28' Ranger-type Yacht by Mark Pearse - FINISHED - 1:12

[Mark Pearse]

I plan to build a 1:12 model of a 28 foot yacht. This design has never been built, but is a variant of a 24 foot yacht design usually called ‘a Ranger’ (see Wooden Boat magazine issue 227). The first of the type was called Ranger, launched in 1933. They are popular & loved because the design fits the purpose so well: day use on Sydney Harbour, with short coastal trips & overnighting capacity. The design was adapted by the designer to a 32’ ocean-going variant, & also a 28’ ocean-going variant. The 28 footer came 8th on IRC handicap in the 2006 Sydney Hobart Race (see youtube video of her in 2012 in 30-35 knots http://www.youtube.com/watch?v=Dd9LqrDP510). The design I will build is slimmer & with less buoyancy in the bow than the ocean-going 28 footer.

 

The ‘Ranger’ yachts are generally 24 foot (7.3m) waterline & on deck, with bowsprit, gaff rig & a raised deck. They are very beamy at around 9’6” (2.9m), or a beam/length proportion of about 40%. This version is 28’ & 9’6” beam, so it’s basically stretched, not scaled up.

 

This design is of interest generally because: the smaller ones are admired & loved, at least locally; this 28’ design has never been built; the designer (Cliff Gale) was a self-taught boat designer & in his day was considered one of Sydney’s best yachtsman. But it’s also personal: I’m lucky enough to have one of the 24 footers. I love the design, that they can be so beamy yet look good & sail so well, & they are a terrific motor boat as well. They sail well in 5 knots & can also sail unreefed in 40 knots.

 

These photos show well the nuggety shape:

 

 

 

This is the existing ocean going 28 footer, she's the most similar boat to the design I'm building, but much fuller. It's a big little boat:

 

 

 

 

Cliff Gale was a self-taught designer, who learned by towing carved models behind a dinghy. Ranger was designed by carving a bread & butter half model, which was taken apart & measured. Cliff’s son Bill recently wrote this about his father:

 

"Cliff Gale left school in 1898 aged twelve, & knew arithmetic but had insufficient mathematics to be useful in boat design. As a boy he lived at Woolwich & the family owned a rowing skiff for transport & pleasure. From thirteen to nineteen he made in excess of one hundred rough sailing models, each one progressively different, which he tested from the skiff. At nineteen he felt he had completed his design self-education.”

 

I would like to build the model plank on ribs, & possibly make it RC sailing - although plain sailing is an alternative as well. But I’ll leave that alternative open until I get to that point, I will also be happy if a nice display model is the result.

 

The issue that needs to be resolved is actually what to build... I do have the original drawings as done by a naval architect to Cliff’s design, but having looked carefully at them, they do not relate accurately between the different drawings. The history of the Ranger design makes this even worse: for Ranger herself we have Cliff’s original half model, we have the original drawings done from the half model, & we have lines drawing of Ranger meticulously done by 2 local shipwrights … & they don’t match up.

 

If you compare station 4 on the drawings below, the design drawing shows more tumblehome, & much less buoyancy - the volume below the waterline was increased while being built, to increase her load-carrying capacity:

 

 

 

Bill Gale tells me that his father went to the boatbuilder often to supervise the construction, & that he made a number of modifications to the lines while she was being built.

 

For the model, I will have to adapt the lines drawing, trying to do it in a similar way that the lines drawing of Ranger was adapted to the built design. Because of the uncertainty, the model building method needs to help resolve thoughtfully these differences between the various possible shapes, & not be a way of getting caught up in plotting lines on a screen that fit but might be going away from the design. Initially I spent some hours trying to resolve a set of lines that is consistent, as they do not quite match up on the original drawing. My CAD skills are fair but you can’t really see a subtle 3D curved object in a drawing, so making changes to a curve on screen seems risky in this case. So I’ve concluded that I must see the shape in the flesh, & so carve the solid hull shape, based on a set of lines I adapted from the original lines drawing. The shape will be fair, so then I know the molds will work. If the method is too difficult I will be reluctant to make corrections, so it needs to be fairly simple & easy to make & to change.

 

In putting this up early, I hope to benefit from the knowledge & experience of this forum. So I’ve done some sketches below that show the idea for my construction method, & hope that I can get some constructive criticism & help to iron out any issues now. In a few weeks I’ll get back to the computer & finalise the lines drawings; but for now I’ll describe the idea for the building method - as I see it now.

 

1

Work up a set of lines in CAD, from the original drawings.

 

2

Cut plywood molds from the station lines.

 

20141103145702436.pdf

 

3

Assemble the molds with solid balsa blocking between them, the balsa blocking is to be removable. Possibly brass rods inserted at angles through the balsa & molds.

 

20141103145708075.pdf

 

20141103145720688.pdf

 

4

Carve the hull shape out of the solid, using the molds as indicators. If I need to add to the molds, glue strips of timber on the mold edges.

 

5

Make the stem, forefoot, keelson, keel, transom etc, to sit neatly over the hull shape.

 

20141103145726052.pdf

 

6

Remove some of the solid blocking, where the ribs can sit directly on the molds; leave the blocking where the ribs want to lie at angles, I’ll probably need to put in temporary spacers to help hold the model together. By keeping blocking in the bow area, the ribs can follow their natural line rather be pushed into being straight across the hull. It's not so bad for the aft 2/3s of the hull shape, I think they'll be able to sit on the plywood ribs.

 

7

Cut the rabbet, rib the hull.

 

8

Plank the hull.

 

9

Remove molds & remaining blocking, progressively putting in some deck beams as it goes.

 

10

Have a cup of tea

 

thanks for reading this, I hope to learn a bit more before starting, & maybe revise the method if needed

 

MP

[Bedford]

She's beautiful! Think I will have to watch this take shape.

[Mark Pearse]

thank you Bedford, I'm working on the moulds now - the attached shows one of them, with 2mm deducted for planking & 2 for ribs.

 

 

the pale grey is the plywood

 

MP

[michael mott]

Mark, Oh this is going to be fun to follow. looking forward to seeing the wood chips fly. I have the issue that you mention and it is a boat that I have also admired for its  sea worthiness

 

michael

[Mark Pearse]

Thank you for the interest, the encouragement helps.

 

I've pretty much worked up the lines now, adapting them in the way that the lines of the original Ranger was adapted for construction. Below I have laid the drawn & built lines of Ranger to make this change clearer.

 

 

They are pretty close but vary in the amount of tumblehome (less as built) & the water entry (finer as built). I wondered why they had reduced the tumblehome so much, & I asked a boatbuilder about whether it's more difficult to plank than a fairly vertical face & in his opinion they were not so different in difficulty. He felt that the probable reason was when they set up the stations to start building they didn't like the look of the tumblehome. It doesn't really affect the underwater shape. The water entry is something I'll have a go at & possibly change the lines, possibly not, Sydney Harbour can be terrifically choppy, so that's an obvious reason for the change. The question is whether I am able to vary the lines or not. I'll try & see what happens.

 

This is the lines drawing of the 28 footer, the similarities to the drawn 24 footer is clear, the general roundness  of the topsides aft of the midships.

 

 

This is the lines I've worked up, plus a version which also shows the drawn version overlaid with the build version. A big difference is the midships lines, which are very round as drawn & less firm, all I can say is that the lines I drew (station 3) are a better match for the original drawn lines (plan drawing) than the original lines for station 3. The transition to the lines aft will reveal what does work - a job for the carved shape. I also am inclined to go for the firmer shape because as a yacht they are fairly lightly ballasted & get quite a lot of their righting moment from the positive buoyancy of the hull shape when heeled - the beaminess, firm midships shape.

 

 

 

This is the side & plan view of the 28 footer, the station lines were removed as they obscured the drawn lines.

 

 

Next step is to review the lines again, then work out a setup for the plywood stations once they are cut, then cut them. Also start looking at the keel construction, particularly in the stern area where the bilges are very narrow & deep.

 

thanks

 

MP

Edited November 13, 2014 by Mark Pearse

[Mark Pearse]

Ok, some progress, but mainly planning & fishing the odd bit of wood from building sites. It would be nice to get a cutting list done soon & some timber pieces ready for the time over the Christmas break.

 

I've never built a scale model yacht before, so I'm using pictures to help visualise the main structural elements, where & how to join them. I don't plan to make the construction an exact copy a full sized yacht build, but make probably make the method similar & try to avoid any parts that looks really difficult due to the size. I can chisel well enough, but I've never done it at 1:12…..

 

The side views below show the main elements: I propose to do the keelson & keel separately, initially make the keelson & inner stem, & make the keel & stem later. I'm thinking of making the inner keel glue-laminated, as I imagine there's quite a bit of pad at times during building, it would be nice to be able to rely on it. I may glue-laminate the stem as well, so the joint lines are notional at this stage.

 

 

 

 

The yellow piece on top of the keelson is a stiffening piece, shown here at actual size 4 x 19mm (19mm is a standard timber thickness here). There a fair bit of spring on the keelson, & boatbuilders - at least modern ones - often bolt the keelson to a concrete slab & force the spring into it, & once she's planked they cut the bolts. I need something to do the same job.

 

Some of the stations:

 

 

 

 

 

I'm thinking of using Australian hardwoods for the inner & outer keel & stem pieces, they will resist damage later & be stronger during construction sooner. Blackbutt or Spotted Gum for the keelson, Spotted Gum for the inner stem, possibly Kauri Pine for the keel itself (just to keep the hull weight down so that the ballast ratio can be higher, I imagine that the volumetric issues of scale make a hull less stiff). Spotted Gum for the ribs, Huon Pine for the planking, Blackbutt or Spotted Gum for the transom.

 

bye for now, thanks 

[michael mott]

Mark, I like the way that you are approaching this build. thinking about full size practice although obviously there are many differences with regard to mass and flexibility, I think that it gives one a more integrated feel for the model. Nice drawings, I like the colour and they remind me of the linen ones that I looked at at the Science Museum in London many years ago while researching the construction of the John Bull locomotive built in 1831 by Robert Stephenson.

 

Michael

[Mark Pearse]

Thanks Michael, I really admire the true scale builders on this forum, but I don't see my own aim for this model as being a true scale replica.. Maybe somewhere between a pond yacht & a scale replica. The hull shape as close as possible, but many details will be abstracted. There's also the pleasure of something lovely in itself.

 

That's interesting on the colour, thanks for sharing that, & sometimes I feel a bit 19th century.

[JPZ66]

Mark,

 

That looks to be a real dandy ! .....nothing wrong with 19th Century that I can see !

 

Joe

[Jim Lad]

I wondered how I missed this thread, Mark, and then realised that you started it while I was away on holiday.

 

What a great project.  I love this type of small yacht.

 

John

[Mark Pearse]

Thank you all, it really does give a burst of energy to hear that others are interested also. To me, the whole Cliff Gale story is one of our great local yachting tales, & to be able to build an unbuilt design of this intuitive designer is extra special. As an aside, his son Bill retired earlier this year after 70 seasons of racing, excluding the war years, the last 50 or so seasons on his beloved Ranger.

[Mark Pearse]

some more progress: a test mould in plywood & some timber cutting

 

test mould - the cut removed some timber so I'll adjust them to allow for the 0.5mm loss

 

 

timber strips L to R: stringers (Spotted Gum & Blackbutt); transom (Huon Pine); strips for stern knee, stem & forefoot, keelson beam (Spotted Gum); keelson laminations (2 @ 3mm, Spotted Gum); Inner stem laminations (4 @1.5mm, Spotted Gum)

 

 

Planking, (Huon Pine 2 x 12ish)

 

 

Huon Pine is a famous timber for planking boats, its durability is highly respected, but what is probably not well recognised is its amazing suppleness, the ability to happily take curves & twists. This is a strip of the future planking 2 x 12mm.

 

 

thanks, bye for now

 

MP

 

 

 

 

[Jim Lad]

That's interesting!  The Huon Pine  I have is quite brittle.  It must vary from piece to piece.

 

John

[Mark Pearse]

I started the building frame, & liked the idea of using aluminium as it is straight & accurate off the shelf, so I'm going to use RHS sections as rails with angles to hold the moulds. I like the way you can set out using a knife to accurately mark distances.

 

For the laminated keelson I made a laminating form by tacking a print of the profile on to a piece of wood & bandsawing it to shape. The timber strips are still too rigid at 3mm thick to want to do this shape so I'll try the heat gun to soften them.

 

The moulds were all cut.

 

I also made a double piece laminating jig from acrylic & styrene, to glue laminate the inner stem piece. The acrylic is laser cut from 3mm sheet, 3 pieces each part of the jig. They were stacked with double 4.5mm strips between the sheets to achieve a total thickness of 27mm, & the meeting faces lined with 1mm styrene. The outer faces are parallel so that they can be clamped up. I will probably soak the timber, boil & clamp it, then let it cool, dry them & then glue laminate with epoxy.

 

I've been discussing the build with a boatbuilding friend, who advised against the method I was planning to use - he commented that to build the moulds to the inner faces of the ribs was used as a boatbuilding method but because it was less accurate in achieving the intended final shape, it was usually used for cheaper boats (2 layers before the outer face of the planking - ribs plus planking - instead of just one - the planking itself). He strongly recommended doing the mould shape to the inside of the planking for the sake of accuracy to the designed shape. So, this is the revised method: to plank straight on to the moulds & then fit the ribs to the hull. Originally I was going to lay the ribs on to the moulds, but now they will fit at whatever spacing in between the moulds & can lie in their own best-fit angles, I just need to provide notches in the keelson to push them into. For the most difficult ribs near the stern I might do some solid knees up to the turn of the bilge. The planks will just have to be well glued to each other to hold their shape, then fit ribs, some deck beams.

 

thanks, bye for now

 

MP

Edited December 27, 2014 by Mark Pearse

[Jim Lad]

You're making good progress there, Mark.

 

I bet you're keeping a close eye on 'Maluka' during the Hobart race!

 

John

[Mark Pearse]

Thanks John, yes I have been following Maluka - I asked if there was a crew spot available on her, & for my sins I was nearly "lucky" enough to get the spot. If they are still outside come Tuesday afternoon they'll be in for a dusting ....

 

More photos soon

[Mark Pearse]

Sorry about the photos being out of place & unrotated, I'm using an unfamiliar computer.

 

The moulds have been assembled on the framework (2 photos). In assembling it all, holes were drilled slightly oversized to give a little wriggle room in the alignment. I have put in the keel beam, it looks nice to have the beam in, as it helps to show off the shape. The beam is there to help hold the curve of the keelson to the right shape. The moulds are quite light & flexible, so bracing will be required to give it all enough rigidity to take the loads of planking. I'm thinking of using bamboo BBQ skewers for the bracing, as they are strong enough & can be removed easily with side cutters. I imagine having to remove some of them as the work progresses. Each end of the frame on top of the rails I've screwed ply panels, to brace the thing & they will be surfaces that the stem & transom will be supported off, in time.

 

The keelson was glued today (photo) after curving the 2 laminations using a heat gun & then clamping them until they cooled. I will then shape the keel beam & glue & pin them together, the pins will be brass rods of around 1.5mm diameter, pushed into drilled holes & then sanded flush. The glue used is epoxy.

 

The inner stem laminations were soaked in cold water for 4 hours, which didn't seem to make them any more pliable, so I boiled them for 20 minutes & clamped them up in the jig (photo), then after a few hours put them in a drying jig, separated so that they will dry (photo). They will be glued up with epoxy tomorrow, & reclamped in the acrylic jig.

 

On a slightly separate note, the yacht Maluka mentioned earlier (an ocean-going version of this yacht) is currently competing in the Sydney-Hobart race, & as of tonight is 1st on handicap in all of the 4 divisions that she is eligible for, including the main one, IRC. That's pretty good for a small fat, heavy old boat with a gaff mainsail.

 

bye for now, MP

[Mirabell61]

Nice build so far Mark,

 

Nils

[michael mott]

looks great Mark nice to see the shape coming together.

 

Michael

[Jim Lad]

Looking good, Mark!

 

John

[Mark Pearse]

thank you Nils, Michael & John - & also the people who liked - or just looked in

 

The inner stem was glued up & I've been bracing the moulds using bamboo skewers; the skewers look rough but they are effective; the material is quite rigid in short lengths & it is cheap & easy as well.

 

Next will be the slow & careful work of shaping the laminated keelson & inner stem, then fixing them to each other; then I'll work on the stern pieces & the transom. After that I can fair the moulds.

 

 

MP

 

 

[Twister]

Mark,

 

A very beautiful yacht that will, I'm sure, give a wonderful model.

 

Your comments and diagrams about the differences between drawn lines and built lines got my grey cells working overtime until I managed to drag from the dusty & cobwebbed far reaches a saying attributed to L Francis Herreshoff. Apparently when talking about one of his J Class designs he complained bitterly that the finished yacht, beautiful though she was, bore little or no resemblance to what he'd actually drawn...

 

In this instance a fair curve always trumps a blue print! (Another quotation, the provenance of which I'm not entirely sure - that aforementioned grey matter letting me down again!!).

 

I'll definitely be trying my upmost to keep popping in to monitor your progress if that's ok,

 

 

Regards,

 

Row

[Mark Pearse]

Thanks Row, you're welcome.

 

I'm starting to wonder if the ribbing after planking is such a good idea - my concern is that the planks may not want to stay exactly in the right curve without being fixed as they go to ribs or bulkheads.....mmm

 

I haven't seen a build log for a scale boat where the hull is fully planked & then ribbed afterwards, it might need some testing to trial it.

 

MP

[Twister]

Mark,

 

Although a very different hull shape, many years ago I built a mahogany planked 'Marblehead' class model yacht which was built over taped shadows (to stop the planking from sticking) the planks being glued only to each others' edge, the bow former, the transom and the keel. Once the planking was finished the shadows were removed and then ribs were bonded in, steamed first where necessary. In that particular instance I'm not entirely sure how much additional strength the ribs added - the monocoque structure formed by the planking was phenomenally strong & maintained a very accurate hull shape.

 

Regards,

 

Row

[Mark Pearse]

Row, that's good to know. Sounds interesting, & I have a couple of questions - what glue did you use, & how did you set up the clamping on the planks? Epoxy is great glue but it's hard to clamp (as you know - I looked at your J boat log), as it's quite slippery for a while. I'm tempted to use a cross-linked PVA or one of the Titebond glues, & rely on paint to keep the water out of the glue. Your thoughts would be appreciated.

 

Ta, MP

[Bedford]

You're a brave man to rely only on paint to keep water out of the glue, in my schooner build I painted the whole thing inside and out with thinned epoxy resin to guarantee protection for the timber and glue.

 

The other side of doing this is that it increases the strength of the timber and the joints by bonding the whole thing into one.

[Mark Pearse]

Thanks Bedford, I'll sit on it for a while.

[Twister]

Row, that's good to know. Sounds interesting, & I have a couple of questions - what glue did you use, & how did you set up the clamping on the planks? Epoxy is great glue but it's hard to clamp (as you know - I looked at your J boat log), as it's quite slippery for a while. I'm tempted to use a cross-linked PVA or one of the Titebond glues, & rely on paint to keep the water out of the glue. Your thoughts would be appreciated.

 

Ta, MP

The glue used was one of the Urea Formaldehyde's - can't remember exactly but it would have been either Aerolite, Cascomite or Cascophen, all of which are pretty water resistant IIRC ( We're talking early to mid 1980's here). Clamping was a mixture of minature 'G' clamps, rubber bands & string to keep planks in place and securely held to neighbouring plank.

 

The 'Enterprise' plug was planked using a water resistant PVA type glue and when completed after basic fairing, was painted with resin internally with the outside being given a layer of light weight glass fabric ( without checking I can't be sure but it was almost certainly something around 80g/m2 - 100g/m2). As it was a plug for taking a molding from, the primary purpose of the glass/epoxy layer was for waterproofing so that there would be no plank movement when it came to cutting back using wet & dry prior to polishing/waxing. If you intend to use the model as a pond sailor or even consider R/c then I'd definitely give serious thought of going down the route of a glass/epoxy layer to the outside of the hull, if nothing else it'll give you peace of mind!

 

Hope that's of some use - any further questions then please don't hesitate to ask.

 

Looking forward to your next instalment,

 

Row

[Mark Pearse]

The glue-laminated keelson & inner stem were roughly shaped, & their joint was worked out & shaped.

 

The keelson beam was shaped (not a member that would exist on a real yacht construction, but I put it there to help hold the keelson curve to the correct shape), & the aft end was trimmed to suit the shape that stern knee will be (not sure if stern knee is the correct name, but the the end piece that brings the keel structure up to the transom).

 

For the main hull members I want to use epoxy for its strength & durability, but I don't like the way it tends to make things slippery - clamping can be really difficult. So to hold it accurately while the glue sets, I drilled the timbers for 1/16" brass rod, using a 1.6mm drill bit which gave a good amount of friction - they aren't nails, but for holding it all in place & will also give some extra strength overall. The rod ends will be clipped & sanded smooth. 

 

The keelson/inner stem joint was clamped to ensure good contact between the glued faces - the brass rods hold the two members in alignment

 

 

 

the aft end of the keel beam has been trimmed for profile of the stern knee

 

With the glue set, it is now quite strong.

 

Next will be making & fitting the stern knee. Then I'll make a temporary plywood transom for final shaping & fairing, so that I don't spoil the actual one. It has been made from two 3mm thick pieces of  Huon Pine, which were edge-glued with a couple of brass pins inside for strength.

 

When the temporary transom is set up in position I can fair the moulds & transom; after that I'll fit the sheer clamp & possibly another stringer or two - I'll just see how it seems at the time.

 

I may also replace the lower parts of some of the moulds with solid ti,her members of the same shape, to be built in as permanent parts of the hull - the aft moulds particularly.

 

thanks, MP

 

 

 

 

 

 

 

[Twister]

Mark,

 

She's coming along nicely, very good progress!

 

I'm not 100% sure I follow your reasoning re: replacing the lower parts of some of the aft frames - is it because they'll be visible in the finished model? If it's purely an aesthetic issue, would it be worth considering a thin veneer overlay?

 

I must say I'm very impressed by your use of epoxy on such small components, yes, it's incredibly effective etc etc, but I always find the 'cleaning up' of the joint (especially when one needs to use lots of clamps) a complete nightmare!! If I may offer one piece of unsolicited advice, I've generally found that once the epoxy/filler material has been mixed (be it cellulose fibres, colloidal silica etc etc), loading it into a small syringe greatly assists controlling of its application.

 

Definitely looking forward to your next 'chapter' so to speak,

 

 

Regards,

 

Row