Hull

Planked Hull
Plaster Half Mould


 
 
 
 
 
 

Initial Planked Hull


 

Initial Keel

Keel

The plans show that the keel is made up of various sections. Using the slotted method of construction, I made the keel in one part using plywood. A photocopy of the keel was stuck down on 9mm plywood (4ft x 2ft) and cutout with a Band Saw.

Keel

The top/deck is cut on the line shown for the deck on the centre line (Pont au centre). It was cut off at the point where the rudder shaft would go. The cutting line for the central part used the top of the keel but added more to the aft end.

Initial Frames

framesl
framesl

Photocopies of the frames were stuck down on 6mm plywood and cutout with the band saw leaving 10mm excess on the top.

Initial Keel and Frames

frames
framesl

The frames were cut to fit the keel. The bottom of the frame lined up with the dotted line on the keel. The top of the frames were cut so they aligned with the top of the keel. Note that the bottom of the cutouts in the frames aligned. I cut too much off the slots. The amount cut off from the top of the frames varied considerabily.
The more I tried to make corrections the worse it got, so I decided to start again.
 
 

Revised Keel Design

New keel

This time I am going to use 6mm multiply as I can source a better quality product from a model shop. Also it can be used for the frames.
The whole lenght of the keel is included as the stern section is critical. A section for the rudder pipe is cut out and then the two sections rejoined with 1.5mm ply plates. The plates are v-grooved out one ply to accept the larger 7.5mm rudder tube.
The top is cut 2.5mm down from the deck centre line to allow for 1.5 ply deck and 1mm planking.


 
Revised Frame Design

The frames were cutout from 6mm ply. The drawings on the plans were inaccurate. I photocopied the plan, cutout templates for each frame. I folded them along the centre line only to find they were not symetrical. I corrected them.
I cutout slots 10 x 3 to accept a fore/aft stringers 5mm in from the edge of the frame. I found that you could not bend them so I cut them in half to 5 x 3. In hindsight, they were not needed.

New keel

Chamfered ply pieces 1.5mm are glued at the bows to locate the hull planking, (shown below). The two triangular pieces strengthen the underside of the deck for the Winch Bitts.


 
Hull and Frames

New keel

When I tried a hull plank at the top of the frames it looked wrong, It did not bend in a smooth curve. They should match the curve of the deck. So my next step was to cutout a template for the deck 1.5mm ply. I again folded along the centre line to see if it was symetrical. Yet again it was incorrect. I made corrections and cutout the deck ply.


 
Deck Ply

ply deck fittedl

The deck was screwed down along the center line of the keel to keep it straight. The edges of the deck were screwed down at various points to pull it down to the frames. This showed up the fault. The frame tops are incorrect.
The deck edge was adjusted to a smooth curve using the screws. Blocks were glued to the frames to locate the deck.


 
First Plank Set-out

fitting first plank

The first hull plank was glued and nailed on using a jig to set it 5mm below the top of the deck planking.


 
4 Half Planks

first 5 planks at stern

The 10 x 2 hull planks were cut in half to 5 x 2 so they can be bent and twisted to fit the frames at the bow and stern. Many nails are partially inserted then removed when the glue is set. Some have to be fully nailed to bend the planks. A nail punch is used to drive the heads below the surface.


 
Bow Stiffeners

Planking at the Bow

The original 1.5mm ply was not thick enough to support the plank when nailing. It was changed to 6mm.


 
Keel Enlargement

Keel extension at stern

To solve the problem with the stern area, the keel was increased in depth by 25mm. Ply plates were used to hold it to the existing keel. This allowed the Transom to be attached and the hull planks have a good shape at the stern. Strengthening ply fillets were added between the Transom and the rear frames, they also act as supports for the Futtocks


 
Keel Thickening

Keel thickners

The keel was thickened up to 9mm by adding 1.5mm ply along the bottom upto the Stem. This allows for a smooth transition from the keel to the hull planks.


 
Middle Plank

Mid plank

A plank was positioned half way up the frames parallel to the deck at the middle frames. It was spaced by using 7 pieces of planking. To bend it to the bow and stern it was necessary to chamfer both end from 10mm to 5mm for a distance of 300mm. This also means that all the planks will fit.


 
More Planks

More Planks

More Planks were added both sides until I ran out. I only ordered enough for one side.


 
Bulwark Posts

Bulwark Posts
Bulwark Posts Jigs

The 42 Bulwark Posts were cut to length. They had to then be cut to match the cuve of the hull. Surprisingly, little wood had to be removed, some could be glued straight on.
The top hull plank had been carefully fixed using a jig so that it was a smooth curve at the correct distance down from the deck planking. I made a jig to set out the corrcet angle for the podt top and its height.
The hull had been set on its supports level with the watwrline. A large Tri Square was used to set the posts vertical fore/aft.
Finally, the posts had to be vertical across the hull. I made a jig that sat on the hull planks with a series of lines at right angles. Allowance had to be made for the deck curvature.
Only one post was slightly out of alignment, causing the bulwark plank to bend inwards.


 
Bulwark Rail

Bulwark Rails

The Mahogany rails 12 x 2.5 were cut from a sheet in two parts. Both rails were cut from the same template, this shows the accuracy achievable using jigs to set the Posts.
One side was glued at a time using rubber bands and timber strips to bend the rail to shape and to level across.
The rails were planed, filed and sanded to shape using a 2mm off cut as a gauge for the overhang.


 
Transom

Stern

The stern section was made up as I went along as the plans gave little detail. The stern posts were made too thick at the top so the Stern Rail is straight on the inside and curved aft.
The plans show a curved stern and the photo below shows a smaller transom. Next time I can correct this. The transom has been fitted at an angle so the rear section of the hull is slightly twisted. It will be interesting to see if this becomes apparent when in the water.


 
Ballast

Triall - Ballast placed on hull

When I first placed the hull in the water, it just floated on top like a duck. 4kg bags of potatoes were loaded on to bring it down to the waterline (masking tape).
Knowing the weight of ballast needed was the easy bit. Finding a supplier at a reasonable price took a long time. The pre bagged lead shot costs delivered £19 to £23 per Kilo. The local Roofer wanted £2/kg for scrap lead sheet. I could get lead shot for £5 for a minimun half ton! I found a good source but I had to buy a lot more than I needed so I will sell the remainder in small quantities at www.leadshotballast.co.uk

Its amazing how small a kilo of lead shot takes up. I filled thick plastic bags with half a kilo and distributed them along the bottom. I placed the lead acid battery in its location as it weighed nearly a kilo.
The deck fittings, spars, sails will add weight so I only used 3 kg leaving space to ballast down to the waterline on completion.
A tablespoon of exterior spirit base varnish was added to the bag and coated the shot. It was then poured into the hull and leveled. The hull was put in the garden pond to check the level. Adjustments were made for the battery. Next day I added a thin layer of plastic padding to seal to top, using strips of thin plastic bags to even it out.

Ballast in hull
Ballast in hull

 


 
Rudder

The rudder shaft is made from 1/4 inch solid brass with a 2.5mm hole drilled in the bottom end, this fits on the 2mm pin at the bottom of the keel. The brass rudder tube is a loose fit on the rudder shaft. The lower part is attached to the rudder blade. The top part goes through the keel to the deck. It is glued and sealed in place.
 
The rudder blade is made from 6mm ply faced either side with 2.5mm mahogany sheet which is slightly wider and chamfered to go up the side of the tube.
 
The blade is fixed to the tube with Plastic Padding which also fills in the gaps. Two holes are drilled through the tube to take the fixing screws. The rudder assembly is then filed and sanded to radius the ends. Primed and sprayed painted finished off with coats of laquer.
The black blade is the original which had little effect on the steering during the initial trial.

Rudder details

The rudder shaft is feed down the rudder tube from the deck passing through the rudder blade until it mates with the rudder pin. 2 holes are marked on the bar. When removed, these holes are drilled 3mm and chamfered to suit the No4 x 25mm brass countersink woodscrew. The parts are reassembled and the screws fitted so the tops are just below the surface of the tube. Blue-tack is used to fill the screw heads flush with the tube and then painted over. They can be easily removed.
The rudder blade surface area nearly doubled from 49 to 85 cm sq. The two crosses show how the blade's centre of effort moved.

Rudder details

The top end of the rudder shaft is cut horizontally. A 3mm hole is drilled at right angles for the tiller. A 1mm hole is cross drilled through both to lock them together with a short brass pin.
A hole is drilled to take the 1mm brass rudder arm. 0.75mm brown RC control string is tied to a loop giving 3cm leverage.
The cord is feed through vents on the bulwarks and then down plastic tubes to the rudder drum. The white plastic dummy vents were drilled and filed smooth before gluing the halves together.
 
The drum on the servo is made from 3 layers of 2.5mm ply. It is used rather than a lever as this gives a constant torque over the whole rotation. The middle is 70mm diameter and the two 80mm side retain the cord as it turns. The drum diameter and the rudder arm length were found by trial and error. The servo has to travel to its end stops with the tiller 5mm from the bulwark rails. The adjuster on the transmitter centres the tiller. The drum is atached to the servo by nailing on the cross arm actuator. A central hole is drilled to suit the screwdriver used the fix on the cross arm to the servo.
 
The location of the RC components were moved before the trial to try to stop the rudder servo clitching. When the rudder was moved quickly to one side, it would suddenly move right across to the othe side then back again. This still occured during the test on Penn Street pond


 


 
Name and Number

Name and numbers on hull side

Font style taken from the plans is Century. Font height for name is 24pt and 75pt for numbers. Computer printed then laquered to give a near matching black gloss; Cut out and glued on (no double sided available).
From pictures, the name and port are on seperate curved boards to suit the curved transom. Here they are straight.


 
 

Plaster half mould

The side view of the hull was drawn first getting the waterline length (73.4 cm) correct and the 10 frames spaced equally.
 
The heel of the keel was a problem. If the hull draught was to be correctly, the angle of the rudder would significantly alter, as the bottom end is tied to frame 8 and the heel. The draught was decreased by 5mm to compensate.
 
The dimensions of the stem, height and curve of the bulwark rail were very vague. I made a best guess using both plans and photos of the Jolie Brise. The curvature of the bulwark rail governs the hull planking and deck.
 
The whole point of this exercise is to establish the shape of the stern. Neither plans were of much use. Photos of the Joile Brise were taken after a complete refit in the late 70's.
 
The keel was cut from 5mm ply and screwd onto 12mm laminated chipboard. The top is curved to the underside of the bulwark rail.

half plaster mould 1

4mm ply was cut to the bulwark rail from stem to stern. It slots into the grove and then fixed at right angles using blocks and small rectangles of ply near each section.

half plaster mould 2

Each frame was drawn on thin card and slightly adjusted to fit. 4mm ply was cut from the template, chamfered to suit the curve and glued in position. Blockes were added for strength.

half plaster mould 3

The gaps between the frames were filled with crumpled newspaper and layers of finishing plaster leaving a 5mm space to the hull surface. Cheaper than Plaster of Paris and has a longer setting time.

half plaster mould 4

Batterns were nailed across some frames to show to curvature of the hull. Plaster was built up in layers to get the shape. Plaster of Paris can be smoothed with a chisel or straight edge. If I did it again I would nail batterns across 4 frames to give smooth curves with no gaps then pour in the plaster. Do a small section at a time, Plaster of Paris sets rapidly. I used about 4kg of plaster. A lot of water has to evaporate. It took 7 days to dry out completely.

half plaster mould 5

Plaster of Paris is easy to work with a chisel and abrasive paper. I use oxide rather than glass/sand paper as it does not clog so easily.
The shadow of the frames are just visible below the plaster. Frame 8 was the biggest problem and had to be cut back. Frame 9 was wrong and frame 11 was added but you cannot see it.


 
 
half plaster mould hull starboard aft

The aft section worked out well looking like the photo's of "Jolie Brise" from the book and website. I was able to create a smooth flat run off to the aft and get the stern curved and angled.
The aft bulwark section took a lot of filling and cutting to achieve the correct look. The original French plans were useless.


 
 
half plaster mould hull bow

As I want to keep the original half model, I will take a mould and produce a solid plaster duplicate which can then be cut along the frame lines. Accurate frame and half frame drawings can be made by tracing the plaster sections.