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Hi there,

I am trying to figure out if I could build a ‘traditional’ Amatasi! Traditional in the way that she is build with solid wood, no ply, (almost) no epoxy!

My idea is to build the hulls klinker with solid sawn frames where the bulkheads are. In between bulkheads some smalles frames, copper rivers, screws en sealed with polymeer-kit.

because this will be a bit heavier, thought I like to use cedar for frames and planking, maybe add an extra plank to get better freeboard?

What are your ideas! Is this been done before? What are the pits I am falling into?

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Hello- I can only comment from a timber point of view, and have to say that as far as I can see cedar is unsuitable for frames and clinker planking for many reasons: it's too soft and too weak.  It's not that much better than balsa in those respects.I have been using both of these just now to construct a very light chart table/box, sheathed in 2mm ply. I have often thought about solid wood construction of a boat like this, but have never been able to resolve the problem of weight in any traditional form of construction: unfortunately, as I prefer working with solid wood.

I have some fantastic terrifically expensive Japanese cedar, in 300 wide x 4 mm planks left over from a Japanese Teahouse I constructed for a multi-millionaire where it was used as a ceiling finish. I used some of it laminated underneath the main cabin roof of my Tiki 31. It smells wonderful and there's never any condensation on it. But I wouldn't like to go to sea in any unless it was multi -multi-laminated....

It would be interesting to know of any solid wood clinker built catamarans that have been made.

Cheers   Ian

Hi Ian,

thank you very much for your comment.

I build many dinghies up to 14’ with 10mm cedar planking but never used cedar for framing. My idea was to use 20x60mm thick sawn framing, build together as triangles of which one side is the top (deck) side, and the other two sides will be the framing itself.

in between these 7 frames, at the same spot as the drawn plywood bulkheads, I would use some intermediate frames but only the ‘standing’ parts of it, no ‘deck’ side.

If I doubt this would work, and therefor I would need your and other advise, I could use Spanish Ceder (cedrella moderata) in stead?

I hope on more comments from many of you.

When this succeeds, we would like to build a 65’ Islander cat to sail freight in The Polynesian Islands. The shipyard in Costa Rica uses 3 layers of cedrella for the 90mm planking on a 150’ schooner. It is light en very durable. They only want to work traditionally, thats why ...!

They use guapinol for framing, but that is very heavy ‘iron-wood’. From their leftovers we could build that islander. So, there will be a lot of trying and figuring out what works best.

Thanks for your remarks!

cheers,

Bert

Ian R said:

Hello- I can only comment from a timber point of view, and have to say that as far as I can see cedar is unsuitable for frames and clinker planking for many reasons: it's too soft and too weak.  It's not that much better than balsa in those respects.I have been using both of these just now to construct a very light chart table/box, sheathed in 2mm ply. I have often thought about solid wood construction of a boat like this, but have never been able to resolve the problem of weight in any traditional form of construction: unfortunately, as I prefer working with solid wood.

I have some fantastic terrifically expensive Japanese cedar, in 300 wide x 4 mm planks left over from a Japanese Teahouse I constructed for a multi-millionaire where it was used as a ceiling finish. I used some of it laminated underneath the main cabin roof of my Tiki 31. It smells wonderful and there's never any condensation on it. But I wouldn't like to go to sea in any unless it was multi -multi-laminated....

It would be interesting to know of any solid wood clinker built catamarans that have been made.

Cheers   Ian

Hello Bert

That's very interesting, what you say about your dinghy planking and future plans.

It may be true that I have been unduly influenced by my experience of Western Red Cedar. I have made lightweight joinery out of it and indeed boarded the pitched roof of the 60 sq m teahouse (mentioned before) with it before I covered that roof with copper tiles. I remember that the nailholding was pretty poor on that roof with copper nails. I resorted to gripfast I think and that was better and the roof has stood the test of time since.

In my copy of "Clinker Boatbuilding"  by John Leather (1973), he refers to British Honduras Cedar and Central American Cedar (weight around 30lbs/cu ft) as "often used for clinker planking in light dinghies and racing boats".

Regarding White Cedar, also called Northern White Cedar and Eastern White Cedar he says:

"...ideal for planking small boats. Varies in weight and hardness but is often as light as 21 lb/cu ft. There is considerable variation in the seasoned weight of White Cedar. The best quality Northern White Cedar weighs 18 lb/cu ft while New Jersey and Virginia Cedar weigh 28 lb/cu ft. However, Virginia Cedar is not very suitable for clinker planking as it tends to split when nailed and is rather brittle when bent. Pale brown in colour, White Cedar is usually available in small dimensions but works well and retains its shape without warping. Durable...it absorbs water easily and must be kept well coated with paint and varnish. White Cedar roots were once used as crooks from which to cut grown frames, stems and knees for American small boats"

That last sentence is a bit of an eye-opener!

Cheers  Ian

Hi Ian,

That last remark about the roots I have heard before, even here in the Netherlands somebody tried to sell me some; I have always regretted it not buying them.

The ceder I am talking about is a light weight sort of mahogany. In Holland we call it ‘sigar-box mahogany’. The use it for building 12’ racing dinghies. It tasts like asprine while working with it.

I have heard that there is a difference between cedar and ceder! The former is a sort of pine, the latter something else.

because my test will be in Holland and the final build in Costa Rica, I have to choose ...

Hello Bert

Is your Spanish Cedar cedrella odorata? If so it seems to be on the CITES vulnerable classification.

Here are some of the other cedars:

Alaska                                               Chamaecyparis nootkatensis

Eastern Red                                      Juniperus virginiana

Incense                                             Libocedrus decurrens

Northern White                                 Thuja occidentalis

Port Orford                                        Chamaecyparis lawsonia

Southern White                                 Chamaecyparis thyoides

Western Red                                     Thuja plicata

I think the Japanese Cedar I have is one of the E. Asian species of Chamaecyparis like Chamaecyparis lawsonia,

Port Orford Cedar. Port Orford is rated as one of the strongest and hardest of the cedars.

Port Orford lumber is available in USA  as FSC eg as 2" x 6" but I have no idea of the price. In my "Wood: A manual for its use in wooden vessels " US Navy 1948, Port Orford is rated as Group 2 along with other timbers rated for planking in small and high speed boats, with excellent decay resistance.

Back to Spanish Cedar or cedro, my Wood Encyclopedia states:

"...comprises a group of about seven species that are widely distributed in tropical America from southern Mexico to northern Argentina. ..

The wood is more or less distinctly ring porous, and the heartwood varies from light reddish brown to dark reddish brown. The texture is rather fine and uniform to coarse and uneven. The grain is usually straight. The heartwood is characterised by a distinctive cedarlike odour.

..it is not high in strength but is rated to be similar to Central American mahogany in most properties except in hardness and compression perpendicular to the grain where mahogany is definitely superior...works and glues well....In the USA is favoured for cabinets, millwork, fine furniture, boatbuilding patterns, cigar wrappers and boxes...decorative and utility plywoods."

I wouldn't mind getting my hands on some high grade Port Orford lumber which when glued into a couple of laminations or so I would guess would be light and strong and resistant to decay. As planking it would seem to be  acceptable for a smallish lightweight boat.

Cheers   Ian

T

....

Yes its Cedrella Odorata! Your wood ecyclopedia and mine stat the same story, maybe one is the translation of the other!

The reason why I want to use it in Costa Rica is its abundance in nature. They tell you it is not native to the region, must be imported by the Spanish. They harvest the wood on projects where they start ecological coffee plantations and where other projects are started, like the doubling of the Inter America Highway close by.

Also they collect trees from falling from hills in the raining season: We had rains that lasted 5 days at a rate of 3” per hour! Whole hills came down and covered roads, smashed houses!

But here in Holland I am stuck to other species! 

Thanks for your intensive surge and thinkwork!

cheers

Bert

PS here is a 14’ ships boat we have build in Spanish Ceder with backbone and a topsides from Guapinol. Not finished her yet!

Nice work Bert and thanks for the opportunity for me to think a little harder about cedar, there is always more to learn about wood.

From what you say, I can't see why the species you are interested in from Costa Rica should be on any endangered list.

The Port Orford cedar is known also as Lawson's Cypress....that can make it a bit confusing, because we have that here in the UK of course in some plantations. I was looking at a storm- felled tree today which looks like one, about 50 years old. My sawing/planking brain almost started up again but it had a lot of side shoots and storm-felled is often dodgy timber........I'm lucky,  I live next to woods in a deer park with many species of old trees and spend a couple of hours there every day. My backpack is always full.....

Cheers  Ian

Where you live??? You are a lucky guy!!

Devon, near the River Dart, 3 miles from the sea. Took me a long time to get here (and a few £'s)!

If I could build boats from the hazel or beech around me I would be even luckier but no one has worked out how to do that yet....

I have a small wood in France which has got poplar and a Douglas Fir plantation though and a few old oaks I have just about saved from the ivy. The poplar are really tall and clean of limbs but would be difficult to extract and would definitely need barrel loads of epoxy to use on the water, it must be one of the fastest rotting timbers on the planet - but it's light. I have a logosol planking saw which I could use to plank the Douglas Fir in situ, but the Fir is fairly fast- grown and not as good as N. American.

A French guy I know told me that poplar - peuplier in French - wasn't any good for beams either, because peu-plier means little bendability therefore prone to fracture. That might be just another French guy taking the p*ss out of us poor isolationist Brits though.... I have read somewhere that it's ok for internal structural timbers up to a point. It's good for French cheese-boxes of course.

When I used to sell timber I once sold an elm tree (the best I ever saw- pun intended)  to a Cornish gig-builder who used it for a gig he said he built for the Queen of Holland, can you ask her if that's true that she had a Cornish gig built, Holland isn't too big, you must know her?

Devon, Dart river: then you must know Anton Fitzpatrick!

As far as I know: our queen has no Cornish Gig!

And polplar we use for wooden shoes!

Hello Bert

I have been reading 'The Last Navigator' by Steve Thomas (Micronesian navigation) and the author says the voyaging canoes wa serak or waanewai are made from breadfruit tree timber lashed with coconut fibre. They have to be re-lashed every couple of years and the seams refilled.

The breadfruit tree is light and resistant to termites etc. The genus is autocarpus I think. It looks a bit like Atlas Cedar to me.

Someone in Asia or thereabouts might be able to comment on the availability of planks....

Ref Anton Fitzpatrick, I know who that is but not personally. Best known Anton in these parts is Anton Coaker up on Dartmoor who is a specialist local timber supplier/sawyer, as well as being a farmer and a writer (sounds busy to me).

Cheers  Ian

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