Solo dinghy refurb' update

With the centreboard seal replaced, I turned the boat over and started to remove the rubbing strakes. They were 4 strips of spruce 10mm wide and with at least 40 screws on each side, mostly hidden. I also removed the trim inside the cockpit to expose the edges of the ply decking. This too had about 35 screws on each side. I managed to prise the 4 ply pieces off without breaking them. The number of fastenings used was serious. The deck had been pinned down with 2 kinds of panel pin, bronze screws and stainless screws in an attempt to tighten everything up.  

Old failed glue joints

All the glue holding the deck on and holding the deck beams together had failed and I literally lifted them out with 2 fingers. I scraped all the joints clean, dried everything out and bonded them back in place. The old ply will be used as rough templates for the new deck.

Joints cleaned up

The mast partners are wet, rotten and will need re-making before the new ply deck goes on. 

The next step is to order the 5mm ply for the deck and some timber for the rubbing strakes and trim parts. The new rubbing strakes will be quite a lot slimmer and smarter.

One side dried, cleaned up and bonded back together.

  

Solo dinghy refurb'

The latest project in the workshop is a 1980's Solo dinghy. The local sailing club has quite a few of these boats and they race regularly. This one is in to have the ply deck and possibly rubbing strakes replaced and everything else stripped and re-varnished. The boat has seen better days and the GRP hull is faded and chalky with a nice layer of algae.

The deck is really tatty and needs re-doing

First I had to get the ancient gold pinstripes off with a heat gun. Then I washed and sanded the entire hull through the grades of abrasive discs. Next I polished it up with a lambswool mop on a polisher. I gave it a coat of wax polish to help keep future muck off.

The seal on the centreboard slot needs replacing too. When that arrives and is fitted I can flip the boat and take the deck and fittings off and see what lurks beneath!

14' Strip plank canoe update

This week I have found time to get some canoe work done. It has to go on hold for a month or so and leave the workshop temporarily to make way for another project. This meant getting the gunwales machined and scarfed together (12 separate pieces), details cut out and then bonded onto the hull. I used ash as a local chap has a woodland that he manages sustainably, and he also has all the machinery for felling, cutting and ripping it into planks. After finding timber without any worm and with as few knots as possible we ripped it into 20 mm square strips. We also took advantage of his sliding table on his table saw to cut all the scarfs saving me a lot of time.

Inwale trial fit

The scuppered inwales were made first and bonded in with about 20 clamps and thickened epoxy. Once this was cured the outwales were bent around this new rigid shape.
Next came the stress of some of the heaviest rainfall in the South West in years. This fell on already sodden fields that ran straight off into the stream at the back of the workshop. The sedate trickle turned into a 1.5m deep by 1m channel of water that was tearing by. This was too much for the gulley upstream and it overflowed coming down the road and straight into the yard. Sandbags and ply boards diverted it and disaster was averted saving the canoe from an unplanned launch. Some folks up the road had their houses flooded and were pumped out by the fire service.

Scuppered inwale details

I got back to work the next day and planed the top faces of the new timber flush and put a chamfer, then a round on the outside faces. You could do this before you fit it but it makes clamping to a curved face more awkward. Next up was the thwart to make the structure strong enough to be strapped to the car roof bars. I cut it from a piece of ash I had from a previous project. This was then routered to take the edges off and bolted to the inwales. The bolt heads were sunk into the wood and epoxied in with grain plugs to finish them off. This was then put on top of the car and put in a safe place until I get a chance to finish it. That's it on the canoe for a while as the next project,  a solo sailing dinghy, is in tomorrow. More details to follow...

14' Strip plank canoe sheathing inside

This weekend I decided to epoxy/glass the inside of the canoe. I used the same 200g/m cloth as the outside. I went through the same procedure of tack clothing the surface, getting the humidity and temp right and making sure the resin was room temp. This time I did it on my own and it took a fair while, most of this was dispensing and mixing the resin. The room was fairly airtight and it was starting to smell of curing epoxy pretty strongly towards the end of wetting out of the cloth. Next time I will wear a mask with charcoal filters.
I rolled the cloth out over the boat and cut it to length. Then I dropped it into the hull and tried to smooth it by pulling rather than brushing with my hand. I still got a couple of ripples in the finished item.

This pic shows the weave that is visible after one coat of epoxy. The next 2 coats do hide this to an extent. On previous canoes I have used 145g/m cloth that seems to be less liable to rippling and is less visible.

One thing to check if you have a go at doing this is how much epoxy is gathering in the middle of the hull at the bow and stern. This can mean the epoxy goes cloudy and bubbly as it exotherms. I had to keep mopping up the excess with a brush. Don't be tempted to spread it around to try and get rid of it as you will get a cloudy patch.

 I didn't get too fussy about the glass at the stems as it gets sanded neatly later and will be hidden behind small bulkheads. The bulkheads are just cedar strips glued together on a flat surface. The shape was taken from the hull by using a process called spiling, its a bit like scribing. These also got sheathed at the same time.

Next up is sanding the inside and planning and making the gunwales. I'm going to leave the sanding for a few days to get a full cure.

14' strip plank canoe inside prep'

This week I managed to get time to sand the outside of the hull and scrape and sand the inside. The outside sanded fairly easily thanks to being able to maintain a decent temperature and humidity during the cure. I used a dual action sander, first with 80 grit then 120 grit, both without an interface pad. I was sure to keep the machine moving all the time and used diagonal strokes to try and fair out any anomalies. I wore a protective waxed paper suit, nitrile gloves and a proper face mask to stop the epoxy dust. From what I've read, once you are sensitised to epoxy it seems you just have to stop using it or wear a space suit!

Next came the removal of the moulds. I took out the screws that were holding them to the strongback (building table) and gave them each a twist. Most of them came away easily and I pulled them out from under the hull. The formers for the stems had to be hammered out to free them. I drew around one of the narrow station moulds and made a kind of shoe to hold the canoe at both ends once it was turned right way up. I flipped the canoe with the aid of a helper (this time Mrs Newton Boatworks) and then sighed after seeing the amount of scraping and sanding to do on the inside!

Despite wiping the hull inside with a damp cloth when the glue was still wet, there were hard bands of glue where the station moulds sat. Although the cedar strips interlocked nicely, they are a series of flat surfaces that form a curved shape. This means having to scrape/sand the inner surface to lose the flats. I filed a paint scraper to a decent curve and used that to get rid of the glue bands and fair the shape. This means walking a fine line between skidding over the glue surface and digging into the soft grain and tearing a chunk out.

With this done, I got out the sand paper and sanded the hull 80 grit and 120 grit. It's essential to wear a dust mask or you end up coughing all night. I even shaved off my beard to get a good seal on the mask. I vacuumed the dust/shavings up and then mixed some epoxy/different fillers/sanding dust and flush filled any gaps. I used a high proportion of the hollow glass microspheres as they lower the density of the epoxy mix and mean you are less likely to sand a hollow into the cedar either side of the filler.

I then re-sanded the filled areas and cleaned up ready for sheathing the inside. 

 

14' Strip plank canoe sheathing

In a bid to get the hull finished I checked the humidity and temperature in the workshop to see if I could crack on with the epoxy/glass cloth stage.

 The hygrometer showed 97% and the temperature was just 11 deg C. It's important that the epoxy coating is applied when the humidity is lower (max 85%) and the temperature higher, to avoid an under-cure and a cloudy finish. I didn't want to wait for the weather to improve so I put the dehumidifier in the workshop for a day. This didn't bring the humidity down a great deal as the workshop is pretty draughty. I fitted foam tape to the door seals and a thick polythene sheet to catch any drips of condensation on the underside of the corrugated iron roofing.

The next day I got up at 6 am and set the fan heater up under the hull. The outside temp was 5 degrees. I got the temperature up to 15 degrees and the humidity down to 70%. The resin had been warmed in the house for a couple of days. I read somewhere that you should aim to to get a dew point that is at least 3 degrees lower than the air temperature to stop condensation forming on the epoxy and making it cloudy. The hull has to be the same temp or warmer than the air. I used this dewpoint calculator. Other advice is keep an eye on the temperature whilst doing the sheathing of the canoe as an increase in temp will cause air in the wood or voids to expand forming bubbles under the cloth.

The cloth is 200g/m and a little thicker than I have used before. I used West System resins and the 207 hardener which is intended for this kind of clear coating. It's great to see the first batch of resin poured on and the wood showing through. After I had wet out each quarter of the hull with a brush I went back over it with a filler card to take off the excess and get rid of air bubbles. 

Once this first coat was tacky I brushed on another coat with as few runs as possible. The idea of this is to create a chemical bond between layers. Once this was tacky (8pm) I brushed a on final coat. I left the heater running for 24hrs to keep the temp up and get as good a cure as possible. The ouside temp was only 3 degrees at night. Trying to sand chewy epoxy is bad for your health (skin and respiratory sensitisation) and uses up loads of sanding discs.

The shape of this hull has some tumblehome which meant that the spare skirt of glass cloth was trying to pull the cloth off the hull. I trimmed this as I went and smoothed it back on.
Once the three coats were all on I could get an idea what the completed canoe will look like when varnished.
This is then sanded, the moulds removed and the boat turned over.

I've just got to do the same on the inside!

Hull sheathed and 3 coats of epoxy on: time for a beer

www.newtonboatworks.co.uk

Coastal rowing boat

Over the last few weeks I have made repairs to a plywood coastal rowing boat. It is well used and the bow and rudder were damaged, a wooden outrigger was broken and the bilge pump had ripped its mounting block from the bulkhead. Further work is needed to epoxy/glass tape along the full length internally.

 

The bow damage was caused by rubbing against the trailer and being beached. Both ends of the boat had splits between the hull and deck allowing the bouyancy chambers to fill up with water. The old glass tape was sanded off and replaced with a couple of layers of epoxy/glass. This was sanded smooth and epoxy primed ready for the club to repaint the whole boat at a later stage. A similar process was used for the other repairs.


The cracked outrigger had been held on with a strip of aluminum screwed into 4mm ply. This was removed and the broken grp ground off. The crack was dried and filled with thickened epoxy. This and the surrounding area was relaminated, stepped down to one layer at the edge. All this was sanded smooth and epoxy filled and faired, then primed.

The finished repair

Swift rowing boats

I've had several repairs to complete on the local club rowing boats this year. The racing shells are tricky to work on and have epoxy/kevlar/carbon hulls. On these boats I have done a repair to a delaminated area of coremat in the hull skin, a rudder tube that had broken out at the deck end and a fin box repair. The hull had distorted around the site of a previous repair to the fin box at the stern. It seems that the fin had been caught on something and had ripped the fin box out. Someone had bonded it back in slightly proud of the hull and the aluminium had corroded, expanded and distorted the area around it forming a bulge, like a snake swallowing an egg.

Distorted hull area

The hull did not return to its previous shape when the fin box was removed so I cut the whole section out and  moulded up a repair patch from epoxy/glass with carbon strands laid along the keel line. This was then bonded in on both sides, epoxy filled and faired. This was not straightforward as I only had access to the outside.

The finished repair

A new fin box and fin were bonded in and then the repair was primed and spray painted in 2 pack automotive paint.

14' Strip plank canoe

The cedar canoe is now taking shape. Any spare time has been devoted to it to keep it progressing before the weather turns truly cold. Fitting the strips went really smoothly, with the final closing strips going in without drama. There is a lot of force required to bend them into place which can break the fragile cove on the strips. After many hours taking the edges off the strips with a block plane and spoke shave it was time to start boarding the hull with sandpaper.

When all the sanding was done I took a spare cedar strip and spring clamped it to the hull to form a smooth curve to cut the sheer line. I used a Japanese saw to follow the curve. This is a nice point in the project to open the workshop and look at what now appears very canoe like.

I am now looking to get the workspace as warm and dry as possible to avoid any issues with the epoxy and fibreglass sheathing.

www.newtonboatworks.co.uk