And then there's cedar strip...

[Rob Gates]

Lately there's been a bit of a stir concerning the relative merits of solid planking vs. plywood for a clinker boat. I wonder if passions run similarly high when cedar strip hits the water?
Some might see cedar strip as having usurped the traditional plank-on-frame, copper-fastened and oakum-caulked carvel hull - albeit somewhat Lego-like by comparison.
As Adrian Morgan says of plywood, so cedar strip also looks a little strange (to me anyway) when finished with a clear coating; I'd want to cover up all those abrupt changes in grain and colour using something opaque.
Nonetheless, I see cedar strip as just another good method for engineering a boat and, more than that, keeping the whole wooden boat scene alive and relevant. I do wonder how long cedar strip and epoxy will last - perhaps some owners of early cedar strip boats can comment on that? And how easy is it to repair? Since the (strip) planks are joined edge to edge by convexities fitting inside concavities it must be virtually impossible to replace small areas of planking - would a damaged hull be a write-off? But it's supposed to be a pretty durable recipe. (One designer told me the epoxy was strong enough by itself to hold the lead keel, without bolts, and maybe he was right but they fitted bolts anyway).
The older I get the more I think buoyancy is the thing, however it's constructed. Crikey, these days I get a lift even boarding a pontoon and the ruddy thing's built of polystyrene!

 

[Sequoiah1]

Epoxy would hold a keel on (provided the surfaces were large enough) but would not stop the keel falling off once it had any sideways load on it. They would always need keelbolts.

 

[DownWest]

Andrew Simpson held his keel on with epoxy, no bolts. Not a simple flat joint though.
Strip planking has been around for a long time, cedar and epoxy are just the most recent version. Earlier (60s) boats used resin glues and nails with square strips. I have seen a few from that era going strong.
A

You aren't trying to start an argument by any chance? ;<))

 

[Woodlouse]

Naming no names, but I do know of some strip plank epoxy builds that went rotten within 10 years of their being built. People tend to forget that even though you are covering the wood in epoxy, it still needs to be of a good quality.

As far as repairing it goes, all you need to do is cut out the bad bits and graft new bits in it's place. Pretty simple really. And quite cheap.

 

[Rob Gates]

Thanks all for your informative replies; it's the performance of the materials in the built boat I'm hazy on - how they wear and repair.
I've just been reading what designer Paul Gartside has to say here - he's not a fan!
About 35 years ago there was a sweet strip planked sloop in Chichester marina (can't recall name or make) and the method aroused my curiosity then - though I don't think she was cedar and epoxy.
As an amateur, with the bottom line being enjoyment of the experience, the build process is at least as important as the finished article, and I fear I'd lose interest in sticking and pinning so many identical pieces, probably with catastrophic consequences.

 

[fishermantwo]

I would prefer double diaganal cedar and epoxy but strip cedar and epoxy would be my choice when it comes to buying a second hand yacht. Locally the resale of these vessels is less because punters are scared of "wood", they would prefer osmosis in fibreglass. One off racers that cost hundreds of thousands of dollars are available at realistic money.

 

[DownWest]

Rob,
A neighbour is about to start a Bolger Chebacco in cedar strip, so it should be interesting. It will be his third, after a 15ft gaff day sailer and a little 7fter for the grandson. Looking at Gartside's notes, it is worth mentioning that the 15ft was 6mm cedar strip t&g, 2 layers of 2mm diagonal cold moulding and a layer of glass cloth, all set in epoxy. Lot of work, but a pretty tough hull.
A

 

[Rob Gates]

Good point about the resale value for old strip-planked racing boats. I guess these would be good case studies for seeing how the materials stand up to stress and strain, having been well tortured.

Phil Bolger's Chebacco is going to look a picture in cedar strip. I see it was originally designed to be cold moulded before becoming a popular hard chine plywood boat and then adapted for clinker construction. Just been looking at the Chebacco website here - interesting.

And also reading about Phil Bolger the man - what an amazingly inventive designer. Good names he gave his designs too - Romp, Brick, Unpretentious Cabin Cruiser, One Man Liveaboard Concept. Someone who brought variety into the field. Died as courageously as he designed, it seems.

 

[Rum_Pirate]

“Kate” is a First Rule (1907) International Twelve Metre.

LOA 23.75 metres (tip of bowsprit to boom end).
LOD 18.40 metres.
LWL 12.00 metres.
Beam 3.45 metres.
Draft 2.30 metres.
Displacement 20 tonnes.
Sail area 250 square metres

---- “Kate” was designed by Alfred Mylne in 1908 and built by Philip Walwyn and his small team of woodworkers in St. Kitts. Launch date was December 2006.
Copies of Mylne’s drawings and calculations were used. Displacement is as designed, as is ballast ratio and rig. Construction, engineered by Ian Nicolson with plan approval from the Twelve Metre Class is wood, epoxy, bronze fastened throughout and glass sheathed using two layers of 300gsm biaxial. Walwyn has used this method over the past 30 years to build a number of boats for himself. Epoxy, additives and glass cloth are from SP Systems in the Isle of Wight. Coatings are by Awlgrip.

Frames are laminated mahogany as is the centerline structure. Planking, screwed and glued to the frames is 35 mm Oregon pine, a 2mm veneer of Okoume covers the interior planking. Deck beams are laminated Oregon pine. Decks are two layers of 10mm Bruynzeel ply with a laid deck of Oregon pine of 4mm glued over. The spars are Sitka spruce, made hollow. Sails are cream Dacron by Gowen of West Mersea. The keel of 11.5 tonnes is lead with 18 bronze keel bolts. Rigging is by Spencer of Cowes using Sta-Lok terminals and rigging screws. Ten bronze, Meissner, self tailing winches handle halyards, runners and sheets. Bronze and steel hardware is by Classic Marine in Woodbridge.

With experience gained building half a dozen boats up to 23 metres on deck engineered in wood/epoxy, “Kate’s” interior and furniture is designed to be both functional and add strength and it makes for a particularly stiff structure.

There is no engine, no tanks and apart from a masthead tricolour, no electrics. Handheld GPS and VHF are on board. The boat is a symphony in simplicity.

More info

http://www.1906-twelvemetre.com/

 

[Keith 66]

As has been said strip planking has been around for a long time, i have seen quite a few well built yachts built with good materials, without exception they always succumb to cracked glue lines here & there, there are simply too many stresses lined up in one plane. Cedar strip being normally coated in epoxy & glass is more akin to a wood cored composite , repair should be easy as the concave convex edges are not essential for full strength.
Western red cedar is extremely durable but will suck up water like blotting paper so the real issue is one of water ingress through damage.

 

[Rob Gates]

The three-year-old Kate is an impressive replica, a thoroughly modern mix of techniques. I guess we will not have the real data on how well such a vessel wears until she is actually as old as she is designed to look - and who is to say she will not last 100 years?

I'm sure many of the claims made for modern materials will prove to be well founded, but until yachts using them have been afloat for as long as their more traditionally constructed ancestors I tend to regard claims as projections. The history of the supposedly infallible yacht is littered with keels unexpectedly dropping off, rigs crashing over the side etc.

Regarding that concave-convex join in strip planking, I'm reading Lionel Casson's Ships and Seafaring in Ancient Times where he talks about the Bronze Age boats discovered by the late Ted Wright at North Ferriby in the 1930s.
These are the oldest plank-built boats in Western Europe, recently dated to around 4000 years old, and their planks were assembled by just such a joint. So you could say the concave-convex profile used for cedar strip-planked boats uses the oldest technique there is - far pre-dating the join of more recent carvel seams. That said, these planks were oak several inches thick and maybe cedar is a tad less durable.

Back then they used moss in the seams to make them watertight and sewed them together with withies of yew.

The Ferriby boats website is well worth a visit.