Gone to a New Home.

 

After doing no work on the launch for over 2 years I had to accept that I wasn't going to finish the project. I simply ran out of time and energy. Here she is heading off to her new home.

Work on Canopy and Floor

Since the last post there has been a lot of sanding, sealing, fibre-glassing and painting. None of this is very photogenic but here are some of the steps along the way.

The canopy was covered with 3mm thick ply.

After filling the holes where the plastic nails went in to hold the ply while the glue set (seemed to be hundreds of them) and sanding the whole thing the fibreglass went on.

Then the sanding started and it took hours to flatten it out!

Here's the first coat of primer going on the underside; the top of the canopy has been primed and undercoated.

The canopy is now undercoated all over and will wait a while for the finishing coats.

The four plywood panels that make up the floor were sealed with Wattyl SeaPro TP80 sealer and then covered on the top with strips of White Beech so the will match the fore and aft decks. Here are the panels laid in the boat.

Another photo of the panels after the gaps between the strips were filled with black Sikaflex. I put masking tape either side of the gaps to try to keep the Sikaflex under control. Once the gaps are full and the flattend with a spatula the tape peels off and leaves a fairly clean surface on the timber. After a couple of days for the Sikaflex to cure the whole surface can be sanded flat.

The planking was then coated with Deks Olje Number 1, applying multiple coats wet on wet until no more would soak in. The excess was wioed  off with a cloth.

Here are the floor panels turned over, primed and undercoated ready to put back in the boat.

I needed to add a couple more floors to support the end of the aft floor panel and the board behind this panel that will carry two of the batteries. Here they are, glued in place and primed.

Here is the aft floor panel in place. One of the new floors is visible behind it. I'm pleased that the paint matches the original colour - I was a bit worried about this as I created the original colour by adding a bit of dark green paint to gloss white.

I've put the temporary seat back in so I can figure out how to make and support the final horseshoe shaped seat.

Canopy, Cockpit Floor, Seats, Batteries, New Motor and Controller.

It has been a long time since the last post on this blog because I have been doing other things. I built another boat. It is a Derwent Skiff for rowing with a sliding seat. Click on the link to read more about it.

And I built a bridge to replace the old one over the pond in my garden.

Eventually, I started on this launch again beginning with the canopy. The canopy will stand on four stainless steel legs when it is up and will form a lid over the cockpit opening when it is down. Being able to raise and lower the canopy has presented a lot of problems which are mainly solved now. At least I now know how to make it all happen but still have to do the work!

I propped the canopy up on temporary short legs in the shed so that I could position the bases for the legs on the side decks and the fittings on the canopy to attach the top of the legs.This is what the temporary legs looked like.

The deck is sloping where the bases land on it and the legs have to be vertical. I shaped some wooden blocks to fit under each leg. The legs will be held firmly in the bases. The fitting at the top is hinged and the reason for this will become clear, read on.

Once the bases were screwed in place (temporarily) I pulled the boat out of the shed for a trial raising of the canopy. Here is the boat with the canopy in its down position.

First stage is to lift the front of the canopy about half way where it is supported on a temporary prop. The aft end of the canopy is sitting on a cross piece of timber so that it can slide for and aft but not tilt to either side as the front is raised.

This is the hard part! The two legs are put in place passing outside the half raised canopy. I stand on the foredeck and lift the canopy to its full height up and over the top of the legs holding it with with one hand while the other hand locates the legs into the hinged fittings inside the canopy.

Standing on the stern deck the canopy is lifted and held with one hand while the other hand puts the legs in the bases and hinged fittings.  The canopy is now quite firmly supported but I will add some stays at both ends to stop it blowing away in a breeze!

 Lowering the canopy is done by reversing the above process. The whole business of raising with canopy would be much easier with two people. It may turn out that, when the canopy is complete and has solar panels added to it, two people are essential. Time will tell.

The boat has had a temporary floor made out of four pieces of 12mm thick plywood. Three of these run fore and aft; a straight piece down the middle and two shaped pieces on either side. The fourth piece fits behind these. They can be seen in the next photo. I want the floor to have a "planked" appearance similar to the fore and aft decks. I investigated a product called "Top Teak", a synthetic teak looking material and ordered a sample. Here it is:

It looks ok and is a good match to the White Beech decks. It is hard wearing, doesn't stain and has other good features. The manufacturers claim it is less than half the price of a real Teak deck and this is probably correct IF the labout cost is included. My labour is free and the Top Teak material costs at least twice as much as the real timber so I will be using White Beech.

The stern seat is a horse shoe shaped arrangement and I had to make a mock up to get a better idea of proportions and how it would work. The seat has to fit around the motor and its cover. The centre part of the seat needs to be removable to allow access to the batteries that will be under it. The side sections will have lockers underneath.

It is hard to make out in the photo but the two black boxes under the seat are mock-ups of 100 Ah 12V batteries. They are a tight fit!

I need 4 of these batteries and the other two will be under the foredeck. Here they are in place, again a tight fit and, given that they weigh about 30kg each putting them in there will be hard work.

While all the above has been going on I have selected a replacement motor and speed controller to replace the noisy motor - click on this link to hear the noisy motor in operation. The replacement motor is about the same size as the noisy one but has more power. The new speed controller is much bigger and is represented by the cardboard box mock-up in the photo above. The new motor and controller come from The Lynch Motor Co in the UK and won't arrive here for quite a while.

The Canopy.

After a long absence I'm back! Some overseas travel,some health issues and some inertia as I contemplated the making of a canopy for the launch. Now I have been working on the canopy for a few weeks and this is a catch up post to cover progress so far.

The canopy is to protect the passengers from the Australian sunshine. If the boat didn't have to travel on a trailer the canopy could simply stay in place on four legs. However, the boat is on a trailer and so the canopy has to be removable, collapsible or something for traveling down the road. My solution is an oval shaped canopy, same as the cockpit coaming, that can be lowered to form a "lid" over the cockpit for road travel. This will "cover the load" for legal trailer travel and keep the rain, leaves and dust out.

Note that the canopy has now become the lid! To work as a lid it has to be slightly larger than the cockpit coaming. Large enough to accommodate some sort of folding or hinged legs to support it in the up position. For aesthetic reasons it has to follow the sheer line of the hull. So, now it is oval and curved when viewed from the side.

I decided to laminate the rim of the lid from 3 layers of 5mm bendy ply; same as the cockpit coaming. Rather than making a mould to laminate around I used the boat by making a lot of formers that would clamp onto the cockpit coaming. This is what the formers looked like:

The notch fits over the edge of the coaming and the screw clamps the former in place. The L shaped piece at the bottom hooks around the bottom of the coaming to provide more support .

Here they are in place. I found that they didn't automatically stand vertically and needed individual fine tuning. This was done by inserting small packing pieces between the former and the coaming, tedious but it worked.
To hold the formers in place I wrapped a layer of 4mm MDF around them, and screwed it to the formers. This whole structure was surprisingly rigid.

Here the first layer of bendy ply is being fitted. The circumference of the lid is about 8 metres, the bendy ply is 2.4 metres so there are scarf joints where necessary.

Photo of the 2nd (and 3rd) layers of bendy ply going on. This was a very messy business and used a lot of epoxy! The combination of clamps and straps held the laminations together quite well.

After a trip around with the scraper and belt sander to remove the epoxy runs I marked the lines of the top and bottom edges of the lid following the curve of the deck. Now you can see why the laminations needed to be 250mm wide to give me a 100mm wide rim.

I cut along the top edge using a small hand held circular saw (about 70mm diameter blade which follows a shallow curve like this easily) and added some temporary bracing to keep the lid in shape. I don't think this bracing was necessary as the off cuts of laminated bendy ply were stiff enough to hold their shape.

Here the lid is lifted off the boat ready to be turned over and have the lower edge trimmed off.

With the lower edge trimmed the temporary supports were transferred from the top to the bottom and some permanent bracing  added to the top edge. Glue blocks at the ends of all the bracing and halved joints along the centre. I put fillets of epoxy bog around all the joints .

Here is the result, about 3 metres long and 1.5 wide. I have thought a lot about what to cover the lid with, canvas or solid material? I've settled on 3mm ply because it won't sag and puddle when it is rained on and it will provide a better support for the solar panels I will eventually add to the boat.

Here's a prototype leg. Hinged at the top so it can swing fore and aft and also from side to side. At the bottom is a rigid fixing on the deck.

Unfortunately the round bases would not fit in the available space. I could have machined enough off the inside of the base but the result would have been ugly. Eventually I obtained some rectangular bases that solve this problem.

Where do the legs go when the lid is down? Here is one solution but the trick here is - how to clip the legs in the hinged up position when the lid is down? Difficult to get access under the lid to do this and the "clipping" needs to be firm enough to hold the legs so they don't come loose and bounce around inside the boat. Still working on this.

Here is the lid sitting on the boat.

And here it is raised up on some temporary legs as I work out how high is should be. This seems about right but 6 foot people will have to bend a little or wear hard hats.

At the moment I am waiting for the stainless steel to arrive from the supplier. It has been more than two weeks now - I think it is "unobtainium" not simple stainless!

There is a further impediment to progress on the lid and the launch generally: I have decided to build myself a sliding seat rowing skiff. I have been doing a lot of rowing in my Acorn 15 since late last year because I enjoy it and because it keeps me fit and builds up some to the strength I lost while "resting and taking it easy" for health reasons. You can read about my choice of skiff in the new blog.

The Decks

In the last post I had rough cut the white beech deck strips to length. Over the last 10 days I have completed the decking, at least for the time being! A series of photos shows the steps in the process.

The strips were trimmed to fit lengthwise and positioned using 4 mm thick plywood spacers. When all looked OK the strips were taken up, coated with epoxy and laid down in a bed of thickened epoxy. This white beech has an oily or waxy feel to it and so I wiped the surface with an acetone soaked rag before putting the epoxy on. The spacers had to be wrapped in thin plastic; cutting up the plastic garbage bag was a nightmare - static electricity stuck the pieces of plastic to my hands, the scissors, the benchtop, etc. Bear in mind that I needed a couple of hundred of them!

The section at the far side of this photo has the "paver" clamps applied. Unfortunately, once the pavers are there it is impossible to clean up any squeezed out epoxy. There must be a better way. The section in the foreground is waiting for the pavers.

Here is the foredeck after sanding and cleaning out the epoxy from the gaps, a dreadful job but fortunately there wasn't a lot of places where the squeeze came near the top of the groove.

I gave all the margin planks a coat of epoxy before applying tape to all the strips and the margin planks. Then the messy business of putting Sikaflex 291 into the grooves. I worked out the volume of the grooves roughly and bought three tubes of Sikaflex. The black stuff gets everywhere and there is quite a lot of wastage - I had to buy another 2 tubes. Four and a bit tubes did the job.

Here is the after deck after pulling up the tape which came up quite easily and cleanly; I was pleasantly surprised! I went over the whole area carefully with the belt sander (80 grit) and then with the random orbital sander (120 grit).

The white beech strips were coated with Deks Olje number 1 flooded on with a brush until no more was taken up. The white beech didn't want to take up much of this oil and I will put more on later. I prefer the satin look and none slip nature of  this oiled surface; I've done it before and it seems to wear well. The margin planks were given another coat of epoxy and the last 2 photos taken.

I think it looks pretty good!

There won't be anything posted here for some weeks because I am going away for a holiday in the UK. More when I return.

Propeller and Deck Planking

In an attempt to clear up my confusion about the propeller calculations I bought a copy of Dave Gerr's "Propeller Handbook".   This book has far more information than I need but I will follow his process carefully to determine the diam,eter and pitch of the propeller. It will be interesting to see how the result compares with the prop that is on the boat.

I have been working on the planking of the deck. There will be a "margin" plank 65mm wide around the gunwales and the coaming. Along the sides of the boat the 2 planks (along gunwale and around cockpit coaming) will over lap so they will be done in a single piece. I made templates out of cheap plywood for all the pieces because they are all curved. The templates were laid out on the planking stock to minimise waste. The stock was marked and the pieces cut out. Each piece was carefully trimmed to fit in its place and then they were all glued down. A couple of photos show the pieces being glued using 200 mm square concrete pavers.

One drawback of using pavers is that they make it diffcult to clean off any squeezed out epoxy so this has to be removed after it has set and the pavers removed. The trimming of the pieces and gluing them down was done in stages over a period of 3 days.

Here is a photo of the aft deck with the margin and king planks in place.

The space in side is going to be planked with parallel strips of white beech. The beech I bought was rough sawn 100 x 50 mm and 3 metres mm long. I put it through the thicknesser to reduce it to 45 mm thick and then through the bandsaw to get strips 45 x 8 mm.

I rough cut and laid the strips on the deck with 4mm gaps. Here are photos of both fore and aft decks with the strips on.

It will take 2 or 3 days to cut the strips accurately and glue them in pace - more paver clamping!

Maiden Voyage and Test Run Numbers.

There have now been a number of launches in my local lake ad I am delighted with the outcome. There is still a lot of work to do on the woodwork and the final battery arrangements and controls. This short video (thanks Paul) shows the maiden voyage.

I am disappointed by the whining noise from the motor; it is a 3 kW BLDC motor from Golden Motor in China. I will build a sound insulated cover for it and hope this will quiet it down. Apart from that it works well.

By weighing the vehicle and trailer with and without the boat I find that the boat with the temporary batteries weighs about 430 Kg. With me (about 70 Kg) at the front of the cockpit the boat floats level about 30 mm above the DWL. I worked out that the area on the DWL is about 4.4 sq metres so the volume of the 30mm thick slab is about 130 litres or 130 Kg. The total weight (displacement) of the boat when at the DWL is 430 + 70 + 130 = 630 Kg. This is close to the figure of 620 Kg given by the designer.

With the boat floating 30 mm high I made some test runs and took measurements of speed, amps, volts and prop RPM. See below. From the measured numbers on the left I calculated the power required in watts and equivalent HP.

NOTE. This table is a revised version of the original; The measured current was low by a factor of 3.33 and the the calculated speed and slip have been removed. 

The power required is lower than I expected and I believe this is, to some extent, because the boat is floating high so less water to displace and less wetted area. I caught some weed on the prop and had to paddle the boat to the bank so I could clear it. Sitting on the gunwale with a single ended paddle I managed about 1 knot so the boat is easily driven.

Water line length is about 15.25 feet so hull speed is around 5.25 knots. In the video the boat is travelling (right to left) at between 4 and 5 knots.

The prop is second hand from EBay. It is 11.5” diameter x 15” pitch. The calculated slip is much higher than the 40% number I had in my mind and this puzzles me. The calculated slip decreases as prop RPM increases. I don’t understand this at all!

It was (still is) my intention to replace the EBay prop with a better one after making some test runs. I was thinking 12” or 13” diameter and more pitch. On the other hand the EBay one works so need to know what would be gained by changing it and to what.