Wednesday, June 29, 2011

Comment regarding "Photos of a good flat-bottomed skiff"

Graham has written with a comment about leeboards: -

Nice pics. My life seems to be one long series of overdue jobs, so I know what a relief it is to be back on task!

The external chine logs I don't mind so much, but the leeboard?? I know there are some really good practical reasons for going down that path, and I know that Phil Bolger was a great advocate of them, but they take some getting used to.

Apart from the increased internal space, do you think you could just remind me what the benefits of a leeboard are; especially when used in conjunction with a flat bottomed hull like this one.

Well, I'm not an expert on the subjuect, but the most obvious advantage of leeboards is exactly what Graham has pointed out - less clutter inside the part of the boat in which people want to sit. Now, having a centreboard case in there with you is not necessarily a bad thing. I've found a case to be a great way to brace one's feet; to bundle people away from each other when sleeping; and to use as a sort of improvised set of hiking straps by hooking the soles of your feet under the upper external framing of the case while hiking out.

Another advantage of leeboards is that they are providing lateral plane from the surface of the water down to their tips, rather than from the bottom of the centreboard case to the tip. The problem there is that I suspect that the "end plate" effect of the bottom of the hull over the centreboard more than makes up for the increased effective area of the leeboard.

But despite all of that (including arguements about better hull strength without a centreboard slot), there is one overwhelming practical advantage of leeboards for a cruising dinghy, and that is avoiding the plague of having sand and shell-grit pumped up into the centreboard slot while the boat is pulled onto the beach with wavelets surrounding her. That is the reason why my centreboard designs have a positive method of forcing the centreboard down, rather than just relying on a block of ballasting lead in the board - a jambed board is a potentially serious problem, particularly when leaving a lee shore - you must be able to get the board down quickly, and the combination of sand and shel-grit inside a case is a serious problem. It is also a very good arguement in favour of a dagger board rather than a pivoting centreboard.

I've been having an interesting discussion with a fellow in Maine about the effectivness of long, shallow keels. He sails a Phil Bolger Oldshoe and I occasionally sail a Bolger Micro - both of which have long, shallow keels. Both of us have been pleasantly surprised by just how effective these keels are - despite what the theorists will tell you. If you get the chance, read Arthur Ramsome's books in the Swallows and Amazons series (I read my first one at about eight years of age, and I'm still reading the twelve-book series on a regular basis - they are that good), where he describes Swallow, a 14 ft clinker sailing dinghy with a shallow keel.
Here is me sailing along happily in my leeboard-equipped Bolger Nymph. The boat is on a run, with the boards raised, but I can assure you that they worked very well indeed!
This jpg shows my Whimbrel design (17ft x 6ft 9in), which incorporates leeboards for many of the above reasons. These plans are quite detailed, and although close to being finished, will still be a month or so. Too much work on my plate, and only one person to do the jobs!

Up-Date on Seating Positions in Dinghies

Rick has written an excellent comment about the previous post - please take the time to look at it, as the idea is very good indeed. I have thought of a similar system, but Rick's is the best idea yet.

Having sailed in a few small boats myself, I concur very strongly with Ross regarding side benches. If the seaway gets a bit active, they get in the way very quickly. If one really MUST have them, they should always be removable, but latched down with buttons so they don't come loose when things get really rough, as sooner or later they will if you sail much.

As for me, same as Ross; sitting low in the bottom of the boat with back against the coaming, or sitting on the windward washboard (side deck) is the way to sail a small boat.

For sleeping with a decent amount of dry, level room in a small open boat, one you won't roll off of, why not build in a pair of risers just above the height of the thwart and the sternsheets, with buttons on the backside of each, facing outward to the hull's planking? Then when you want to sleep aboard, you unroll your strong canvas trampoline, slip its grommets over the buttons, stretching it between the risers, and sleep on that up out of bilgewater and high enough above the thwart and sternsheets to avoid hard corners in your back. On some boats that might create a space wide enough for two to sleep.

No need for the obstruction of side benches at all, and the risers, if made a bit wide in their vertical plane and thought out carefully, notched into half frames, should make a good backrest supplementing the coaming or washboard carlin each side. Adds a bit of weight, but I'll wager that it'll be a lot less than the side benches, with no obstruction of internal space and no loose hunks of wood coming loose on you at the worst possible time.

Also, Geoff Leedham has emailed me to say that there is no obvious support for the seats when in the centre location. The cleats for the centre location hadn't been installed at the time the photos of the seats in the "side seat" location were taken. However, in the shot where you can see the seats butted together in the centre "sleeping flat" position, there are 19mm x 19mm (3/4" x 3/4") cleats screwed to the forward face of the stern sheets, and to the aft face of the main thwart. Look at this photo and you can see the outer cleats - there are similar ones under the "sleeping flat" set-up on the centreline. It is a very simple arrangement.

Sunday, June 26, 2011

Seating Positions in Cruising Dinghies

I'm now nearly 57 years old, and for most of my life I've been sailing small cruising and racing dinghies.

As far as I'm concerned, there are only two places to sit - either on the bottom of the boat with one's weight in the turn of bilge, or on the gunwale/side decks to work the boat in heavier conditions. I love the inside position, as the side-deck carlins support the back and shoulder blades nicely, the view is unobstructed by the sails, and there is an enhanced sense of speed due to having sight lines which are closer to the surface of the water.

You may have seen this photo before, but it shows two of my sons and me at the end of a nice afternoon sail on Moreton Bay. Conditions outside had been quite lively, but the only person who had to change sides was the skipper.

The above photo shows the relaxed position, and the one below shows the only other position I think worth considering.
That is me, enjoying a gentle afternoon sail in my wooden International Finn.  This particular boat was built for the 1956 Olympic Games. In a Finn you need to be hiking out in just about any wind.
Despite what I've just said, there is still a strong demand for side seats from people who enquire about my dinghy plans. On paper these side seats appear to be very comfortable and convenient, but in my experience they rob the interior of the boat of room to move, and the seating position is neither one thing nor the other. The crew end up too high to see under the sails, are too high to receive meaningful back support, and are too low to be able to hike out. Other than when hiking out on the rail, the turn of bilge sitting position provides the best live ballast location, and provides protection from the elements.

Ok! You now know where I think people should sit, but the fact is that many crew members like the idea of side seats. In order to give the option of side seating without ruining the boat, I have come up with an idea which provides removable side seating, and also solves one of the major problems when beachcruising in a small boat, which is where to sleep out of bilge water, with room to store gear.

The concept works on both my Phoenix III and First Mate designs, but is adaptable to many others. Paul Hernes, who built the first Phoenix III thought it worth a try, and here are some pictures.
This is Phoenix III showing the main thwart in the foreground and the stern sheets (aft thwart) in the middle distance. The aft edge of the main thwart and the forward edge of the stern sheets are parallel and at a similar level.
This is First Mate under construction. You can see the same arrangement of main thwart and stern sheets as in Phoenix III.  In fact both boats have identical internal arrangements - just the hull construction (and therefore, shape) are different. 
My proposed method involved gluing and screwing some 3/4" x 3/4" (19mm x 19mm) wooden cleats to the aft face of the main thwart, and to the forward face of the stern sheets, and dropping a pair of removable side seats onto those cleats. Easy to remove if required, and they can then be stored upright against the side of the centreboard case, taking up very little room. Better still, remove them altogether and leave them at home.....
This is Paul's Phoenix III with a nice set of side seats installed.
Another view. The cleats are hidden under the ends of the seats.
Now for the important part. My idea had been that the side seats could be slid into the centre of the boat, giving a sleeping platform which is up out of the bilge water, with stowage space underneath. After a night's sleep, the bunk flat turns back into side seats, or better still, gets removed and stowed alongside the centreboard case. The length for sleeping is the total of the width of the main thwart, the width of the stern sheets, and the length of the side seats - this turns out to be adequate for most normal-sized humans in these small boats, and the sleeping width is the accepted standard of 22 inches.
Paul's Phoenix III with the seats arranged for sleeping. The system works very well indeed.
So there you go, folks - multi-tasking!

Wednesday, June 22, 2011

Photos of a Good Flat-Bottomed Skiff

Back in April I wrote two posts about flat-bottomed sailing and rowing boats (see Discussion About Flat-Bottomed Boats and Sharpie Hulls and Fine Sections ).

Things have been pretty hectic at our place since the disasterous flash-flooding which hit our area on January 10, 2011, but over the last few weeks I've been getting back to work on some over-due jobs, one of which is a nice flat-bottomed skiff for a customer in Brisbane. She is a Jim Michalak-designed Mayfly 14 and is a good example of a well-designed flat-bottomed hull. The point to note is the relationship between the curve (or rocker) of the bottom when viewed in profile, and the curve of the topsides when viewed in plan-view. These two shapes, in combination, determine the chine-line, and the the flow of water around that chine. The aim is to reduce cross-flow to a minimum in order to minimise eddying.

A nice, simple boat, showing the pivoting leeboard, centreline hatches, and external chine log.
Many people find external chine logs difficult to accept, but they have some advantages. They are much easier to install on a boat which isn't built on a strongback, avoiding compound bevels and determination of length. In addition, they provide good protection to the chine, which is somewhat vulnerable on a flat-bottomed boat. Phil Bolger had a theory that if the hull was properly shaped, an external chine log may reduce drag, by delaying the point at which cross-flow occurred. In addition, I guess that they provide a bit of extra lateral resistance, which is good in a sailing boat.
Brutally simple pivoting rudder design which requires only one rudder cheek. The key is the amount of blade above the pivot point, as it provides support to the blade regardless of which tack the boat is on. The patch at the bottom of the blade is where I've cast in a block of lead to sink the blade. It is covered with a small patch of 200gsm/6oz glass to prevent cracking between the lead and the plywood. The white is epoxy and sanding filler. 
Very simple, but rugged, mast step and mast partner, well braced by framing on the other side of the bulkhead.
Close-up of the mast step showing the very necessary drain hole to get rid of water in the step. This is all a bit rough at this stage, still waiting for some clean-up and fairing work.
Close-up of the external chine log, rounded over on both edges, and showing how I've brought the epoxy/glass bottom sheathing around the bottom edge and up over the chine log. This is to protect the vulnerable edge grain of the 1/2" plywood bottom.
Outer stem made from a superb piece of Celery Top Pine from Tasmania. Hard, dense, and strong. Still waiting for finishing work and fairing.
Close-up of the external gunwale/sheer clamp, laminated from two beautiful pieces of Silver Quandong. Note how in a simple boat like this, there are plenty of places where the edge grain of plywood planking is vulnerable - this needs to be considered, with action taken to protect the edge. The edge of this plywood will be treated with three or four soaking coats of epoxy prior to being painted, but even then it will have to be watched in service.
Detail of the corner joints in the hatch framing. Once again, Silver Quandong
The single-sided pivoting leeboard allows for a clean and open interior. Although simple in concept, the leeboard design requires great attention from the builder when fabricating the leeboard upper and lower guards, so that the board is absolutely parallel to the centreline of the boat. Trickier than it looks!
A nice, simple, rugged boat. The external stem cap is yet to be trimmed, and at this stage I'm planning on finishing it off with a Jonesport Cleat.
So, there you have a nice little boat. But you don't get something for nothing. These boats might be easy to build, but they consume large numbers of silicon bronze screws, and the structure is quite heavy. However, she should give long and trouble-free service, given that she is painted properly (she will be) and stored properly

Saturday, June 18, 2011

Glued-Lapstrake (clinker) Plank Fairing

Glued-lapstrake is a deservedly popular method for building one-off boats in wood/epoxy - for a number of good reasons. In the case of the amateur and small-time professional builder it gives just about the fastest path to a handsome, round-bilged hull, with the added benefits of being light, strong, attractive given the plank lap lines. Very importantly, the building jig is simple and easy to build.

I'll write more about the particular advantages of the glued-lapstrake building method in another posting, and I've previously pointed out the way in which a fine entrance combined with the prominant plank laps keeps spray knocked down in a fashion similar to sprayrails.

In the above video, you can see how well the plank laps work at knocking down spray, although the boat (my Periwinkle design) is running in very light winds - but you can clearly see the principle.

To get back to the point, one particular advantage of glued-lapstrake construction is that the building jig need only consist of relatively few, widely-spaced molds or frames, with the plywood planks bridging the gaps between the molds in a fair curve.
Here is a typical glued-lapstrake jig, showing widely spaced molds made from disposable material. In this case the boat was a Francois Vivier-designed Aber which I built for a customer about five years ago.
Plywood is a wonderful material if you can locate good-quality sheets, but one of its virtues is also a liability. Plywood is of almost equal strength in all directions, and is frequently used in much reduced thickness compared with solid timber. The problem is that very occasionally the planks may tend to flatten out between the molds.

Plywood planks going on over widely-spaced frames and molds. This is Periwinkle

Some people put stringers into their molds, but this adds a lot of complexity to what should be a simple set-up, and adds considerably to the cost of the mold. In addition, it makes removing the boat from the mold difficult, especially if the boat has any tumble-home (that is where the sides of the boat curve in towards the centreline of the boat as they get towards the gunwale as frequently seen on "Canadian" canoes for example).

If the building jig is a simple one without stringers, it is easy to access the inside of the boat during construction, and when it comes time to remove the boat from the jig, all one has to do is knock the individual molds out one at a time.

However, there are occasions where the thin planking refuses to lie in a smooth, fair curve - usually just in a few odd places. When I am faced with that situation I use a technique where a stringer, or batten, is applied to the outside  of the hull. It need not even be a full-length batten - just enough length is required to span three or four molds. Temporary plank fasteners are driven through the batten to hold the plank while glue is curing, just as in the rest of the planking job.

Here you can see a temporary batten sitting over a plank lap on the original Periwinkle. There was a little flatness towards the bow (which has been fixed now with a minor alteration to the plans)
Close-up of the batten showing how it sits over the plank lap, and also showing where one of the temporary fasteners has been driven through.
For a job such as this you can usually get away with a single batten, re-used on subsequent planks if and where required. On Periwinkle the batten shown did the entire boat. But it needs to be empasised that the extra fairing is very rarely needed - but it is nice to have the technique available in situations where the ply is a bit too limber, or there is an inaccuracy in the jig.

Monday, June 13, 2011

Removing Temporary Screws

Modern wood/epoxy construction needs very few permanent fasteners. When building Glued-Lapstrake, Stitch-and-Glue, Glued Strip Plank, or Cold-Molded hulls, almost no permanent screws or nails are required. But you will need LOTS of temporary fasteners!
Some of the eighteen thousand(!) 316 grade stainless-steel staples which went into a fifteen foot long Cat Boat we built using the strip/diagonal method. Every single one was pulled out when the glue had cured.
The picture above shows an extreme example, but I do use plenty of staples, nails, and most particularly, stainless-steel screws. When building glued-lapstrake boats, I use self-tapping stainless screws to hold the plank laps together while planking. A lot of books will advise you to use various combinations of clamps, but I am concerned that the combined weight of the clamps may distort the structure. If properly built, a glued-lapstrake boat does not need enormous pressure to keep the glue joints together, and light screws work for me.
Here you can see where I have removed temporary plank fasteners after the glue has cured. The ones at the hood ends (forward ends of the planks) have been left in, and are made of silicon bronze.
The problem with temporary nails and screws is that the epoxy glues them in as well. If you get to them before the epoxy has gone rock-hard it is possible to ease them out with a tile nippers (on of my all-time favourite tools - I'll write a post on them one day!) or a screw driver. But much of the time the fasteners will break off in the timber.

The most reliable method I know of for removing stubborn screws and nails is to apply heat. I have a relatively small soldering iron which has had its tip cut off to a flat end. After heating to working temperature, I place the iron squarely against the head of the screw (or nail) and let the heat penetrate for about 45 seconds. The time depends on the thickness and length of the fastening, but for usual sizes the 45 seconds works.

End of soldering iron cut and filed off square

I then move onto heating the next one while I back the previous one out. In this way, there is very little wasted time - certainly less than what is required to extract a broken-off screw or nail.

Heating the head of a temporary stainless-steel self-tapping screw
People ask why I bother with stainless-steel for a temporary fastener? Well, it is just so that if a breakage occurs, the metal left in the boat is sort of marine in grade. Stainless-steel is ok if protected from moisture, or is out in a completely oxygen-rich water or air environment. But if in a situation where water can reach the fastening along a crack or other poorly flushed area, crevice corrosion will occur, and the fastening will de-grade rapidly.

Ever wondered why you can see a beautifully polished stainless steel fitting on a boat with no sign of corrosion on its outer surface, and yet there are horrible rust stains running down  from the point where the fitting is flush against the hull? Same fitting - shiny one side and rusting away on the other. That is crevice corrosion for you. If attaching stainless-steel fittings, always set them in a bed of high-quality bedding compound such as 3m 4200 or Sikaflex 291.

Sunday, June 5, 2011

Phoenix III and the Perfect Customer

Mist on Lake Cootharaba -courtesy Paul Hernes
Sometime early in 2005, a fellow walked into my workshop in Brisbane, Australia. At the time we were extremely busy with a number of boats under construction, and I remember that I was unable to attend to the visitor for quite a while. He had told me that he wanted to look at a boat we were building, with the intention of purchasing a set of the plans for his own use. His name was Paul Hernes, and he appeared to be typical of the sort of amateur builder who frequently came to the shop.

In those days the telephone would ring constantly, and I had to leave Paul to his own devices for five or ten minutes. While he was waiting patiently, the visitor wandered around the workshop, and struck up a conversation with my friend, Doug Laver, who was working on one of our jobs. Doug is a man of action, and after listening to Paul's story he said that he should abandon any idea of buying the plans he had in mind. Doug told him confidently that he needed a better boat, and said, "...Ross will design it for you."

Now, Doug's promise was made with the very best of intentions, but the problem was that I didn't have any idea the the promise had been made!

For quite a long time I had been drawing designs as a method of educating myself. Despite a lifetime of reading about boats and boat design, I still didn't know anywhere near as much as I wanted to about the design process. I began my design work as a strictly private affair to help me better understand the work of the designers  from whose plans I built. But a promise is a promise - Doug and Rhonnie were both of the opinion I could do the job, and Paul Hernes didn't know of my misgivings.

Designing a boat - at least one with detailed drawings, rather than just a set of lines or a 3D model - takes up an enormous amount of time, and time was something I had very little of in those days. We were working fourteen hours a day, six days-per-week, and after work I still had to do all of the accounting, ordering, and invoicing. Consequently, Paul's new design was done in very late-night sessions, and I had to feed him the drawings one or two at a time. The instructions - other than some notes on the plan sheets - were verbal, and delivered over the telephone. (These days there is a fifty-page instruction manual with the plans).

To cut a long story short, Paul Hernes turned out to be one of those rare people who have intelligence, patience, good-humour, and initiative in equal measure. Despite having only built a tiny pram dinghy by way of past experience, Paul had the very first Phoenix III done in about five months.
Paul (dark shirt) listening to another of my friends, Ian Hamilton, (red shirt) giving him advice that he didn't seem to need! The hull of the very first Phoenix III.
Time and again I have explained to people that the thing to do when building a boat is just to get on with it, and most of the thousands of questions which fill up your mind at night time will be answered by the job itself. What is needed is what Paul displayed so very well - common-sense and initiative.

Well, it is now six years since the first Phoenix III was launched, and Paul has sailed her on an average of once a week for that entire time - sometimes he sails much more frequently, and occasionally poor weather keeps him off the water for a little while. But I have met few people who use their boat more consistently (yes, Rick, I know you do too...)

Paul on launching day. He and I spent plenty of time getting the boat rigged and sorted before going to the water. No fanfare and no hurry - that is always the correct approach.

Paul and me about five minutes after the very first launching under sail. The crease in the mainsail is because the brand-new snotter line had stretched, but she was going nicely anyway.
Paul's Phoenix III tacking away from Rick's Pooduck Skiff
Phoenix III in a tranquil beachcruising scene.
That is me testing her stability on launching day. Very good for such a slim boat.
Paul repainted her a while back. Here she is showing her new hull paint and her optional balance lug rig.
As the above photo shows, you can rig Phoenix III in a number of different ways, using the same mast and the same mast step and partner. There is even a Bermudan rig which requires stays - but it still uses the standard mast step and partner. Being able to swap rigs without carrying out any modifications to the boat is a distinct advantage, particularly if you are interested in cruising as well as day-sailing. I took great care to proportion all of the rigs to allow for proper hull-balance while still using a standard mast stepping position.

There are plenty of examples of Phoenix III around now - this is a nice one sailing on the U.S. west coast

Since Paul finished his boat there have been a lot of other examples of Phoenix III launched. At the time I designed her, I had decided that the ideal size for a beachcruiser which would carry one or two people, be a pleasure to row, and be light enough to manhandle onto a trailer when operating alone was somewhere around 15ft long and with a breadth of 4-1/2ft to 5ft. I have not changed my opinion.

Paul's boat on a Queensland beach, showing off her lovely Allwood sails.
Since the first day when Paul walked into my workshop, he has become a good friend and an inspiration to me and to many other sailing people in this part of the world. It is largely due to him that Phoenix III has become such a success. Paul has quietly and steadily worked over his boat, developing the running rigging and making small alterations to his stowage arrangements etc. This is how things should be - a boat used frequently, maintained well, and developed so that the combination of skipper and boat become a smoothly-functioning team.

You can download free study plans here and see my web page of designs here