Tuesday, February 19, 2013

Current jobs in the workshop include a Jim Michalak-designed Scram Pram I'm finishing off for a customer who has done a lot of work on the job already, but whose work commitments have prevented him from carrying out the final few jobs. See my previous post for photos. I have to say that this boat is very exciting and I look forward to the test sailing so that I can gain first-hand experience of the "Bird Watcher"concept.

Ian Hamilton's First Mate is nearing completion finally. The interior has been painted using a water-reducible linear polyurethane paint, and despite the difficulty in applying this sort of paint in very hot conditions (over the last month or so, the temperature inside my shed during the day has reached 43C/109.4F on many occasions), the end result has been very satisfactory. Properly applied, the paint ends up being as tough as the conventional two-pack polyurethanes, but has a pleasing subdued gloss which is appropriate for wooden boats, and the paint can be applied with much less concern about the dangers of VOCs (Volitile Organic Compounds). Brushes wash out in water, and as they say, you can drink the thinners (water!). I've used this sort of paint on many occasions in the past, and I can tell you that it is not easy to apply unless the conditions are perfect. However, if you follow the manufacturer's instructions to the letter, the end result is worth the effort.

Three Brothers. Ian's version will have the layout shown in the upper profile

As soon as either the Scram Pram or the First Mate has left the workshop, I'll be making a start on Three Brothers - this is also for Ian Hamilton. It is Ian's intention to use this boat on an extended journey along the Kimberley coast of Western Australia.

The intention with Three Brothers is to produce a boat which is simple and quick to build using the 'stitch-and-glue' construction method, and which will operate effectively in the semi-displacement mode. My aim was to get efficient running at a speed/length ratio of 2.2 which in the case of this boat means 10.5 knots or 12.1 mph. According to my calculations, with a reasonable load, this speed could be achieved with 15.6hp.

My performance predictions with 288kg (634lbs) passenger weight and 85kg (187lbs) for engine and fuel are as follows: -
·         Assume displacement of 820kg (1804 lbs) NOTE: This is for the performance calculations only. Displacement as shown in the drawings is 1191kg (2620 lbs) so the boat is capable of carrying significantly more than the 288kg (634lb) passenger load.

·         Salt water
·         LWL 22.6 ft
·         Power to achieve 10kts                                                           -           13.9hp
·         Power to achieve optimum SL ratio 2.2                              -           15.6hp
·         Speed with 30hp (Crouch’s Planing Speed Formula)             -           19.3kts
·         Speed with 40hp (Crouch’s Planing Speed Formula)             -           22.3kts
·         Speed with 50hp (Crouch’s Planing Speed Formula)             -           25kts
My choice of motor would be either:
·         18hp four-cycle outboard, giving a full-throttle fuel consumption of approximately 5.7 lt/hr (1.5 gal/hr);
·         30hp four-cycle outboard, giving a full-throttle fuel consumption of approximately 9.8 lt/hr (2.6 gal/hr);
·         30hp two-cycle outboard, giving a full-throttle fuel consumption of approximately 13.0 lt/hr ( 3.4 gal/hr), but with a weight and cost advantage.

      Due to the initial load that Ian thinks he will have to carry, he intends equipping his boat with a 50hp outboard, although this is still open to discussion.

      The construction of  Three Brothers will take place over about two years, as Ian needs to earn money to feed into the project, and I will only be able to devote a limited number of hours eack week due to other jobs.

      In addition to the building jobs mentioned, I have another First Mate to finish off, and three sets of plans to complete for publication.  The First Mate has been brought to a structurally complete hull stage by her owner, but changes to his work space mean that he must reluctantly pass the boat on to me for completion. However, he will do some work on her whenever he is able to get to my place.

      Plans for Whimbrel, Little Egret, and Fleet are all very close to publication stage, and in fact boats could be build using what is already available. However, I need to finish off some detail drawings and instructions before letting them loose.

Little Egret

     More information soon.

Thursday, February 14, 2013

Workshop News

It is about time I said a little bit about what is going on in the workshop. Being a one-man-band is very satisfying, but it means that just a few concurrent jobs take up all of my time. I like writing and designing, but at the moment I'm definitely burning the candle at both ends!

Annapolis Wherry Tandem
In late 2012 I reported on the construction of a CLC Annapolis Wherry Tandem in this post  and showed some photos of the finished boat in this one. After completion the Annapolis Wherry Tandem sat for a number of months under shelter beside my workshop because the owner was overseas doing post-graduate studies. 

Well, the day finally came for a test row and the boat went very well indeed. The only problem was a slight bow-down trim, but that was sorted out on the second outing, and turned out to have simply been caused by having the foot stretcher set too far forward. With that adjusted the trim is now perfect. The following photos were taken on the initial outing, so you may just detect the trim I mentioned. Despite that the boat went fine, and on the second outing a few weeks later she was perfect.

That is the owner, Dr McArthur, looking on as I make preparations for the initial launching.  Dr McArthur is a very experienced oarsman, having rowed for 55 years of his long life.
Just getting the feel of the boat about two minutes after the launching.  You can see how we have the excellent  Piantedosi Row Wing adjusted for a "left-over-right" rigging.
A "turtle's eye view" as Dr McArthur  becomes more familiar with the boat. 
Even though we had the foot stretcher too far forward, the boat is still trimmed  reasonably, and she certainly ran nicely, with excellent directional stability.
The boat proved to be stable and fast. Subsequent outings have been  longer, and we've  explored more of the performance envelope. She is a practical and enjoyable package.

Jim Michalak Scram Pram

In this post I mentioned that I had been given the job of finishing off the construction of a Jim Michalak Scram Pram

My part in the project is nearing completion, with just some detail work around the hull, initial coating work on the spars, and setting up the running rigging and sail to go. The owner will pick-up the boat and do the remainder of the painting and varnishing. However, I hope that he and I will be able to fit in a day or two of sea-trials prior to her departure (by road) for her home waters. Here are just a few pictures: -

View from the helmsman's position, port side, looking forward. You can see what an enormously roomy vessel she is for a light fifteen footer. It is easy to see that if the boat suffered a knock-down, the windows (not yet installed) and the raised deck on either side of the centre walkway would keep the boat dry and buoyant.
Forward/port window dry-installed with Pencil Cedar surrounds.  Window and internal framing held in with silicon bronze screws throughout. See the aft/port window loosely fitted and waiting for the surrounds to be fabricated.
Close-up of internal framing showing how I have stamped markings at the top/right to identify the components after disassembly. The window installation was a much more difficult and time-consuming process that I had anticipated, as each window is  slightly different from its fellows, and there were a number of lurking "tricks for young players".

Windows from the outside. The protective film and paper will be left in place as long as possible. Fore and aft decks will be screwed down onto flexible bedding compount to allow future removal for maintenance. When I did it, it took 93  #8 x 1-1/4" silicon bronze screws! However, it is a very good idea.
Filling/draining bungs for the three water ballast tanks were sourced from Duckworks. They come as a brass tube (see longest tube in the photo) and an expanding rubber or plastic plug. When the lever is pushed down the plug expands and grips the inside of the tube. My problem was that the bottom of the boat is only 9mm/3/8" thick and the tube would protrude. I worked out the shortest length that the tube could be and still allow the plug a full-depth grip, and cut the tube (see cut tube in foreground). I then fabricated some blocks so that the tube protruded only 9mm/3/8" below the block. When set in the tanks on the bottom of the hull, the brass tube and plug fit neatly without extending past the outer surface of the hull. Note how I cut holes in the blocks and the brass tube to allow water to drain right down to the bottom of the tank.
Bung set into the bottom of the tank, positioned below the inspection port to allow opening and closing.  The block was very thoroughly sealed with about four full coats of epoxy prior to installation, and the tube and block were set in polyurethane bedding compound during installation. This was done so that the expansion and contraction of the brass would be taken up by the bedding compound - an epoxy joint would surely show hair-line cracks before long.

Mast partner is held to the forward bulkhead by four 5/16" bolts - two of them are silicon bronze and two (which you can see) extend through the aft face of the partner and act also as attachment and pivot for the mast gate, which I made from 8mm alloy plate. These two bolts are from 316 stainless steel, and if I can locate the required plate, I may replace the alloy with 316 stainless.
1-1/2" thick laminated mast step sitting upside-down on the bench prior to installation in the hull. Note the groove to act as a drain to prevent water accumulating in the step, and also the very thorough sealing of the internal surfaces with epoxy. This was done ahead of installation because access is difficult after. The rounded-over edge at the rear of the step (as it sits in the photo) is to allow it to sit neatly against the glass fillet between the forward bulkhead and the floor of the cabin (which is also the top of one of the water-ballast tanks).
More about jobs, both in the workshop and coming up, and also some progress reports on stock designs such as Whimbrel and Fleet in a day or so. I need to go to bed!

Tuesday, February 5, 2013

Following the Canoe Yawl Track

I've written before about Canoe Yawls here and here . There is something about the elegant simplicity and sense of independence which exerts a very powerful grip, although I'm beginning to wonder whether pure romanticism is the real driver

A George Holmes sketch of Ethel and Nan in Denmark in 1886. (Sail and Oar) John Leather
My brain seems to be particularly subject to distractions, and I find myself repeatedly going off on boat-related tangents which follow a predictable, if meandering, course. My latest one was started when I re-read some sections of L. Francis Herreshoff's superb book, The Common Sense of Yacht Design, in search of a particular bit of technical data. Something in the book about the optimum forefoot shape for a sailing boat lead me eventually back to Albert Strange's beautiful Wenda design, a longtime favourite of mine

Albert Strange Wenda (forum.woodenboat.com)

A photo of Wenda 's beautiful stern. This example was built for Dick Wynne by boatbuilder Fabian Bush. 
Another view of Wenda.  www.fabianbush.com
Being on a roll (once again) about canoe yawls, I got talking with my boating friend, Ian Hamilton, in the hope that he would get swept up in the process also. Ian had for years been smitten by another of Albert Strange's designs - in this case the designer's own favourite, Cherub II, so I expected his full support. Strangely he was ambivalent, saying that he had come to realise over the years, that the canoe yawls which appealed to us so much were "...cold water boats...".

Albert Strange's personal favourite, Cherub II  (Sail and Oar by John Leather)

Cherub II - Lines and General Arrangement (Sail and Oar by John Leather)
Over the last week or so I've been pondering Ian's comment about the canoe yawls being "...cold water boats..." and I'm not sure I agree with him. However, it did stop me from marching off blindly on another enthusiasm, and gave me pause for thought.

What it comes down to is that the activity and the boats change depending on geographical location, but the philosophy remains unchanged.

A William Garden-designed Eel, complete with hinged cuddy-cabin top just like the canoe yawls of the late 1800's. This particular example was built glued-lapstrake, with epoxy-bonded marine plywood planking. She is a very "open" sort of boat, but I think she would look at home on just about any coastal waterway.

Two pictures of my Little Egret design, which would make an excellent  "warm and shallow water"  canoe yawl.  Remember, canoe yawls are not necessarily canoes, and aren't always rigged as yawls. The name relates to boats which evolved from canoes, some of which resembled ship's yawl boats. 
Around the time that I was in full canoe yawl swing, one of my sons was beginning to make repeated comments about setting up a syndicate and having me build a Phil Bolger-designed Black Skimmer for use on Moreton Bay and the Great Sandy Straits (Queensland, Australia). Black Skimmer is a 25ft 3in x 7ft x 10in cat yawl-rigged leeboard sharpie built from plywood and epoxy.

Tashtego, a beautiful example of Phil Bolger's Black Skimmer-design, built around 1980 by Walter Baron of Old Wharf Dory Co.   www.oldwharf.com
I had been putting son David off about a Black Skimmer, on the basis that we couldn't justify a boat of that size. But with my new attitude towards the sorts of boats suited to the canoe yawl function in our part of the word (hot, and lots of shallow water), and given the possibility of a family syndicate to spread costs and maybe keep the boat in the one family for generations, excitement started to build.

Black Skimmer (plans here) has been my dreamboat (along with Rozinante) for the last 33 years. But in the last decade or so, I've been preaching the "small boats get used more" line so strongly that I had just about convinced myself that my dreamboats were off the agenda. I hadn't considered the enthusiasm, optimism, and idealism of youth ever coming back to me, but I hadn't counted on the advantage of having kids!

So, what is special about Black Skimmer? Here is a partial list: -

  • shoal draft - 10 or 11 inches/ 279mm;
  • free-standing rig with masts which do not pierce the watertight volume and can be raised and lowered without a crane;
  • self-vanging sails (due to the sprit booms);
  • self-righting with a self-draining cockpit;
  • effective watertight ventilation arrangement;
  • leeboards and the resultant open interior and strong bottom;
  • simple, but well engineered, structure;
  • self-draining well forward (for anchor, chain, mud, and sail handling;
  • self-draining well aft for outboard, fuel, anchor, mud, and crabs;
  • wonderful sprawling space in a cabin arranged with a raised deck. This is a strong, easily-built cabin-structure, and it provides important reserve buoyancy in the event of a knock-down;
  • sitting headroom in the cabin;
  • proven performance.
Having said all that, I am still haunted by the vision of a beautiful double-ended canoe yawl like Wenda or Rozinante.  Just today I was contacted by an exceptionally knowledgable and experienced friend who told me that I had only one life, and that if I didn't build a Rozinante  I would go to my grave a lesser man.