How to Build a Thames Punt
Capt. R.F. Wykeham-Martin,
from The Yachting Monthly, March, 1919.
Quoted by R T Rivington in his book "Punts and Punting", 1983
R T Rivington in his book "Punts and Punting", 1983 ISBN 0 95080452 5
has this article in an appendix, and comments:
Note: Capt. Wykeham-Martin adopted and described a method of fixing knees to treads devised by himself; he was obviously satisfied with it. It would never have been used by punt builders on the Thames. He screwed the knees to the sides of the treads. Knees were morticed into treads and fixed with dowel pins in different ways by different builders. In the best punts, however, the knees were dovetailed into the treads and fixed with screws.
THE punt described is the ordinary Thames pleasure punt, 28ft. long, with 3ft. beam.
The materials used on the Thames for building these craft are as follows:-
§Sides, mahogany, 5/8in. thick.
§Bottom, yeo deal, 1in. thick.
§Treads (as the floor timbers are called), teak or oak, 6in, and 1 1/4in.
§Knees, oak or teak, 5/8in. thick.
§Huffs (the end thwartship boards of the punt), 11in. and 1 1/4in., oak or teak.
§Deck, 1/2in. mahogany or teak, and 1/2in. pine.
§Grating slats, 1in. x 5/8in. mahogany beaded on both edges.
§Grating slat bearers, l 1/2in. x 5/8in. mahogany.
I built the punt I am describing in Mesopotamia, with Oregon pine sides and gratings, teak treads and knees. The sides had to be in two pieces, the top strake about 3in. wide, close jointed with a thread of caulking cotton pressed into the joint which made a watertight job.
The punt turned out a light and easy running one, and pine sides look very well when varnished.
The boards for the sides should be about 15in. wide, and the grating stuff can he bought ready beaded.
The stocks should first be set up as shown in Figs. 2 and 4.
To make these, screw a piece of 3in. by 2in. flatwise on the floor; on the side of this screw two pieces of 7in. and 1in, floor board in a vertical position; and across the top of these screw a piece of 9in, by 1in. board, horizontally. The top of this must be perfectly level and 2ft. 6in, above the floor and 27in. wide. Projecting pieces can be left on the board, as shown in Fig. 4, to assist in putting up the sides.
Two sets of body stocks as described must be set up with the tops level with one another and the outside faces of the top boards 10ft. apart.
A pair of stocks for each end must be set up also, similar to the others, but with tops 1ft. 4in. wide, and the top board must he level and 11in. above the height of the body stocks and spaced apart from them, as shown in Fig. 2.
A lighter set of stocks 2ft. 6in. wide must be erected midway between the body stocks to give the rocker of the bottom when it is shored down; the height of these must be 1in. below the level of the top of the body stocks.
When all these stocks are up, properly levelled and braced, as shown in Fig. 2, the bottom boards may be planed up on one side.
The bottom will take four 9in. boards, and, as it is only 2ft. 6in, wide, there will he some wood to spare and a long drawing batten can be made out of it.
Spring a chalk line down one of the boards, two inches from the edge, saw out the batten and plane up the edges true and square. Then take the narrow board, spring chalk lines down it, and saw out a 1in, wide board with straight and parallel edges. Lay this board on the floor with one 9in. board on one side of it and two on the other, and, if the four boards cannot be made to close up by pulling them together by hand, the edges of the boards must be shot true till they touch.
The floor boards must now be cleated together with four battens, screwed on the underside to leave the top clear for drawing upon.
The joints must be left slightly open (the thickness of two pennies in a gauge used by some punt builders) and on no account must the boards be cramped up close, for a reason which will appear later.
The four boards being cleated together, snap a chalk line down the centre of them and pencil this line in with a straight edge.
Then, starting from the centre of the floor, mark off distances of 21in. each way and square off lines right across the boards, at these points, which mark the centres of the “ treads.”
Number off the stations so marked, as shown in Fig. 1, and from the line showing “top of floor” mark off the half breadths at five stations as follows:-
1ft. 1 1/2in.
1ft. 1 1/2in.
Drive some panel pins into these half breadth marks, and bend the long 2in. fairing batten, round the nails, fair it with the eye and pencil in the curve of the side.
Mark off half breaths at each station on the other side, so as to get the two sides alike, and draw in the line of the side as before.
From the centre lines of the “treads" measure off distances of 3in. both sides and square lines across the boards, which will give the position of the 6in. treads.
Now set a bevel to the angle of the flare of the side, which in this punt is 99º, and saw out the bottom of the punt as near as possible to this bevel, but just outside the line to allow for trueing up.
The floor must now be set up on edge and the edges planed up to the correct angle of flare.
This must he very carefully done, not only to get the correct bevel, but to also make a true fair curve to the edge, without “ humps” in it, so that the sides when screwed to the bottom will bed in close and make a watertight joint.
When both edges are bevelled, the bottom can be shored down into position on to the body stocks, and screwed to them with four fine screws.
Now take a length of the 6in. x 1 1/4in. oak or teak and lay it across the "tread" station at No. 8 and mark the shape of the top of the bottom of the punt on the underside of the tread, with a marking knife; then with the bevel mark up each side of the tread the angle of flare, and join the two lines across the top; do this for both ends of the tread and then saw it out and plane up the ends to the angle of flare.
Now out of a 5/8in. board cut out two knees of the shape shown in sketch (Fig. 3), taking the height of the stem plan (Fig. 2) and allowing for the flare, rabbet out the side of each knee 1/8in. deep, to fit the side of the tread; then notch out the side of the tread 1/2in. deep and fit the knees carefully and screw them on to the tread with two 1 1/2in. No. 10 brass screws.
Note.—Thames punt builders generally mortice the knees. into the centres of the treads and through fasten them with a 1/4in. brass pin, but I think the shouldered method is the best.
Now the tread with its pair of knees complete can be screwed into position on the punt floor, using 1 1/2in. No. 10 screws, countersinking them well in from the outside, as the bottom will have to be planed up.
Try the angle of the flare of the knees and bend a piece of board round the edge and the knee to see that it is all fair and that the knee does not project too much; if it does it must be planed away.
Next, two complete treads and knees must be fitted at Stations Nos.5 and 11, but in these the knees must be given the proper bevel in a fore and aft direction as well . Also, as all knees are to
be fitted vertically, the angle of the notch in the side of the tread must be marked on the end of the tread with a plumb rule.
These three frames, when fitted, are used as moulds to fit the sides on to the bottom; all the other treads and knees are fitted after the sides have been screwed on.
Before fixing the sides mark off all the other treads ready for sawing out, as it is much easier to do this at the present stage than later on.
Also it will save time if all the grating stuff is sawn up, as the 1 in. by 5/8in. battens can be laid across the bottom on a couple of the 1 1/2in. by 5/8in. grating bearers and a straight edge laid across two treads, and the size of the grating is in this manner more easily got at than by fitting in each batten, when the sides are up.
The grating battens should be cut to the flare level and should be 1/4in. slack between the sides and the grating beams the same between the treads, as they swell considerably when wet.
The grating stuff can be kept cut up till the sides are up and then nailed together, when the after treads are fitted; the nails should be 1 1/2in. by 14 gauge countersunk head copper nails clinched on the under side.
The three sets of knees being set up, the sides can now be marked off.
Put up one of the side boards on to the horns left on the stocks, cramp it on to the three knees, and shore it in to the bottom edge with a couple of shores, near the body stocks; then the side board must be carefully bent round until it reaches the ends of the punt, taking care that the board follows its natural curve and is not forced in an up or down direction.
Shore the side board in at each end of the punt and pencil round it the curve of the outside of the bottom; make a couple of fitting marks between the side and the bottom, and take down and saw it out.
Then put the side up again and refit it, as mahogany usually “casts” when the end pieces are cut off, and it may be 3/4in. out.
If the side is not bent round carefully to the natural curve of the wood and is forced into position, when the punt is completed and is unscrewed from the stocks, the spring of the sides will twist the punt, and this looks very bad.
The side being up in position and correctly lined off, mark off on the side the height of the outside of the side at the two swim knees, the centre knee and the ends, which are as follows
The ends are marked at the point where the underside of the bottom cuts across the underside of the "huffs", that is 3 in. inside the overall length each end, so as to allow of the "huff" being notched into the side 1 1/8 deep.
Take the side down, drive some panel pins into the marks made as above, and bend the long fairing batten round the nails, altering the nails slightly till the batten shows a curve fair to the eye. Then mark off and saw it out. The curve so marked should give about 3/4in. sheer to the punt’s side, when fixed.
Plane up the edge to a fair curve. The top edge of the side will finish with a horizontal surface, and, as the side is flared, there will be a corner to plane off the inner edge. This should be done before the knees are fitted, or they will be too high.
Before fixing this side up mark out the other board, saw it out and refit it, if it casts.
Make the two sides exactly similar, then shore one up into position, and screw it to the bottom with 1 1/2 in. No. 10 brass screws spaced 4 in. apart and countersunk just flush with the surface.
Lute the joint beforehand with thick paint or white lead and boiled oil.
Starting from amidships, take each of the treads which have already been sawn out to the approximate size, and fit them into position; cut out the notches for the knees, and, when they are fitted to the correct bevel and flare, screw them to the side of the tread with two 1 1/2 in. No. 10 brass screws, and screw the tread into position so that the whole fits in without forcing the side out of its fair curve.
When all the knees and treads are fitted, screw the sides the knees with two 1 1/2in. No. 8 brass screws to each of the longer knees, keeping the screws the same distance down from the top and countersinking them neatly in flush.
The top of the knee should be through fastened to the side with an 1 1/4 in. No. 15 gauge copper nail rooved.
The "huffs" should now be fitted; these are made of 11 in. by 1 1/4in. oak or teak, which will finish about 1 1/8 in. thick.
The “huffs” will project 3 in. over the ends of the sides; so first cut a notch down the end of each side 1 1/8in. deep by 8 in. long, then chisel and plane off horizontally the portion of the bottom boards which project above the level of the bottom of this notch in the side, so that the bottom boards finish to a feather edge and the huffs when placed in position bed down flat on the splayed part of the bottom boards.
Bevel the huffs fair to the side and round the ends.
At the end of the punt, where the deck comes, notch down the side 1/2 in. deep to take the deck, and rabbet out the fore edge of the after end huff 1 in. wide and 1/2 in. deep to receive the ends of the deck planks.
Now screw the huff in, luteing the joint with whitelead and boiled oil.
Deck beams can now be fitted; these can be out of 3/4 in. deal 2in. deep at ends and rounded out to 1 1/2 in. deep at centre; and, by the way, the knees under the deck should not finish to a feather edge, but should have the top ends left 3/4 in. wide to receive the beams.
A bulkhead 5/8 in. thick is fitted across the punt and screwed to the forward face of a pair of knees, as shown in the drawing, and a small door formed to give access to the locker so made.
Now paint two coats white paint the interior of the locker.
The deck can now be fitted; this can be in two pieces, but it is much better to make it out of alternate narrow planks of teak and pine about 3 in. wide, and each tapered off to suit the width of the huff at the other end.
The deck planks must oversail 5/8 in. the fore edge of the bulkhead and be finished half round.
The gratings can now be fitted as before described.
Now turn the punt over, plane up the bottom and give one coat of paint before turning back.
There should be a brass lashing eye, with loose ring, fitted into the centre of the fore end huff, and on each side of it a brass plate let in flush, size 2 in. by 2 in. by 1/2 in., with a 5/8 in. hole in centre. This hole is continued through the huff.
The lashing eye usually has a 6 ft. length of 1/8 in. galvanised chain shackled to it and a galvanised pin about 8 in. long at the end of the chain, which can be dropped through the brass flush plates after passing the chain round a post.
Two backs of the shape shown in sketch can he made, out of 1/2 in. mahogany and fitted as shown, the lower end dropping between two grating battens, and the top sloping back and resting against two small stops screwed to the sides.
Screw on to the inside of the sides, about 1.0 ft. apart, small teak hooks to which a piece of white line can he spliced and carried round a punt pole slung outside and dropped over the hook; the poles are always so slung when not in use.
A 3 ft. length of 1/2 in. half-round brass should be bent round the end of each huff, then drilled and countersunk and screwed into position, and a rubbing bead of the same size of teak should he bradded to the sides.
Two paddles can he made of clean pine or teak of the shape shown in Fig.6. They should be 5 ft. over all, blade 5in. wide, blade portion 2ft. 6in. long, handle 1 1/8 in. in centre fined down about a 1/16 in. or so towards the ends. The body of blade should be 1/2 in. thick in centre to 3/16 in. at edge and the blade should reduce in thickness at the lower end to 5/16 in.
A couple of poles can he made, or, probably better, purchased; they are 14 ft. to 18 ft. long, according to the depth of water where the boat is used, and are generally about 1 3/4 in. at the shoe, tapering to 1 1/4 in. at top, and made of Quebec spruce.
The punt is now complete and should be given three coats of paint and one of enamel, and all the hardwood should be varnished, with at least four coats, or, better, six for a new craft.
Between the coats rub well down with fine glass paper, and then rub whiting all over the surface, and dust it lightly off. This will make the varnish flow on properly and not gather up like water on a greasy surface, or "sis", as it is called.
The best boat varnish should be used: it does not pay to use inferior kinds, as they turn white in water almost at once and quickly lose their gloss.
The seams and screw holes in the bottom should be filled with putty after the first coat of paint; this stopping will mostly squeeze out when the punt is launched and the boards taken up.
The reason the seams are left open is that when the bottom swells, the sides would be pushed away from lie ends of the treads and the punt would also probably twist, if there was not this allowance.
The skilled worker may think I have entered too much into detail, but I am writing for the novice, and I may say that it is not so easy to make a smart looking craft such as most Thames builders turn out.
I fitted the punt I am describing with mast and sail of about 150 square feet in mainsail and jib. The mast was a 2 1/2 in. bamboo, 19 ft. from underside of step to shoulder of the pole; the bottom end was plugged and the plug made with an 1 1/2 in. square, to fit a hole cut in a tread; a thwart l 1/2 in. thick was fitted across the boat to take the mast.
Having no fittings, I made a leg of mutton sail with a small semi-circular board at the head about 4 in. across. The boom was carried on a couple of inches forward of the mast in the same manner as a balance lug’s boom, and had a single rope tack and parrel. Single halliard and lacing to the mast. The sail was made out of Coat Lining and does quite well for the thin airs here.
The rudder is 1/8 in. plate tongued into a 3/4 in. post, squared at the top and screwed 1/2 in. Whitworth thread. A rudder trunk was fitted with slotted brass plates top and bottom so that the rudder could be lifted right out.
The leeboards were cut out of 1 1/4 in. Oregon, 2 ft. 6 in. long by 12 in. wide, left full thickness at the top end and tapered off to 1/2 in. thick like a paddle blade; they were bolted to the side, through a block screwed to the side, with a 1/2 in. bolt and wing nut and washer.
This simple gear is easily fitted, does not in the least spoil the boat for shoving, and is worth adding. I have had some very pleasant sailing on the Shatt-el-Arab in my punt. The leeboards, however, might be somewhat larger.