Visit our Popular Forums

**Wotname** · 30-01-2016, 15:40

Quote:

Originally Posted by Delancey

As mentioned wood epoxy composite construction in it's myriad forms (strip plank, cold molded, plywood) can be an excellent boatbuilding technique.

Wood is a great boatbuilding material with many fine qualities and is also a renewable resource. After all wood really does grow on trees as they say. Wood epoxy composite construction techniques maximize the structural potential of wood while ameliorating it's inherent weaknesses.

Not mentioned so far is that many fine plank-on-frame boats were killed by well intending individuals who skinned them with fiberglass. I have installed on my boat pairs of halyard and secondary winches salvaged from a once beautiful Herreshoff which suffered this fate and has since been acrimoniously resigned to a dumpster.

Without more information I think your task lies in determining which of the two types of build the boat you are considering is made of. One red flag that stands out to me from your description, a mention on the strip plank thickness being one inch.

The Gougeon brothers, who pretty much wrote the book on wood epoxy composite construction, are specific in advising against attempting to epoxy encapsulate wood more than 3/8" thick. Encapsulation being a critical element of successful wood epoxy composite construction.

If you are really interested in this boat, I think it would behove you to familiarize yourself with the contents of book the Gougeon brothers wrote, for which I have include a link below. It is a wonderful treasury of information.

Cheers

http://www.westsystem.com/ss/assets/...k%20061205.pdf

FWIW, the OP has advised the wood is not encapsulated so that red flag can be lowered

.

However I do concur with the points you raise!

Delancey · 30-01-2016, 16:02

Quote:

Originally Posted by Wotname

FWIW, the OP has advised the wood is not encapsulated so that red flag can be lowered

.

However I do concur with the points you raise!

I didn't get that from the OP's description. He only said it was glassed on the outside. From this I am inclined to infer it was not glassed on the inside.

While glass on the inside can be used to guarantee encapsulation, it is not requisite. Multiple coats of epoxy alone can provide encapsulation.

Glass provides a guarantee because it serves as a visual indicator to prevent sanding through the epoxy between coats.

Without glass, I believe three coats is the accepted minimum. Raised-grain wood fuzz can compromise encapsulation, hence the three coat minimum.

Those things said, if as you suggest the wood is not encapsulated, I personally would run away from this boat as quick as I was to score those winches off the Herreshoff. Glass over unencapsulated wood equals rot sooner or later.

Reflections101 · 30-01-2016, 16:06

Thanks very much!

A few answers and clarifications:

@Wotname: Yes, only the exterior is glassed over. The interior is painted, as far as it can be inspected.
@barnakiel: Good idea, but I don't think the current owner would allow me to strip the paint to check for the wood underneath. I wonder whether there are less destructive ways to thoroughly check for the wood in a pre-purchase inspection.
@Delancy: Thanks very much for the link to the Gougeon book. Great resource! I just had a quick look through it. Seems the answer is: *IF* it is well done it is a great construction option.
@Cheechako: When I spoke to the boat builder's son he was quite adament that the boat was strip planked with brass nails tying the planks together and edge glued.

**Jim Cate** · 30-01-2016, 16:45

Far be it for me to argue with the G. brothers, but I reckon that all the epoxy composite boats over say 35 feet will have planking greater than 3/8 inch in thickness. Our 46 foot example is 25 mm, and larger boats will likely be thicker yet. 3/8 inch is perhaps appropriate for 20-28 foot hulls, and a bit scanty at that!

I guess I don't understand this point.

And for the OP: have we determined that the resin used is in fact epoxy?

Jim

Reflections101 · 30-01-2016, 16:57

Hi Jim,

Nope, not sure regarding the resin but I have contacted the builder's son to find out.

clockwork orange · 30-01-2016, 18:01

Very common boatbuilding method, I see the op is from NZ so if the boat was built there it was most likely glued with epoxy or possibly resorcinol and sheathed with one or two layers of either 6oz or so glass cloth or dynel with epoxy. While as minaret suggests in 1981 epoxy was unlikely, that may be so in the US but in NZ epoxy was the most common resin used to sheath a wood boat ( cold molded, glued strip plank or plywood only) since the 1950s. I very much doubt that brass nails would have been used for the planking by a professional yard, ever, they would have been bronze ring shank nails. This construction method is not the same as Jim Cates boat which uses the wrc as a core and the glass skins are structural, just the same as a typical foam or balsa cored production boat except with better materials and engineering. A much better book on this type of construction is written by John Guzzwell, I believe his Laurent Giles designed "Treasure" was built exactly the way the op described in the 1960s. How about sharing who the builder was, lots of good designer builders of modern wood construction down there, I see you have a Jim Young design, He did lots of strip boats and is the very first that I know of to build the way Jims boat is built.

Steve.

Steve

Delancey · 30-01-2016, 18:02

Quote:

Originally Posted by Jim Cate

I guess I don't understand this point.

That's because you didn't pay attention to what I specifically said and chose instead read into it notions that satisfied your outlook.

The OP said the thickness of his strip planking was 1" thick.

I never said the Gougeon brothers said hull thickness that was to be encapsulated should not be more than 3/8" thick.

What I said the Gougeon brothers said is that "wood to be encapsulated should not be more than 3/8 thick".

If the builder of the boat in question built the boat to the Gougeon brothers recommendations they would have laid down an initial layer of strip planking 3/8" thick and then followed with subsequent layers of laminations not exceeding 3/8" thick (so called cold molded) to achieve the required hull thickness.

Basically, the greater the thickness of individual laminations, greater the movement. Beyond the recommended maximum lamination thickness you are exceeding the epoxy's ability to resist that movement and to maintain the encapsulation. Hence the limit.

It's prolly been twenty years since I last read the book in question so I can't cite the page offhand, pretty darn sure it's in there somewhere. Maybe I am wrong, like I said it's been twenty years and there are always exceptions to rules, but I invite you to prove me wrong since you seem to doubt me.

One thing is for sure, I never saw plywood laid up from 3/8" veneer. Have you?

Reflections101 · 30-01-2016, 18:26

@clockwork orange: Thanks for your very insightful comments. The designer/builder was Allan Smith. His yard was in Whangarei.

PS: You are probably right about the bronze rather than brass nails.

(The Jim Young that I currently have is a trailer yacht and as far as I can tell just ply without any glass over.)

**Jim Cate** · 30-01-2016, 18:29

Quote:

This construction method is not the same as Jim Cates boat which uses the wrc as a core and the glass skins are structural, just the same as a typical foam or balsa cored production boat except with better materials and engineering.

This is not the way I understand the engineering on Insatiable. The skins, except in high stress areas like the stem, skeg and so on, are only one layer of 650 gram biax IIRC. The strip planks are not functioning as a core between those thin skins, but as a true composite. At least that is the way the builder explained it to me, and how Jon Sayer explained it to him. Possible that something was lost in the telling...

Jim

ozskipper · 30-01-2016, 18:40

Quote:

Originally Posted by Reflections101

The boat is a one-off 42ft design built by a professional yard in 1981.

The hull is edge glued and nailed 1 inch mahogany. And here is the crux: The hull is fibreglassed over the mahogany (only on the outside). The boat has been in the water for the last 35 years, but had not done any significant cruising for a while. There are no obvious signs of problems.

Typically I get two types of comments:

"Run!!! Wouldn't touch it with a barge pole!"

"It has been professionally built like that from the start. If the survey does not show up any issues there is nothing wrong with such a construction."

PS: I searched the web about the issue but most pages refer to retrofit fibreglassing a wooden hull rather than as the original design.

PPS: And a final question. How would you rate a construction like this for strength/safety. Weaker than steel. But compared to GRP?

Thanks!

I have owned a multitude of assorted boats over the years. The first question I ask myself before I buy a boat is "can I sell it?"

In other words, will it be easy to move on when its time to change boats again.

If the answer is no, then I walk away.

You need to consider what other buyers will think of your boat when you go sell it.

'

**Jim Cate** · 30-01-2016, 18:44

Quote:

Originally Posted by Delancey

That's because you didn't pay attention to what I specifically said and chose instead read into it notions that satisfied your outlook.

The OP said the thickness of his strip planking was 1" thick.

I never said the Gougeon brothers said hull thickness that was to be encapsulated should not be more than 3/8" thick.

What I said the Gougeon brothers said is that "wood to be encapsulated should not be more than 3/8 thick".

If the builder of the boat in question built the boat to the Gougeon brothers recommendations they would have laid down an initial layer of strip planking 3/8" thick and then followed with subsequent layers of laminations not exceeding 3/8" thick (so called cold molded) to achieve the required hull thickness.

Basically, the greater the thickness of individual laminations, greater the movement. Beyond the recommended maximum lamination thickness you are exceeding the epoxy's ability to resist that movement and to maintain the encapsulation. Hence the limit.

It's prolly been twenty years since I last read the book in question so I can't cite the page offhand, pretty darn sure it's in there somewhere. Maybe I am wrong, like I said it's been twenty years and there are always exceptions to rules, but I invite you to prove me wrong since you seem to doubt me.

One thing is for sure, I never saw plywood laid up from 3/8" veneer. Have you?

That's very interesting, but somewhat at odds with the common practice of strip plank composite construction. Joel White's yard in the NE USA used that combination of strip planking followed by layers of cold moulding, (and did it very well indeed) but there are a lot of boats built like mine is, ie thicker strip planks with glass in and out, or just out. Their long term success is well documented so I'm reluctant to condemn the technique on the basis of your quotation.

Jim

deblen · 30-01-2016, 19:11

How We Build: // Covey Island Boatworks // Custom Yachts for the World Since 1979

These guys have built a lot of nice epoxy wood boats

Paul J. Nolan · 30-01-2016, 22:04

Very interesting discussion. A lot of interesting comments on the boat's construction, condition, etc. (and thank you, Delaney, for that link!) but as ozskipper points out, there are other factors to consider, namely, you are thinking of buying a wooden boat.. Nothing wrong with that, but go into it with your eyes open.

1). From personal experience, it is very hard to sell a wood boat. Very hard.. Did I say it would be hard? Take this into consideration before you buy. You must get a wood boat in very good to excellent condition at not a good price, but at a ROCK BOTTOM price. You cannot pay up for anything: not condition, not equipment, not emotion (I love this boat), not anything. Remember, rock bottom price.

2) During your ownership you must be much more engaged with a wood boat than a glass one. I recall the words of Steve Haarstick, "You know the difference between a glass boat and a wood one? You can ignore a glass boat, sometimes for years, and with a power washer, some Star Brite polish, and a little wax, bring her back to Bristol fashion. Ignore a wood boat for only a season or two, and she's gone forever." He was thinking of Starboats when he said it, but his words apply to all boats (his next boat was wood). With a wood boat you must not let her be uncovered even for a few weeks, you must see that her bilge is always dry, her decks have no leaks, she is well ventilated. She must be used, sailed, frequently. A wood boat is more demanding of your time and attention than a dog and almost as much as a needy or demanding woman.

3) Every single dollar you put into her will go up in smoke. Yes, you might as well burn them. I had a wood boat, a wonderful Nickels and Holman Lightning, #7312. She was in excellent condition when I bought her, but I spent an entire summer in the alley behind my apartment scraping her, sanding, painting, varnishing. New Harken fittings all around. New Allen trailer. New trailing cover. New full-chine deck cover. Mast cover. Rudder cover. Hiking stick. Even new padded hiking straps (I was in love). New Murphy Nye sails (the gold standard of the day) bought from Bruce Goldsmith himself (God, in my young opinion). When the class rules changed that winter, new oval mast and boom. Do you know what all that effort and expense were worth on the market when I went to sell her after contracting New Boat Fever? That's right: Zero! Yes, I sold that boat for exactly the same amount as I bought her and wept with joy in doing so. In my opinion, the same awaits you. I say this not to discourage you, but simply to remind you of the cost of your decisions.

All of that said, of all the boats I've owned, that old wood Lightning is the one I'd most like to have today. Not unlike an ex-wife you truly loved with all your heart, but could never live with. Make up your own mind, but consider these things in doing so.

Paul