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...

Sunday, 13 July 2014

Back on Strike

July, week 2.

As I tentatively tap the crease (middle and leg) and await the deliveries of the coming weeks, a small retrospective of the the past 8 weeks or so.

It was possible to slap on a coat of varnish or 12 during the early stages of the last work intrusion and the cockpit seat locker fronts are now done and propped into their positions:



The seats were laid on top to determine position of the riser at the back, but due to replacement of the bulkhead bearer, they are now a few millimetres too long and need to be trimmed or they will scratch the varnish on the bulkheads.

Decks are in the process of being covered with the plywood substrate in advance of the final glass mat / epoxy finish. Using the pneumatic nylon brad nailer, it's a breeze. They seem to hold well, the only proviso is that the planting of a size 9 on the edges and banging in a brad every 1" is the only way of pulling down the edges. Ensuring that you kneel on the glued panel as you bang in the remaining brads means - one hopes - the panel is pulled down onto the deck planking and hopefully epoxy, without any voids and  leaving a smooth continuous surface.

The heads of the brads do bury themselves a bit, so the whole surface will need to be filled and fayed, which is a bit of a P.I.T.A. but beggars......

Monday, 19 May 2014

Topping and Tailing

Week 3.

Rushed write up before flying out to Russia again.

Major re-constructive surgery on starboard frame was completed. Some interesting experimental joints, but got there in the end.

First the end extension:




Then the more complex insertion:



When done and tidied up, a fitting session and a check to see where the seat join would be so I could remake the back pad to accept the dovetailed cross member: 


Last thing Sunday - 1st coat of varnish:





Sunday, 11 May 2014

Moving back

Week 2.

Waiting for the new bronze coach bolts to arrive for the stem, attention turned elsewhere.

Not wanting to crawl about too much in the boat without the bow props in place, decided to look at the cockpit seat locker fronts.

These are similar construction to the panelled cabin bulkhead, without the panels of course:



The above is looking toward the back - so the right hand seat is port and vice versa.

The port seat is simpler because it is a single plank; the starboard one is split 1/3 forward: 2/3 aft, this is because the forward section is hinged and lifts to gain access to the stove. At some stage the locker frame was butchered, presumably to enable some kind of door perhaps to use an oven that had once been installed. This had the effect of destroying the structural rigidity of the frame. During the process one of the staves had been shifted about a couple of inches aft. This was achieved by sawing through the tenons that secured it in the frame, and then the top rail was severed - nice....

This butchery didn't go well 


The hinged element was incorporated into the moved stave by slicing it down the middle...



This has to rectified, as does similar damage to the forward end of this section


First is the hinged stave that has to recombined and the tenons replaced and the infill dutchmen inserted to disguise the original mortice sockets removed:


The forward stave reconstructed:


Next will be the interesting insertion to replace the rotten infill piece - interesting as there is little wood to play with around the mortice of the upper stave:



Meanwhile grotty sections of the port side were replaced:



...and then the whole lot reassembled, glued and wedged:


...and finally rubbed down prior to test fitting into boat (as position of bulkheads may have moved slightly and minor adjustments necessary).


Coating the inner topsides in the cockpit with shellac was also started until I spilt half a pint of the bloody stuff all over the new red lead paint of the bilges - not happy. So that'll need a re-coat later in the coming week - leaving it to harden for a fortnight during my next Russian sojourn away starting the 3rd week of May...