Gunnel Bend Construction

Having ordered the wood for the boat, (clear Larch) tis time to start thinking about the bending form. The wood is going to be green this time so I anticipate it will be easier to bend but I'm still going to build  a tolerance in for springback. For those who don't know, this is the amount that the wood will spring back after you release it from the clamps after having steam bent it. I'm going to allow roughly 25% springback going by the last time we did it and if I get it wrong then we can still make it work, easier to work back from too much bend then to try bending again when it's out.
These are the dimensions that I will be working to, and I will start building this form today or tomorrow more than likely.

Interlude before the main event

Just a brief update.
I ordered the wood for the gunnels from the sawmill today so will hopefully hear something on that next week. In the meantime I had another leak from the same spot on the copper cylinder but I have patched it again and ran another test and got to 97degrees celcius with no leaks at all so we're ready to go on that front.
While I am waiting for the wood to be milled I will start building the form that it will bent around, going to do a more thorough job this time as I have a feeling I will be using these forms more than once. Started drawing a dimensioned plan view of it in SketchUp tonight and will finish it on Monday more than likely. I will put up a picture of this to give you an idea of the shape I will be aiming for even though the finished product may not turn out to be those exact dimensions.
Expect another post after the weekend...

Steambox, second trial

Ok so the first trial had some issues, it was leaking like a sieve (though in fairness I expected that) the tank holding the water was leaking and so was the box itself. So on the tank I did some patching with silicone and hopefully that will hold up to the heat from underneath and then at the back of the box where I expected it to leak I just sealed it on with some silicone last night.
I actually tried to go get wood today to be ready for bending the sides but the sawmill wasn't open cos it's Saturday so that will have to wait til during the week, some day when I get off early from work and can make it out there or else I'll get one of the lads to pick it up for me.


Now I am basically ready to start the building proper, next on the list is the form that the gunwales will bend around and I will have to make some kind of boom/holder for the camera so I can video things properly. As I am building the forms I will discuss the sizes and the way to lay it out

Steambox setup

Well I promised more frequent updates and I fully intend delivering. Every bit of the build is going to be discussed this time and there will be a lot more videos of the process as it really is the only way to accurately describe the process. I actually did another wee video of the steambox coming up to temperature but forgot to turn the phone the right way so I'll just redo that at the weekend. Issues that cropped up during this test... the box is not sealed well enough, this is reasonably easy fix as I kinda knew it would need soem sealing at the back part of the box as I only pushed it in and didn't do any kind of airtight seal. I will pick up something in the builders providers tomorrow and seal it up tomorrow evening ready for a proper test on Sat. There was a decent old leak in the cylinder where the coil comes in, I suspected there would be one because there had to some reason the cylinder was thrown in the shed so I just put somesilicone type stuff on there and hopefully that will work. There won't be any pressure on the cylinder so hopefully the silicone can stand up to the heat and that will be that problem fixed. Other than that there were really no negatives at all, the insulation did the job really really well, once the cylinder started boiling the temp climbed very very fast, somewhere close to a degree every two seconds I think but will get all nerdy about that on Sat and get some more accurate figures. Tonight the temp got to 97.4C but wouldn't go any higher because of the amount of steam escaping, we'll see if we can to the magical 99.9 at the weekend, the temp where wood gets very malleable indeed...

....and we're back...

Well finally I'm back to building this currach again. Been working lots and getting things a bit more ship shape in The Barley Loft ,as the workshop is known.
So the basic overview of the steps to building the naomhog is as follows.. (or at least the way I plan to build it)

1) Build the gunwales

2) Make the tachtaí and join top and bottom gunwale

3) Make the seats and join them to the gunwale

4) Bend the ribs and fit them to the lower gunnel

5) Put the stringers on

6) Cover the currach in fabric and waterproof it

7) Make the oars and and oarlocks and go rowing!


So as before when started Currach One, one of the first things we do is steam and bend the gunwales. So we need a steambox, I decided to build this one from insulation mostly, have never really seen anyone build a steambox quite like this before so I guess we'll soon see if there's a reason for that!

 As you can see on the left I made corners out of 75mm rips of ply screwed together, The steam box is obviously going to be around about 2400mm or 8ft long.
Currach Two is going to be shorter than Currach One, going to go for a length of about 17ft/5200mm this time and it will be designed for two people to row I think.


<---- That's Poutine!!



I then ripped the insulation with a straight edge and my Hilti circular saw with the bigger blade. Hooked the Hilti up to the Mafell automatic vacuum I have and it worked a treat, normally cutting insulation like this is a an awful balls and results in dust everywhere, particularly down your ENT!

I then made the insulation rips and the corners into sides 

Here's a little video of the final result and the setup for the steam part of things.

So the posts are going to be a lot more regular now, don't really have too many nixers on at the moment and I am very eager to get going on this currach... it's been a long time coming, we'll see if my theory about it being easier to get wood in Ireland than Canada holds true or not. 

Should have another post and video by the end of the week with more detail on how the steambox is working out ... if that all works fine then it will be on to making the form for the bend at the prow of the boat.