Kiri properties

[masalai]

http://www.kiripark.com.au/

Have a look here. a plantation of kiri/pawlina "ripening"

[rwatson]

Surely Kiri or Paulonia must be exported to the US - but I have no idea who by. I would be surprised if it isnt grown there as well. Lots of places would suit.

[Willallison]

To date I've been unable to get a cost from the QLD guys. They don't have a published price list like Highpoint, I gather they mill to request, so price each job separately. I did ask for a price some time back, but haven't heard anything back from them....

As for the US, I don't know. I'm certainly no Kirri expert, so there are probably others with better info than me. A couple of US builders and NA's that I've spoken to had never heard of it, so it's obviously not too wide spread there.

[masalai]

At the bottom of one of the "kiripark" pages is guideline pricing per cubic meter in Australian dollars, milling and sizeing for marine use will cost more.

There is a "contact us" point also

[masalai]

I seem to recall boatcraftPacific advertising Kiri at one stage. They have a base on Gold Coast, Queensland.

[Willallison]

No longer any mention of Kirri on the Boat Craft site.

the prices you mentioned from Kirripark are from 2004 but list A-Grade paulownia at $1700 per m^3

[Willallison]

Properties testing rom the Kirripark site that Masalai posted:

http://www.kiripark.com.au/pdf/paulowniatesting.pdf

Apart from the strength data, one of the most interesting aspects is the variation in density between various sources: 260 kg/m^3 for QLD grown, 290 for Chinese and 330 for WA grown.
That's a massive difference - particularly when doing your weight estimates.
If considering the WA material its density is on a par with western red cedar, so suddenly one of it's primary advantages has disappeared....

[masalai]

Will,
The key aspect that got me was low resin in material & similar properties ensuring NO TOXIC issues as per WRC

It appears that tropically grown & with summer rains may be advantageous.

There is some privately growing in whitsundays area (not sure where though)

[masalai]

An email enquiry may get a response from Boat Craft

[rwatson]

Dont forget too that the lighter normally lighter weight of Kiri is at the expense of strength. Usually you need to increase the size of Kiri to get the same structural strength equivalent to WRC.
The WA Kiri is a similar weight to WRC, and the figures indicate vastly better bending strength, which would be important for boatbuilders.

[BOATMIK]

Originally Posted by waikikin

Will, I read somewhere an increase in thickness over WRcedar was required in conversion to Kiri, Buy some range of kiri & test it before commitment might be the best bet, nothing beats knowing for sure. Regards from Jeff.

Howdy All,

It might not be useful if you are planning to build an America's cupper out of the stuff, but if you are building something more normal there is usually a huge reserve in the strip planked structures that we mostly talk about.

So you can just multiply the Western Red cedar figures by the difference in densities that you can get very close indeed.

I'll vouch for few differences :-)

I've done a bit of digging round in finding if it was useful and what sorts of compensation you would have to make.

In canoe and dinghy type sizes - none at all - the boats are so highly overspecified that there is no need to change glass weight or increase the plank thickness.

After all I built the Balsa strip canoe with 0.75oz glass on both sides as a joke and it was around for 5 years before I sold it - for good money too - all 12lbs of it. This is one of the pics - a Rushton Wee Lassie.


The problem with that boat was the very light glass (1/8 the normal weight) made it prone to denting but that was tolerable as I have reasonable handling habits both on land and on water.

However I managed to track down a chap who has been building seakayaks of paulownia in NZ and using them in a fairly extreme way - rock landings, surf landings.

His comment was that it was a bit softer than cedar when building - a little more dent prone (but you can use the normal trick of steaming or moistening the dents so they come out) but he didn't notice any practical difference with the end boat from a cedar one using the same glassing schedule as normal of 6oz for something robust and 4oz for something a bit lighter.



So there it is ... at least for smaller boats. There may start to be some denting issues in bigger sizes, but after being involved in a few paulownia boats now I don't think it will be a biggie. I might be a bit reluctant to specify it for a 40 footer without making up a few test panels and dropping some heavy things on them - just to protect the clients investment!

Some nice things about the paulownia are that it has a very straight grain - you won't split it like you can with the wandering grain of cedar - and it does fair up pretty nice.



One detail design point is that with the balsa I used Q-cels and epoxy as a glue because I was worried about getting ridges from a glue mix with higher mechanical properties when the hull was sanded. It worked well. With the paulownia boats we have done so far - we used the same mix.



More pics interspersed with this lot
http://www.flickr.com/photos/boatmik...7602281214723/

Best wishes!

[kengrome]

As for the US, I don't know. I'm certainly no Kirri expert, so there are probably others with better info than me. A couple of US builders and NA's that I've spoken to had never heard of it, so it's obviously not too wide spread there.

I checked on availability last year in the USA and there are a number of places growing it commercially now, although none of them are that big or have enough to produce substantial quantities yet. It seems to be a rather young industry there.

No one I inquired with called it Kiri in the USA either, they all referred to it as Paulownia, so using this term might help with further research into U.S. sources. I didn't even know it was the same specie until this afternoon myself, but I haven't had any good reason to research it lately either, until a potential client asked me about it yesterday.

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We have a tropical plantation grown lumber here in the Philippines called Gmelina that's heavy when green but seems to kiln dry to a very light density. I haven't checked it to compare with Paulownia or WRC but I suspect this is another relatively unknown wood that is "in the ballpark" in terms of its weight and performance as a strip planked core material. Gmelina also seems to be a strong wood, my shop sawhorses are made of the stuff and two of those sawhorses held two skids of plywood -- I was amazed, I thought they were going to snap in two and collapse. The local guys trusted it of course, but they've had more experience with it than I have.