Tuesday, May 19, 2009

Bottoms down, frames up and yeeeha!~

This is really exciting!!!!!!

I am starting feel that I am making a boat instead of a jigsaw puzzle now.
The centreboard case, stem and first five frames went in easily but not without some significant levels of anxiety and fear of the unknown mistake! This is me having a steam bath over an old kettle and some flexible hose.

When it came to bending the chine stringer I was very worried about snapping the timber as the bend is quite significant. I decided that I would bend it incrementally in baby steps by applying steam along the length in the vicinity of the frames where "first contact" and the new bend was being made. There is no doubt that this help as after steaming for a few minutes, I could easily tweak a bit more "slack" out of the tiedown I was using at the transom to pull the stringer home.

Anyway, the bend was done then released, epoxied and reapplied and screwed into place with clamps and I went to sleep feeling very satisfied, two nights in a row.
Now I am off to bed with a hot cup of honey, lemon and whisky to ward off the evil winter spirits which have returned with swine to haunt us!

The pics tell the rest of the story. Onwards and seawards!

Transom Assembly

Now, where is my lovely wife with my coffee and that brush and pan...she does such a good job when I need some tidying done in the shed.

Ah yes...the transom...

At the outset I wanted a modified transom area that would accommodate an insulated lazarette locker with a drain for ice and cold storage of liquid refreshments. I was quite concerned that because I was deviating from Johns plans and "flying solo" so to speak I was on shaky ground when it came to this part of the boat so I decided to build the entire transom locker arrangement with frame 6a as a sub assembly on the bench.
The result is very pleasing and in fact I think it made fitting the chine stringer and seat fronts a lot easier for two reasons:

1. I could fit the chine stringer to the ply bottom and trim it before installing the transom and
2. Standing the transom up at the correct angle off line gave me more confidence because there is no turning back when you are epoxying to the bottom plank.

I have since installed the assembly into the boat and put additional drains in. I have drained the ice box (starboard side) and centre lazarette locker into the cockpit and drained the cockpit into the motor well because I dont want holes in the transom. I'm not sure that this was in fact the best option but it is done so time will tell. Actually the transom assembly was pretty time consuming because of all the fiddly bits. I plan to use the centre locker for my grab bag with flares etc. There is sufficient space between the tiller and the top of the locker for the day storage of cell phone, vhf, sunnies etc. or if required a small auxilary fuel tank for the outboard. I have left a small lip to stop things falling off the top of the locker.

Monday, May 18, 2009

Centreboard and Case

I have grouped the activities related to the centreboard and case here so that I can add to this part as the build progresses. I had an interesting time with both the case and the board.
Having decided that the board itself was to be 50mm wide between the cheeks in the case, I proceded to build the case with a 9mm doubler on either inside faces. I put another pair of 9mm ply doublers on the outside of the centre case between frames 3 and 4 which was rebated into the bunk flat supports and the centre case logs on the bottom panel. This effectively give a 3x 9mm ply lay-up stiffened by the centre case logs and bunk flat supports to withstand the lateral loads of the centreboard.
I also installed a centre case bush arrangement with rubber o-rings as shown (the o-ring and sleeve in the pic are not fully seated yet) which virtually eliminates the possiblity of leaks and prevents the centrecase from "pinching" the centreboard which is sandwiched between the inner doublers. The foil is also bushed and seats against the case bushes on either side. I just realise the pic is on its side but if you turn your head you will understand, look funny and get a sore neck like me.

When I shaped the foil itself, I used one side of a NACA 2412 wing ordinates for the profile of the foil. I made a jig for my skilsaw which I used to cut grooves lengthways into the laminated stock. The problem is the jig sagged without me realising it and I ended up with slots that went deeper at the end of each cut...ayeeee!!!!! Step away from the saw, have a wine and go back another day when the head is clear. All is not lost thanks to the miracles of epoxy and a bit of thickener.
When it came to the lead for the board I was keen for a jelly tip so I set about making a mould for the lead. I started by using the offcut from the centreboard as a profile around which I wrapped a thin sheet of aluminium which I crimped closed. I took the mould to a local chap who casts fishing sinkers to see whether he would pour the lead thus saving me a lot of time and hassle. He agreed and I left him to it returning about an hour later to pick up the tip.

My reception when I returned was decidedly "cool". It transpired that the laminated offcut at the bottom of the mould "fizzed" and together with the burning epoxy blew a chasm into the bottom of the mould through which molten lead proceded to spurt all over the foundry! Luckily no harm was done and they all managed to see the funny side of the event. They even agreed to allow me another go using an improved mould design. The second mould was a huge success and the pics speak for themselves.

Oh, I nearly forgot...having bolted the lead tip to the board (I used two 8mm SS threaded rods screwed into the foil to a depth of about 150mm with liberal amounts of epoxy "lube" on the threads), applied two layers of glass to the cheeks and leading edge, I had faired the transition from timber to lead and applied two coats of epoxy to the board while it hung from a piece of wire. When I was taking it down I forgot I was dealing with 14Kg of lead plus the weight of the board and it slipped from the wire and smashed into the floor about two inches from my toe (I was barefoot at the time). I nearly wept with relief and then fear that I would have to start all over again. To my amazement the damage was negligable and I simply filed off the slightly mushroomed leading tip, reapplied some thickened epoxy and hey presto...we have a centreboard! Needless to say I am more than happy with the result.

I still need to do a final sand, dry fitting and paint. I can't do a real dry fit the centreboard to the case until later when I roll the boat or cut the obstructing cross members from the building frame - probably once the planks are in place. She seems to go in ok upside down from the top.