Week 18/19 - Canvas / Rails / Benches

Sheating with canvas was one of my big wishes but I didn't want to use it on the maindeck. So the plan was to use it on the coachtop.
I found an excellent quality of canvas at John's Traditional Boat Supply 

http://www.tradboats.com

John was also very helpful with tipps about the correct use.

My idea was to use that traditional material with the possibilities and the high durability of modern epoxy.

And indeed the idea worked really well. We started with some samples to find out which would be the best way to apply it.
That canvas comes in a width of 2.74m which allows to lay quite big surfaces without any need for seams.

After cutting to size with an appropriate overlapp at the edges we first coated the whole coachtop with plain epoxy resin. Then we layed the canvasfabric relaxed over the whole surface and molded it from the centre to the sides just with our hands (with gloves for sure). It's really important to do this with 2 persons so that all molding can be done symmetrically.

The next workingstep is to add epoxy with a wide brush and stipple it on the canvas until all is fully wetted through. It finishes by using squegees and working again from the centre symmetrically to the sides.
The target is to achieve a topsurface showing a relatively rough fabricpattern which acts as an antislipsurface.
At the edges the fabric should be pulled and glued over the edge with coppertacks. The amount of overlapp depends on the later covering  rubrail, just make sure to cover all fabric and some mils more.
As visible on the photo all edges and roundings have to be treated with all necessary cuts and the canvas can be cut after getting green (time depends on the temperature).

Before finishing the boat for all painting and varnishing we had to fashion and fasten all rails and rubbers. The photo below shows the rubber along the coachtop, the quadrant covering the deck-coaming joint, the toerail and rubber along the sheer with holes for waterdrainage and fenderfastenings as well as the slotted rails for the slidinghatch on the top.

All these elements were fashioned from sapele mahogani, scarfed to extend the length were necessary and smoothly rounded.

The toerails needed beeing steambent some weeks before allready otherwise there would have been to much stress in the material with the risk for cracking. During the decklayingwork we had possibilities to fix temporary wooden blocks from the underdecktop into the beamshelf. This allowed to use the boats sheer as a former when steambending (see photo).

This works really well but two aspects are important to be considered. One is the fact that after clamping for about 24 hours when releasing the clamps there is quite a bit of springback in the material. This is no problem but the elements should then be stored somehow in the bend shape.

The other point is that there should be an appropriate time of drying to get the moisturecontent in the timber down to 12-15 percent before glueing with epoxy.
All fastenings are both glued with epoxy and screwed with siliconbronze screws. We used screwdiggers and grainplugcutters to get all mechanical fastenings covered with wood (see on photo).

And this is how the finish looked at the end.
I should name that the filigrane quadrant between the deck and the coamings is fastened with brass panelpins instead of screws... to get a more descreed detail. But the panelpins are punshed 1 mil in and the gap got filled with thickened epoxy with also added sapeledust to get a similar color.

Now some details about the benches in the cockpit. The basic construction consists of marine plywood combined with some hardwoodframing.
Connected to the cabin there is a benchbridge which can't be opened. It works as a extension of the insidespace! The aft bench towards the stern is a buoncytank with a watertight hatch (can be used to store fenders).

The sittingarea of the benches ends with a smoothly rounded hardwoodpiece which sticks up about 3/4" over the surface. Behind thisone there is a storagesurface for all kind of things which are in use when sailing (polsters, books, lifejackets etc.). We called them backbenches.
This is also the space where the two oars are stored but hanging on the deckunderside.

The two sidebenches are equiped with openable lids (benchboards hinched to the sapeleframe) with a waterdrainagechannel to keep water from the sea or rain outside. They are not fully watertight but will in case of an emergency also act as buoncy, at least for a limited time.
The benches are fashioned of prudently selected sapele mahogani boards. We will later see pictures of the final varnished look!

On this picture you can see the storagespace which is available round the whole cockpit. On those backbenches we used normal marine plywood which later will be painted white.
Considering the fact that Glóey is a little cruiser I designed the benchdepth extra generous.
The photo to the left gives an idea of the dimensions :-)

Week 18 - Rudder / Centreboard

Both the rudder and the centreboard were fashioned in a similar way.
I decided to build them out of a 6mm core of 316 stainless steel and glue marineplywood on each side of it. This results in a very strong sandwich which resists undesired contact with  the ground or other things that could affect damage.

The first photos show the rudder with the 6mm steelplate welded on a 1" stock.
I changed both designs a little bit compared to the original drawings. The rudder to keep it lower for a free view on the transom and the centreboard because of the changed centreboardcase relating to the benchbridge and the cabindesign.

The marine plywood was glued on the steelplate with thickened epoxy (with colloidial silica) after a prudent surfaceclean and sanding. Then I shaped a profile with the target of getting a smooth transition from the deadwood of the woodkeel to the rudderend. For that reason the rudderblade became quite fat in it's dimensions! But later when seeing it fastened on the boat it will be balanced proportions I promise.

The final profileshape of the rudder is visible on the photo to the left.
You can also see the centreboard ready for sheeting with fibreglasscloth and epoxy. In both cases we used a plain weave and not biaxial cloth as on the hull.

When sheating the first side we pulled the glasscloth over the edge and cut it after the epoxy got "green" (depending on the temperature about 2 hours after mixing).
Then we laminated the other side in the same way which results in an overlapp at the edges.

Back to the rudder... thank's to the fact that the rudderblade was welded on a stock we could clamp the whole thing in a vice which allowed to sheat both sides at the same time.
Beside that the photo also shows the different veneerlayers of the plywood which were shaped to a profile and therefore got that special pattern.

The glasscloth could be pulled around the rudderstock and along the outlineedge we made a lot of small cuts with a scissor to make it easier to get the weave molded around the rounded edge.
The pictures don't show the process of spreading a coat of thickened epoxy with added glassbubbles after about 1 1/2 hours over the whole surface. This will be an easy to sand surface to later get rudder and the centreboard nice and fair.

On the right side you can see the finished centreboard just before getting fitted on the boat. The whole surface has got 2 coats of antifoul.
At the pivotingpoint we glued a stainless steel bush in and on the topside there is a hole in the corematerial which formes an eye. This is the point where the shackle of the pulley-block is attached. This arrangement allowes a comfortable control from the cockpit.

Some chiselwork had to be done for fitting the rudderheel at the aft end of the woodkeel.
The fitting is an own design and is welded together out of 5mm 316 stainless steel.
The flange of the rudderstock is gliding on the visible nylonbush which has got a drainhole on the bottom.

Finally we got the rudderstock in and skrewed the fitting fast.
But before screwing we sealed the whole bare wood with epoxy and also covered the whole contactsurface with butyl mastic.
Well... that should be really rigid!

Week 17/18 - Transom / Mast

Until now Glóey's raked transom consisted of 2 sheets of 1/2" marine ply. This was a very rigid and formstable solution but now it was time to cover the plywood with the final sapele mahogani veneers which are 1/4" strong.
We selected a nice straight grained board and glued the whole transom together out of 4 pieces. A shootingboard and a Nr.7 jointerplane did an excellent job to get an absolutely tight fit.


The transom veneer then was glued with epoxy by using the vacuum bagging method.

With other words... we used the atmospheric pressure to get the transom veneer best possible flat on the transom.

The photo on the side shows the setup relatively well... there is an external vacuumpump and through a plastic-hose the air got sucked out of the polythenebag which is sealed around the transom.


Inside the bag there is a breathercloth, and a perforated releasefilm.

After mixing the epoxyresign with it's hardener we've let the pump run for about 6 hours to make sure it is cured enough.
Before glueing we screwed the transomveneer fast with 2 screws which were positioned under the future nameplate. 

There were just no really good clamping-possibilities and it should absolutely not move also not when the vacuum starts shrinking the bag.

And this is how the transom looked finally with the nameplate on. The last one is waterjet cut out of a 3mm piece of naval brass, one piece fixed with 4 screws and easy to take off when refreshing the varnish in the future.

The mast was another part that was fashioned parallel to the transom.
We used Douglas Fir which is very long grained and even stronger than Sitka Spruce. But it is also quite a bit heavier.
The mast consists of 8 strips that were machined with a so called birdsmouth.


When fitting them together it forms an octagon.
This method creates a hollow and very stiff mast.

All strips had to be extended with scarfjoints to reach a total length of about 6.3m.

Inside The mast we bedded a nylon tube for the electrocabel of the toplight and several massive wooden cores were mastbands could be fitted.
When glueing the birdsmouthconstruction with jubileeclips two opposite joints were left glueless to first get 2 halfs. This is the way how to access the inside.

To get a nice and smooth round surface of the mast the workingprocess is the same as earlier described on the post about oarmaking.

The mast is tapered and it has 2 diameter steps or rebates which help to keep the bronze mastbands in place.

At the bottom end the mast is shaped square to fit into a tabernacle with a pivotingbolt. This solution makes it easier to rigg the boat.

The crucial point here is to avoid loads on the bolt when the mast is in use... the hole for the pivotingbolt is a little oversized so that the pressure on the bolt gets relaxed as soon as the mast reaches the upright position... from that moment on the loads are stepped down to the tabernaclegroundplate.



The tabernacle is an own design which is drawn in CAD. It is fashioned out of 8mm strong pieces of 316 stainless steel plates that were lasercut directly from the CAD-files.
I welded the parts with a TIG welder and let the whole tabernacle through a sand- and finally glas-blasting process which resulted in a smooth silvergrey finish.



On the photo below the mast is sitting in the tabernacle and all 6 turning-blocks for halyards etc. are mounted on the groundplate.

Week 17 - General fitout cabin

It's a bit different now to write posts in my diary of the built of Glóey...

The reason is that she is finished since some days! We launched her on december the 5th in the COBB harbour of Lyme Regis on an amazing sunny morning with a ideal breeze.

The last 4 weeks were so intense that I didn't find time to also go on writing my diary...

However there are about 8 posts left to complet the documentation of the whole buildingprocess of my little gaff cutter and I will absolutely bring this to an end which can be a inspiration to any other boatbuilder or any friend of wooden boatbuilding.

OK... week 17 was dominated by a range of different general fitouttasks on the cabinstructure.

The first thing was the frameconstruction for the dropboards. As shown on the photo I fashioned this frame twosided... clamped around the 1/2" plywood of the mainbulkhead.

Framecorners are rigid and nice looking halfingjoints made with saw, chisel and plane.

It is very important that this framingelements as well as the rails for the sliding hatch (comes later) are positioned very accurately to ensure a smooth gliding when opening and closing the cabin.

A long awaited moment... fitting the portholes!
These beautiful portholes are made in very solid bronze and have a inner diameter of 100mm (outer diameter 170mm). They where placed just in the centre of the scarf where the coamings are joint. This reduces the visibility of the scarfjoints.
The portholes are openable and therefore a good possibility to ventilate the cabin.
I found them at www.toplicht.de a fantastic store with parts for classic boats in Hamburg.

Before completing the coachroof in marine plywood we had to build several reinforcing elements into the roofbeam-structure.
Between the laminated beams of mahogani (3mm Khaya veneers) we added a strong 1" plypad positioned under the future masttabernacle and a 2" round stainless compressionpost inside.

There also were two 60 mm strong knees to bring the loads of the mast into the coaming and deckstructure. The "mastpartner knees" are made with laminated khaya veneers in the same way as earlier explained on the stem and sternpost etc..
The bend laminatepackage got fitted into a concave shaped solid back.

It's hard to believe that the following two photos where made at nearly the same moment. It shows that the insideparts of the cabin-structure were totally finished at that stage while the outside still is rough and unvarnished.

In the near future the interior of Glóey's cabin will be completed with 2 berth so that she can be used as a little cruiser.
But during the time at the Boat Building Academy we'll only keep the interior empty... she is anyway quite an ambitious project to be completed in 22 weeks :-)