors. www.jamestowndistributors.com

Ryan · Post by **Ryan** » Thu Aug 18, 2005 2:07 pm

Tim

Would it be easier to wet the mat side first, and then flip it over and put it on the reapir area? I think I can see where it would be a bear to wet from the top side, but then again, I have never used it.

Post by **Tim** » Thu Aug 18, 2005 3:07 pm

Yes, it is easier if you wet the mat first. However, sometimes this can be tough when laying up larger pieces, so the method must fit the situation.

If you can, though, it helps to wet the bottom first. You must use care to not disturb the mat too much when wetting, but this isn't hard.

Bob L · Post by **Bob L** » Tue Feb 14, 2006 7:56 pm

Are you talking about biax with epoxy, or polyester resin?

Post by **Tim** » Tue Feb 14, 2006 8:14 pm

I always mean epoxy resin.

Post by **dasein668** » Tue Feb 14, 2006 8:36 pm

Tim wrote:I always mean epoxy resin.

Hey, I saw you use polyester resin. Once.

Hehe.

Post by **dasein668** » Tue Feb 14, 2006 8:38 pm

Looking at those pics brought back some memories! That was a fun day!

Now that I've taken this thread wildly off topic... I must have channeled Mr. Cooke....

bcooke · Post by **bcooke** » Tue Feb 14, 2006 8:46 pm

Soon Your Minds Will All Be Bending To My Will...<insert evil laugh here>

bcooke · Post by **bcooke** » Tue Feb 14, 2006 8:50 pm

So the Boatege is beginning to exert his own independence. Pray, do tell us more :-)

Tim using poly?!! I guess that means he forfeits his right to say NEVER...

Hey Tim, I can still say never :-)

-Britton

Post by **Tim** » Tue Feb 14, 2006 9:40 pm

Regarding the photo referenced above:

I used polyester to bond a spiked-up pair of 2x4s as a brace across the daysailor hull to help hold the shape when we cut the deck off. This was only a temporary construction brace, and the polyester was not part of the finished boat. Really, I used it to tack the 2x4s in place; I chose the polyester in this case because I could create a very hot mix that would (and did) cure in only a few minutes.

Here's another view showing the brace. I removed the whole arrangement some time laterr and ground off the offending polyester!

I think this is about the only legitimate use of polyester resin in a repair scenario. But I guess that Britton is right, and I can no longer say "never"! Semantics, but I'll grant this one since I'm feeling charitable tonight! hehe

Post by **Tim** » Tue Feb 14, 2006 9:41 pm

bcooke wrote:Soon Your Minds Will All Be Bending To My Will

No wonder my head hurt all day today...

Post by **dasein668** » Tue Feb 14, 2006 9:51 pm

Tim wrote:I chose the polyester in this case because I could create a very hot mix that would (and did) cure in only a few minutes.

Hard as a rock in about 3 minutes as I recall. I also recall a very melted and smoking bucket containing about half a gallon of resin! Like I said: "a fun day!" hehe. In fact, I totally forgot that that was also the day I got restructured out of a job at Walch! A GREAT day! hehe

bcooke · Post by **bcooke** » Tue Feb 14, 2006 11:10 pm

Hard as a rock in about 3 minutes as I recall. I also recall a very melted and smoking bucket containing about half a gallon of resin!

Yeah, who would have thought that a few extra drops of accelerator could do so much! Now was that five drops or six, oh well, what is a few more.

How do I know?... well um... we were talking about poly resin on boats weren't we... yeah, that was pretty clear... you all knew what I was talking about... what was I talking about?... well, you know.... wait, gotta run, I think my mom is calling me...

Remember the wise sage's advice. "Charity". hehe.

In fact, I totally forgot that that was also the day I got restructured out of a job at Walch! A GREAT day!

You were sick of that job anyway. As I remember you were putting in a few extra hours on the boat prior to launch last spring. You couldn't have done that if Walch hadn't helped you out. I imagine large scale destruction must have felt good too.

-Britton

Post by **dasein668** » Tue Feb 14, 2006 11:43 pm

bcooke wrote:Now was that five drops or six, oh well, what is a few more.

It was something like 1/3 gallon of resin into the bucket, then add the whole container of catalyst.

bcooke wrote:You were sick of that job anyway.

Yup!

bcooke · Post by **bcooke** » Wed Feb 15, 2006 1:25 am

Fire in the Hole!... :-)

You guys have altogether too much fun up there.

Post by **Tim** » Wed Feb 15, 2006 8:30 am

bcooke wrote:How do I know?... well um... we were talking about poly resin on boats weren't we... yeah, that was pretty clear... you all knew what I was talking about... what was I talking about?... well, you know.... wait, gotta run, I think my mom is calling me...

Remember the wise sage's advice. "Charity". hehe.

Britton, what in the world was in those brownies you made the other day, anyway? Holy moly...

Ryan · Post by **Ryan** » Mon Feb 20, 2006 5:11 pm

Tim

What method do you use to wet out biax (with mat attached) that has been cut to fit an is already in place? Do you just pout the resin on top of the biax and work it in with a spreader and/or roller, or would it be worth the trouble to pour unthickened resin on the deck (this is a recore specific question) and lay the biax in the resin and get to rolling?

Ryan

Post by **Tim** » Mon Feb 20, 2006 6:14 pm

It's easier to wet out if there is resin on the surface to begin with, but you can also effectively soak the resin through the material from the top only. It's just slower and a bit harder to ensure that you get the material completely saturated.

Ryan · Post by **Ryan** » Tue Feb 21, 2006 5:57 pm

When using scored balsa for a recore (from the top of the deck) job, do you guys put the scrim up or down? An article I read mentioned opening and filling all spaces between each individual balsa block with thickened epoxy and laying the balsa down with the scrim up. Since I am laminating a new top skin, I had planned on setting the balsa scrim down in a bed of thickened epoxy and then only filling in from the top any spots where the blocks of balsa separate. Is there a preferred method or a reason to choose on over the other? The method in the article sure seems like a lot of extra work and a lot of squeeze out once the core is laid down.

Ryan

Post by **Tim** » Tue Feb 21, 2006 7:02 pm

The scrim is there to allow the core to be used on a contoured surface while holding the blocks together as required. But where contours aren't an issue, it doesn't matter which way you place the scrim, other than allowing access to the kerfs if needed.

However, you should attempt to fill/seal all the kerfs with epoxy no matter how you install the core. Filling the kerfs is a critical step, since it prohibits the transfer of water through the kerfs, which we now know is the main avenue through which water travels inside a cored deck. Ensuring that all the kerfs are filled will greatly increase the chance of long-term success with your new core.

An easy way to do this is to drape the core (scrim side down) over some curved surface, which will open the kerfs. The epoxy should be only slightly thickened--just enough so that it sort of stays where you put it, rather than running away. Slather the stuff in the kerfs and then install the core. You don't need to use a ton--just go for full coverage.

Yes, this constitutes extra work and epoxy squeezeout. But the effect is worth the effort. You can scrape up the squeezeout and use it to fill some of your gaps around the core and such once you place the core into the deck, so it won't truly be wasted.

Rachel · Post by **Rachel** » Tue Feb 21, 2006 11:07 pm

I just recently skimmed an article in Professional Boatbuilder (which I should go back and read thoroughly), wherein they were talking about causes of moisture/water getting into core and one thing they mention was problems caused by air channels running through the core (i.e. unfilled kerfs).

I really must go back and read the article, but I think they mentioned temperature differentials (expansion and contraction) as contributing to the problem. Apparently if there are any openings, the boat "breathes" through the channels and you can end up with a moisture problem.

Tell you what: If no-one else chimes in (perhaps having read the article), I promise I'll read it and then clarify this a bit.

I think worrying about every bit of air would probably be obsessive, but it does make filling long kerfs seem like even more of a good idea.

--- Rachel

Curmudgeon · Post by **Curmudgeon** » Wed Feb 22, 2006 9:21 pm

Tim wrote:However, you should attempt to fill/seal all the kerfs with epoxy no matter how you install the core.

Both Baltek and DIAB offer a bonding material for their balsa core products. Baltek-Bond for the Baltek balsa and Divilette for DIABs ProBalsa. Both are polyester-based compounds. Heaven help me for even mentioning the 'P' word, but is there anything to be gained by using these products? I'm recoring my decks with balsa and certainly plan to use epoxy for bonding the core to the deck and for the biaxial cloth, but was toying with the idea of the poly putty as a filler between the core blocks only. Touching bases with the product reps is on my to-do list.

Oh, and for any of you feeling sorry for youselves about having to deal with the mess of a recore... I chose to do mine from the inside-out. Yep, gonna do it upside down, and am aready feeling sorry for myself!

Post by **Tim** » Thu Feb 23, 2006 9:39 am

Those polyester bonding materials are most likely optimized for use in a new construction scenario, where primary (chemical) bonding between the polyester laminate and polyester core bonding material will still occur--and often under vacuum pressure.

For a repair scenario, I don't see a lot of benefit, if any, particularly when it means you must buy an additional product. If you're already set up with epoxy and fillers and plan to use it for the bulk of the job, I'd suggest it makes the most sense to continue using epoxy for your kerf fillers.

And to clarify, I don't have a problem with polyester products during new construction, though I think we'll see a trend towards vinylester and epoxy construction in the future, especially for higher quality boats. I just don't believe that polyester resin is the right choice for repair scenarios.

As to the specifics of the polyester core bonding materials, I'll leave that to the product rep, as I don't have a clue other than what I wrote above. But it takes an extremely straightforward product rep to suggest something other than their own product, so keep that in mind.