Wednesday, August 31, 2011

Have Fun Boatbuilding

In these days of over regulation and elimination of risk, building your own boat is one of the few remaining areas of practical self-expression. It seems to me that more and more, people are searching for some escape from the shackles of the consumer society, and the desire to build a boat is a stream which runs deep within the soul of many individuals. I say individuals, because the boatbuilding public is made up of some of the most individual of people. Everybody wants something just a bit different. 

Why the desire to build a boat is so strong in the victim is difficult to determine, but if the spark is there, it is just about impossible to dodge. To paraphrase the late Arthur Ransome (of Swallows and Amazons fame), “The desire to build a boat starts as a single cloud on the horizon, but before long it grows to cover the entire sky”.

When you finally give in to the urge to build a boat, invest some time and some money in reading the right books. I’ve seen so many instances of people spending time, effort, and money traveling down the wrong path, just because they didn’t have the proper advice. Just like the time spent sharpening tools, time spent reading the right books is time saved. Not only is it time saved, but it is money saved as well.

Although building your own boat requires dedication, it is a source of great pleasure when done properly. Even though I build boats for a living, I still get up early to have a look at the results of the previous day’s gluing, cutting, painting etc. The excitement has never left me. But if you are building or renovating your own boat, the pleasure is magnified many times.

To quote the Atkins, father and son, “Working for a living or profit is seldom a continuous pleasure; it is something that must be done; therefore there is compulsion behind it. And, wherever there is compulsion one’s freedom of will is restricted. A living must be made and so we all accept work as an ingrained duty. Somehow painting one’s own boat, tending one’s own cow, doing one’s own chores are pleasurable pastimes – but attempt the same occupations for a neighbor or boss for pay and, presto, pleasure quickly turns into work.
And so I would like to remind prospective builders of Sprite, or any other boat, not to feel duty-bound to complete the building at any particular time; rather just put the little skiff together when the urge to add another plank or two persists and the needed recreation sweeps away all thoughts of work. In this spirit how spare time will fly and, by the same token, how easily and quickly the boat will be completed!” (from Volume 38 of Motor Boating’s Ideal series – The Hearst Corporation, New York).

When you build your boat, do it the way William and John Atkin suggest – take your time and do it properly. Quick-and-Dirty boats just don’t return long term satisfaction, whereas a properly built boat will display the love that the builder has put into the job, and if she is built of good quality wood, well painted, she will age with a grace that a manufactured article can never match.

Supply of components for home building of boats can be a problem for some. Avoid the temptation of accepting a second-rate building material (for example exterior ply instead of properly stamped AS/NZ2272 or BS1088 Marine Plywood). Any money you save on buying low grade materials will be lost many times over in the resulting boat. Look at the advertisers in this magazine – you will find may fine suppliers dotted around Australia. If you can’t locate what you need locally, try which is the Boat Builder’s Supply section of the great Duckworks in Texas. They have an increasing line of excellent components at really good prices.

Summer is approaching, and I’m looking forward to more sailing and less work. We are restoring my old Iain Oughtred designed MacGregor sailing canoe. She is so light that there is no excuse not to be on the water frequently. I remember a trip I did in her a couple of years ago – down Moreton Bay from Cleveland to the mouth of the Logan River, and then back via the bay islands such as Russell, Macleay and Coochiemudlo. The trip would have been routine (maybe even boring) in a large power boat – but for us in our tiny craft, it was a great adventure, filled with mild adventure, healthy exercise, and a hint of danger. Twelve hours of satisfaction and fun for the cost of a packet of peanuts! You can do it too…

Thursday, August 18, 2011

An Old Head on Young Shoulders

It is often said that words of wisdom come from the mouths of babes...

The other week one of my sons mentioned that he wanted to build one of my First Mate designs. I was full of enthusiasm and told him that I'd build one too, and maybe I could arrange to have the parts for both boats cut by CNC.

He looked at me and said, "Marking and cutting is easy and fun - can you arrange to have the sanding and painting done by CNC instead?"

First Mate is a nice boat - you can see more designs on my website here.

Kid's Adventures - Boatbuilding and Venturing

About eight years ago I wrote this piece as part of article published in the print magazine Australian Amateur Boatbuilder. At the time I felt that kids were having their creativity stifled by over-regulation in a society where concerns about liability and political correctness prevented natural behaviour. We complain about kids spending too much time in front of screens and not getting out into the real world - and yet we sanitise that world to such an extent that the spontaneous, adventurous activities which teach our children to identify (and take) risks have been replaced by artificial forms of entertainment.

It might look irresponsible, but the kids were well trained, carried the required safety gear, and were under supervision at this early stage. The boat in this photo is a home-built Phil Bolger Bee with a 6hp outboard.

Perhaps this philosophy does prevent a few deaths and injuries, but the kids are less likely to learn how to identify, and deal with risk. No matter how regulated our systems become, there will still be plenty of situations faced by us all which involve risk. I would much prefer to have my children exposed to the inevitable dangers of outdoor activity and have them grow up with some appreciation of what needs to be done in order to deal with unexpected challenges.

As Arthur Ransome wrote in the wonderful novel Swallows and Amazons in reference to a father's telegram to his wife regarding their decision to allow their four children to sail and camp independently on a large lake in England, "...BETTER DROWNED THAN DUFFERS IF NOT DUFFERS WONT DROWN..."  The same fictitious father also said to his kids, "Grab a chance and you won't be sorry for a might-have-been"

The boys referred to in the article - my nephew (left) and middle son (right) building a 12ft sailing dinghy

Here is the old article I wrote...

Traveler’s Tales 

Many times I have bemoaned the lack of freedom which has come from regulation. Kids are driven to and from organised activities, the carriage of safety equipment is mandated, and irresponsible behavior can result in litigation. 

Regulation has come at a price, and one of the costs is the lack of freedom which nautical children experience. It is a well-worn line, but things aren’t what they used to be… When I was a kid, school holidays meant being away from the house from dawn until dusk without parental supervision. We were usually on the water, in the water, beside the water, or in the bush. If anything bad had happened, our parents would not have known before nightfall. 

Until recently, I had accepted that my own sons would be victims of this change in society’s attitude to risk, and that I would be seen as a member of one of the last few generations of fortunate, unregulated Australian kids. 

However, I had fallen for the trap of assuming that being subject to regulation is synonymous with having fewer adventures. In fact, it just means having safer adventures for those who want to participate.  

During the recent school holidays, one of my sons and one of my nephews had a “regulated” adventure which made me jealous. They both used wooden boats which were built at home, and they had each taken a large part in the building projects. The six horsepower outboards had been maintained and/or restored by the boys, and their own money had gone into the projects.  

One morning on the way to work, I dropped the two boats and two boys at the Manly boat harbour. Carrying the required safety gear and ground tackle, they traveled north along the coast to the mouth of the Brisbane River, passing inside Fisherman Island.  

Bee, one of the boats used on the trip, with her captain on-board

From there they explored up-river past tugs and cargo ships, stopping to touch the pylons of the massive Gateway Bridge. At Breakfast Creek they tied up at the wharf, bought chips from a vendor, and then set off again. Passing through the centre of the city, the two travelers continued past multi-million dollar houses until arriving at Queensland University. The picture of two young boys passing through all that evidence of wealth played over and over in my mind – their boats had only cost a couple of hundred dollars.  

The journey home was completed without incident, but not without adventure. They telephoned me from the ramp at four o’clock, having been gone for seven and a half hours. Instructions had been complied with and regulations (I hope) followed.  

These boys had earned the privilege of conducting the trip, and it had not been done without experience. I guess that they could have come to harm, but the decision to let them go was based on careful thought and observation. I can well remember the first time they were allowed out in my old sailing dinghy, operating solo under supervision. Even though the boat didn’t have the sailing rig set and the outboard was a mere 3.5hp, I was concerned enough to stand waist deep in the waters of Moreton Bay for over an hour while keeping them under observation. They were much smaller then. 

Time passes fast, I know. The rate at which they have learned has increased with the passage of the months and years, and they are now very competent seamen within the boundaries allowed. I am proud, and I enjoy their company.  

So if you want to free your kids from a screen-based existence, consider buying some plywood and glue, and in the process change them from spectators into participants in life.

Wednesday, August 10, 2011

More on External Chine Logs

Phil Bolger's 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 don't want to bore people with an on-going debate, but I think Graeme's 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.) It's 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 Payson's "Gloucester Light Dory"].

Dynamite Payson first built a #140-4 in 1967 (Bolger drew #140-6 for Payson's plans sales business much later in the 1970's due to issues with Orrell and proprietry rights. However, what goes around... later, upon Orrell's 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 it's 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 "doesn't 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 don't help either? (Type VIs have been built with external chine logs too. As far as I know there's been no comparison made with a standard VI.)

best to you

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 don't raise any objections to external keel battens, bilge runners, or lapstrake planking...

Regarding Graeme's 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 don't 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 don't have a picture credit and will remove it if anybody is concerned)

Monday, August 8, 2011

External Chine Logs

An anonymous contributor has posted a comment on one of my earlier posts about flat bottomed boats. The comment was made in relation to my assertion that Phil Bolger had a theory that external chine logs may reduce resistance. The contributor has pointed out with a quote Phil made in his essay on the Light Dory Type V that he was not claiming a reduction in resistance: -

Ross, Bolger had a theory of water flow and how that applied to sharpies. With respect, what he wrote about exterior chine logs of relevance here was: "The external chine log... adds a minute amount to the stability, which certainly needs anything it can get (Light Dory Type V); I don't think it increases the resistance but I can't prove it yet." He worried that it may increase resistance, not reduce it.

Well, I have another quote from Phil Bolger on the subject, and I think I have more available but I can't remember where to find them right now. Anyway, here is my reply to the person making the comment: -

Yes, and he also wrote, regarding Poohsticks, on page eight of "Small Boats",

"This was the first design I made using the outside chine log, which I've since adopted quite often in constant-deadrise boats: it saves some labor in fitting the log, and gives better bearing and fastening for the size of the log. It also gains a bit of stability, and I have an idea, just conjecture, that it reduces eddying along under the chine by carrying the side flow aft......"

I don't have the qualifications in hydrodynamics to give an educated guess one way or the other, but this I do believe: -
Jim Michalak's Mayfly 14 design, showing off her external chine logs
  • External chine logs are much easier to fit, for a whole range of reasons I'm not going to write about here;
  • External chine logs do protect the vulnerable topside planking at the chine;
  • External chine logs provide a very useful hand grip when the boat is capsized, and a good toe-hold when climbing aboard;
  • I am still in two minds about drag reduction, but I do know that a hard chine with an internal chine log can pull a long and powerful underwater eddy (I've experienced it), and I see no reason why Phil Bolger's statement above should not be worth thinking about;
  • On a sailing boat, the increased lateral resistance from external chine logs may well give back more than is lost to resistance - if there is any loss in the first place.
If anybody has some worthwhile information on this subject, I'd be keen to learn more.

Sunday, August 7, 2011

Bilge Keels

In regard to a couple of articles I wrote recently, Mike sent in this comment. The comment was made in the context of some queries made about ballasting for my Whimbrel design (not yet available, but she promises to be an interesting boat).

An un-finished drawing of Whimbrel, showing her general proportions. As you can see, she carries leeboards, which have just enough ballast to sink the boards reliably, but are not intended to add significantly to the boat's stability.

Ross - I have often thought that stubby little bilge keels combined with leeboards might be just the ticket. The bilge keels could have through holes or threaded inserts in them. When ultimate stability in heavy weather was called for, a long heavy steel plate could be bolted to each keel. In light weather, etc the steel plates could be left off. And the little bilge keels would more or less allow her to sit level when the tide is out. If designed just right the boat could travel on a flat trailer or a traditional boat trailer. The steel plates could just stay right on the trailer in position to be bolted on or off as needed - no lifting or grunting required.
I am not any sort of designer or engineer but I have often thought that this sort of arrangement would offer lots of flexibility and simplicity and be budget friendly.
Feel free to shoot holes in my thoughts - I am just always dreaming of my ultimate boat on a budget.
Thanks Ross!

I read Mike's comment with interest, but my thoughts were limited by a prejudice I've long held against bilge keels. My understanding of the behaviour of bilge keels had been based purely on the comments of others, without any personal experience on my part. Not a good way to form opinions!

Picture of a typical bilge keeler, taken from a sales brochure on the web
My feeling had been that bilge-keelers (quite popular with the English) tended to be slugs - slow with poor handling, and only good for drying out level in areas of high tidal range. The theory was that the wetted surface area required for bilge keels would be substantially higer than for a well designed single keel. More importantly, I had been led to believe that the flow of water along a displacement hull swept in towards the centreline from the bow to midships, and then out towards the bilge or chine from midships to the stern. If you look at the hollow formed in the waterline of a displacement vessel travelling at speed you will get the idea.

A boat we built, running just over displacement speed - note the hollow in the waterline.
The problem shown up by this theory of flow around the hull is that while the bilge keel may be positioned parallel with the centreline of the boat, the water flow would not be parallel with the centreline. In effect, the bilge keel would be passing through the water at an angle to the flow lines i.e. being pulled through the water in a partially sideways fashion, causing great drag.

Now, I had accepted this theory without any significant thought, and I was going to write back to Mike with such an answer. However, to illustrate my thoughts, I decided to do a flow analysis on the computer using DELFTship Professional software with Whimbrel as the example. The flow prediction facility in DELFTship Professional is a much simplified system than that used in CFD (computational fluid dynamics), but the results are said to be remarkably similar to those gained from CFD, and in this case we only need to get an impression of flow.

A perspective view of Whimbrel showing the predicted flowlines
Well, to say that I was surprised is an understatment! The flow lines, at least on the undersuface of the hull, were almost parallel with the centreline. According to the computer, bilge keels would not necessarily be such a problem after all, as long as surface area was kept to the minimum for the required lateral resistance. There are clues to this when one looks at the performance of some of the current ocean racing designs which use bilge boards, which are in effect, retractable bilge keels.

Here is a link to an article from Bray Yacht Design and Research in Canada about the advantages of bilge keels

If anybody has more information on this subject, I am very keen to learn! In the meantime, I'll just wipe egg off my face....