What this is about

We live by the D'Entrecasteaux Channel in Southern Tasmania. It, and much of the Tasmanian coast, offer amazing cruising possibilities. Previously, we owned an old, sturdy and fast 33 ft Huon pine sloop that we loved. The things it didn't offer - easy portability to other waters, shoal draft, beachability and the simplicity of dinghy-like sailing - are the things we gradually craved more and more.
For at least a few years I have thought that I should build an open, or mostly open, 20-something footer that would satisfy these urges. After much looking around at designs, we finally settled on the Stir Ven.
She is beautiful, fast, seaworthy, floats in 25cm of water and is designed as an adventure boat on which one can spend a few nights.
We hope she will be ready for use by the summer of 2012/13!

Saturday, December 24, 2011

Painted by Christmas


When I started building, I set myself the goal of being painted by Christmas. Yesterday (Christmas eve) I put the last coat of bottom paint on so, amazingly, I made it!
Painting was a long and slow experience fraught with a few issues.
I decided that I was going to use an epoxy primer/undercoat followed by a 2-part polyurethane on the topsides and then an epoxy paint for the bottom (more on this below).
Andrew Denman of Denman marine has been a great source of information regarding paints and paint systems that hey use on the Bayraiders that they build. He told me that they use Wattyl UC230 primer/undercoat which I used. This is an excellent, high build product that is easily sanded to provide great substrate for single or two-part paints. I applied 3 coats with a short nap mohair roller and then sanded. I wasn't completely happy with the surface so I filled a few of the slightly bigger dents with epoxy fairing compound then applied another 2 coats and sanded again (with 120 grit - random orbital sander). Now I had a beautiful smooth surface - not perfect but good enough that a visitor asked if it was my finished paint job.

When I went to Wattyl I think there was a slight miscommunication. Andrew had told me that they used Poly U400 on their boats' topsides and although they sprayed it on, I would be able to roller it on, followed by tipping off with a brush much like I had been doing for years with enamels on our previous boat. I talked to the agent there and he said that could be used and also told me about Colourthane their special polyurethane formulation for marine use. He said there was no effective difference between the two but that I could get any colour made up in Colourthane and I could buy as little as one litre ( I would have to buy 5 litres in Poly U400).

I had noted that Colourthane is a 2:1 mix whilst Poly U400 is a 4:1 mix so there must be some difference in the formulation. Anyhow, I applied a coat of it using a foam roller and it pretty much instantly hardened once rollered making it impossible to tip off. I sanded off the roller stipple and tried coat number 2, this time adding more thinner (reducer) to try and retard the reaction. Again, the paint hardened almost straight away. I went to talk to the guys at Wattyl who then told me that Colourthane can't be rollered and MUST be sprayed. Only Poly U400 can be rollered!
Luckily, I have a friend who has been spray painting boats for 20 years. He offered to spray my boat but I initially declined because I wanted a more hand-done job. I called him and begged for forgiveness and he came around to give the boat a spray. I sanded off the roller stipple with 320 grit (by hand as he said that the tiny spirals from the random orbital sander would show through the paint). I was delighted with the finish that I got and should have just got him to spray it in the first place!

"Marlin Green"
I used an $80 bosch laser level to mark the waterline from the marks that I took off the moulds onto a post in the workshop. I added 7cm as recommended by Francois Vivier (2cm because he originally underestimated the boat weight + 5 cm in order to have some bottom paint showing).





For the bottom paint I used Wattyl DTM985 as recommended by Andrew Denman. This is a high-build fully immersible and incredibly tough paint that can be rollered. I got it tinted to a cream colour and will use the remainder inside the bilges and in lockers. This is applied with a short nap mohair roller and leaves a fine stipple. I did two coats past the water line then sanded it to a feather edge before taping the line and applying the topcoat. I then did one more coat of bottom paint.

I am really pleased with the results and, after fastening the brass strips will be flipping the boat over - hopefully next week sometime. It was nice to be able to just walk past and admire the boat several times today before, during and after Christmas lunch.

Here's what I cooked for lunch using all our own produce (except the salmon which was bought and the pork which was raised by my friend)


gravlax with dill sauce

roast porchetta with pink eye potatoes, beets, carrots and spinach








Sunday, November 20, 2011

ready to paint

I have been very poor at keeping this blog up to date. Partly that's because all the little jobs after planking seem too insignificant to write about individually but when you list them all and then think back on the work, it seems like a lot:

- fill all screw holes where the temporary clamping blocks were for planking
- trim off the overlap between the garboards and the sole and get angry about how many times you have to sharpen planer blades as epoxy thickened with silica is just like stone!
- trim off the planks at the transom
- put epoxy fillets into the plank overlaps (paint the edge/end grain first with penetrating epoxy)
- shape and fit the outer stem. I used high strength filler (with fibres) and silicon bronze screws plus bolts on either side of the hole for the painter/winch strap
- fibreglass the sole and garboards. I used 300gsm -/+ 45o biaxial glass
- laminate, shape and fit the skeg. Just like for the stem I used swamp gum (Eucalyptus regnans) and then high strength filler and silicon bronze screws and threaded rod to attach it. This was further reinforced with 400gsm biaxial tape over epoxy fillets.
- sand everything a lot!
- coat with one coat of penetrating epoxy (bote-cote mixed with 20% TPRDA)
- wet-on-wet application of another coat of straight epoxy
- sand the whole boat with 120 grit paper to roughen the surface for applying the undercoat (I will be using Wattyl UC230 which is a high-build, epoxy primer/undercoat)
- sweep up the whole workshop to remove as much dust as possible in readiness for painting


I have learnt a lot about how epoxy behaves and how strong it is . It's amazing stuff. I think that there is little requirement for permanent fastenings in boats constructed like this so I have chosen to minimise fastenings and where I leave them in place use only silicon bronze ones. Stainless steel is probably OK but it must be exposed to air to be non-corrosive and I don't want to take the risk of rust potentially happening inside somewhere that will be very hard to access.

Friday, September 16, 2011

planked!

I have had a lot of fun and it's been intense but I got the planking all done. I have had the last 2 weeks off work and split the time between boatbuilding, housebuilding (for my best friend who is very sick) and childminding. I feel exhausted and am ready to go back to work next week back to meetings, bureaucracy, dealing with difficult people and occasionally getting to talk and do science. Well, maybe I'm not.

Planking is fun albeit a bit stressful at times. I decided early on not to try and do a pair of planks in one day. So, my routine was to cut the planking bevel and gains (I used my hand rebate plane then cleaned up with a block plane for both)

bevels and gains cut
check the planking fit and mark some key positions relative to bulkheads and then put a belt of 400gsm biax cloth over the inner side of the puzzle joints of the new plank. This took me about 3-4 hours. The next day I would coat the bevel with epoxy (thinned with TPRDA) so that the joints wouldn't starve and then mix up a batch of thickened epoxy smear it on, put the plank on with a whole lot of screws on blocks (thin strips of 20mm thick ply were also good for this)

plank in place and clamped


I learnt a few things while I was planking that I had stuffed up during my set up. Firstly, somehow, either the centreboard case or one of the bulkheads that it contacts weren't exactly plumb. While planking, I could see that two bulkheads were slightly bowed when I sighted across them. I think that it won't matter or that I will be able to adjust them when I turn the boat over (by breaking the small tabs of epoxy and moving them before doing the proper fillets). I also noticed earlier on that my stem was a bit thicker than it should have been. This placed it and the forward end of the sole a little higher than they should have been by about 3 mm. This meant that I had to have a tiny gap between planks and bulkhead A and between the planks and mould 1 in order to keep the hull shape fair (otherwise the planks would have looked pinched in). This also, I don't think will be a problem in the long run. Overall, I'm very happy with how the planking went. The hull looks great and symmetrical and fair. I'm now looking forward (!) to filling screw holes, sanding, fairing, glassing and painting!









Tuesday, September 6, 2011

strake 2 is done

I've been lucky enough to have the last few days with uninterrupted building. Well, I did have to look after the kids a bit but mostly, I got to build until I had to come inside to cook dinner.
After getting the garboards on with no worries, I thought it would be simple to get on the next strakes. In retrospect it was but in practice it took me most of a day to cut the planking bevel then work out and cut my gains. After talking to Mike Randall (of Vicky Bee), I decided to gain the planks at the transom end and the bow end. As I didn't want to remove too much material, I spent a long time planing then checking then planing then checking.....By the time I got them right and had them both dry fastened in place it was too late in the day to get he epoxy on.
So, this morning, I started gluing them on and was finished and had the squeezed out epoxy cleaned up by about lunchtime.

Here are some pictures of my progress:

transom with the planks gained in

looks like a beak 
view from above of lots of clamping blocks

another beak picture

Monday, September 5, 2011

Bevelling the sole and adding the garboards


Now, I'm getting excited as this is where the boat takes shape. The Garboards are the lowest pair of planks and on this boat they are the biggest and require a reasonable bit of twist forward. Andrew Denman warned me that hoop pine ply is stiffer than Gaboon/okoume and this made me worry that I wouldn't be able to put this plank on solo. I made a bunch of the L-clamps that Vivier recommends and that Mike Randall strongly advised to help in this regard.

First thing was to bevel the edges of the sole to accept the garboards. This was done by cutting with a tenon saw at each station to match the angle of that station. I then lined up the cut marks with a batten and drew a line. Then I used a power plane and finished with a hand smoother and felt pretty happy with the results

witness cuts to match the station angle
 I then coated the beveled edges with Bote-cote epoxy with TPRDA added. This is their epoxy monomer (it's not thinners) which makes the product soak into the end grain very well and edge grain as well but to a lesser extent. It's the mix that Mike Randall also used and I coated all my planks and bulkheads with it (especially the edges).
this looks OK dad
Next thing was fitting the garboard. I test fitted it and once I was happy, marked on the position relative to bulkhead C. Then I mixed up a batch of thickened glue and smeared it on the bevel and the edges of the bulkheads and started attaching it from amidships and then gradually forward and aft. This wasn't as bad as I thought it might be. The plank lined up nicely with all the marks as I screwed through the top into tape-covered plywood blocks to clamp it into place


starboard garboard attached
another view
bulkheadA/stem/keelson/sole/garboard join

 Now, I need to stick the other side on.

attaching the sole

After checking the rough fit of the stem and being satisfied with it, I beveled the forward face as per the rough bevels indicated in the plans. It was nice to be able to use a drawknife and my beautiful birthday present from Briony - a Lie-Nielsen rabbet block plane - to tidy it up


I glued this in place attached to the keelson and bulkhead A and then bolted the forward end to the building jig. When I did this, I pushed it aftwards about 5mm to rectify the springback that I got after glue laminating the stem.

Next, I sanded back the bottom surfaces of glue lumps and to key in the glue to attach the sole. Here is the bottom of the centreboard case where the logs meet the keelson with intervening stuffers (all these timbers are regrowth mountain ash/ swamp gum/E. regnans - which is very strong and more durable but a similar density to Douglas fir)


After a dry test with the sole and after giving it a second coat of epoxy on the inside surface, I glued it on. This was a little exciting and nervewracking as it means the start of the planking.


I lined up the centreboard case cutout with the centreboard case and the edge of the sole nicely lined up with the planking marks on the stations. My only concern was that the sole did not come as far forward as it showed on the plans. I wasn't too worried about this as there was plenty of gluing surface for the sole and it might just mean that there is a small gap that I need to fill before I eventually glue on the outer stem. It's hard to know what that gap might be as I can't really visualise yet what the garboards might look like in this zone

Saturday, August 13, 2011

building jig is ready

After much fussing around - coating all the planks and bulkheads with epoxy and building the centreboard case with all of the external battens and posts


I have finally completed the mounting all the moulds and bulkheads onto the strongback. This was a fiddly job but I may have made it worse for myself by being fussy about accuracy. I reborrowed Mike's dumpy level and checked each position along the strongback for level. Once these were levelled (a couple of spots needed shims up to 2mm thick) I was able to attach the uprights for the stations. These uprights were pine studs (90 x 35) that I ripped a true straightedge onto. I screwed these into the inside face of the two big beams at the positions that I had marked from the plans. You must make sure that you doublecheck as some measurements refer to the front of the station and some to the rear, The studs were made as plumb as possible using a tall level for accuracy.
The stations were then all placed on with the marked waterlines 800mm above the top of the strongback.
Following a great idea from Mike, I drilled a small hole (where necessary) at the intersection between the waterline mark and central axis (which I marked from the plans). This allowed me to set up a string line through all the moulds and bulkheads and check for level and centre.
Finally, I did it and feel very happy that everything is level and the boat will (or should) be straight!


I roughly cut the aft end of the stem to the bevel that will meet up with the sole and test fitted it. The pattern that I have for the keelson fit perfectly under the stem and into the slots at stations 2, 3 and 4.

Now, I have to insert the centreboard case, cut the keelson, then mount the keelson and stem (with glue) and I will be able to start planking. This is good timing as I was hoping to work on the planking during the kids school holidays  (2 weeks away) which I will be having off as well.

Thursday, July 21, 2011

puzzle solved

After drying the planks indoors (our house is nice and warm) for a week and a half, I found that the wood shrunk enough that the joints would now fit! It was very difficult still for the sole, presumably because this is thicker (16 mm) ply and it may still have had more shrinking to do or just simply due to a higher surface area and a stiffer set of fingers. The other planks, cut from 9.5mm ply went in with a moderate tap once "lubricated" with epoxy.



 

All the planks are now joined and ready to be epoxy coated prior to hull assembly


 

Monday, July 11, 2011

puzzling problem

One of the benefits of buying the CNC-cut kit is that all the planking comes with puzzle joints in order to produce long planks without scarfing. These joints lock in place, with epoxy, and then can be glassed or butt-blocked on the inside face for added strength. I'm not sure if this will be required given that there is a lot of surface area for the epoxy to create a strong bond.
Just this weekend, I attempted to dry fit the puzzle joints of the sole of the boat and was shocked to discover that they simply would not fit!


I expected this to slot in with a light tap!


The width of a finger is clearly too big for the "hole"


by approximately half a millimetre


In a panic, I checked all the other planks and the same was true for all. The fingers were 0.4 to 0.8mm too wide for the "holes". Vivier advised that this should not be the case and that the joints should be the exact size. Possibly there was an error at the cutter (somewhere in Queensland). I may have to sand or rasp the fingers to get them to fit! I certainly wasn't looking forward to that.
I wondered if the ply may have expanded due to humidity from the air here in our Tasmanian winter. Wood certainly expands with humidity and hoop pine can expand and contract by 2-3%.
So, I brought the sole pieces inside our warm house. Each day I have been checking them to see if they will fit. No luck yet but the fingers seem to be shrinking.
I hope that after a few more days i will be able to report back that they fit without any (or at least minimal) sanding.

an almost finished Stir Ven

No, sadly, it's not mine! I visited Mike Randall on Saturday in Melbourne. He has been building his Stir Ven for the last 2-3 years and is almost (days away) ready to launch. He has maintained an excellent blog on the construction that is really very useful for anyone building a Stir Ven. Ours will be the second one in Australia (unless there's someone else building one now that I don't know about).





I spent several hours chatting to Mike asking him lots of questions and taking lots of photos of details that will be very useful when I come around to building them.

Thanks Mike and good luck with your launch

Tuesday, July 5, 2011

making the stem

One option that Vivier provides is to purchase all the ply components of the boat pre-cut with a CNC router. After much deliberation, I went with this option as I decided that the extra cost was worth my time. It is estimated to take an extra 200 hours to cut all the ply parts. I believe it as there are many pieces. Also, this method ensures a much higher accuracy than hand cutting (at least my hand cutting!).
Once receiving the kit there are lots of things that must be done before hull assembly can begin. All the parts must be precoated with epoxy, the centreboard case must be assembled, the building jig or strongback built and the stem and false stem made.
The stem - the piece of timber that continues on from the keelson forwards and "accepts" the planking at the bow end, is laminated from 8 pieces @ 50mm by 5mm.
I used regrowth swamp gum/mountain ash (Eucalyptus regnans) which is very strong, relatively light and glues very well. I got a load of this timber from a sawmill in Huonville. It was already airdried but I airdried it further. As it was all roughsawn, I had to square off a piece before rough ripping the laminates on a table saw. These were then reduced to 5mm thickness on the thicknesser.
The kit comes with a template for many of the components that are curved, including the stem. So, it was a relatively easy matter to slap epoxy onto the pieces and clamp them against blocks that formed this curve.


Once the glue went off, which was a good 24 hours given our cool winter temperatures here in Tassie, I cleaned it up in the thicknesser and got it to the final thickness of 48mm



After this, the stem is used as a mould for the false stem. The false stem is glued in front of the stem once the planking is complete. This is seen on the finished boat and makes it look traditional. I made the false stem also with 8 5mm laminates and these are now put aside ready for the planking.