Epoxy or not? CPES?

[Steve Miller]

I know this will generate lots of opinions but that is what I want from you guys. Building a Glen-L Utility Skiff for my daughter. Have the stem, breasthook, frames and transom done. Now I get to scarf plywood and setup the strong back.

How to finish the boat? It is a ply on frame design similar to most of the Glen-L boats. I don't mind glassing the exterior but was thinking I want to avoid epoxy if I can. I am learning to hate the stuff.

The hull and deck ply will be good BS1088 okume or meranti. I can get either locally. Thinking no glass at all. The boat will live on a trailer mostly stored inside.

So sealer then paint and varish? What sealer?
I have not used CPES. Thoughts on using it to seal the whole boat inside and out?

What about the frames. I have read mixed opinions on trying to get a good seal with epoxy over solid wood. The frames are mahogany with 1/4" okume ply gussets.

[Ian McColgin]

CPES is an epoxy. It is a wonderful sealer, especially over plywood. As you'll see from its lables, it's a bit of a biohazard and you'll need to work with proper lung and skin protection.

I've not used other epoxies as sealers or final coats with anything like the success I've had with CPES under almost anything - paint, varnish, whatever.

G'luck

[Steve Miller]

I guess I should add that I am thinking no glass on this boat. Or should I just glass the bottom? The boat obviously does not need glass for structural reasons.

Ian - I understand that CPES is epoxy but like what I read about it as a sealer as opposed to standard System 3 or West epoxies. I am good about using my respirator and protection from epoxy for sure.

Is CPES a multiple coat deal or is one coat the norm?

[NormMessinger]

One coat deal. Top coat before it has cured so to get a chemical bond between the CPES and the top coat.

To coat with epoxy and glass depends on the kind of plywood you used. Glassing will prevent fir plywood from checking. Epoxy alone will help some.

[JimD]

Steve, glad to hear you are making good progress. I would say go ahead and glass. When I built mine I preglassed all the 8'X4' sheets of plywood before cutting the panels and assembling which is the easiest way there is to glass a boat but too late for that for you now. Agreed that epoxy gets to be pretty miserable stuff to work with after the novelty wears off but wetting out fg cloth on a flat sided hull is not all that difficult. I'd say the worst is behind you.

[Ian McColgin]

As Norm said. CPES is vastly superior as a sealer to thinned out sealer attempts to turn other formulations from glues to sealers. It really penetrates. A very different sort of sealer - tends to lie thick on the surface - is "GluVit." Also terrific stuff in a different way. For the GlennL, I'd use CPES.

CPES under paint or varnish will prevent surface checking. However, you might want to glass the very bottom and lap the chines for strength. While most epoxies are good with glass, I have an expecial fondness for GluVit in this application. If you do use GluVit, be prepared to let it cure fully (like days!) and both sand and acetone wash. The stuff can make a wicked amine blush and will not "wet bond" under a different material like any known paint.

G'luck

[Cuyahoga Chuck]

Don't know why you have reservations about epoxy. It's probably the best all-around glue/sealer available to boatbuilders. For scrafing plywood I wouldn't use anything else.
As to the downside of using epoxy for lumber to ply joints, I've never heard of a problem with the joint itself just the effect of lumber's greater movement with changes in moisture. If everything is epoxy encapsulated the moisture problem shouldn't be evident.
Never used CPES but have heard that it penetrates because it is thinned with a solvent. If that's the case, you'll be getting vapors that are not present with straight epoxy.
If you use 'glass for any purpose you must use 'glass that has the proper binder coating for the intended resin. I've never heard of CPES being used with 'glass but my experience is fairly limited.
Charlie

[Steve Miller]

Charlie, I don't have any issues with epoxy as an adhesive or for applying glass cloth. Very happy with my System 3 and various fillers to make glue. No problems using System 3 to glass and as fill coats for glass. I was looking for opinions on sealers for a ply on frame boat that will not be glassed inside for sure and maybe not on the outside either. But I am leaning on glassing at least the bottom up and over the chine joint.

[Steve Miller]

Ok, here is another question. If I decide to glass the bottom of the boat would I CPES first? Or would that be overkill?

[JimD]

Originally posted by Steve Miller:
Ok, here is another question. If I decide to glass the bottom of the boat would I CPES first? Or would that be overkill?You won't need cpes

[paul oman]

Whatever brand of epoxy you use in your construction, just thin it out about 25% with any solvent stronger than paint thinner and coat the wood surfaces. This will give you a better bond as the pure epoxy will basically only bond to the exact surface.

Ideally if you apply more epoxy within a few days you get a chemical bond as well as a mechanical bond between the epoxies (because epoxies keep curing for upwards of a week), but hard to say how real this is vs the theory....

Lots of claims about all sorts of products in the marine industry - mostly their purpose is to get you to pay more for the products than common sense would suggest (sort of like the pre-marriage stage of life!)

regards
paul oman
progressive epoxy polymers
www.epoxyproducts.com (http://www.epoxyproducts.com)

[RodB]

First, the boat will last much longer and be pretty much maintenance free if you glass all surfaces that will be exposed to sun and weather. There is no contest, painted epoxy glassed panels will last the longest with the least amount of care.

The epoxy work is no big deal but its much easier to glass and sand panels before assembly on the horizontal. I guess you have to determine if this boat is worth the expense of using epoxy or not...

If you are determined to not glass, 2nd best would be to coat with CPES and paint within the allotted time (before cure) for a terrific bond. This would result in a great sealer coat plus a tremendous bond to the paint. Note: one gallon kits of CPES (one gallon of both A and B) costs around $150 including shipping)

You could buy one gallon of hardener and 2 1/2 gallons of resin (System III Epoxy) for under $200 plus a bit more for fiberglass...?
You better be sure to seal the end grain of your panels (CPES best and most expensive). Mr Smith from Smith and Company (CPES) will be glad to answer any questions you may have...I did ask about using CPES in new construction on my stitch and glue skiff, and he said it was not necessary.

You could just seal end grain and then prime and paint her... and keep her covered when not in use. Remember, a piece of unprotected furniture will last for years in your garage if kept out of the sun and rain. I guess reasonable protection of sealed plywood (primed and painted) can allow for pretty good longevity. I would think a boat worth building is one that you would want to be around for a while and one that you may be able to sell one day if you didn't use it anymore.

I used over 25 sheets of plywood to build my 18 ft skiff and all exterior surfaces that will be exposed to the sun are glassed. All other surfaces are double coated with epoxy including douglas fir 1 X 3 deck beams and 1X2 cleats. All end grain is glassed/taped. Once painted with Kirbys she should last longer than I'll be alive...no maintenance except for not letting standing water set in her bottom which is pretty much a generally accepted ideology in boatdom... I also will put a cool white cover on her when stored to protect my paint job and make it last a lot longer.

RB

[ 01-18-2005, 05:15 PM: Message edited by: RodB ]

[Gary E]

"I used over 25 sheets of plywood to build my 18 ft skiff and ..."

25 SHEETS?? of 4x8 ??
How many layers? or did you build a really big cabin or just practice a lot? I am confused here.

Maybe you built a fleet?

[ 01-18-2005, 06:12 PM: Message edited by: Gary E ]

[RodB]

All sheets 4 X8' ... Believe me, I would not have bought any more than I had to to get the panels required.....

The sides were 3/8" cut crosswise and scarffed for additional stiffness...(4 joints per side ). The Bottom was 3/8" scarffed as above with an additional layer of 1/4" Merranti scarffed in place once the hull was turned over...bottom thickness total: 5/8". With an 18 foot LOA (really almost 20 feet because of sponsons attached to the transom) and a 33' width bottom the sides and bottom took up 10 sheets. Bulkheads, cockpit sole, decks (front and back) took up another 15 sheets of 3/8" and 1/2" ply. With a hull that is 18 feet long, 33" wide, 12 foot floor, 4 foot deck at the stern, a 6 foot deck at the bow...and the console took
2 1/2 sheets. Correction, I have some larger scraps but I used 28 sheets to get the required panels... and am pretty much done.

Well, photos are worth thousands of words. Cockpit is installed but not shown here except in diagram.

My skiff before console installed... http://www.imagestation.com/picture/sraid147/p2dc0745227e826b9f6c94db87b6c6b6b/f63520e1.jpg
http://www.imagestation.com/picture/sraid147/p7626718082eef33014bf12a398f834f4/f63520dc.jpg
http://www.imagestation.com/picture/sraid147/p25c62b82e46f6bd187063a58b3c4a9e6/f6351219.jpg

CONSOLE (BUILT AND INSTALLED NOW).
http://www.imagestation.com/picture/sraid148/p24f20acf56174abcece1b5a8da6a3453/f60fc8f2.jpg

Cockpit sole pix to illustrate the amount of materials needed to lay in the floor and hull bottom (which was double layered). Photo is looking towards the bow...with first section of the floor fitted and bonded. Note plenty of stringers to support weight of fuel and batteries.
http://www.imagestation.com/picture/sraid70/pd0ab1f83115c1bef20d9a88e28e2cc2e/fba287ae.jpg

28 sheets of plywood to get here.

RB

[ 01-19-2005, 02:39 AM: Message edited by: RodB ]

[Steve Miller]

JimD - do you have information on how long the bottom and side panels need to be after scarfing? i would like to scrarf them up before I build the strong back due to the small size of my shop.

To all the rest who responded - Thanks for info!

[Jamaica Mike]

Goin' fishin for some reds?

JM