Sealing Marine Ply

[Niall]

Hi all,

I’m new to the forum and want to ask a question that I know has been asked many times in the past (before someone points me to previous posts!), and one that I also know people have contradicting views about and indeed some who are viciously opposed to even the suggestion.

The situation is this; I have an 18ft6 Ian Proctor designed Bell Woodworking ‘Seagull’ sloop. It is of marine ply construction built sometime in the late 1960’s early 1970’s. The Seagull had quite a following in the UK (many were also sold as kits and sold on the US eastern seaboard.) and is generally recognised as a plywood classic in sailing circles. It is a hard-chine bulbed lifting-keel design with lapstrakes – see pictures below (http://www.hurstojs.members.beeb.net/gullmew/diagrams.htm (http://www.hurstojs.members.beeb.net/gullmew/diagrams.htm). -scroll down for line drawings) I acquired it recently and I would naturally like to do the best I can with it to seal the hull well, thus minimising (not eliminating- I’m a realist!) future maintenance, before floating it for the 2007 sailing season. On inspection of the hull decks and superstructure, it is clear that the exterior of the hull is in sound condition, however all of the paint in the cabin interior is peeling very-badly (saves me having to strip it!). So, here are my questions:

1) I do not want to sheath the hull in glass/epoxy – I know that this is a touchy subject but quite apart from the cost, I do realise that this type of boat when designed, was never meant to have any sheathing (otherwise they would have made it out of GRP!). Therefore I have started to strip all of the paint back on the hull before I apply a thin-epoxy zinc-based primer to the bare ply followed by a coat of ordinary thick epoxy – still expensive but I would like to know what people think of this idea? Is it worthwhile, etc.

2) As mentioned all of the paint in both the cabin interior and the bilges etc is peeling back to bare wood. What should I paint the bilges with – is epoxy ok? What about the old favourite – metallic pink primer followed by a coat of something else?

Any advice with respect to the above points would be much appreciated.

Thanks all,

Niall

http://www.flickr.com/photos/48061444@N00/252353574/

[hansp77]

Hello Niall,

I am no pro,
so take any advice from me with more than a grain of salt,

however,
I have recently restored my first boat, an early 60's marine ply 30 ft Van De Stadt Seahorse. (This involved replacing most of the deck, half the cabin roof, extensive restructuring, replacing chain plates, etc etc... a lot of work)

You say you don't want to sheath the boat, then you talk about applying a layer of normal thick epoxy on top of your primer?
This is sheathing, without the reinforcement of glass- the worst of both worlds.

If you want to cover your boat in resin (IMHO a bad idea) then sheath it properly with Dynel or something.
As far as I know, resin on its own is no good.

If I was you, I would go for a really good above and below water primer, and then simply go with whatever topside and antifoul paint you choose.

The absence of resin sheathing means that proplems can be found sooner, and repaired easier.
Hairline cracks in resin can let water in unknown, keep it in, and cause and spread rot without your knowledge.

My boat came to me painted with normal exterior house enamel, so this is what I continued to use. It has kept the boat in good order for over forty years, and hopefully will continue to for another:rolleyes: . Any colour you want, good finish, cheaper and reliable.
There are of course many other marine-specific options, but many a wooden boater I have met will swear by exterior house enamel. (obviously many here may disagree).

Similarly, in the interior of my boat, the paint was peeling. From what I can gather, this was because of moisture. I had considerable rot in the deck and cabin, and a lot of fresh water had seeped in. Everything was damp or wet.
After we hauled her out, and dryed her out, and stopped further ingress of fresh water, the interior paint just started peeling and flaking more and more- it has now come off in sheets.

Similar thought to you- easy, saves me stripping it;)

Inside my boat (after priming) I am going for a hard wearing interior, water based acrylic. I like the idea of this because it allows the wood to 'breath' more than an oil based paint does. However, as far as I know, an enamel would have done fine as well.

again, I would think that painting on the interior of the cabin with epoxy is a bad idea.
What are you hoping to achieve by painting your wooden boat in epoxy?

Bilges- I am not too sure, someone else will hopefully fill you in on this.

Anyway, welcome, best of luck,
I hope you get some good advice.

Hans.

[Keith Wilson]

Epoxy alone doesn't seal very well. Thin layers are quite permeable, and thick layers will crack and leak unless reinforced with fibers (glass, Dynel, etc). The sheathing fabric functions rather like re-bar in concrete. Some think epoxy is a good primer coat under paint; I've never seen much point in in myself. It costs more and doesn't seem to last any longer than ordinary primers.

If it were my boat, I'd use Smith's CPES as a primer under ordinary marine paint, or good-quality porch and floor enamel. CPES is a penetrating solvent-thinned epoxy. It's also one one of the nastiest-smelling substances known to man, and toxic too - use a really GOOD organic-vapor respirator. Porch and floor paint is much harder and abrasion-resistant than ordinary house paint. CPES seals a bit, and cures slowly so the paint adheres very well. You didn't specify a location, so I don't know if you can get it where you are, but it's available all over the US

[hansp77]

Hey Keith,
In finding another penetrating epoxy believer;)

what is your thoughts on making your own, by thinning down normal epoxy?
I started a thread on this in boatdesign.net and interestingly Steve Smith (the owner of CPES) replied upon it, to back up the ligitimacy and uniquness of his product.
http://boatdesign.net/forums/showthread.php?t=12061
(Steve Smiths post is page 2 post 27)

It wasn't gone into in great depth here, but my thoughts are that the best off the shelf thinner, that most closely matches the mix of solvents that are in CPES, is laquer thinner.

What do you reckon?

(I most certainly do not want to start another CPES argument on Niall's thread- so anyone that thinks CPES original or homemade is rubbish- BITE YOUR TONGE!:D )

Anyway, for me,
next time, I will be making my own.

[Thorne]

Ditto what Keith says - take the ply back to bare wood, use Smith's CPES as a sealer/primer and then paint. Use the cold weather formula (it outgasses quicker which is why they recommend it for indoor use) and wear a good respirator with organic filters and do it on a windy day with a box fan in the hatch. Give it as many coats as it will soak up around the edges of the ply and anywhere near water.

http://www.smithandcompany.org/images/potlife.jpg

I am biting my tonge on the home-made thinned epoxy subject....as requested.

From Smith's website -
http://www.smithandcompany.org/CPES/index.html
-------------
Clear Penetrating Epoxy Sealer (CPES) consists of a tough, flexible resin system in a solvent blend which dissolves the sap, oil and moisture found in wood. The resin system is derived from natural wood resin and develops a chemical adhesive bond to the wood fibers themselves.


The "metallic pink" stuff you mention is red lead paint -- which is a good alternative to CPES for the bilge areas, and either the second-best or best (opinions vary) primer/sealer when compared to CPES. Kirby's paints sells it, hard to find otherwise unless you mix up your own (Bob S.'s recommendations on this available in previous threads on this hot topic).

I like using red lead on all faying surfaces -- where wood is attached to / touching other wood -- as it kills rot that otherwise might form. For exposed surfaces I prefer CPES.

[Cuyahoga Chuck]

Applying epoxy over paint is a waste of time. The longevity of this technique is still dependent on the bond of the paint to the wood. Epoxy, of course, has a much higher bond strength than paint so it is normally applied to the wood as the sealing coat. The epoxy then becomes your protective layer and the paint or varnish goes on to pretty things up and to protect the epoxy from harmful UV rays.
I'm not going to get into the arguement over the amount of permiability of epoxy other than to say what ordinary coating is better? If the levels of water and air in the wood don't get to the levels where wood-eating microbes can survive then the coating is doing it's job. Epoxy doesnt seal perfectly but it's cross-linked structure has to be stouter than any solvent based paint.
And, on plywood, epoxy is excellent at sealing those water-sucking edges.
My experience is quite limited but I have researched most of the recommended techniques and epoxy over paint is not one of them.

[hansp77]

Hey Thorne,
feel free to dispute the homemade CPES option- as in let that tonge loose!
I just didn't want to start another debate over the worth of CPES in general-

Steve Smith makes some pretty good points about his products, his resins are largely wood resins, rather than petrochemical, however, his solvents are just solvents (as far as I know) and this solvent blend is pretty damn close to laquer thinner.
Of course you could make a more accurate blend yourself by mixing up the different substances, but a off the shelf product has that much more appeal.

He puts up a good argument, but there are many, including of course his competitors, that believe a lot of this is just sales hype.

I don't know. But for my buck, next time, I am going to try my own.

[Thorne]

Chuck - I don't think that either Keith or myself are recommending using CPES or epoxy over paint -- he says the old paint is peeling off.

But just in case there is any confusion, yes, take everything back to bare wood before using any new coatings, be they epoxy, primers, or paint.

[Niall]

Thanks all for your replies and suggested advice. Perhaps I should clarify that I have not suggested anywhere in my original post that I would apply epoxy over paint. The original post reads:

"...before I apply a thin-epoxy zinc-based primer to the bare ply followed by a coat of ordinary thick epoxy..."


The reason I was thinking of adopting this strategy was that this was what the epoxy supplier recommended.

Niall

[pcford]

I would probably use Petit sealer #2018. I've been using it on one of my current projects. It is only moderately skunky; it seems to form a tough film. Good stuff.

One should understand that for whatever reason, Smith's CPES has a following here which is unmatched in the real world. The impression that I get from local professional boat restorers is that some use it but not with the peculiar amount of enthusiasm which is exhibited here.

One further point, I don't think you mentioned the type of plywood. If it is Douglas fir plywood....there is really no way to get the grain to behave without covering with glass. Your screen name, Niall, is more common in Britain, maybe you are from that part of the world and thus is likely that your boat is not made of doug fir.

[Cuyahoga Chuck]

My remark was directed at Niall's original post, Thorne. I may have gotten it wrong. That font is so small I was having trouble reading it thru' my trifocals.
Apologies to all.

[JimD]

The reason I was thinking of adopting this strategy was that this was what the epoxy supplier recommended.

It's not much of a surprise that an epoxy supplier is recommending a thick coat of epoxy. I am in agreement that epoxy in cloth will hold up much better than a coat of epoxy without cloth even though a lot of folks do it.

[pcford]

It's not much of a surprise that an epoxy supplier is recommending a thick coat of epoxy. I am in agreement that epoxy in cloth will hold up much better than a coat of epoxy without cloth even though a lot of folks do it.

I agree.

[Niall]

In reply to pcford, I'm not sure what type of ply is involved. It is possible that it is Doug fir - I have no idea!

BTW:No I'm not from Britain (my name is Irish (pron. Nee-al)) The boat is however!

[pcford]

In reply to pcford, I'm not sure what type of ply is involved. It is possible that it is Doug fir - I have no idea!

BTW:No I'm not from Britain (my name is Irish (pron. Nee-al)) The boat is however!

Sorry I presumed you were British.

I would guess that the boat does not use fir ply. You can see a very obvious grain pattern with fir. I'd guess the ply is African mahogany.

[Niall]

Mahogany, yes - that would make sense as the top layer would appear to be a darkwood. See: http://www.flickr.com/photos/48061444@N00/252362957/ perhaps you can make out what type of ply it is from this?

Niall

[JimD]

If it's quality old mahogany and its never had a resin on it (polyester or epoxy) and its held up all these years its sounds like it ain't broke and don't need fixing if you know what I mean. Seal and repaint ought to be enough.

[pcford]

Mahogany, yes - that would make sense as the top layer would appear to be a darkwood. See: http://www.flickr.com/photos/48061444@N00/252362957/ perhaps you can make out what type of ply it is from this?

Niall

I agree with you.

[RodB]

I'll preface my remarks with the fact that I have used about two gallons of CPES and more or less accept the merits of this product to the extent that I personally have used it on old and new construction. As others here, I am no expert or chemist, but have tried to research most data on this subject matter while building my boat over the past four years.

Smith doesn't just say, "buy this, it's great and does everything"...he offers some detailed studies to back up how his product works. What made up my mind was the results observed when using CPEs when a friend was restoring an old woody Lightning. We applied CPES to some of the wood that had been degenerated/weathered for several years and then dried out completely. The CPES soaked into the wood to a great degree and once cured the material was well sealed.. and from our examination, stabilized quite well. Applying paint was the next step and only time will tell how stabilized and protected the hull will be. We were mainly impressed with the degree of "soaking in" of the CPES and how much it seemed to add to the material's toughness and strength...evaluated from simple tests like trying to break a piece before and after CPES application and cutting up treated pieces for examination. The guy who was restoring the Lightning is a custom gunsmith and since this project has adopted the use of CPEs as a sealer in any wooden stocks he uses on his customers guns.

There are several "non-epoxy" ways to approach your project...but I would think, for those who think the merits of CPES are real...that this would be a perfect project for using CPES.

An older boat that has weathered wood all over inside and out...seems a perfect candidate for some sanding, CPES, and painting...

I can't remember ever reading of applying a primer of any kind to bare wood... and then applying epoxy on top of it... except for CPES as the primer?

So...applying CPES to bare wood and then applying epoxy before painting...now that "may" make sense if you give credence to the merits of CPES. The CPES would do a good job sinking in the old weathered wood and then make for a really strong bond to the epoxy. But alas...plain epoxy doesn't offer near the protection as epoxy and a layer of fiberglass or Xynol cloth and if you wanted to use epoxy anyway, why not glass?

Glassing the exterior of the hull would result in the toughest finish to protect the hull exterior...and to balance the structure...CPES then plain epoxy and paint on the interior of the hull. Applying the CPES would be a breeze, and then the paint you applied would have a very stong bond to the surface...plus you have the added insurance of the layer of CPES under the paint hopefully offering some degree of protection. Due to the hull construction, it may not be practical to glass the exterior of your hull, but it would result in the toughest barrier if it could be done.

I agree with those above, CPES and quality exterior enamel seems a good approach... also, PCFORD obviously restores many old weathered boats and has many years seeing the results of his methods. I may not agree with him on the merits of CPES, but I do recognize the value of experience in what has worked in the past...


RB

[Keith Wilson]

I don't have any strong opinions about "roll-your-own" thinned epoxy sealer. I do think Smith's bit about "wood resins, not petrochemicals" is utter BS, and IIRC "The Chemist" who used to post here said the same.

OTOH, my experience with CPES has been nothing but good; the only drawbacks are cost and smell. I've never tried to make my own, so I don't know if it would work or not. I like Kirby paint over CPES; the best of old and new technology.

[RodB]

What Keith said.

I just remembered that I have played around with thinned epoxy in wetting out Dynel as a non-skid test panel. Having used CPES and thinned epoxy enough to see the cured results...I must say that the CPES seemed to have more substance in a simple examination once cured. I base this on examining cured thinned epoxy and CPES on a wood surface. I felt the CPES tougher and to have more substance (hard to put it into words) on examination...just my humble opinion from casual observation. I don't think thinned epoxy and CPES are the same at all.


RB

[pipefitter]

If you must thin your own then you can use an epoxy paint thinner such as interlux's 233N. It contains ethylene glycol or one of it's derivitives which has been shown to help prevent rot. The one advantage to using thin glass layup epoxy is it will fill in the checks or cracks in the outer veneer in plywood which may help to slow them from growing or help keep the veneer down in those areas.Keeping the edge of the veneer in the check from curling up there if the crack is thru to the glue line.

[hansp77]

Glycols are no good for epoxy-
Smith makes a big deal of this, and other penetrating epoxy sellers mainly agree.
International (evidure) used to have glycols in it, now is doesn't.

On the thread I linked to above,
Roly provided me with this proportionate (not percentile) list of solvents in CPES

Aromatic Naphtha
xylene (common paint store solvent)
toluene (common paint store solvent)
isopropyl alcohol (2-propanol) (common, cheap rubbing alcohol)
2-butanone
4-methyl 2-pentanone
2-heptanone
4-methyl 2-hexanone
2-pentanone
dipropylene glycol monomethylether
diisobutyl ketone
ethyl acetate
isobutyl acetate
ethyl 3-ethoxy propionate
propylene glycol monomethylether acetate
hexyl acetate
isobutyl isobutyrate
diacetone alcohol
cyclohexanone

The top ones are the main ingredients, and argumentatively some of the bottoms ones are there to make it all look good and complicated;)

This is a pretty similar mix to lacquer thinner.

I have experimented with thinning my own epoxy, West System,
with a mix of Acetone, and paint thinners (toluene and xylene I think).
I used this in comparison to Evidure, not CPES, however, the results of the thinned epoxy on the wood were the same, and so were the results from the leftovers setting up in the jar.

Both went to the same consistency rubber-like substance, that would tear or shatter upon stress.

This was of course just superficial appearance, and no real tests or anything was done.

If I was going to do my entire hull, and I had the money to burn, fair enough I would probably go straight to CPES-
however for a lot of other less critical jobs, or for someone with a slightly more restrained budget like myself-
the home thinned stuff looks and performs pretty damn well.

[hansp77]

If it's quality old mahogany and its never had a resin on it (polyester or epoxy) and its held up all these years its sounds like it ain't broke and don't need fixing if you know what I mean. Seal and repaint ought to be enough.

This is what I would do.

[Stiletto]

I used to advocate mixing my own epoxy thinned with alcohol.
I think it was the chemist who used to post here who pointed out that thinned epoxy is not impermeable. A simple test is to take some of the timber or ply you will be using and coat it. Next, weigh it and record the weight. then immerse the test piece in water for a period of time, (a couple of weeks did it for me), and then weigh it.

The increase in weight is due to water uptake.

In similar situations I now coat my timber with neat epoxy, warmed timber helps penetration somewhat.

In practice most paint is permeable too.

[RodB]

West did some experiments adding EG to epoxy and I think they did find a percent additive that did not seem to effect the epoxy performance and curing.

It would be interesting to develop a test where CPES and thinned epoxy (of a similar consistency) were compared. From my personal non-skid tests and then using CPES to coat wood, I think them quite different, but only an objective test would confirm a superior substance.

If I were restoring a older weathered boat I wouldn't think twice about using CPES before any other products whether paint or more epoxy.

RB

[pipefitter]

I don't find any reason to thin it at all. In a surfacing primer,you have to build mils for the final fairing. On plywood,or a dry sailed boat,I don't see the need for the micro difference in penetration.If it was solid wood and was getting a little soft or punky then I might consider it. Not saying it is bad to use CPES. In my situation I just don't think I needed it. On the boat in the topic,what was on it obviously worked also. On my boat,a good primer would have worked but I was able to do it in 2 coats with regular thin layup epoxy for a perfect fairing surface.The one part paint stuck to it very well and all I have to do from now on is scuff and paint without much worry of oxydized primer under the paint.WHat I disliked about standard,compatible primer surfacers was that at any significant build as a surfacer,they tend to shrink more and at different rates than the topcoats which I think lends to longevity issues.Epoxy is pretty much stabilized after it sets up and cures completely. For some reason,paint lasts longer over epoxy than on primer.

I am sure that those of you that have used cpes may find satisfactory results as well with your findings. Usually,the people that reply to these threads with careful mechanical chemical considerations are going to know their boat and their products well enough to maintain them accordingly.

[RodB]

Paul,

I was suggesting using the CPES because of its soaking into any weathered porous wood, hardening and sealing it, and then you get the great bond from the paint to the CPES as a primer. I think that lots of boats that looked and surveyed ok in northern climates, when brought to the warm south have begun to show rot areas after just a few months. I know a surveyor here that once did this and he states he will never do it again.

I once asked Steve Smith if building new, would he use CPES in any parts of the construction...and he replied," probably not". He seemed to agree that applying to end grain on drilled holes would be a good use... which you would also add a couple of laters of epoxy atop the CPES.

I assume you applied epoxy to a pretty fair surface to start and probably have the mil tickness to make for a pretty good barrier. Are you concerned that you may get chipping if any corners get trauma hard enough to do some damage? Just curious. BTW, you did a great job on your boat...

I saw a Parker's "Exuma 36" in south Texas about a year or so ago, where the interior of the cockpit and supporting bulkheads extending down into the companionway floor rotted after a few years. The builder was not very careful in tarping the craft he was building, and also used exterior grade plywood for most of the plywood on the interior.... which was first coated with thinned epoxy until no more would soak in, then painted with linear polyurathane per Reuel Parker's directions.

The boat was about 90% finished... then left stored for a few years in its cradle where intermittent fresh water gained entry, then of course the climate was warm and humid...

The rot was quite extensive in the cockpit flooring, the vertical bulkheads beneath the flooring, etc. etc. I was quite shocked at the lack of protection the thinned epoxy and quality Linear Polyurathane paint allowed. Now granted this was the absolute worse conditions a boat could undergo and the materials were not marine ply... but it sure made an impression on me. I'm not even sure if all panels inside and out had been glassed if she would not have undergone quite a bit of rot.

I would not consider building a modern epoxy composite hull without glassing the interior surface of the hull and probably any other areas subject to exposure to water like bulkheads attached to the hull bottom and bilge area.

Its amazing how much damage can result with lots of humidity, higher temps, and an intermittent influx of water...which is a reminder that boats need to be cared for well no matter what the costruction.

RB

[Niall]

So from what I can gather, in general:

1. Some people like CPES and would recommend it as a primer to ordinary
ordinary paint, because it is more stable than ordinary paints.

2. Some people reckon CPES (or any type thinned epoxy) is rubbish and reckon I should just stick to ordinary pink primer and enamel - if it's not broken etc.

3. One person reckons - just use unthinned epoxy but warm the ply to aid ingress/penetration.

4. No-one thinks coating CPES/thin epoxy with a barrier coat is a good idea - or am I confused?


Since I have already purchased a thin-epoxy primer - I have therefore have the following options.

1. Use the thin-epoxy primer in the approach as described in 1 above and over-coat with ordinary enamel.

2. Forget about putting epoxy or resin of any type near my hull. Recoat with ordinary pink primer and again over-coat with ordinary enamel. Use the primer I have bought

3. Buy unthinned epoxy (forget about the primer - use it as a doorstop etc.), warm the ply and apply a coating of epoxy (and overcoat with ordinary enamel??)

Is this a good general summary or am I missing something?


Niall

[Thorne]

I think so -- you've walked into a standing controversy and the fallout can be confusing.

One additional complication -- you might want to consider different methods & materials for different parts of the boat.

The bilge, in my personal opinion, should have either red lead (don't call it "pink") primer or CPES -- you want something that will last and not rot. Ditto for stuff below the waterline outside the hull. Since you **already** have red lead in the bilge, if you have any reservations about using CPES, I'd say go with red lead, available from Kirbys. Lead is toxic, so of course use nitrile gloves when painting and a good respirator when sanding.

The interior of the cabin and other non-hull locations can be more flexible as to what can be used.

Try to not be confused by the "epoxy is epoxy is epoxy" crowd -- CPES is a primer/sealer, just like other primers that contain some epoxy, and red lead. Using it is not the same as pouring regular thick epoxy all over the hull, and/or using glass fabric. But you do need to then deal with the required UV protection for either CPES or thinned epoxy on any surfaces exposed to the sun -- overcoat with either paint or UV-rated varnish.

Good luck and post some pics, OK?

;0 )

[Pericles]

Niall,

You will get good advice at http://www.fishyfish.com/tolmanskiff.html and http://www.devlinboat.com/sgfp.htm
Why? Marine ply boats have changed and so have the techniques to build them. Whilst Epoxy is not completely and utterly waterproof, it's the best option you have.

The ply must not get wet. See the articles page about New Epoxy Wood Sytem at http://www.brayyachtdesign.bc.ca/

The article about "Home build or not" is also helpful.

Good luck,

Pericles

[pcford]

It's certainly not necessary to seal with epoxy.

[pipefitter]

Paul,

I assume you applied epoxy to a pretty fair surface to start and probably have the mil tickness to make for a pretty good barrier. Are you concerned that you may get chipping if any corners get trauma hard enough to do some damage? Just curious. BTW, you did a great job on your boat...

RB

Mine is glassed below waterline but in the Simmons,It has large panels forming a pan for the submersible part of the hull so to speak so it is easy to glass. The glued lap ply above waterline just gets wet from spray.The water beads and runs off the brightsides. It doesn't get wet. Some paints absorb water readily such as flat finishes and gradually dry. If I get any damage,I am on it as the paint is easy to repair. I repaired a spot where I put the bow eye in and where the boat got damaged by the bow roller. It's as easy as any other part of the detail process and rather satisfying.

When I used to paint cars,if we used sandable primer we always applied a sealer over it as it was very porous and would rust under the primer if left as it was.My thoughts were the same about primers for boats. Sandable primers would leave minimal protection if the glossy topcoat was compromised or even lost it's sealing capabilities with age and oxydation.So I just used epoxy as a stand alone primer/surfacer/sealer.

I don't know how much of a real barrier the epoxy coating will provide but the one thing it did do was make the entire surface very predictable to paint. All the paint dried at the same rate without dry spots sucking up more paint faster than not so absorbant parts which can be found with the inconsistencies of most wood in it's natural condition.The only reasons I dislike primers is because they take months to shrink and cure and I have seen primers chalk under paint.CPES would probably do much the same in homogenizing the surface for paint.

All the corners on my boat are glassed. I glassed the entire transom because the bottom part of it was glassed anyways below waterline so this just gave me an even surface to fair and I carried the glass out to the end grains of the side planks where they were sanded flush with the stern. I also glassed the bow and faired that in as well.

The hardest part about repairing or repainting is when paint flakes and chips and I would always end up sanding the whole thing because sure as hell I would think I got all the loose paint checked,I would recoat and find some others and be chasing them throughout.

I saw a boat recently that had used fibreglass tape for a repair and the paint was nerly completely worn(could totally see the grain pattern) thru where there was plain wood. The epoxied area was still solid paint even beyond the tape where the excess epoxy was. All the screw spots that were filled were also still holding paint as well. The plain wood was very much more checked and dry and with mildew spots.Whether the epoxy will add any protection on a molecular/absorption level,I don't know but it will make my maintenence procedures much more predictable. That one absorbent swirly grain area in the ply won't need different consideration than the rest of the hull. Sofar it is working well. I almost cant wait to repaint.

The regular thin epoxy does penetrate subsurface as evident when you go to sand ,you can see the epoxy stain in the wood. Maybe not quite as far as CPES but maybe enough.

Thanks for the compliments RodB. I worked at it.I am very satisfied with the finish.Hopefully we can keep in touch over the next few years and compare notes on to the different products we used and their longevities or lack of. Way to go on that flats boat too. Awesome fishing machine. Sure could have used that jet drive last weekend. :)

Niall,I am not familiar with the older mahogany plies and you might find issue when you sand it all to wood.If the primer has given up the ghost,you might benefit from a more aggressive sealer or an epoxy primer. If you do go with the original paint schedule,try an inconspicuous area of a different approach and see what the results are over time so that if you do have to do it again,you will have your own firsthand comparison and we may all learn from it.

[RodB]

Paul,

It sounds like you only applied plain epoxy in more or less flat areas where glassing wouldn't be necessary. My boat is completely glassed on all exposed surfaces, and quite easy to repair. I was just wondering if there were any real dangers of plain epoxy without fiberglass cloth chipping off if you applied it to good materials in a proper manner. Probably not...except for corners that might get dinged...and you said they were glassed.

I already have several dings that I will have to fix, and its quite easy to sand a little being sure the glass is not damaged....then prime and paint the small area. I use the hi-build hot solvent primer that dries very fast and sands really nice. Then just throw on some Kirbys.

My next paint job on the topsides will definitely be Brightsides.

We will be comming through Tampa in May again on our annual Tarpon flyfishing trip to the Keys. Perhaps we can meet up and fish for a day.

RodB

[pipefitter]

The epoxy wont chip off and if it does,wood is going with it. Thats about what my repairs consist of about the same as yours.I only glassed the exterior bottom up to the first side plank and the decks inside up over the first side plank.I dont get water in the bilge often.If I do,after we are set up, I take a minute and open the hatch to get it with the sponge as part of the cleanup of grass and such from the cast net.

For what it's worth,during hurricane season last year I got 4" of water in the bilge and it stayed in there for a week. I didn't know it had leaked under the tarp. There was no discoloration of the ply or frames where the water sat on top of the plain epoxy.Figured I would try it without glass first and if it failed,I could always glass it after.

Make a plan to stop on thru and we can see what we can stir up if you have time.I would like to see your boat.

[Niall]

Ok,

Thanks once more for all of the advice. By the way Thorne I call it pink primer because thats what International call it - in fact on the tin it's called (and I quote) "Metallic Pink Primer". I'm not sure if it's the same stuff as you refer to as red lead - there is no indication that there is any lead in it all in fact - but then I'm not sure.

Niall


Niall

[buccaneer]

I find these posts interesting. Two years age I dropped the keel of my 25 van der stadt, Primaat, ply construction hard chine, yacht. It was out of the water for three months--replaced upper section of dead keelson and two springs, new keel bolts and replaced keel. On returning some bilge seepage occurred where the hull meets the keelson, at lowest part of bilge, and has been the same since, taking up about one half tissue full of water every 14 days, in winter mainly when less evaporation is possible. This seems very little and I am not too concerned as the boat is permanently moored in Simonstown, a small harbour in the Cape Towen area of South Africa, in sea water. I think the problem lies with soggy, ply at the point where the hull meets the keelson. It bothers me however, but without major surgery it cannot be eliminated. Any suggestions along the lines already discussed that may be applied to my problem. For example can anything be done (from preferably the inside) to re-constitute the ply, like inner laminates.