My (limited) experience with stitch & glue fabrication (one CLC Pro Kit... so far) tells me pre-coating some ply surfaces before assembly may improve the building experience and quality of the outcome.

I've never built a Peeler.

Structurally one needs to ensure proper preparation for pre-coated surfaces that are to be joined / bonded to other parts, or those areas that are to be covered with fillets and maybe a layer of cloth over them so that the mechanical strength the designer envisioned is achieved. With attention to this aspect the resulting structure ought to be just as strong and durable as a "dry-ply" assembly.

Backing away from a 100% pre-coat approach would have a builder masking off areas where joints are to be bonded or fillets laid down so the ply remains raw after the pre-coat's been applied, allowed to cure then sanded, maybe even re-coated.

This might be more work with all the taping & such but ease of coating then sanding flat panels ought to offset the time spent for masking. This may also use more epoxy than supplied with a kit yett shouldn't result in the eventual project being any heavier than if built according to the manual. Indeed it may even be a tad lighter from the uniformity achieved!

I've read lots of opinions on chemical vs. mechanical strength of epoxy bonding. Came away believing that for the home enthusiast there's little difference in outcome if proper preparation and application techniques are employed.

   Thanks for the feed back.  i built the Chester yawl this past Dec. it seemed that there was more sanding then building { my firdt time using epoxy }. it came out beautiful and was worth all the sanding.

    I just started the Peeler Skiff and as per instructions the deck was fiberglassed and 2 coats of epoxy and sanding it so there is no shine left on the deck. Then add the sides and transom and bulkheads. So i was thinking if i csn precoat the deck why not other parts. Guess i'll call CLC and see what they say.

Take notes as they tell you what their thinking is on this, pass along what they tell you please!

Pre-coating flat panels may make them harder to bend into proper shape, will make stitching tricky unless you clean out any pre-drilled stitch holes that have filled with epoxy.

If lap seams are in the plans, maybe leave the lap insides raw (masking tape?) so when it comes time to complete them the unthickened epoxy will soak in deeply besides partirally filling up any open areas between the lapped panels. Then follow with thickened epoxy for ultimate durability of those klnd of joints.

Let's be clear here too about amine blush and whether it's present or not. Most epoxy formulations will leave that on a cured surface even if meticulous attention is paid to conditions in the workplace during applicaion and cure. MAS LV resin isn't one of these formulas so that gives its users a break.

Where blush is possible, it's easy enough to remove with Scotchbrite-type non-woven abrasives and plain water, followed by a water rinse and then thorough drying. Any blush present will inhibit a future bond, and it's not removed by just sanding.

My supposition is that when a cured pre-coat is sanded you're mechanically breaking epoxy bonds to some degree at the immediate surface. Follow that with proper removal of sanding dust (careful about using solvents other than plain water) the next coat of epoxy will 'key' into the sanding texture created as well as bond to whatever open chemical bonds may still be present. (I'm no epoxy chemist so I have no way of knowing whether my thinking on this has merit or not so there's that.)

Here's some reading:

https://wessexresins.co.uk/support/how-to-use-pro-set-epoxy/secondary-prep-for-surface-bonding/

https://www.westsystem.com/instruction-2/epoxy-basics/bonding-clamping/

http://www.jemwatercraft.com/forum/viewtopic.php?t=3753

Keep in mind epoxy chemistry isn't exactly body tissue-friendly so it's a Best Practice to minimize bodily contact with the uncured components (use gloves, respirator, maybe goggles) and that includes dust created from sanding operations once epoxy's cured hard enough to sand but maybe not thoroughly enough to produce non-toxic dust.

Formulas differ a lot on the conditions for this 100% cure (time + temperature) so read the manufacturer's instructions, then act accordingly. If the cure's not yet 100% completed then chemical links will be available for bonding to subsequent coating whether the surface has been sanded or not.

If you can arrange your work sessions to do "wet" or "hot" recoats, the resulting bonds will be as strong as possible. Whatever else you can do to prep properly for subsequent coats will provide a structure that's "strong enough for the job".

The curves on a Peeler are gentle enough that a coat of epoxy will not make the panels too stiff to bend. Even a layer of 4 oz glass would be OK. When I built my schooner I glassed the panels while flat and it still bent just fine. CLC did the same thing with the Outrigger Junior prototypes - glassed flat, then assembled - so it is definitely a done thing on boats with flat panels and gently curved surfaces.

The key to drastically reducing sanding by reducing drips is not just building flat, though that helps a lot. It's controlling the amount of epoxy that you apply in the first place. Epoxy won't run and drip unless you add too much. So you can reduce sanding, the final boat weight and epoxy waste simply by applying multiple thin coats instead of a couple of thick ones. And that works whether you are pre-coating flat or not. The only downside of lots of thin coats is that it takes a bit more time than a couple of thick ones, but you get that time back with interest because of reduced sanding.

Laszlo

100% agree with everything you said there Laszlo. Ability to minimize amount of epoxy needed to complete a contemplated task comes with experience, practice. A first-timer's prone to over/under-estimate volume at the beginning.

We can save a discussion of the merits (several) and drawbacks (mainly cost) of PeelPly for another thread. Having explored its utility in both my Waterlust kit build and the amas + aka from plans I wouldn't be without it for flatwork.

  As a young lad back in 1978 I worked for a small boatbuilding shop in central Wisconsin. The Gougeon brothers sold thier DN iceboat business to this shop and we worked very closely with them in learning the best techniques for what was then a pretty new product for boatbuilding; epoxy. We built many boats of various sizes and types and learned some hard lessons. The thing that sticks with me to this day is the rule the Gougeons passed down to us, always coat and finish sand as many parts as possible before assembly. This one tip saved us countless hours of kneeling, laying upside down and crawling around in boats while trying to sand to a good finished surface. Standing up with your work surface at a correct and comfortable height under good lighting is always better than trying to sand in a cramped position. The panels never felt noticibly stiffer and bent easily onto the moulds or bulkheads.

I've build and restored a number of boats since then as a hobby and I've always followed that rule. I built the Peeler Skiff last fall and winter and pre-coated and sanded every part prior to installation. This technique has saved me lots of time and pain over the years.

That's good info Luke485!

When I started messing with epoxy (about the same time you were building iceboats) it was Gougeon Brothers who guided me along my paths to success!

I have to ask where that shop was in central WI? I'm in the Driftless region now, back then I was in NE Illinois, not far from Chicago proper. Bud Melges' operation was just over the border, I knew a couple of other builders up around the Baraboo area.

Over on the WoodenBoat Forum there's a contributor by the name of Todd Bradshaw (another cheesehead) who's been doing this stuff for 50+ years, messed with iceboats (among other things) along the way... maybe you've met him?

 spclark, I was employed for 2 years in the late 70's with Norton Boat Works in Green Lake Wisconsin. The company is still in business today under different ownerrship but with Joe Norton still managing the operations. They do mostly classic boat repair and restoration work now. 

I was very lucky many years later to be re-acquanted with Meade Gougeon when he retired to the area of Florida where I lived. I was able to spend many hours discussing boats, sailing tactics, epoxy, boatbuilding and life with Meade in the years before he passed away.  

   I heard from clc and they said it was ok to precoat the panels but to leave a strip of bare wood where they will be joined to another panel. I started doing this today and it seems the way to go. It doesn't eliminate the sanding but it makes it a lot easier.

  Sorry for not joining this thread earlier.  I built a Goat Island Skiff four years ago, and the Designer (Micheal Storer) advocates percoating AND pre-sanding prior to assembly.  This works well with boats like my Goat and your peeler that do not have very sharp bends.  For boats with a lot of bend (like the S&G Petrel Play), I would not advise do to increased stiffness.  Personally, I do not leave bare wood where it will be glued together later.  I just make sure that I sand the area prior to glue so that the epoxy will have a good mechanical bond. 

Some pictures below.

Here are the major components ready to test/dry fit.  The interior surface of the hull and both sides of the bulkheads are precoated with 3 coats epoxy.

Here the boat is dry fit together.  Note the areas with blue tape "x".  These will be interior areas not to be sanded.

Here I have presanded the inside of a hull panel and bottom.  Note the unsanded areas that will be inside of the floatation compartments.

Here is the boat all together.  The only sanding required prior to varnish is along the seams where epoxy was used to glue it together.

All done!

Sweet job on that GIS you built Mark_N, you enjoying how she performs?