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Design by Reinier Scheele - The Netherlands

Designing and building a 9’rowing/sailing boat

My on-and-off girlfriend recently stipulated that she needed her boat again. The boat she referred to was an 8’rowing/sailing boat I built for her two young daughters 30 years ago. In those days she herself considered it logical to be on board as ballast. So her offspring soon became accustomed to crawling over her and the little spare room left after she had spread out her gorgeous body on most of the bottom area. They did not bother and actually considered it practical as this way they could effectively keep the many admirers she attracted and still attracts at bay. Times went by and along came two grandchildren, now three years old, thus reminding her of her maritime responsibilities. But the old boat has done quite some circulation in the large family, teaching many children the principles of rowing and sailing on its way. However, it was not always properly protected but abused. The latest reports tell that its working days are over as the traditional ply construction is falling apart.

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My present ’epoxy vacation’ (a side-effect in the process of building a 40’ sailing vessel) met with a growing feeling of guilt towards the needs of my girlfriend. So, another little boat had to be built.

My present ’epoxy vacation’ (a side-effect in the process of building a 40’ sailing vessel) met with a growing feeling of guilt towards the needs of my girlfriend. So, another little boat had to be built, this time in the open air outside my shed for maximum ventilation. As an amateur I have always liked to genuinely design boats, but now I took a less formal approach, even the other way around, not unfamiliar to Duckworks readers. Having in mind a stitch and glue project I bought some sheets of stiff paper and cut and glued for a couple of hours until I had a satisfactory model that more or less did express the very shape I had in mind. The only restriction I had was the fact that the backdoor of my car accepts a maximum width of 2’ 7 ½”. So that was to be the –still acceptable- width of the bottom panel. I needed as a start two 4’x 8’sheets of 3.6 mm. interior Meranti ply, which at least in my experience has proved to be quite resistant to whatever the weather may throw at it. One sheet was cut in length at a width of 2’ 7 1/2:” to provide for the bottom and transom panels. The other in three panels respectively 17”, 17”and 14”wide to provide for the sides. Some scarfing was necessary to get the proper length. The bottom panel needed an 11”extension at the bow. The side panels needed all an extension of 22”, gained from the 14”wide leftover (See sheet I and II and their cuts).

I needed as a start two 4’x 8’sheets of 3.6 mm. interior Meranti ply, which at least in my experience has proved to be quite resistant to whatever the weather may throw at it.

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This story is primarily about how to assemble a little hull. Measurements and stitching start at the bottom of the transom and move forward. Please note that on sheet I the station 0 is at the left side of the sheet (bottom sheet), while station 0 on sheet II (side panel sheet) starts at 3 ¾” from the left side. The side panels consist of a lower and a upper strake, and only need to be curved at the intersection of the lower and higher panels. Both twist from stem to stern, especially the lower one. Put on top of each other they are stitched loosely together along their curved edges, starting at the after end. After carefully unwrapping them into a proper angle and tightening the stitches as needed, it was pretty straightforward to stitch them to the bottom panel and the transom panel. The bottom chines as well as the sheer conveniently accept the straight edges of the ply, although after adding the gunwales a minor trimming of less than ½”of the ply sheer near the stem took place.

Stitching was done using nylon fishing thread, although cable ties might have done the job also or even better. Chosen stitch intervals were mostly at 8, but 3 mm. holes 4”apart were drilled to put them closer if necessary. Bringing the forward ends together and stitching them to the stem brought about the rough shape of the hull. The stem was in my case a piece of hard blue foam, cut to shape. Forming the transom needs some explanation though. The back of the boat actually consists of two flat parts interconnected at the upper chine. The straight and sharp bend of the chine results from cutting halfway (some 1/16”) deep into the ply with a precisely set circular saw. Then carefully bend the ply along some straight edge. The remaining ‘gutter’ on the inside is filleted afterwards. (I also use this method whenever I have to bend ply to a nice flowing short curve, in which case making multiple cuts alongside each other; sometimes reinforced with glass on the inside of the bend.)

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After two days of preparatory work, cutting the panels and fiddling with them, the boat had derived its rough shape.

After two days of preparatory work, cutting the panels and fiddling with them, the boat had derived its rough shape. A temporarily fitted cross brace produced (a trifle more than) the proper breadth (4’) and a desired rocker bottom of 4”resulted. It was expelled with afterwards, but the remaining studs were used to attach cleats. The next day the epoxy fillets were applied to stiffen the hull on the inside. After curing (pretty fast using the heat from an electrical radiator) the hull was turned over. The outside of the boat got the usual planing, sanding and filleting treatment, and the lower outside of the boat was entirely wrapped in one glass sheet, cut to about three inches up on the sides. For reasons of preserving light weight (empty hull weight to be less than 70 lbs) the glassing was kept restricted to this most critical and abused area.

The gunwale took some extra concern. The idea was to apply a fender of thick rope all around. It asked for a recess in which the four strand 1 3/8”diameter rope would largely be encapsulated.

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The gunwale took some extra concern. The idea was to apply a fender of thick rope all around. It asked for a recess in which the four strand 1 3/8”diameter rope would largely be encapsulated. I started with the application of pine strips that had three sides one of which was hollow. A pair of the right dimensions and opposite of each other would produce a neat and tight cove. However, I noticed that when bending, forces caused uncontrollable twisting of the strips and prevented a direct and easy application. For that reason I prefabricated gunwales consisting of three components. A flat piece of wood, 1 ½”wide would be situated against the outside of the ply sheer, and glued to that strip are the upper and lower hollow strips. But then it turned out that the outer hollow elements in this rubrail needed to be of excellent quality. Although the portside went on flawlessly, minor imperfections of grain run out twice caused premature breakage of the starboard side, when (almost) put in place. Although not very costly, it took an extra day to get it right. In general, I now would hesitate to recommend to beginners the application of gunwales this way. Redoing this gunwale thing I might try and use a less elegant approach, applying laminations of rectangular hardwood strips of some ¾”x ½”, fitting two laminates 1 ½”apart and trimming them to accept the rope. Whatever the method, the result is worth the trouble, if only for the ‘salty looks’ of the boat as passers-by commented.

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Redoing this gunwale thing I might try and use a less elegant approach. Whatever the method, the result is worth the trouble, if only for the ‘salty looks’ of the boat as passers-by commented.

In order to adequately strengthen the bottom panel, four floor battens of hardwood stringers ½”x 1 ½”have been applied. Leftovers of Okoume marine ply were used for the rudder (3/4”) and daggerboard (5/8”). The daggerboard trunk case is of the usual construction, making sure that its sides run to the bottom and that it has a 4”wide base to accept sideway forces. A 7-1/8”wide and one foot high case was also built around the trunk case. It was firmly glued to the bottom panel, the outside of the inner floor battens and the front end of the trunk. It helps to reinforce the trunk case, but is primarily intended for storage of small items while its top cover offers access to the case, at the same time providing the rowing seat for Her Majesty (rowing is especially envisaged in the city canals during the many festivities). A small foredeck of leftover 5 mm. Mahogany marine ply has some structural function and a hole in it accepts the mast, which is stepped further into a rectangular notch glued to the bottom panel. No benches. They would interfere with the aforesaid dynamic system of ballasting the boat while sailing. No built-in buoyancy either, as I doubt whether a boat of this size could be righted in the water anyway. It will not sink and the children always wear lifejackets and should stay with it until help arrives.

A 7-1/8”wide and one foot high case was built around the trunk case. It was firmly glued to the bottom panel, the outside of the inner floor battens and the front end of the trunk...

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... It helps to reinforce the trunk case, but is primarily intended for storage of small items while its top cover offers access to the case, at the same time providing the rowing seat for Her Majesty.

The gunwale fender rope is supposed to be replaceable and hence was attached with thin stainless steel wire through small holes. For cosmetic reasons and protection the wire was worked into the contlines, the spiral spaces between the strands. To this end the rope was put in place and the holes were drilled in the upper and lower ‘cheeks’ of the gunwale cove, at a total of 15 positions, which were some two feet interspaced.

The mast is unstayed with a lugger sail. The boom has a claw around the mast. Setting sail is straightforward and takes hardly any time. I like the final result which comes close to the concept I had in mind. The panel specifics are in the table and diagram. For non-commercial purposes the diagrams, data and photographs are free for use. Given the concise information, building may require some experience, especially working out a multi chine construction with warped and initially flabby panels on two saw horses. Furthermore, one should be familiar with the different uses of epoxy. All in all, the project took exactly three weeks, including shopping and making the spars oars and sail. The earlier dink took only two weeks, so I might have slowed down a bit. But, while the former project normally could go on, this time I also had to pause for the epoxy to cure or for inclement weather (the former boat was built inside and the glued resorcinol connections were doubled by screws.).

Costs were restricted as my main project (40-footer) produced scrap material, epoxy stuff and paint. Even the Oregon pine spars and oars were leftovers from mast building.

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Costs were restricted as my main project (40-footer) produced scrap material, epoxy stuff and paint. Even the Oregon pine spars and oars were leftovers from mast building. Two ply sheets did cost $30, 20’ of polypropylene gunwale fender rope $50, sail cloth $55, wooden strips $40, hardware may be $90, totalling some $265.

Diagrams
(click images for larger, printable versions)


Sheet 1

Sheet 2

Sheet 3

List of relevant measurements, all in inches

Measurements are usually one foot apart; starting at the bottom/transom intersection. (station 0). The bottom and side panels continue beyond the limits of the 4”x 8”sheets, so some scarfing will be needed to arrive at the proper lengths. I like to scarf already shaped ’end panels’, instead of scarfing large panels beforehand. I clamp the side to be worked on along the edge of a bench, marking the width of the scarf and using a power plane. Pretty fast to me.

Station
Bottom
Lower side
Upper side
Stern
*
**
0
21-¾
11-¼
3-5/8
1
26
11-½
4-3/8
2
29-½
11-¼
4-3/4
3
31-3/8
12
4-7/8
4
30-½
13-3/8
4-3/4
5
27
13-¾
4-1/8
6
21
13-3/8
3-1/8
7
14-1/8
13-1/8
2-5/8
8
7
13-¾
2-1/8
9
1-½
13-¼
2
Stem
***
****

* lower edge of the panel meets the after end of bottom end transom panels at station 0; the upper edge of the panel starts -3 ¾”(because of backward rake of transom)

** entire upper side panel starts at -3 ¾”

*** the lower panel extends 22”beyond the ply sheet; the lower edge of the panel along the bottom chine is 110 1/4”in length; the upper edge of the panel extends some more because of the forward bow rake

**** the lower edge of this slim panel is equal in length to the upper edge of the lower side panel; the forward upper edge of this panel, the sheer at the bow, extends a bit further because of the rake of the bow

The stern panel – the transom

The bottom side of the panel is 21 3/4”long; the gunwale side is 35-¾”, which is about the width of the boat at the stern. The entire height (without folding) of the panel is 13 1/8”, but add a camber of at least ½”to the top of the panel for better looks. The chine fold is 9 ¾”from the bottom of the panel.


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