Building the Hull The project started with a platform down in the mangroves, close to where the old scow was built. The old scow is on the right, just out of the photo. Marcus owns her now. Marcus helped me to drive the piles, and some of the planking used is from the previous scow project.

Summer late 2018 Sheets of plywood were laid down, and the lofting done full-size. The original plan was to build the hull upside down, standing on the cabin top, so a mould was made for the cabin top.

However this idea was discarded as being impractical, so the mould was scrapped.

Two sides and two “strongbacks” were made on the flat, and coated with resin. These two “strongbacks” will run fore and aft along the “buttock” lines to give rigidity to the hull. They will be incorporated into the internal fit-out later – and also will be integral with twin skegs. It was also planned to fit a “centreboard case” on each of these strongbacks.

Bulkheads, stem and kelson were made, and the “flat pack” was assembled.

Floor timbers were fitted. All of the framing is made from housebuilding lumber (tanalised radiata pine). The plywood panels are tanalised radiata pine imported from Argentina, second grade, cheaper than the local product. The sides and strongbacks are 15mm 5-ply. The bottom will be 19mm.

It is spring high tide, some time in 2018.

It was planned to build “off-centreboard” cases at the strongbacks (buttocks) The plywood off-centreboard case sides are shown here.

However, another change of plans. It was decided that the off-centreboard cases should be integral with the sides of the boat. Centreboard cases were made in two parts and assembled with dowels for alignment. Fittings (made from 316 ss nipples) were added to the two pairs, and aligned – these are to take the pin for the swinging centreboard. Centreboards were made, and “dry trials” were carried out to ensure alignment etc.

centreboard under construction. Made from 4”x2” pine and hardwood timber, glued and through-bolted with threaded rod “drifts”.

Here is a completed centreboard, swinging inside an unglued case, to test alignment of pin etc. The pin is a length of 1” ss propeller shaft. The timber framing which carries the pins is hardwood. The leading edge and one other strake in the centreboard is also hardwood.

The off-centreboard cases are now dry-assembled and dry-fitted into the hull. Alignment is checked.

Behind the centreboard cases is the hull with its framing. In behind the off-centreboard cases, the gaps between the hull framing is filled with offcuts of 50mm solid timber, so the hull in the area of the centreboard cases is now 65mm (2 ½ “) thick, solid timber.

A start was made to some rough fairing. At this stage it was decided to add chine runners, partly as an experiment to see if they can add lateral resistance to the hull, when sailing to windward. The twin centreboards are rather small in area.

The chine runners can also conveniently act as strengthening members, to bolster the chines and sides of the hull in the area of the centreboard case slots.

The chine runners are “winglets” which do not add to the draft. They will add a little to “drag”.

The outsides of the off-centreboard cases are now fitted permanently to the sides of the hull, meshed and plastered.

The dowels shown here in the framing are to ensure accurate alignment when the cases are finally assembled.

The photo below shows the detail of the 1” ss nipple. They are carried by hardwood timber in this area. There are two pairs of these, they will carry the centreboard pins. It is important when the two halves of each centreboard case are assembled, that the nipples are perfectly aligned.

The insides of the off-centreboard cases are also plastered, ready for assembly.

The ferrocement surfaces are now given two good coatings of epoxy resin, glued, bolted and assembled. The dowels ensured true alignment, and the pins slid easily into the fittings. The centreboard cases are in place, and the floors are now being fitted.

January 9 2019

January 25 2019 It was decided to fit the beltings at this stage.

In February 2019 the bottom planking was commenced.

The floors go right through the buttock strongbacks. Cleats have been glued and bolted to both sides of the strongback/skegs, ready for the planking.

This seems to be about the limit for bending 19mm plywood.

Provision is made for the installation of an outboard motor well.

The transom is fitted…..

….. and the weight tested with a farm jack.

By the time the bottom planking was done, winter was approaching.

A wet day and a spring tide.

A roof and an improved platform will be needed.

Late 2019 Cleats are added to the stem to make a “rabbit” and battens are fitted to follow the conical shape of the bow.

The buttock frames are made “freehand” and then the whole is faired with a power planer. The bow is now ready for planking.

The first sheet of 19mm ply is wrapped around the bow. The plywood has been deeply cut to allow it take up the bend. These saw cuts are later filled with epoxy. More ply is added. The remaining piece at the bow is a flat section and will not need any cuts.

Marcus now appeared on the scene, and within two days we had a roof, made from old pallets for the framing, and the left-over covers from the old scow. No measurements were taken. Marcus fitted the roof neatly under the Pohutukawa branches with inches to spare.

During the last year, the piles down the right hand side have sunk slightly. That doesn’t matter, now.

It is now around 20th February 2020 and the first layer of reinforcing has gone on. It is a combination of #8 and #4 gauge rods, to create a heavier and stronger sheath just in the flat bottom area.

The entire hull is then covered with 50x50 (2”x2”) square welded galvanised #10g mesh. This is the skeletal steel.

This is followed by two layers of 13 x 13 (1/2 “ x ½ “) galvanised #18g square mesh.

It was fastened down with (literally) thousands of #18g staples driven by this electric staple gun. The gun can drive a 1½ “ staple up to the hilt into pine. I burnt the first one out. The next one got dropped over the side one day when the tide was in. Shown here is the third one.

The meshing up was completed in early March. It was now time to start making preparations for the onset of the covid19 pandemic. I could foresee a lockdown, and began to gather the materials I might need in order to keep busy (and fed) over the next few months. First, I purchased 38 bags of sand (38x20kg) and 17 bags of cement (17x20). (I think the sand and cement in that ratio was due to the number of bags in a pallet. The is not the mix ratio). I had also requested Gary to send me 25lb of Kalmatron from the US. Kalmatron is not available in New Zealand. It locks the hydrating water into the cement, so a wet cure is not necessary. Its only disadvantage is that it does not allow the use of plasticisers.

(For the record, I used 24x20kg bags sand, 15x20 kg bags of cement and 6.45 kg kalmatron. That is: 1.6 : 1 for sand:cement – a little rich, perhaps. The ratio for kalmatron was about what is recommended (1:47 Kalmatron:cement) With an appropriate calculation for hydrated water (0.23 x cement), the total weight of mortar is approximately 850kg. With an allowance for steel reinforcing, the finished ferrocement sheath adds about 1 tonne to the weight of the hull. This weight is in lieu of ballast.) I was now rushing to get the plastering done before the lockdown. Marcus and Bob Ferris were keen to help. Bob is very good with a trowel. Marcus is a boatbuilder, but has never worked with plaster before. Some boxing and screeds were prepared. I made a start on my own, screeded off and did the centreboard case openings, and the outboard motor well.

The team turned up and we made a late start on the first day, and got the area between the skegs done, and the transom.

Running out of time now, two days before the level 4 deadline.

Next morning we shifted to the bow. Bob putting The finishing touches Marcus on the mixer By early afternoon we had to stop. Both Bob and Marcus had urgent things they needed to attend to before the lockdown.

The bottom and sides remain to be done and I will have to do them in stages on my own.

April 8 2020 The plastering re-started, this time on my own. I battened off half of one side, and plastered above the waterline.

That’s a day’s work for me – mixing, placing, shaping, floating off and sponging. There is about 30 - 40 kg of plaster here.

Plaster was trowelled and vibrated in with an orbital sander. After the batten was removed, the penetration looks pretty good.

A ¼” groove is chiselled out at the gunnel. This will be filled with a flexible sealant later. Chipping occurred, as clearing out the groove was started too soon.

The sides were completed in this way over the next three days, half a side at a time. I quickly found that it is difficult to join on a corner – better to move away from a chine and put the batten where there is a “flat” surface. Joins were primed with water-borne epoxy resin, which seems to be very compatible with cement. Thin plywood makes a good guide to plaster up to. The timber batten keeps it fair.

After the sides were finished, the SE corner had to be protected from wind and driving rain for a couple of days.

The fore and aft quarters were plastered over a two day period.

Now the thicker bottom sections are to be plastered. Work has slowed as greater volumes of plaster are needed here. This orbital sander was given to me by the local hardware shop. I went there just before the lockdown and he didn’t have one, so he went out the back and got his own and told me to just keep it. It is an Ozito, a cheapy. I wanted to use it as a vibrator for vibrating in the mortar. Within a few minutes it started running at varying speeds and it didn’t look as if it would last for long, so I rushed out to Mitre 10 and bought two cheapies as standbys. (You can get these things for as little as $29 but they were out of those. The ones I bought cost $50 each. I did not want to be without one during the lockdown.) Anyway, the Ozito just kept going and has done the entire job. All the plaster (about 850 kg) has been vibrated down by this orbital sander and believe it or not, it still runs. The pad is now solid with cement, it won’t work as a sander any more but still good as a vibrator. (Its $80 per day to hire a proper concrete vibrator, but for this job an orbital sander is perfect.)

A close look at the edges shows the mortar is penetrating the mesh and vibrating down very well.

This is near the middle of the bottom where there is quite heavy reinforcing and the plaster is about 20mm thick here. (The sides and topsides are meant to be about 8-9 mm.) Here we are on the last day. The edge batten from yesterday’s section has been removed.

After cleaning and chipping around the edges, and vacuuming all the crumbs out of the remaining mesh – started plastering the last section at about 11.30 this morning.

Back out again at 8pm under the lights, for the final sponging off.

All done. 17th April 2020 Actually, the job is not quite finished. Underneath the chine runners the plastering will be over-head. I do not know how to do this without incurring voids, so may decide to leave this until the hull is turned over.

The next job is stoning off the hull. I decided to take a few days off and test some ferrocement-sheath panels I made the year before when the off-centreboard cases were plastered. I want to put these panels into bending, see what happens and see if I can get some numbers.