Monday, 22 September 2014

Glass

Week 3.

Whilst I had a run of continuous days left to me, it seemed sensible to tackle possible the last big job - fibreglassing the deck.

I want to get this done before the weather gets too damp; thus avoiding the irritation of amine blush on the epoxy (likely to be impossible to clean on the dimpled surface of the glass).As usual the logical start point is the most complex - just in front of the cabin, with the intrusion of the tabernacle, forepeak hatch and curved corners of the cabin sides.

Preparation involved getting a few plastic paint kettles to mix larger quantities of epoxy and some firm rollers to apply it. The glass I already had from the start of the project, though had used some for the punt restoration a few years ago; hopefully I'll have enough left to finish...

Marking out a 4' strip that extended 3" behind the cabin front, down the side decks and 45" forward (the roll of glass is 4' wide) was the start point. The ply on the deck had already been filled and rubbed down several weeks ago, so was swept and wiped over with a tissue soaked in acetone to remove any greasy residues. Also the small strip of teak cabin sides that the glass would lap up onto was washed thoroughly with acetone to remove its natural oils.

The glass would be trimmed on the cabin sides 1/4" up from the deck and similarly 1/4" down from the overlap of the hull planking. this is done when the epoxy is half cured or "green". I wanted an even cut so knocked up a sliding guillotine contraption with appropriate spaces and a Stanley blade sandwiched between blocks of wood; one 1 3/8" deep for the hull (spanning the deck thickness plus overlap) and one 1/4" for the cabin.



The first swathe was a P.I.T.A. but eventually went down. 4 hours later it had gone off however the bloody thing was covered with bubbles centred round the nail positions... Curious. 


Advice from those that do much more of this epoxy / ply thing was that the acetone from the wipe down was probably being drawn up by the less dense filler used over the nail heads was evaporating after the glass skin was laid, pushing it up. Lay off the acetone (on the ply at least). This advice came too late for the 2nd panel...

Third panel - sans acetone - was laid down the side deck in the evening and laid like a dream.

Fourth panel around and in front of the forepeak hatch (probably the largest) was also laid without acetone the next morning. By the afternoon it had gone off and covered in sodding bubbles again!

Decided to seal the rest of the deck with a layer of epoxy to cover the bloody nail heads, This then was covered in amine blush the next morning, which had to be laboriously washed off and then the whole lot sanded down smooth to accept the glass.

Meanwhile further advice indicates that "gassng out" of epoxy is exacerbated by temperature; thus application in the morning will increase the likelihood of bubbles as the temperature rises during the day - bloody plastic boat building...

Fifth panel is a small one right at the front of the deck; now laid over epoxy primed ply and in the evening - perfect.



Trick now is to start the glassing late enough in the day to prevent bubbles, but early enough to catch the epoxy "green" to cut off the edges.

Meanwhile, I've several score bubbles to sand off and patch.

Sunday, 14 September 2014

Chainplates

Week 2.

The time had come (the Walrus said ...) to fit the chain plates. The ridiculously expensive 82 deg countersunk arrived and the mock-up for the offsets seemed to work. The definitive offsets were marked onto the hull planking.

First measure a couple more times and then centre punch the location for the 3 holes in the chainplate. Drill all three with a 2.5 mm drill and offer up the plate to the offset lines and hold very firmly in place.

Mark the position of the chainplate holes on the planking by drilling through the 2.5 mm holes just drilled. Remove the chainplate and replace with the  2.5 mm guide block pre-drilled on the pillar drill - this would ensure the holes would be perpendicular to the planking.

Drill through the planking to the extent of the drill's length and finish off through the frame with a spoke drill. A quick check on the inside confirms all holes are in line and through the centre of the frame. Bingo.

Next, enlarge the holes 0.5 mm at a time until 9.5 mm.

Back to the drill press and enlarge the holes in the chainplate to 9.5 mm and countersink to 9/10 of the finished depth.

Offer up the chainplate to the hull and check the bolts pass through the chainplate and hull whilst still lodging just under the plank lands - tight but good. Success. Only 3 more to go.




The other 3 go OK, the only hiccough is that the aft bolts are too long and I need to extend the thread a bit up the bolts - awaiting an imperial tap and die set now to do this.

It seems I might have a 12 month overseas work project in the offing and therefore extended time on the boat might be difficult in the coming months, so complicated jobs need to come forward; so that means fibreglassing the deck.

As the fibreglass will wrap over the deck and 1/4" onto the hull planking, the corner of the deck needs to be rounded - glass doesn't like 90 deg corners. Using an old moulding plane of my Great Grandfather's, the edge is knocked off. Similarly the glass will wrap up the junction with the cabin sides.  Here there is a little forethought required; when the sides are stripped for repair and varnishing, the heat gun can / will damage the epoxy of the newly glassed deck, so I need to strip back the varnish some way away from the deck. This means removing the windows...

Windows are laminated glass and not cut too well either - they fit pretty poorly. With judicious use of heat, hacksaw blade, chisel and patience the (very) old putty was mostly cleared away and they are out (not without cracking two of them). Later I will make some snug fitting templates and have some replacements properly cut to the correct shape and size.


Sunday, 7 September 2014

Bronze

September, Week 1.

Getting close to the end of my 3 month Summer Holiday and thoughts turn to the finishing straight. Stuff is beginning to go back into the boat and wherever I find brass (unless the original Admiralty screws which are as good as modern bronze) it will be replaced by silicon bronze.

With some trepidation made a shopping list for most screw lengths from size 6 to 14. It worked out at about 1,700 screws plus a dozen bolts for the chainplates and cost .........£715. When received and packed away occupied about 70% of a drawer unit less 2' x 18" x 3".

Varnishing the seats has continued all week, trying to lose the grain but proved very difficult with ancient teak. After about 20 coats and a litre of varnish called it a day. They will be laid up for some days/weeks to harden before I consider whether to fit them yet - the issue being that with continual climbing into the boat through the cockpit they will inevitably get damaged.

The webbing for the cabin bunk slats arrived and after the had been sealed and the stainless staples arrived they were all connected together. The last slats and middle screwed to the riser and locker front to prevent the lot sliding off. Worked well; and when they need to be removed all you do is roll them up!




Thoughts now moving toward making the hatch surrounds. Firstly the forepeak hatch, which is an odd shape (coffin like) and needs to be designed to prevent water getting in and not trap water so as it rots. It was this part that failed before I got the boat, resulting in all the rot damage to the planking.

A long time measuring and working out tolerances, drawing in CAD, making mock-ups of likely sections and a probable solution emerges:-


The frame will be made up of 2 elements, one forming the upright stop the other forming the watershed. The junction of the two needs to be watertight and strong. This was one  of the failures of the old one. Also this is quite a bit structurally lighter to keep the height down - don't want ropes catching on an overly raised hatch cover if at all possible. This will give an overall height from the deck to top of hatch of 1.75". The joint will be epoxied (probably G-Flex). The next decision is what wood? I have lots of Oak, but that is what rotted last time. I do have about half a dozen Iroko sleepers which I could use, but before I consider them, I need to make the faux panelling for the cabin bulkhead....

In any event, the idea is to make up lengths of the above "composite" moulding and fabricate the frame on the boat, probably with mitred half lap joints. 

But before that, the panelling in the cabin and I think the fibreglassing of the deck and perhaps the chainplates.

Sunday, 31 August 2014

Bunks

Week 4.

Varnish patching first thing each morning on the repairs to the cockpit seats and locker fronts:-


Starboard seat

Port seat

Starboard locker fronts
The main job of the week is to produce the slats for the cabin bunks. These vary in width from 1.5" to 2.5" depending on where they are - narrow at the ends and wider in the middle. Two reasons for this; less wastage from the stock timber and the middle section is where people's fat arses will sit at the dining table!

Each slat is machined to 1/2" thickness and spaced 3/4" apart.



Once cut, they're all removed and sealed with CPES to prevent mould growth under the seat squabs. For the final fitting each slat will be stapled to two strips of webbing underneath and every 10th slat screwed to the supports.

Running out of "light" jobs, thoughts turn to the chainplates.

These need to be bolted through the planking and frames (or backing plates for the aft pair). This issue here is that the frames are relatively narrow and the planking lies at an angle at the outer face. Hole drilled from outside through and perpendicular to the planking could run out too far toward the inside face of the frame. Therefore the holes need to be started forward of the centreline of the frame - the question is how far forward...

The safest solution seems to be make a mock-up of the plank/frame structure, replicating the angles and dimensions:



Judging by the results, it seems feasible, but tight. Need to decide what diameter bolt now. Clearly the thinner the bolt the more wiggle room but less strength, the reverse for thicker ones. The mock-up shows 9.5mm or 3/8", which is the size of the bolts removed, but I'm wondering if 5/16" is OK or even perhaps as little as 1/4"? 

I am thinking that since I have re-cast the chainplates so they are stepped and these now have notches that act directly on the plank edges, releasing some of the forces on the bolts by quite some margin, so I could get away with smaller bolts.



Added to the mix is that the forward bulkhead is fixed to this frame, so too far towards the back edge and the nuts of the chainplate bolts will foul with the bulkhead panelling...



The circles above show the old holes (I would aim to get them all in line and maybe vertical...?). This introduces another little issue - I want to drill as close to the centre of each plank, but it would appear that the top bolt must pass below the main beam and that is only about 1" above the bottom edge of the sheerstrake... hmmmm.

Sunday, 24 August 2014

Seats

Week 3.

Cockpit seat risers were completed and the task of sorting out the bearers commenced. On the port side the original bearers were still in existence, though it was not clear if they were originally fixed to the risers as I propose (I suspect not...). Fitting the seat temporarily and aligning as best possible to the front of the locker fronts at the ends, ensuring about 1/4" overhang,  it was clear that the locker fronts were flatter and probably sprung back whilst being of the boat for a few years. Therefore I needed to pull them out somehow to induce a curve that followed that of the inside edge of the seat. The simplest way seemed to be to used ratchet straps around the new riser and the top of the locker fronts. Adjusting the tightness until reasonable curve was made. It became clear that perhaps the seats had suffered  the effects of enthusiastic sanding / wear of decades in the middle section, as it seemed too much to force a common overhang along the whole length, so there will be a bit less of an overhang (more like 1/8") in the middle.


Happy with the curve, the seat was removed and the new length of the bearers measured to the back of each dovetail sockets. The outboard ends of the bearers were then cut and adjusted until a snug fit was achieved and the locker fronts remained in position after the straps were removed. The seats were then replaced to make sure everything was OK.


Not too bad, all that remains now is to establish new fixing holes from the undersides. For the starboard side both original bearers bearers were missing and their replacements total crap, so new were made from scratch out of Oak. The forward one complicated in as much as the seat is split to provide the cooker locker and so the bearer follows the shut line and is therefore twice the width of all the others.

The locker fronts are screwed to framework attached to the bulkheads, this means that the central section is unsupported. There are three pocket screw holes in the lower frames, that accept screws that are driven straight into the timbers. However there are gaps between that need to be wedged first, so a few hours knocking up some wedges. 

During this time, I decided to refit the sole bearers. Big mistake - due to re-establishment of the boats true shape, the timbers are different and most of the bearers removed no longer fit. Four new bearers were made up. 

It was about this time I noticed that I hadn't filled in half a dozen screw screw holes in the (nicely varnished and refurbished) locker fronts. In my defence I had seen and left them, thinking they were required for refitting, no longer though. The bullet being bitten, theses holes would be tidied and plugged - revarnished over the next week.... but first, the cockpit floor was repainted with red lead (after the great shellac disaster earlier in the year when I spilt about a pint al over the freshly painted planking).

At the same time noticed two sodding great holes in the teak seats, next to the cabin cockpit - again inexplicably left some years ago.


I suspect the legacy of a cabin roof lifting system, struts running from under the seat to the roof; either way, bloody stupid thing to leave... but an involved procedure to sort out.

First the hole was cleaned up and made circular. I only have spade bits and these don't like being used in old holes; they chatter against the sides and sod it up worse than before, so the hole had to be temporarily filled with a sacrificial core, then re-drilled. Finding a lump of teak, I cut permanent cores and glued in place.

The darker ring in the picture above, represents a recess cut into the face of the seat (to accept some form fascia plate associated with the lift system I assume) about 3mm deep. This would need to be filled with a circular teak veneer.

Levelling the new plugs to the level of the recess, old varnish and crap was scraped away and the edges sharpened up to accept a veneer. Finding an area of the teak plank that showed a good grain match, a circular plug was cut out and a 5mm disc cut of it. Each disc was then painstakingly fitted to the recess and epoxied in, trimmed and prepared for varnish.

Next week, bunk bases.

Sunday, 17 August 2014

Drilling holes

Week 2.

With the deck ply finished, there was no excuse to delay drilling the hole for the rudder, a job that had exercised my little mind for some months. 

Critical to get vertical and central, throughout the rebuild process I had tried to maintain the original position by leaving a central pilot hole in the deck; 




however, dropping a plumb bob through the hole it appeared to be off a little to the port side. Enlarging the hole by increments (keeping within the confines of the ultimate 1 7/8" hole) I was able to fix the position. Temporarily tacking on a guide plate over the adjusted and now oversized original guide hole, I was able to pass through the hole saw drill extension that would allow the drill to be above the deck and the hole cutter below.



On the underside of the hog I scribed the centreline, through which the pilot drill would hopefully emerge... and started cutting:



The depth of cut was limited to the depth of the hole cutter - about 2 and a bit inches. The thickness of the hog is about 4 and a bit inches, however I had bought an extended pilot drill, so that hopefully, once I had reached the limit of cutting depth, the pilot drill would have emerged from the bottom:-



Spot bollock (as they say) - bugger me, the plan was working.

Dissembling the extension bars, I was able now to attack from the bottom, hopefully using the established vertical pilot hole to maintain alignment, thus the hole was completed.




A little bit of misalignment, but it is not possible to fully tighten the cutter to the arbor for some reason (some German logic I'm sure from the designers in Bosch, but it confounds me) so it is more than likely this was the cause for about a 1.5 mm deviation at the meeting point of the two cuts.

Turning attention to the top, I now needed to be sure the top hole was also vertical. If this were just deck (3/4" Douglas fir planking and 1/4" ply), I wouldn't be too bothered, but because this area also takes the eyebolt for the mainsheet, there is a wacking great lump of oak reinforcing it between the two deck beams:-



So things have to be a bit more accurate. I decided to rig up a couple of right angle braces; one laterally and one along the centreline and adjust them so they were both vertical.


Then placing a long shank drill bit in the chuck, brought the two together until the drill was vertical in two planes, and would remain so as the cutter descended:



Swapping out the bit for the hole cutter, the time had come...



A check with the plumb bob seemed to confirm all was OK; at 12 o'clock and all points East, West and South, the string touched both top and bottom holes - she was plumb.

Only now I could accurately measure the final depth from the top of the wooden boss on the deck to the underside of the hog and have final adjustments made to the new rudder shaft that has been sitting in the fabricator's workshop for over 6 months; so a trip to Hoveton to finalise these points, together with confirmation of clearances between the tiller boss and deck as well as the rudder blade with the bottom of the hog.

...Moving into the cockpit, the setting out of the seat risers had to be sorted. The risers run along the timbers and provide a landing for the bearers that will support the seats in the cockpit. The inner edge of the seats rests on the top of the locker fronts, the outer edge follows the line of the coaming and therefore stop some distance short of the hull planking (i.e. the width of the deck). Previously, these risers were about 3/4" by 1 1/4" deal, screwed directly onto the timbers, so that the 3/4" edge was uppermost. The riser was bent to conform to the curve of the hull, the strain being taken at the screw points in the timbers. To my way of thinking, this creates nasty point loadings to the timbers; which whilst not exactly fragile, probably do not need weakening any more than necessary.

In addition, the inner edge of the seats are also curved (outwards), so the the locker fronts too need to be pulled outwards to conform to the curve. The only way to do this is to tie them into the risers with the bearers, so there is additional strain on the riser fixings and thus the timbers.

My plan is somewhat different. I will make some hanging brackets that will be fixed to the timbers that will shaped to fit the curve of the timbers and extend to about 6" long and fixed top and bottom. 




The riser will be steam bent to conform to the curve of the hull to reduce strain on fixings and will be fixed with the 1 1/2" face uppermost. The seat bearers will be dovetailed into the riser (they are already dovetailed into the locker fronts), spreading the strain over the joint rather than a screw fixing.




The junction at the timbers is now more of a vertical shear stress against the 6" face of the bracket, rather than the single screw of the arrangement I removed. I suspect the original design was as I plan to do, otherwise why dovetail into the locker fronts? I suspect this was discarded after the first re-planking in the '80s as it was too time consuming to do properly.

The rest of the week was spent making up the brackets for the cockpit (as well as the cabin for the bunk risers).

Sunday, 10 August 2014

Other stuff


August, week 1

Not quite sure where this week went...

Anyway, spent a couple of days filling the nail holes in the ply deck skin and then sanding off, but not before the final titivation of the apparent sheerline along the top of the deck.

Saturday went to our annual pilgrimage to Hickling Broad for the old dear's birthday and managed to get a few shots of one of Corsair's sisters showing off her knickers:-


A distant cousin from the same designer:-


...and some more unrelated smut(!):-





Sunday, 3 August 2014

Deck skin finished

Week 4

Much of the week put aside to landscaping around the garden - cutting hedges that we have left for about 8 years (if my maths is right) - so that took time; one down and four to go... any way it's been too hot to epoxy really.

However, by Sunday seems I've finished the plywood skinning  of the deck:-



Not sure if it's been discussed before, but since the thought processes involved in laying this stuff - especially by the stem, I have decided not to refit the bowsprit.

I anticipate sailing this boat, most of the time, single handed and coming into moor with a 5' bowsprit sticking out the front is going to be awkward; not to mention the potential for collateral damage as a result of the significant leverage such a pole will do - and quite frankly, after 5+ years rebuilding this, the last thing I want to do is repair the bloody thing.... in any event she wasn't designed to have one; Father shoved piddly little 18" to 2' one one after quite a few years of doing without one - I don't know why and he isn't around to ask - so it stays off (for the time being....)

Sunday, 20 July 2014

Decking - Layer 2

Week 3 (delayed by yet another broadband failure from BT...)

Over the last few days, the 5mm (or is it 6mm? - can't remember) plywood has been laid over the deck planking.

A fairly time consuming task with the shape of each panel being modified until a fag-paper fit is obtained with adjacent structures. There are 14 panels to be done, for each the process is the same. First the deck planking is "wetted out" with un-thickened epoxy, followed by the plywood panel - making sure the edges are well saturated. 

Then batches of thickened epoxy are made up and spread over the wetted out deck planking with a notched scraper. Working as quickly as possible in this heat and trying to use the coolest part of the day first thing in the morning, otherwise the 1st section applied is already going off by the time you get to apply the panel. This will mean limited squeeze-out of excess epoxy, but more importantly leave voids under the ply leading to rot potential.

The ply panel is laid onto the deck and pushed home against adjacent objects i.e. cabin side or neighbouring panel. Then using the nylon brads and pneumatic nail gun, an edge is secured at about 1 to 1.5 inches intervals. Then working towards the outside edge of the deck, a grid pattern of nails at about 2" pitch are driven in, hopefully generating a wave of excess epoxy under the advancing front of secured plywood, until the edge of the boat is reached (and it oozes out all over the floor...). Hopefully this means there will be no air pockets trapped underneath and the surface will be uniform and smooth.

It is only really possible to do one panel at a time - each previous one needing to be cleaned up before the epoxy gets too hard and to making sure that a clean joint can be made between the next panel.




By the end of the week all but the 1st panel at the bow - which has a lot of curvature and is being clamped down for a couple of weeks to induce some bend and a couple of little strips by the aft sheetman's hatch, are fixed.





When these are fitted, the next task is to fair all the sunken nail heads and any undulations that may be present at the panel joints, ready for the application of the glass mat.

However, the main reason for doing this at this stage is to cut the hole for the rudder tube. This will allow me to determine the exact final depth of the tube from the underside of the hog to the top of the boss that sits on the deck and allow the fabricator of the rudder assembly to machine the bronze tiller casting I had done some months ago, so the two mate together without either binding or being too high off the deck...