Thread: Hoop pine for acorn skiff

Why not ,hoop pine might not reach the heights of huon pine,king billy or celery top but I reckon it's got to be better than (to put the cat amongst the pigeons) that stuff called ply wood. A perfect example of our throw away consumer society.

Have you thought about Paulownia? It's very light weight, easy to work, grows in sustainable plantations and used extensively nowadays for planking.

Somewhere along the line, I got the impression glued ply lapstrake needs to be done
in plywood rather than planks of real wood. Don't know why - guessing it's because
glued lapstrake uses the cross-plies to make up for the lack of myriad ribs securing
the planks across the grain as found in clinker & carvel hulls.

A real boat-builder will be along soon to set one or both of us straight on that.

If this is the case, then hoop pine ply is the Rolls Royce of Oz plywoods. Catch is that
hoop pine ply may only be available in 2400 x 1200 sheets, while the plans may
require 2440 x 1220 sheets.

cheers
AJ

Originally Posted by RFNK

It's just a thought as I'm probably too busy with boat restoration projects BUT ... I'd like to build something like an Acorn Skiff to row about in when I'm sick of sanding, scraping, gluing etc. I'm wondering about the suitability of hoop pine rather than plywood for the clinker planking. I'll lay up something else for the stem and keel and use something else for the transom as I'd like to have the contrast for finishing bright. Is hoop pine suitable? I like working with it but I'm unsure of its qualities for this kind of application. Rick

You're working under a couple of misconceptions.

The plywood, lapstrake boats are not clinker boats.

A clinker boat has tightly fitting, overlapping, wooden planks (also called strakes - get the connection?) that rely on good carpentry and the timber getting wet and swelling to stop that horrid water getting into the boat.

A glued lapstrake boat, such as the Acorn, uses plywood and the strakes/planks are glued together. The plywood doesn't move as it gets wet - ie, it won't seal up any gaps like real timber does. The water tight seal comes from the epoxy holding the whole lot together. By gluing all those strakes together, you form a monocoque shell that doesn't need all those ribs to keep all the bits floating in formation.

Glued lapstrake builds a lighter, stronger boat that doesn't need to be wet to be watertight.
A timber boat builds a heavier, more flexible (because all the planks move over each other) boat that relies on being wet to seal ... and also requires far higher carpentry skills.

So, if you were to use hoop pine instead of plywood, you would be looking at a traditional, clinker built hull with tightly fitting planks, no glue between the planks just your skills as a carpenter, ribs to hold it all together and it'll leak until the planks get wet enough to swell up and seal the gaps.

If you were to use plywood and epoxy, you wouldn't need such a high skill level, the boat would be lighter (ie, it'd work better) and you could keep it on a trailer, toss it in the water and it'd be water tight. What's more, no-one would be able to tell the difference just looking at it unless they were astute to notice the lack of ribs.

True clinker construction would be a joy to complete successfully but when the alternative is glued lapstrake, the only reason you'd choose clinker is for the carpentry challenge ... which for some is reason enough

As for whether hoop pine is suitable for clinker? I couldn't tell you. It's a fine timber for boat building when sheathed in epoxy but if you did that, you couldn't build a true clinker boat because the timber won't get wet and swell to seal the gaps. I honestly can't answer for how well it'd resist rot if just painted for use in a clinker hull.

Richard

Rick,

A traditional build or looking to glue the planks?

I haven't used hoop for planking but I have heard it doesn't steam real well ( there'd be a fair bit of twist in the garboards) but not having steamed it myself I can't comment. Not meant to be as durable as some of the other species.

If you are looking for something as a contrast but a bit more durable, what about WRC planking with huon/celery or silver ash ribs?

If you want to go glued clinker, ply is really the only was to go as solid planking will crack.

regards,

AD

Thanks everyone! Andrew, it's a toss up. I'm keen to build a traditional dinghy but not until next year at the earliest, as I'll still be in Vietnam for a few more months at least. I caught a thread on the WB forum with a guy building the Acorn using traditional clinker and it did seem like a really nice project. I'm always defending the use of plywood etc. against the dugout canoe brigade but I guess the challenge of building a traditional clinker boat is tempting too. Of course, once I get back into the Twister restoration I'll probably forget any idea of building another boat, let alone a more challenging one! I like the idea of hoop pine as it's locally available and cheap, and looks nice. I'm not too worried about durability as it'll be stored under shelter. Rick

My opinion.

NEVER ! ! ! Ever epoxy, natural timber planks.

The expansion and contraction of natural timber will cause the plank laps to split.

For glued lap, (clinker) construction, I would only use ply wood.

Roving is not at all difficult. If you want to build a really traditional clinker boat, go with roved nails. No problems at all.
.

Paul.

This boat's going to be used primarily for rowing. I'll just wheel it down to the water and go for a row. Perhaps I'll do a little bit of river touring in it but not much. I want it to be light and dry - even a litre or two leaking into a boat annoys me! It'll be kept out of the water and stored under cover. Thinking it through, keeping the boat dry inside is really important to me so I think I'll go with the glued clinker, as designed. I'll use the hoop ply I think. Thanks for help everyone! Rick