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BUILDING A PLYWOOD HULL There are several ways to build a plywood launch/motor boat hull— 1. The quickest, easiest and lowest cost way, is to use the stitch and tape method—the plywood hull panels/planks are stitched together along their chine seams, the transom and ply frames etc are added and then all seams and joins are finished with epoxy filleting and/or epoxy and glass tape. 2. The more conventional method is to build a framework of ply bulkheads/frames, fit chine stringers and then fit the plywood skin oversize and trim back. 3. Some designs use a combination of the above two methods—the framework is constructed without chine stringers and the hull planks/panels applied from shapes given on the drawings and the chine seams finished with glass and epoxy.

1. The bottom and bilge panels are stitched together and a ply bulkhead is fitted.

THE STITCH AND TAPE METHOD

2. With all the ply components stitched the hull is checked for shape and the seams finished with epoxy and glass tape.

3. A Rufus 17 being stitched together—any gaps are ignored until all the planks etc are stitched together.

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4. The Rufus with most of the planks fitted along wi th the p ly bulkheads some of which will be cut away later.

5. A bow shot—in this case the builder has fitted wood fillets to the edges of the bulkheads/f rames rather than use epoxy fillets.

6. The same hull turned over and filled and sanded ready for glass sheathing.

7. The same hull finished by Frank Kert.

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8. Another way to build a stitch and tape hull is to push the hull planks into external female moulds.

9. The same hull, a Kennet 21’ Slipper Launch by Greg Clapp with the side planks fitted.

10. The same hull structurally completed and with deck beams fitted.

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11. Whether built using the stitch and tape method or plank on frame method, fitting the deck structure is much the same in both cases.

12. With the hul l finished, the hull is turned over and the skeg, shaft etc fitted.

13. The same hull well on the way to being finished.

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14. The Power 2.2 is also built using the stitch and tape method but uses a plywood centre girder as part of a rigid framework.

15. The Power 2.2 with hull planks fitted and stitched.

16. The same hull turned upright and ready for fitting out.

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17. An Egret Classic runabout—the frames have been erected upside down and the intermediate stringers are being fitted.

THE PLY ON FRAME METHOD

18. A view from the transom with the chine and intermediate stringers fitted.

19. Once the framework has been planed up to suit the planking the ply hull planks/panels are fitted oversize.

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20. The framework of a Fanny the Fantail Launch design erected onto a rectangular strongback—note how the stem girder is attached to the first bulkhead/frame.

21. The ch ine st r ingers laminated in place—they have been laminated because of the twist in their shape—laminating them in situ simplifies this process.

22. Bevelling the framework ready to accept the plywood planking.

23. The fantai l is veneered because of it’s curved shape.

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24. A slightly enlarged plywood version of the Lambay Island 22 built using the ply over frame method.

25. Plywood has also been used for much of the superstructure.

26. Almost complete.

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27. Another example of modern ply over frame construction—a CR25 Cruiser racer by Sam W a t t s — h e r e t h e framework is being set up u s i n g p l y w o o d components ( a centre girder/keel case, ply frames/bulkheads) given on our drawings.

28. A stern shot of the framework—note the notches cut at the chines for the chine stringers.

29. A bow shot showing the stem girder.

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30. The stringers have b e e n f i t t e d a n d everything bevelled to suit the planking which is being fitted—note that much of the interior fit-out can be done at this stage whilst it is easy to get at.

31. A bow shot taken at the same stage.

32. The ply planking complete and being sanded and filled ready for sheathing in woven roving glass and epoxy.

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33. The hull sheathed and being filled ready for painting - the skeg is fitted over the sheathing.

34. Turning the hull over is always a worry but can usually be accomplished with little effort using some strategically placed blocks and tackles.

35. Having chocked the hull in the upright position the boat can be fitted out and have it’s cabin top and cockpit added.

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36. S a m ’ s C R 2 5 finished and ready for the water.

37. Above and left, in the water at last.

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Just 3 examples of finished boats

38. L e f t , S h a u n Squyres’ 20’ Rufus used as a water taxi and workboat.

39. R i g h t , N i c k C r o o m e ’ s S h a g h a i cruising junk.

40. L e f t , R i c h a r d G a r d n e r ’ s Y a m a t o Japanese Fishing Boat.

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Note—for more details on the construction of larger plywood boats—

see the new Selway Fisher manual - A Manual of Plywood Boat Construction for Larger Craft.

straydogboatworks.com

- and for help with fitting out and finishing your ply hull see the new

Selway Fisher manual - A Manual of Fit-Out for Yachts & Launches.

straydogboatworks.com

For More Information please contact:

straydogboatworks.comPO Box 843

Mount Barker South Australia

5251

P: 61 8 8391 3705M: 61 (0)428 817 464

E: robert@straydogboatworks.com