seeking advice: new top coat for poly resin poke boat

General Discussion
1

Right up front: this is a question for the laminators here, but isn’t for a surfboard, although some of the discussion will probably also apply to surfcraft restoration in some way. So if the mods decide it is completely OT for Swaylocks, so be it. I could say that I plan to use it as an SUP, if that helps :slight_smile:

What it is: I have a Phoenix Maxi II poke boat, which is a sort of tandem kayak/decked canoe. The boat seems to have been built in 1992. I didn’t pay much for it. It is 18’8" long, 39" wide, and weighs 58 lbs, so you can judge from that that the glass work is pretty light. To my eye, it appears to be several laminations of no more than 4 oz cloth, possibly lighter. The brochures I found (Phoenix in no longer in the boat business) claim it is laminated from fiberglass, nylon, and “a very complex, flexible, high-elongation isophthalic resin, originally developed for rocket motors. We modified this resin for use in our boats. Its strength and durability surpasses any other product that can be used”. I suspect that last statement is mostly marketer-speak. Phoenix’s “other” business is manufacturing rotors for Cobra choppers, and I imagine they have a whole slew of buzz-words on tap to impress the brass hats at the Pentagon. I did some research, and the only reference I found to using nylon for FRP laminating was as a mold release agent, where it (presumably) does not become part of the final product. I’m assuming that their “magic” isophthalic resin is probably more-or-less ordinary polyester. 

Work I need to do: the boat was stored bottom up, outside, in the elements for the past few years, and had quite a lot of creeper, or some similar vine, growing on it. As a result of this abuse, many, many tiny chucks of the top coat of resin have fallen off. None of this seems to have compromised the integrity of the shell, all of the chunks that fell out appear to have been from the voids in the weave, and all appears to be watertight. Nevertheless I think it would be foolish to try to use it as is. So much of the “void fill” resin has been lost that the appearance of the hull exterior is very much the same as a surfboard laminating coat after very aggressive squeegee application. My plan is to treat it as such. I bought a 1/2 gallon kit of low viscosity, no blush, epoxy resin with slow hardener (sold as a sanding coat product). I bought this from Greenlight Surfboard Supply in Manasquan, NJ; they claim it is equivalent to RR low-vis with Additive F. I plan to coat the exterior and squeegee just enough to leave a fairly smooth finish, and reseal any tiny pores that might exist. Obviously, I need to do a lot of surface cleaning and prep first. After the initial coat cures, I’ll sand as lightly as possible, and make a decision about whether or not a second coat is needed. Any thoughts on my description of the existing lamination or my repair plan? I’d very much appreciate any observations about what I may have missed from you more experienced folks. I could take and post a close-up photo of the weave if it would help anyone give me a higher quality answer. Thanks!

2

Of course you seem to understand that there is necessary prep to be done.  So that is a given.  I have been told many times by boat People that Eoxy will stick to Poly, but Poly will not stick to Epoxy.  So I would start there.  Now that I think of it;  This May be the reason that I see so many shoddy repairs coming through my shop lately In which most them have peeling resin.

3

My understanding of the poly over epoxy issue is that epoxy oozes out a substance called “amine blush” onto the surface as it cures, and neither epoxy nor poly will stick to that unless it is removed. I also (seem to) understand that the blush is water-soluble, so removal is not difficult. If there is more to it than that, I’d certainly like to hear about it.

4

I helped a friend with a boat project some 15 years ago, using both epoxy and PE resin.

 

I recall on one part some PE resin rips fell onto some sanded prepped epoxy surface.  I forget which type of epoxy, it was a 4 to 1 ratio, non surfboard specific resin, and lots of  visible blush was not an issue with it

 

I expected the next day to be able to get a razor inder the edge of the drops and pop them off.  When I went to do so I found it had not even hardened.  Only the PE resin which was top the epoxy had not cured.  All elsewhere was fine.

 

Some areas needed that poly over epoxy.  Used SB-112 from System three. They claim this resin can be used as a tie-coat, and that poly sticks to it.  It did. No issues.

 

SB-112 is not prone to blush/ fisheyes, and is my favorite resin for fill the weave/ finish layers, but I’ve not tried all epoxy offerings to compare.  When i tried cheaper surfboard specific epoxies I became aware of just how user friendly system 3 resins are, if a bit too pricey.

5

Okay, a few things- 

Iso isn’t plain polyester, though in some ways it does behave similarly, needing wax to fully harden in contact with air for instance. It’s tougher than plain polyester, according to a writeup I just saw it’s tougher than plain polyester, usually used for molds or other situations where you get a lot of abrasion and impacts. Good for kayaks, in other words, which are light, not terribly rigid, need to flex… High elongation makes sense, it can flex more without cracking. All fine. Not water permeable, which is a very good thing. Polyester is, by the way, which is why you have to do gelcoat replacements on a lot of sailboats. UV light, though, probably doesn’t do it a whole lot of good, which is maybe why your filler coat is going south on you.

If I was a company that did helo rotors, I’d be Really Good at vacuum bagging, which is where I’d guess the nylon ( peel ply permeable stuff) comes in. And high tech resins. And getting the resin makers to play with said resins for ya. 

Anyhow- what would I do? 

First, borrow somebody’s electric ( not real high pressure) pressure washer. Give it a good but gentle once over , get any remaining loose bits of filler coat off. You don’t want to do this again, right?

Let it dry completely. If you used any detergents and such, rinse very very well. Don’t use any abrasive pads or similar, a relatively soft bristled scrub brush should be all you need.

Now, put away the squeegee. Instead, get some  big 4" or better chip brushes, comb well with a fine comb to get any loose bristles out. Pick a cool day, mix up your resin and do a hotcoat. Tape drip edges as need be, then have at it. Work the resin in with your brush as need be, like you would with paint on bare wood.  When the resin has dried ( pull the tape early so you don’t have a bead there) lightly sand the edge, flip, tape, hot coat the other side. Again, sand where the tape was. Have a look at the finish,If you got lucky, you just need to polish.  Failing that, lightly wet sand, rinse, gloss coat it. Or paint it, that epoxy may not be real happy around UV either. 

Personally, I don’t know if I’d bother with epoxy rather than polyester. But that’s me. Then again, if I had this (nearly 19’ long x 39" wide) I’d likely use it chasing ducks, so I’d paint it camo. Reminds me, I gotta repaint the canoe. 

hope that’s of use - duck season’s coming up…

doc…

6

If whatever resin they used is pulling off/popping  off the weave of the fabric, then anything bonded to that weak layer, is not going to be well adhered to weave either no matter how you prep the surface for adhesion

 

See if you can wipe with IPA, to get some masking tape to adhere well, then rip it off.  Does it remove the poorly adhered resin from the weave?   Sometimes the direction in which one rips the tape off, plays a big pat on what/how much comes up with the tape.

 

The green 3m high adhesion concrete masking tape excells at this. It’s often way easier than sanding or scraping of a poorly bonded layer of whatever. Also great for finding the specific areas where the  top layer’s adhesion to substrate is poorest. Uses a lot of tape though and sometimes tape adhesive is left behind, which then needs to be removed.

7

Great answer, thanks! I have a gas power washer, but the soap tip is pretty gentle (I as going to use that withour soap). I had planned to gently scour with Scotchbrite, but I will see how the soft scrub brush fares first. That gets hose rinsed, allowed to dry, then a solvent wash. My first inclination was to brush in the resin, but the squeegee seemed to be the conventional method. I’ll brush. Boat was molded as top and bottom half, then taped together. Only the bottom half has this issue. so I’ll just tape at the join line. I chose epoxy because it is more flexible, and, at least around here lately, has better availability than poly. The color (untinted) is pretty nondescript, a sort of dull pale yellow. My long term plan wes to use it for a few weeks, and If I decided to keep it, paint it duck boat OD.

8

The tape test is a very good suggestion. I will do that, along with following some of the recommendations of the previous poster. Thanks!

9

excellent, the solvent wash will at least clean it even better and ideally etch it a little, making for a better bond… I think you  have better control with a brush in what is essentially a hotcoat job. 

There were some very high end rowing shells built around then, Empachers maybe? , that were a pale yellow. i thought they were kevlar or a similar aramid, but who knows? Likewise, if it’s only the bottom half doing this, I’d suspect somebody goofed at the factory, gel coat a touch off?

In any event, I think you have this well in hand

doc…

10

You make it sound as though Amine Blush is a necessary evil.   The reality is that many people work with Epoxy and never see Blush.  Myself being one of them.  Years of ding repair with Epoxy and many boards glassed with NO Blush.  Blush or no blush Epoxy peels on Poly.  It won’t stick.

11

Polyester resin Can be build from isophtalique acide or orthophtalique acide. Resin from iso have better élongation to break and lower water porosity. No parts for water should be build with ortho but ortho is cheapper…

All resin Can be modify with adjuvent to change properties. Before new easier to use, cheapper epoxy, kayak builder used poly modify (with plasticizer) or vinylester resin with better impact strenght ( flexible than standard poly)

Blush reduce adhérence of any coating systèm. Some amine can also stop poly curing. Poly retrac while curing that reduce élongation to break and adhésion strengh, epoxy no. You can coat epoxy lam well prep with poly but when dinged poly make spider web or pull out while epoxy lam is still great.

Epoxy glue to near anything but it’s not so easy to work with at finish coat.

Nylon wich was Dupont trade name of polyamide 6-6 have poor adhésion with resin even more with standard poly but a high élongation to break. When treated it’s use as Peel ply.

12

The “peel ply” application is what my searches turned up as the most common use of nylon cloth with poly resin in FRP lamination. I had assumed that “peel ply” meant “mold release” - not so?

13

My assumption is that this is occuring only on the bottom half because the top half was much more sheltered trom the weather and did not have the climbing vines growing on it. Those vines were the kind that put out some kind of “root foot” (I’m sure that term is a horticultural abomination of some kind :slight_smile: that glues itself to whatever surface the vine is climbing. I suspect it was the vines that were largely responsible for the loss of tiny bits of resin.

14

I examined the surface with a magnifying glass; the cloth fibers themselves appear to still be completely encapsulated. That is why I compared it to a well-squeegeed laminating coat - that is exactly how it appears. What could have resulted in the apparent reduced adhesion between the resin encapsulating the fibers and the resin in the voids between those encapsulated fibers, I have no idea. But it seems to me to be a reasonable procedure to try to remove any remaining “void chunks” that are not tightly bonded before adding another coat of resin.

15

This model boat did come in a Kevlar variant, but a check on the serial number seemed to indicate is was the glass version. There is deflinitely no tint in the lamination. It is a pale, almost dingy, yellow color, even where ther is no weathering, and it does resemble the color of some untinted Kevlar laminated items I have seen. The only way I could be certain which fiber was used would be to weigh it before I add another coat of resin (the Kevlar version is speced at 9 lbs lighter). At nearly 19’ long, and with no deer or game fish scale handy, I anticipate a bit of trouble with that operation :slight_smile: Unless an aramid would demand a different approach for my recoat, I’m content for the nature of the fiber to remain an open question…

16

Right? The similarity between those and the Empacher rowing shells is probably coincidence. I wouldn’t bother worrying about it, though I like the idea of weighing it to compare to what I’m thinking are posted weights for the different construction methods? And at this stage of the game it’s probably irrelevant, no?

17

Umm, sort of. And I hope somebody who knows more chimes in to correct me. 

In vac bagging, you are shooting for a good resin/laminate balance for maximum strentgth/weight with no voids, so you put a membrane over it and apply vacuum. But if it’s just the membrane, it will just pull down.

So you have the laminate, including resin. Can be several layers of cloth or what have you in one shot.  Then the nylon peel-ply, which is woven tight but not too tight and it has a coating the resin won’t stick to. On top of that is something we’ll call absorbent, similar to cotton wool. Then the airtight mebrane. 

So you apply vacuum, the whole thing is sucked together, you have pressure exerted on the laminate which exudes excess resin through the peel ply and into the absorbent layer. Discard the absorbent, peel off the peel ply and there ya go. 

that help any?

doc…

18

Yes, thanks, that’s pretty much how I pictured it. My point was mostly that the nylon wouldn’t become a permanent part of the boat, so to describe the boat as a fiberglass.nylon laminate would be inaccurate. I wish I had current contact information for my old surf buddy and mentor Bob Lacovara, he built boards locally for several years (until there was a fire at his glassing shed) then leveraged his experience (with some additional education) to become a very successful laminates specialist to defense contractors. I have no doubt Bob could give me pretty much all the detail of the process used to build this hull, he might even be familiar with Phoenix. Unfortunately I lost touch with him about 10 years back.