A Dory for Gazela Primeiro and at the end tips on glass application

A while ago I received a nice email from Tony Souza regarding construction issues with a new dory he intended building for the old Portuguese barkentine Gazela Primeiro.

Hello Ross,
Thanks for your recent article "Stems and Trailers".  In that article you discuss natural timber vs plywood construction and show the merits of plywood glued lapstrake for boats that are dry stored.
Im trying to choose a construction technique to use for a reproduction dory that will be "dry sailed".  The dory is a Grand Banks dory of 17 feet overall, 13 feet on the floor. The new dory has to resemble closely the last of the three dozen Portuguese grand banks dories that sat on the deck of Gazela Primeiro, the 100+ year old Portuguese barkentine on which I am one of the all volunteer crew.  Last winter we patched and repaired the last dory, and this year Id like to build a dory to be used often for the teaching of boat handling, rowing, and dory sailing.  the boat handling includes launching and retrieving over the side using hand operated boatfalls. The new dory will spend most of its time stacked inside the old dory, the two as deck displays of what was used in long line fishing of the early 20th century.
As a matter of resemblance the new dory will have four frame sisters overlapped, removable thwarts, 5/8" cedar planking, solid gunwales, a mast step on the floor and two sets of oarlocks.
For ease of construction and in keeping with the dry storage idea I plan on using modern materials where I can.  The flat bottom will be Meranti plywood already on hand, no need to soak the floor seams closed before putting boat into the water.  The frames are already built from laminated ash. Tree crotch and buttress sections are too difficult to find.  I plan to epoxy the garboard plank to the bottom, glass tape and epoxy the inside seam.  After planking I plan to turn the boat over and glass the bottom and garboard with cloth.
After that long prologue we come to my uncertainty area, the clinker planking joints.  Its tempting to use lap-stitch aka ship lap joints, easily cut with a router and epoxy fastened.  On natural, i.e. not plywood, timber that may lead to splitting along the grain at the join.  Likewise dory lapped (rolling bevel) joints likewise glued might suffer splitting.  I should have said earlier that using modern glues and eliminating metal fastners is a goal.  The old dory is a pincushion of steel nails on the planking joints which has resulted in rusty streaks and rotten wood.  (Of course dories were not supposed to last more than a couple years in ocean service. Old dory is probably 40+ years old.) 
Would it be better to caulk the planking seams with Boat Life, a polysulfide, rather than epoxy fasten?  The frames are there to give cross grain strength.  With your expeience you might see that Im headed for problems not yet envisioned.
Any suggestions will be very welcome and gratefully accepted.
Gazela can be seen at www.gazela.org.
A picture of the old dory is attached. 

Here is part of the text of my reply: -

I agree totally with your concerns regarding "hard" gluing of either "lapstitch" or dory-lap joints when using natural timber rather than plywood - I believe that they would definitely crack at the point where the planking thickness returned to single-plank. Harry Bryan wrote about the matter when he did a couple of articles for WoodebBoat Magazine about the building of his Daisy design. She had either double-planked cedar (glued with epoxy) for the bottom, or a single sheet of plywood. The topsides were planked with lapstrake cedar planks in the normal manner (I think using copper clench nailing from memory). The important thing in our context is that he expected her to be dry-sailed, and after completing the planking in the normal way, he dragged a sharp, flat-blade screw driver along the underside of the lap on the outer side of the planking. This produced a sort of square-shaped groove of about 1/8" x 1/8" in the underside of the lap. He then filled the groove with a bead of polyurethane (I would use 3M 5200 or Sikaflex 292, using a polyurethane-specific primer)

Having said all that, I wonder whether you could just glue the entire lap with polyurethane (I dont know enough about polysulfide to say anything about its adhesive qualities where no fastenings are used). The polyurethane is strong enough, but I dont know whether a fully-glued lap would allow enough movement to overcome the cracking problem, even given the flexibility of the compound - but my guess is that it would be ok, especially if the glue-line was thick.

If I was doing it, Id go the copper-fastened route, with the polyurethane (or polysulphide) run into the groove under the lap.

I think that the garboard arrangement you propose would be fine. The glass on the outer face should supply cross-grain reinforcement, and the tape on the inside will extend some distance beyond the vulnerable line of intersection between the inside faces of the bottom and the garboard.

On two boats I built (one of which ended up in the Jody Foster film, Nims Island - see the recent comment made on Duckworks http://www.duckworksmagazine.com/10/reports/may/index.htm ), I made the bottom from Western Red Cedar glued strip, continuing around the turn of bilge, after which I continued the planking as plywood glued lapstrake. I cut the bevel on the bottom planking to accept the first lapstrake plank before glassing the bottom. When glassing the bottom, I continued the glass right around and onto the bevelled face. This meant that when the first plywood plank was glued on, the glass was sandwiched between the WRC strip planking and the inner face of the plywood - the aim being to prevent splitting in the WRC.  This explanation is a bit clumsy, but I havent got time right now to do a sketch. In your case this will not be necessary, as you will have the glass on the outside of the cedar planking anyway.

??

Western Red Cedar bottom planking

???

Bottom covered with 400gsm (12oz) double-bias glass and the first two planks of plywood lapstrake attached - the first plank going over the glass, which itself had been laid over the bevelled edge of the cedar bottom planking.

???Here is Tonys latest up-date: -

Hiya Ross,
Here are three pix of the dory project to date.  This boat is a copy of the last original belonging to Portuguese fishing barkentine Gazela Primeiro.  You can see more pictures on www.Gazela.org and my facebook page. My version of the dory has a meranti plywood bottom and white cedar planking over laminated ash frames.  The gunwale and cap are white oak. The dory will essentially be dry sailed i.e. living on Gazelas deck most of the time and occasionally be used for crew training and exhibition at home and ports of call.
After corresponding with you some time ago I took your advice and epoxy joined only the garboard plank to the bottom.  The rest of the construction has followed traditional methods. The upper edge of the garboard and the remaining planks are dory lapped and copper riveted.  Planks to frames are joined with Si bronze screws.
I think we talked about covering the bottom and up to the upper edge of the garboard with synthetic cloth and epoxy. 
Now areas where I could use advice:
What cloth would be appropriate? I dont think the dory will ever see a beach, but it might. So a light cloth should do.
Is there an advantage to graphite additive to the epoxy?
Any tricks to applying the cloth?
Thanks for your help,
Tony Souza

And part of my reply: -

Dear Tony,

Thanks very much indeed for the up-date, and for the nice photos. The boat looks super to my eyes, and Id love to take her out in the rough stuff - preferrebly with some weight in the bottom to represent the ballasting effect of a load of Cod!

My appologies for the delayed reply - we have been recovering from the devastating flash-flood which wiped us out on January 10, and priorities tend to be re-arranged!

For the cloth, the simplest would be 200gsm (6oz) woven glass. This is light and easy to use, and gives a good level of protection, and more importantly, provides a sort of screed to ensure an even thickness of epoxy. Dynel is also a good option (4oz, I think, but you would need to check with the supplier). Dynel is bulkier than glass for the same weight, and it has superior abrasion resistance - I like it on decks - but it doesnt have the tensile stiffness of glass so it will have less structural effect on the garboard-to-bottom joint. For a hefty boat like yours which may get handled roughly, Id give serious thought to using 400gsm (12oz) double-bias glass cloth. It isnt woven, so it takes bends fairly well, and with the fibres aligned 45 degrees/45 degrees, every fibre crosses the longitudinal joints. It is cheaper than woven glass, but is heavier than the normal 6oz stuff.

I normally use the dry application method (for weights up to 12oz). I lay the cloth over the dry, sanded, and vacuumed surface, and them smooth it into position with a dustpan brush or a wide, dry paintbrush. Tape any troublesome edges down with temporary bits of masking tape. Then start by mixing small quantities of epoxy and pour them onto the glass (or Dynel) and spread them with a squeegee - I use rectangles of 1/16" model aircraft balsa as they can be bent along the grain if required, and the corners dont snag on the glass.  Dont press too hard, as you will end up aerating the epoxy and making it go creamy with minute air bubbles (just like what happens when whipping cream). Just use a gentle figure-eight sweeping motion to get it out onto the surface. Dont fuss about getting it to wet-out - that will happen automatically. Keep on mixing, pouring and spreading until the entire surface is covered. Small batches are good, as they dont heat up so rapidly in the container.

When the surface is covered, use disposable brushes and/or disposable foam rollers with about a 1/8" nap to distribute the resin evenly. I use dry brushes and rollers - they pick-up from the excessivcely wet areas and put down in the dry areas. When all is even, use the squeegees again (held at about 45 degrees to the surface) to scrape off excess resin so you end up with just the wet cloth, but no visible pooling of liquid resin.

After the epoxy has gone off enough to be certain that the cloth wont float up off the surface - this depends on temperature and rate of cure - but when it gets to a "green"state of cure, lay on several more coats of epoxy to fill the weave so that when you finally sand the surface (after removing any amine blush with water and cloths, sponges or Scotchbrite pads) you are only sanding epoxy and not going through to the glass.

Have a look on my website under the button labelled "First Mate Photos 3" for a brief pictorial demonstration - the thumbnails enlarge if you click on them.

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Some Articles on My Boats

Recently two came out, one in Small Boats Monthly and the other on the brand new, UK-based Barnacle Bill. Small Boats covered the Calendar Islands Yawl and Barnacle Bill had a piece by a customer in the UK who has built and avidly rows a Drake 17.

http://smallboatsmonthly.com/article/calendar-islands-yawl/

A Calendar Islands Yawl based in Duluth, MN

?
http://www.joomag.com/mag/0021558001447415734

The orogonal Drake 17 rowed by me in one of the Small Reach Regattas

Sorry these may not show much unless you have a subscription. Believe it or not I dont read much boats stuff....but these are very well worth he money. Both rags will require good contact and readership. So far the writing is excellent!

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More Detail on the Micro Repair

My recent post http://rosslillistonewoodenboat.blogspot.com.au/2015/04/micro-repair.html about repairs to a Phil Bolger Micro generated quite a bit of interest, and the following comment from Dave is an example:-

Thanks for the blog post, Ross, but you left out the details on the very parts Id be most interested in seeing!

So if you do a future post on the nitty gritty details of truing up and patching the damage, Id be most interested in that. 

Well, after taking initial photos of the damage, I didn’t many more during the repair process, simply because of time pressure – but here is a brief look at some aspects of the job: -

Initial job was to do a rough paint removal around all of the damaged areas to get a clearer idea of the extent of the damage, and to remove components/timber which had been destroyed. It also allowed ventilation and thorough drying.

Initial job was to do a rough paint removal around all of the damaged areas to get a clearer idea of the extent of the damage, and to remove components/timber which had been destroyed. It also allowed ventilation and thorough drying.

A small puncture wound on the forward/starboard topsides on the outside, and

....the corresponding spot on the inside

Brutal removal of paint, damaged timber, and broken epoxy fillets 

Brutal removal of paint, damaged timber, and broken epoxy fillets

Paint removal from around the forward bulkhead on the interior of the cabin, where the floorboards had punched through.

Most of the work shown above was done using a heat-gun and a variety of sharp scrapers. The paint was all two-part epoxy primer/undercoat and two-part polyurethane topcoat (I know, because I built this particular boat myself fourteen years ago!) and removal was not ever going to be easy. However, the heat-gun and scraper combination is a good choice as long as you are very careful about never overheating the material and damaging epoxy adhesive and paint in locations which are not part of the repair. Other primary tools include chisels, 4" angle grinders, drills, sandpaper - and elbow grease!

Next stage was to carry out a more gentle sanding  using (in this case) a 5" random orbit sander, going down through the grits to about 120 or 180. On the internal areas, the job is more difficult to achieve, and I made heavy use of a Fein Multi-master detail sander and plain, simple sandpaper on a sanding block, or folded triple. Hard work!

See above comments

See above comments

I dont have many photos of the next stage, but it mainly involved pulling usable components back into position using a variety of improvised tools such as lengths of purpose-cut steel angle-iron with holes drilled at strategic locations, and also temporary through-bolts and backing pads. This work can be very satisfying if done properly, and with attention to detail. The key is to have an open mind, and to be prepared to be bold with your surgery.

Once I was happy that my bracing would all work, and that all interfering debris was removed from joints, I opened the whole lot up again, and even spread damaged components further apart (using wedges and chisels etc). With the components held apart, it was relatively easy to treat all surfaces with un-thickened epoxy resin and hardener in order to prime the mating and damaged joints using disposable bristle brushes. This is a very important step if you expect to achieve a good structural repair. With the work area well primed, it was then a matter of applying a rich mix of epoxy/hardener combined with the recommended structural glue/filleting powder additive.

With the structural epoxy  mix worked into all joining areas, I screwed, bolted, or clamped the repaired sections together, which is why the previous work dry-fitting the bracing and jigging was such an important step. Where appropriate, I applied structural epoxy fillets at the same time.

The above two photos show steel angle braces screwed into position over the epoxied repair. In the case of Micro I had the luxury of using straight sections of steel to hold things in place, but on more conventionally shaped boats the same thing can be done using shaped and bent timber splints. Ill show an example of this in an up-coming post on a Whitehall repair.

Interior shot of the repaired bow transom, topside planking, and forward bottom planking. This was taken while the initial epoxy work was still wet and ugly. This work was followed by additional cosmetic epoxy filling.

Exterior shot of the starboard, forward topsides repair taking place. The actual puncture damage is quite a small spot underneath the centre of the plywood pad.

Matching plywood pad on the inner surface of the topside panel. As you can see from the exterior shot above this one, I placed twelve screws through the hull and into the internal plywood pad and pulled them in tightly over the epoxied repair. Note that both pads have been covered in a film of plastic to prevent them being glued to the hull permanently. All of those screw holes had to be repaired later, but the repair turned out well. The plywood pads were large enough to take up the curve of the topside planking when screwed together.

Structural work complete, glass applied where required, fill and cosmetic work done, and the two-part epoxy primer/undercoat applied (the white paint - three or four coats)

Topcoat (two-part polyurethane) applied, with just some minor black line work to be done between the green topsides paint and the off-white bottom paint (that is my little step ladder relected in the paint by the way).

Because of a lack of photos, time and space, this has been a very brief overview of the job, but it may give you some inspiration. Unfortunately, I have no photos of the way I repaired the forward watertight bulkhead of the cabin - a job involving more steel angle bracing and numbers of temporary through-bolts, nuts and fender washers.  In a post in the not too distant future, Ill show the repair of a glued-lapstrake Whitehall tender which suffered very serious damage to her hull in an accident. Most people considered her a write-off, but we were able to give her a new life.

Just a word about repairing screw and bolt holes. Many people simply fill the holes with thickened epoxy and sand the surface smooth after curing. I do not do this because the "cylinder" of hard epoxy in the screw hole intersects the surface of the repair at 90 degrees, and is sure to result in a circular crack in the paint after cycles of expansion and contraction due to temperature changes over time.

My approach is to heavily chamfer the hole on the inside and outside surfaces using a wide countersink or by dishing-out the surface using a sander. Then I fill the hole and the chamfered areas - this gives much less of a stress-riser where the epoxy fill intersects with the surface. However, if the repaired holes are going to be covered with a layer of fabric set in epoxy, this step is not necessary.

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More on External Chine Logs

Phil Bolgers Otter II design, showing her external chine logs

The contributor I referred to in my previous post, Graeme, has written back with with some more comments. I dont want to bore people with an on-going debate, but I think Graemes comment is worth printing: - 

Yes but... Poohsticks is design 10-5-57, ie from the early numbering sytem Bolger used (most of that series originals and other early independent Bolger work destroyed in an unfortunate office fire.) Its almost certain the Poohsticks design was completed in 1957. The date of the write-up about it is not clear to me, but the thinking behind it may well be contemporaneous with its design.

The Light Dory Type V is from the later adopted numbering system, post fire, and denoted as design #265 [there are eight types of Bolger light dory (counting the larger ones #526, #555) as modified from #140 (types -1 to -6) and on; #140-4 being the Orrell famed "Gloucester Gull" version, and #140-6 Paysons "Gloucester Light Dory"].

Dynamite Payson first built a #140-4 in 1967 (Bolger drew #140-6 for Paysons plans sales business much later in the 1970s due to issues with Orrell and proprietry rights. However, what goes around... later, upon Orrells death, Payson successfully purchased all Orrell plan rights, and passed most of the Bolger blueprints/rights back to Bolger!). The Type V, #265, the only one with external chine logs was certainly designed around 1973 specifically for publication in "Small Boats."

Now, to our points of difference: if, as you seem to imply, the 1957 Bolger conjecture (with his obvious caveat) that a chine log "reduces eddying along under the chine by carrying the side flow aft......" is evidence of, as you say, a "Phil Bolger theory that if the hull was properly shaped, an external chine log may reduce drag", then, repectfully, I must disagree for the reasons that follow.

First, in my view its a bit too much of a stretch to turn a Bolger conjecture into a Bolger theory. Bolger raised so many conjectures throughout his career, sometimes with wry humour, often with a caveat as here, yet when he stated his theory in any way he was quite serious, and unreservedly adamant (a good example is at page 50 of "Small Boats" "My flow theory accounts for this...")

Second, sixteen years elapse between Poohsticks and the Light Dory Type V, by which time clearly Bolger is not stating an exterior chine log reduces drag, rather that he merely thinks it may not add to it.

Third, a further nine years later still, in 1982, of the projecting edge of the bottom of Lions Paw #404 ("30-ODD BOATS", p97), which is an excrescence effectively the same as an external chine log, Bolger stated that it "doesnt seem to create much added drag in a hull of these proportions". Unlike Poohsticks, or LDT V, the Lions Paw hull is certainly shaped according to his theory as applicable to sharpies to minimise eddying flow at the chine, ie to minimise drag, yet overall the chine excrescence does result in added drag despite it somewhat fencing cross chine flow (in this design it is tolerated for other reasons).

Fourth, well, admittedly not a reason carrying much weight, but allegedly the LDT Type VI actually is a bit faster than the LDT Type V. There is more going on in the way of design modifications to produce the Type V than just the external chine logs, but perhaps the fact is that they dont help either? (Type VIs have been built with external chine logs too. As far as I know theres been no comparison made with a standard VI.)

best to you
Graeme

interrogate the bolger chart,
every phrase, every mark...

Having read what Graeme has written in this piece and in his previous comment, I have to agree that my statement about Phil Bolger having a theory that external chine logs may reduce drag on a properly designed sharpie hull was overstretching the mark. However, he did imply that the increase in drag, if any, was minor - certainly far less than most people would think intuitively. If you look at my previous post, you will see a list of practical advantages to be gained from using external chine logs.

All of this has been generated by a post I wrote about a Jim Michalak-designed boat. My aim was to inform those people who seem to have a prejudice against external chine logs. Perhaps I was not careful enough with my phrasing, but the practical advantages remain. It is interesting that the people who are horrified by external chine logs dont raise any objections to external keel battens, bilge runners, or lapstrake planking...

Regarding Graemes discussion about dates of design and of publication, I have this quote from a re-publication of the books, "Small Boats" and "The Folding Schooner".

The combination book was called "Bolger Boats" I think (I dont have a copy) and in the preface (Dec 1982) he said, "...What I wrote in these two books, as opposed to what I drew, leaves me fairly contented. Draw you own conclusions from that."

Regardless of the resistance argument, Phil Bolger continued using external chine logs on designs for a very long time.

Birdwatcher with her external chine logs (sorry, I dont have a picture credit and will remove it if anybody is concerned)

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Sneaking up on Perfection

For the first time in my short design-build career, I am finally in the stage I have longed for, that is, to be working on mk II and mk III+ versions of already successful boat models. Thus the blog title, "Sneaking up on Perfection". This is certainly the case with the Echo Bay Dory Skiff (EBDS), my first kit, based on a design a friend had drawn 26 year ago. Ive built many Echo Bays with families, corporate teams, and students. When it came time to start the kit business, it was obvious to begin with the EBDS. At that time, I had no idea how powerful 3D modeling programs could be and it didnt matter, I was a long way from knowing how to draw a line segment in 2-dimensions!

The original Echo Bay (left) at 26 years old and the mkIII version as a kit (right). 

The EBDS is the last of my boats to get modeled in the computer. After a couple weeks of side-work, I have just finished the new model. The improvements are:

• improved sheer for aesthetics and sailing purposes
• slightly longer (now 11 10" LOA)
• increased freeboard (about 1")
• more interior options: enclosed plywood tanks for flotation and 2 different solid-wood thwart arrangements.
• improved sprit sail shape and new lug rig option
• dedicated oar plan for the EBDS
• paper plans will be available as well as full size patterns (FSPs) and a plywood kit

The new lug rigged option

Next step is to break the model apart and develop the 2D geometry. Ill start by unrolling the planks and flattening the bulkheads, frames, and other hull structure. This process of generating 2D geometry takes very little time (maybe 2-3 hours). The time consuming part is drawing the plans for how to make these parts from scratch and drafting the construction drawings so she can be built as designed. This will take another couple weeks of side work. Then the CAD files for cutting on a CNC machine will need to be made, another couple days of side work. 

This model shows the standard solid wood thwart arrangement, but a plywood (flotation) tank option is a new addition.

Phew. A lot for a 12-footer. But on par for creating what will be the best 12-foot sail and oar skiff the market has seen for a long time, perhaps ever! But this photo shows why I do it: adventures with the kids.

A recent outing in the EBDS with the skipper (the one in the stern).

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Star 45 Setting Sail on line How To Sail resources

From: "Don Keeney" <1keyknee@281.com>
Date: Sun, 19 Nov 2006 15:39:26 -0600
Subject: [Star45] Sail Trim

A great place to learn about sail trim and sailing in general.
http://www.sailingusa.info/sail_trim.htm

Don Keeney
Star 45 Class Secretary
--
Outstanding recommendation. Wonderful site. full of photographs and all sorts of instructional materials. Pictures of tells and how to read them:)

Another must place to visit (you can try out your sailing skills):
National Geographics Interactive Sailing:

Master rudder and sail to get your boat going as fast as possible no matter what direction youre sailing in-or which way the winds blowing.

Controls available:

Sail Adjuster: Use the left sliding controller to rotate the sail in relation to shifting wind (shown as arrows). When you cross the path of the wind, your sail will swing to the opposite side.

Rudder Adjuster: Using the right sliding controller, steer to port (left) or starboard (right).


Uncle Dave

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Different Rigs on the Same Boat

Most of my published sailing boat plans come complete with a number of different rig options.What makes mine different from most other offerings on the market is that I try to arrange the various rigs so that the original mast can be used for several different rigs, and that the original mast steps and mast partners can be used. By that I mean that a builder can choose one rig at the time of building, and at a later date, rig the boat differently by simply ordering some new sails and, maybe, making a few different yards, or gaffs etc. But no structural changes need to be made to the boat herself, and the rigs can be changed at will.

Each photo below is of Paul Hernes Phoenix III named Willy Wagtail.  Even though she is sporting a green sheer strake in the first, second and fourth photos, and is looking nicer with a more plain colour scheme in the other two, she is the same boat, and nothing has been changed other than the sailing rig.

Phoenix III with her sprit rig set without a boom. This can only be done on boats which have had the correct sheeting geometry designed-in from the beginning.

Here is the very same boat, but with a boom fitted. The boom makes the boat slightly easier to handle, and allows more options for sheet locations, but the boomless rig is more seaworthy, as there is no boom to drag in the water if the boat is over-pressed - a situation which often prevents the helmsman from being able to ease the mainsail and can lead to any boat sailing herself over into a capsise 

Showing off with her new paint job, Willy Wagtail has been rigged with the balance lug sail. The mast is the original, the mast step is original, and the mast partner is original. All Paul did was use a different sail. Some days, he starts off using the larger sprit rig (which can be sailed with or without the jib) and changes to the smaller balance lugsail if the wind comes up, or if he starts to feel lazy.

This shows the boat sailing under mainsail alone

In this photo, Willy Wagtail is carrying the flying jib from the sprit rig, and a standing lugsail taken from a Joel White-designed Poohduck Skiff - which by coincidence is a design which can also be sailed with or without her jib.

The matter of hull/sail balance is frequently brought up, and one cant just put any rig on any boat and expect the boat to perform properly. The rigs have to be proportioned in such a way the hull balance is maintained within certain limits, otherwise you will end up with excess weather-helm or, even worse, lee-helm. At the design stage I put a lot of time into proportioning the various sail plans so that they will balance. However, you can see from the last photo above that there is a lot more tolerance for centre-of-area and centre-of-lateral resistance changes than the theorists will admit (I limit my comments here to small centreboard and leeboard dinghies - and even then, the rudder and centreboard proportions, area, and location must be taken into consideration when following this line of thought).

This is Periwinkle with her Periauger or Cat-Ketch rig as designed...

...and here she is with the mizzen removed altogether, and the main mast moved back to a third mast partner and step. This step was designed-in to allow just this procedure.

Another shot of Periwinkle moving well with the mast and mainsail in the third location. This arrangement changes the sail area from 155 sq.ft to 104 sq.ft without the need to reef both the mizzen and the main.

Here, the crew of Periwinkle were anticipating tricky conditions outside the cove and had not only used the mainsail and mast in the third location, but had tied in a reef as well.

In this photo, owner John Shrapnel has moved the main mast to the third location, and has set the mizzen sail only. In this configuration, the boat is only carrying 52 sq.ft of sail, but she is under good control and is moving fast. John mentioned eight knots by GPS with the boat very lightly loaded - but anyway, she is going well.

This is another shot from the same day (52 sq.ft mizzen sail only) and I am told by a person who I trust (no names) that Periwinkle was actually overtaking the boat in the background.

Another Periwinkle but this one has been rigged with the gaff-headed cat rig (details supplied with the plans in addition to the cat-ketch rig). The mast is exactly the same as the main mast on the cat-ketch rig, and is stepped in the standard forward location. This rig can also set a small jib not shown here.

John Shrapnel is the most experienced Periwinkle owner at the moment, and he has tried a number of different rigs, and configurations, and is currently using the standard balance lug mainsail (the one from the standard cat-ketch rig), but with the mast set in the forward location (normally balanced by a mizzen mast and sail). One would think that this arrangement would induce lee-helm - something to be avoided at all costs. However, John has pulled the forward end of the boom aft to the mast, therefore moving the centre-of-area of the sail aft enough to prevent lee-helm, and in the process the aft end of the boom has cocked up high above any vulnerable heads. The result is that the rig is now a 104 sq.ft Standing Lug.

See in this youtube clip just how well the boat goes when being sailed by a light crew - in this case one person.

The old-fashioned rigs have got a tremendous amount going for them if you know what you are doing, and if you are prepared to be patient with your development. All basically cordage, wood, leather, and cloth.

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Blog on Website

Well, with the help of Mark Bowdidge from Bowdidge Marine Designs I have got a blog up and linked to my website. Mark and I have been having many discussions about boat design and given Marks speciality in powerboat design and mine in sail boat plans, we have been able to expand each others horizons. Take some time to have a look at Marks site - I think you will be impressed.

Work goes on with the clean-up from the recent devastating floods here in eastern Australia. We still havent seen an insurance assessor, but in the meantime the work goes on. We have been overwhelmed by the kindness of people within the local and wider community. It seems that natural (and un-natural) disasters bring out the best in a large proportion of the population. We are grateful beyond expression for the support we have been offerred. Special thanks goes once again to Duckworks Magazine , Craig and Cath from C & C Shipwrights at Redland City Marina at Beveridge Road Thornlands, Queensland Australia, Graham and Judy Marsh, and to Dr Paul Truscott. It goes without saying that our children have been extremely supportive.

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Bow Transom and Cabin Top on Whimbrel

The matter of the bow transom on Whimbrel has stirred up some discussion over the last couple of days - see this post for information.

In the drawing above, you may be able to see that Ive drawn in three separate waterlines with accompanying displacement number attached. The upper waterline shows the displacement (952kg/2094lbs) with the water just touching the lowest point of the bow transom.

Here is an interesting comment from Rick Hayhoe: -

Phil Bolger sometimes said or wrote the strangest things. I have to point out the fact that you dont make the boat faster in any practical sense by drawing out the waterlines to the full LOA, leaving the boat just whacked off in a plumb scow bow that touches the water, or nearly so, at rest. What you do is create a monster that will misbehave in the slightest seaway and almost any wind.

I very much like the concept Ross is promoting in Whimbrel. Ive admired the design since first seeing it almost a year ago, but I certainly would make the boat eighteen inches or two feet longer at the forward end without changing anything else, getting that scow bow up, well out of the water and raked a bit more. Just imagine for a moment the danger of broaching on a downwind point of sail with following sea and opposing chop set up by a rivers outflow agains tide and wind, with that scow bow slamming into the chop and the following waves trying to push your stern ends around. Those are conditions one can expect to encounter routinely when entering many estuaries, let alone the conditions encountered while struggling in a squall or making for home in suddenly rising stormy weather.

Living as I have for many years in Asia, I have had the opportunity to look closely at a variety of scow bowed Asian sailing and motoring craft. Generally, you find that either the bow transom is raised well above the LWL or it is raked well aft. Some are built with a profile like a garvey, that is, raked and rounded, cross planked, to recede as they approach the LWL. In most cases, some compromise has been made in order to reduce the impact of the transom or scow bow against wave and chop.

Bolger was a brilliant designer, but he had a tendency to paint himself into the damnedest corners, and he was stubborn enough to stick to his pet theses no matter what. You have to admire most of his work, perhaps even his stubbornness when he was right, but youd better take some of his philosophizing with a grain of salt. Boats move through a constantly troubled and dynamic pair of fluids that make up one of the least forgiving environments on our planet. You flout at your own risk the limits and dangers they pose.

Rick Hayhoe


I estimate that a hull built from 600kg/cu.m plywood (a conservatively heavy estimate based on the weight of all the ply in the boat and then doubled to account for timber components, glass, epoxy and rig etc) would weigh about 314kg/691lbs. Add to that 240kg/528lbs for crew and gear and you end up with a displacement of 554kg/1219lbs fully loaded displacement. This is a conservative figure which I believe would be reduced significantly in reality.

Below is a perspective and a lines plan showing Whimbrel at the maximum displacement in salt water, and Im reasonably happy that the forrard sections are buoyant enough and shaped well enough (in terms of rocker, distribution of volume, and chine shape) to prevent the disasterous behaviour that Rick predicts. I may well be proven to be wrong, but after having modelled a number of other hull shapes at 18 6" length on deck and with a raised, smaller bow transom, I have elected to stay with the design as drawn at 17 length with the big bow. Storage and building space is a real issue for many people and I was trying to get a roomy and capable boat without excessive outside dimensions. There is no such thing as a perfect boat!

By the way, the bow transom is set at 65 degrees to the waterline, which is a long way from being plumb.

A perspective of Whimbrel showing the waterline at maximum displacement of 554kg/1219lbs in salt water

Whimbrel lines plan at 554kg/1219lbs displacement

Robert relied to the post yesterday regarding his question about sleeping space: -

Ross, I can see why you were taken with the concept. It sounds as if much thought has been given the design. I appreciate the amount of interior room designed in. Is there to be a slot top or more enclosed cabin? If designed to be totally roofed over, could the cabin be modified to add a pass through slot? It is very hot in Florida much of the year and the slot top cabin seems to offer greater forward access.

This is an interesting subject, and I had been giving it a lot of thought myself. You see, I cant stop fantasising about building boats for my own use, and Im quite taken by Whimbrel. While dreaming of the boat, I had decided that I would modify the cabin top if I built her for my own use, and that I would use a Birdwatcher-style slot-top. However, thinking that the majority of the buying public would prefer a conventional companionway with a sliding hatch, that is what I drew.
My opinion is that the slot-top is a superior option for this size of boat, allowing for better ventilation, unlimited headroom, and secure footing right up to the mast.

Just for interest - no plans available in any form - here is a twenty-foot boat I drew up for fun, to visualise a full Birdwatcher cabin on a nicely shaped conventional hull. She has got very firm bilges so that a person can sit comfortably out at the sides.

20x 6

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