Thread: Pawlonia or Western Red Cedar?

Not sure what a nested dinghy is. Is it like nested side tables, where you build several and they all fit inside each other (!) or did you do a typo and mean setnet dinghy? If the latter, I have lots to offer, as I built one last year. If it is actually " nested" then I've no idea.
Andrew allan ( also in melb)

hi Pajeronj
I don't know what a nested dinghy is either but as you posted in the boat building thread I assume it is a water craft. If you believe WRC is a suitable timber to build it then Paulownia would be also but your craft would be 25% lighter in weight and lighter in colour.
I don't know who you asked to supply the Paulownia but I know there are several places including my self that supply natural planks that are not jointed. PM if you want more information.
John

Which plans will be you using? The nested dinghies I've seen have all been made from stitch and glue plywood with no need to frames.

Stay right away from pine - unless it has the words Huon or Hoop out in front of it. Radiata is for framing houses and crappy mass produced furniture.

Western red cedar is a lovely timber, nice grain and colour and very light but I wouldn't frame a boat with it.

Paulownia is even lighter in colour with very fine grain - kind of like a hard non-fuzzy balsa. It takes stain very nicely and is ideal for strip planking but again I wouldn't frame a boat with it.

"Paulownia is even lighter in colour with very fine grain - kind of like a hard non-fuzzy balsa. It takes stain very nicely and is ideal for strip planking but again I wouldn't frame a boat with it. "

Darcie I'm not a naval architect so I can't dispute your statement but you should have a look at the thread "Building Shesha a Hunter valley GIS". Paulownia was used extensively in the construction, apparently with the approval of the designer.

I wouldn't sell it to frame a 6 metre offshore power boat but for small craft it appears to be OK so long as the timber sizes are appropriate.
John

Howdy,

A note of explanation is required for the use of paulownia in Shesha the Goat Island skiff.

There are a range of timbers used in the construction of this boat with species chosen for specific function.

Most of the timber that will get direct hammering from time to time as the boat rubs up against things on the beach or wharves, or when tied down on a trailer (gunwales and inwales) are all much tougher species than Paulownia.

The Paulownia has been used in areas where
provide a glue cleat where ply joins to ply at an angle and the paulownia is well down inside the boat
As a strip built blank for the centreboard and rudder blades which is to be glassed after.

The Goat Island Skiff is a boat that is particularly suitable for this approach as most of the structural integrity is in the ply panels that make up the bulk of the boat. The job of the paulownia is to hold the two pieces of ply together in some of these places. Loads through the paulownia are distributed loads through the whole piece of ply rather than point loads. Point loads are possible of course - boat resting on a rock or hitting something, but Paulownia is either not used for vulnerable areas or is supported by other timber or glass tape.

A more traditional "plank on frame" type construction where framing is separate from the plywood would not be suitable at all. Additionally more traditional construction is based around fasteners. If the particular design relied on fasteners then paulownia could be a poor choice.

It is not a blanket recommendation for paulownia for boat framing, but used with care in the right places it can give a substantial weight saving.

I do expect paulownia use to be expanded in boats as the knowledgebase improves. I would have few concerns about using it to strip plank boats of the size most of us are doing here - kayakers have found it fine for quite heavy use and they use boats in a more extreme way than most sailing/rowing dinghies and small motorboats.

I would still have some concerns about using it for larger yachts and motor boats at this stage. I was peripherally involved in some of the larger balsa strip built boats and while the balsa was fine structurally in terms of handling the "in use" loads, there was a problem with denting. This is not a problem with smaller boats, but having a tonne or several of yacht rubbing up against something might bring the paulownia into denting territory.

So I'm keeping an eye out for good data from bigger boats as people try it.

Best wishes
Michael

My original posts on paulownia for strip planking boats are here

Thank you all for your information
By nested dinghy I mean one that comes apart and the parts "nest" inside each other. I think "stackable" is another.
It is a Toter 2 from a fascinating man called Ken Simpson in USA. I bought the plans and intend to make it primarily out of marine ply but the framing sections are a hardwood. In the materials list it just says "1 X 2 lumber".
As you may have noticed I am a rank amatuer so I found out that WRC is used for frames and bulkheads in Australia and then I discovered Paulownia.
The Toter 2 does indeed have a rub rail so it could be in for a few thumps every now and again.
Ken's website is www.PortableBoatPlans.com

The Toter 2 is an amazing little boat and I am keen to have a go at building one but got stuck on the type of timber.

Your assistance is greatly appreciated.
Peter

Selected quality Paulownia ( the quality varies dramatically in my experience) is similar to,but not as strong as Western Red Cedar & both are easy to work with & have many applications in boat building.

I have used both for the rails/nose-tail blocks in hollow wooden surfboards & some framing in plywood boats,canoes & surf skis.

My bulkheads are framed in WRC in the Jim Michalak "Ladybug" I recently finished for instance,where the WRC stiffens the bulkhead panels & provides a large gluing area when attaching bulkheads to ply sides/bottom.

For a technical summary of a comparison of the two timbers,I have attached an article written a couple of years ago by Bruce McConkey of Boatcraft Pacific,& printed in AABB.I'm sure you'll find it interesting & enlightening (no pun intended!)

Talk to the supplier whose ad I have attached.

Al.

Actually mike,
This article was written in a bias sense at the time, as Bruce was a supplier for WRC and not Paulownia and at the time there was a bit of a war between the two. Also, he states in the article that Paulownia is only 4 years old. Not true. The kiri timber imported from china is only 4 years old, but the Paulownia grown and supplied here in Oz is in actual fact 14 years old when milled. You can really see the difference between the two in their growth rings

We actually had it tested at great expense in comparison to a top peice of WRC we had at the time and supplied this as we wanted an unbias test between the two. The WRC turned up very poor numbers whereas, the paulownia gave very good results.

Just this week we had a Royal Institute of Naval Archtects Tech meeting of laminates. Paulownia was mention as an excellent timber to use in laminate construction for it's high strength to weight ratios.

In regards to it's brittleness, a lot of our clients have built before using WRC and have found that that statement is very erronous. Paulownia is very easy to work with and very easy to bend. Whereas, WRC (even from our past experiences building from both) we've found that WRC is very brittle and can split easy. Talking with a friend of mine in the boatbuilding industry in the US, he said all the top notch WRC is now exported to Japan for top dollar. This leaves only the rubbish behind. From this rubbish, the cream is kept and the rest exported to Oz etc. That would explain the WRC poor numbers in the test.

Its because of this test, that we now use Paulownia in most of our designs.

What it all really boils down to is, what are you using if for in a boat and how are you going to use it. To make a "blanket" statement such as Bruce given in his article above is unfortunatly... poor taste.

Hope this helps
regards
Mark
www.bowdidgemarinedesigns.com

Sorry, forgot to mention hoop pine as well. Are my choices for the bulkheads and framing wrc, paulownia or hoop pine, or are there others?

I'm not a naval architect, shipwright or any other formalised kind of boating dude, just one of those jack-of-all-trades and turn my hand to anything blokes.

I can see the logic which went behind the design of Ken's boats and the design briefs seem to be primarily based around cheap and easy construction. His development of tape and glue also seems based on keeping things simple and cheap.

Even his comments section focuses on how cheap these boats are to build, he even goes so far as to state that he does not want to pay the price of marine ply.

The problem is, as I see it, you get what you pay for. I can't see these boats lasting for more than a couple of years without a lot of care - far more than you would for many other construction methods.

If you're going to build a boat, any boat, you should stick to the designers guidlines unless you have the experience and knowledge to deviate. Whip down to your local hardware store and buy some external grade ply, some sticks of radiata and build your boat like he says. Don't use marine ply, don't use exotic timbers, just buy his material list.

Personally, and I can't think of any nice way to say this, I wouldn't go near the thing. There's quite a few nested boat designs available which look much nicer.

Thanks Darce, for putting into words what had been at the back of my mind anyway! Yes I noticed the emphasis on being cheap but thought I could upgrade the speccies to proper "pink" marine ply and either paulownia, wrc or hoop pine.
I suppose one of the legacies of being a rank amateur is that enthusiasm takes over the space where common sense used to sit.
I absolutely appreciate your post, Darce.


Yeah maybe I should be looking at other nested designs. I have a copy of the PD Mk 2 Racer plans but got scared off by some of the woodworking manoevers I saw. I am not ready to start so who knows? I liked the PD Racer because of its versatility I just hope I have the ability to make one.
I am not really aware of any other nesteds kicking around but would appreciate any links people can give me.

Thanks again, mate.

Peter

I just dug out the PD Racer plans I bought and the timber is in imperial. Would 3/4" be 19mm? And would 7/8ths be 21mm? Does that mean I can use a strip of timber 20mm X 20mm? I wish these things were in metric!!! I don't have, or have access to, a thicknesser either. Argghhh!! All very confusing --- which is why I went to the Toter 2. I am determined to build this puddle duck but I'm not sure I understand enough to even start!!

As Einstein is reported to have said, "Make something as simple as possible - but no simpler"

7/8" is a bee's genital over 22mm. I use a set of Zeus tables to convert metric to imp and back, but I'm sure you can find a similar enough conversion table via Google.
Actually, building things using imperial measurements is easy; the only time it gets a little bit tricky is when for instance you table saw or router table fence can only be set using metric measurements. So you do it the old fashioned way and stick a rule between the blade and the fence..... you could always go retro and use a story stick as well, that way you'll only have to measure once.

Actually you'd be surprised how much we still really use imperial sizes for everything; sheet goods are sold in 2440 X 1220mm (8" X 4") and many are sold in unusual thicknesses, 6.4mm, 12.7mm etc which are obviously 1/4" and 1/2". I think the daftest ones are the lengths of timber you buy in the hardware stores, although priced in lineal meters they are sold in feet and yards. 0.9m is... a yard. 1.2 m is ...4 feet. 5.4m is...6 yards.

If you do go down the imperial route having a calculater that can work with fractions is always handy. I prefer Casio scientifics because they also have all the trig functions I need.