05/15/04

 DISCLAIMER

Before explaining my method of constructing the current punt I must confess to not having any particular expertise in boat building, and can only suggest that one may follow a similar course of action, if reasonably confident and competent in the use of wood and tools.

Prior to embarking on the construction of a punt, I studied as much information as possible on punt design and the desirable characteristics required to perform well. Some of the most useful information came from Sir Ralph Payne-Galloway and Col Peter Hawker who both give instruction on punt construction, unfortunately the materials of 1880 are hard to find today, and the method of construction used, would consequently be expensive and difficult.

REQUIREMENTS OF A PUNT

A punt must carry 1/2 men plus a big gun.

The punt must be able to be handled by one man without the use of power.

The design must be low to the water for both camouflage and to provide the best height of the gun for an effective shot.

A punt should be long and narrow to give steerage with a pole or oar at the rear. (Minimum 17' single 20'+ for a double) Note buoyancy gained by extra beam will spoil the ability to stalk birds, and will cause the bow to ride over waves loosing the gun aim. A good punt will cut through small waves.

It will be obvious that a punt that performs well on birds is not sea kind, and will become a positive liability when conditions get rough or windy. Like in all circumstances of life, a punt design is a compromise!!!

MY APPROACH TO THE PUNT DESIGN

Materials

Where possible I required modern materials and sensible prices.

The frame was to be a structure of thick plywood frames with stringers (long lengths of soft wood) stretched around them to a bow and stern block preferably made of oak.

A skin was to be made up of 9mm plywood sheets 8'X4' (giving an optimal length around 24' i.e. 3 sheets long).

All fixings to be of BRASS.

STARTING THE BUILD

My first acquisition for the build was the stringers. I was lucky to obtain from my local Jewson's yard pieces of Canadian Hemlock 32 feet in length. This was cut specially for me, by a sympathetic saw man, who sliced the required 2"X1" stringers and a 4"X1" Hog (Inner Keel) out of a massive Beam, selected to have no serious knots in the full length.

I then obtained some 18mm ply to produce the cross frames.

Borrowing from Payne-Galloway I shaped 3 frames to the dimensions of his largest double punt at amidships, 5' from the stem and 5' from the stern.

Fixing the frames to the hog, to correspond to the length of punt specified, I screwed the 3 frames in position.

Next 2 stringers were screwed to the middle frame at the gunwale position. The stringers were then cautiously bent to come to a point at stem and stern and then clamped together whilst further brass screws were used to secure the stringers to the front and rear frames. The process was then repeated at the chine position for the last 2 stringers.

At this point the boat builder’s eye becomes important.  To obtain a good line for the punt it is essential to adjust the point where the stringers form the bow and stern to give a suitable rake to the ends and a corresponding flare to the sides. I believe if it looks right it probably is!

When these adjustments were complete my punt had grown to 24' 8".  As the bow and stern blocks would be significant in their length I would still be within my 3 X 8' sheets long.

My next task proved to be one of the hardest I have undertaken, forming the bow block!

My raw material was a farm gate post at least 40 years old and well matured.  I had long sung the old shanty    "Harts of Oak”, but never quite grasped the meaning.  My post was a mature, seasoned, Hart of OAK around 6' long and 6"X6" section.

My plan was to shape this block in about 1-2 evenings after work.

I started with a ½" drill bit and a Black and Decker drill. Drilling holes along the post to the rough outline of the bow block I sought to reduce the amount of sawing and shaping by hand.  After some 10 hours of drilling, punctuated by frequent cooling down sessions for the drill, I had all my holes done and had worn out the Black and Decker.

Next step was to use a very sharp fireman's axe and a sledge hammer to cut and wedge off the excess wood, by cutting between the holes. A week later I was ready to use my plane, a good sturdy old tool with a rock hard blade. With a sharp edge on the blade I took 2 good cuts off the wood, the 3rd cut just didn't!  The blade was blunt again! Sharpening the blade I started again. Same thing again!

The task was finally finished by a combination of wood chiselling and planing it took another 3 weeks of hard work to complete the shaping.

Next task was to fit the new block to the front of the structure. For strength it is essential to have all timbers bearing firmly against the oak block. To do this a series of joints were cut for the stringers to accurately bed into the oak block with a suitable shoulder for the ply wood skin to but against it on all sides. This work with mallet and chisel took a further 3 weeks.

Having trimmed the hog and stringers to fit the bow block, the block was secured with No12 brass screws and Cascamite wood glue.

To produce a strong and rigid framework, a number of frames have to be inserted at intervals throughout the length of the craft. This was achieved by choosing the position of the frame, measuring the sizes required and adding the appropriate curves for deck and bottom and making the frame to size. Where the dimensions were slightly asymmetric this was corrected by taking an average and the stringer pulled to the correct line with the usual brass screws.  A point to note at this stage is the need to allow water to run fore and aft inside the punt by cutting out a suitable notch on each side of the hog, this task is best done at this stage of the build, before securing the frame into structure.  All frames are constructed as a complete "O" with curves on the top and bottom corresponding to the deck and underside curves (aside from the effect on boat handling these curves add great strength and stiffness to the finished craft).

At the Gun Beam (mounting position for the big fun a double thickness of ply was used for extra strength and rigidity and extra knees added to pass any recoil stresses into the stringers at the gunwale.

To form a cockpit, laths of wood were first tacked into the top of the frames to follow a suitable shape in which to operate the boat. Carefully the frames were then be cut to match the curved shape produced (the structure is quite stiff and strong at this point and the timbers should not move). New stringers of 1"X1½" were then affixed to the cut frame ends to form the cockpit after which the laths were removed.

Before fitting the plywood skin, all edges had to be chamfered to match the contact with the ply.

Fitting the skin is a set of challenges, as the material is to be bent in 2 directions and in varying amounts the position of the edges is somewhat unpredictable, to this end a much larger piece of ply has to be cut than would seem logical. Each piece of ply also needs to be overlapped in a half thickness joint to provide waterproofing and a smooth outside line. Starting against the bow block the sides were first fixed. The fist few screws were fitted at the bow block, and the ply bent a little and clamped, two holes were drilled in the chine and gunwale and screws fitted. The clamps were then moved a few inches further along the craft and the process repeated.  To drill more than 2 holes per step causes the holes to become hopelessly miss-aligned. Screws should be about 2" spaced along the frame (even at this distance screws come under shear strain as the work progresses).

Note: it is better to do a little each side of the punt rather than do one side then the other. 

 After carefully fitting the last piece of ply to the stern block, the ply was rough sawn close to the stringers and finally planed to provide the chamfer to accept the bottom and top ply sheets.

Again starting with the all important bow block end a full sheet of ply was screwed to the hog at 1 ' intervals. Next pilot holes were drilled and a second set of screws were partly inserted about 4" from centre line of the hog in each of the cross frames. The screws were slowly tightened a little on each in turn keeping the balance on each side of the punt until the ply was tight on the frame with the curve obvious. The process was then repeated at a further 4" out on both sides, repeating again and again until the bottom sheet was firmly against the chine stringer and side ply.  Again starting at the bow the bottom ply was stitched (screwed) at 2" intervals onto the chine stringer.  The excess ply was then rough sawn to the outline of the craft, (leaving the final trim to planing).

The second and third sheets were applied in the same style, giving a generous half thickness overlap joint between sheets. (The most difficult task here is the careful fitting of the ply to the stern block without gaps or overlap).

NOTE:  The ply must be bent gradually and symmetrically, otherwise alignment problems will occur as the timber is bent in two planes (which it does not like). The curve in the ply gives immense stiffness and strength.

 The bottom was finally planed to the edge of the side ply and finished with a rubbing strip of "D" shaped hard wood.

Fitting the deck ply followed a very similar process, with the exception that the side decks were able to be made from separate pieces of ply and had to be planed to the shape of the inner cockpit as well as the gunwale.  The rubbing strip at the gunwale was made by cutting a stair hand rail length ways giving a much broader "D" section to protect the craft in harbour.

The cockpit edge was lined with ply to provide a splash coving 4" above the deck and extending some 15" onto the forward deck. A small detachable section needs to be provided near the rear for the purpose of poling etc.

The final part of the construction is the fitting of duck boards on which to lay down during stalking the birds this I made from a sheet of ½" ply screwed onto each frame.

Having constructed a punt, the only requirements are the fitting out! i.e. rowlocks, gun crutch a means of fitting the breaching rope to the bow block and a secondary safety rope to the gun beam, and the all important anchor chain to the stern.