Monday, February 8, 2016

Builder's Discussion Group Established

My email load is quite heavy, and I find myself caught in the difficult position of writing lengthy explanations and giving lots of advice - but it only goes out to one person at a time.

I've got literally thousands of email responses to queries, and I'd love to be able to show them to everybody, but I'd have to get permission so that people's privacy was protected.

A frustrating spin-off of this situation is that with my email workload, as well as building and design obligations, I don't have time to write regular posts on this blog.

So - Chuck Leinweber has helped me by setting-up a Group page on Facebook. I'm still very much a novice when it comes to using Facebook, but I'm hoping that builders will be able to address questions to my via the Facebook page, and that way everybody can take part in the conversations.

I'm happy to accept any suggestions about how to develop this page, and I hope that people will be able to help each other and not have to rely on emails from me.

the address is:-

Look forward to seeing some messages!

Sunday, November 1, 2015

Fleet - Videos of performance with Two Different Motors

As some of you already know, Fleet is a planing-hull derivative of my very successful Flint design. For some background you can look at this post and at this post.

Fleet awaiting more trial runs
Fleet was designed from the outset to perform well in the very speed/length ratio spectrum in which normal planing hulls are at their worst. By that I mean the so-called "semi-displacement" or "semi-planing" range - widely thought to be in the S/L ratio range of 1.5 to 2.5.

Speed/Length ratio is basically the speed of a boat (expressed in knots), divided by the square root of the waterline-length (expressed in feet) of the boat. So let us take Fleet as an example: -

  • LWL (length on the waterline) equals 14 feet
  • Assume S/L ratio of 2.5
  • Speed divided by 2.5 equals 3.74 (i.e. square root of 14 ft LWL)
  • Therefore, Speed in knots equals 2.5 times 3.74
  • Speed equals 9.35 knots (10.8 mph, or 17.3kph)
Now those speeds sound modest, but for a small boat like Fleet it represents a very satisfying speed indeed. More importantly, because this hull has been proportioned to operate within this S/L ratio, the boat trims well, instead of pointing her bow in the air like the standard planing hulls, which chew fuel at a high rate just to pull a large wake.

So far I've been able to carry out several test runs in Fleet using both a 9.8hp Tohatsu two-stroke and a 2hp Honda four-stroke. The 9.8hp Tohatsu is based on the powerhead from the 6hp and 8hp models, so is suitable for this light-weight boat. My next test will be using a 4hp motor, which I think is about the optimum size from an efficiency perspective. In my part of Australia, 4hp (2.9kW) is the largest motor allowed without boat registration.

Here are two Youtube clips - firstly using the 2hp Honda, with which I achieved a consistent 7.9 knots measured by GPS with my weight aboard, and 7.1 knots with my wife joining me (she only weighs 60kg/132lbs. The 9.8 Tohatsu gave 15.5 knots (17.8 mph or 28.6 kph) with two heavy men aboard plus gear.

Saturday, October 31, 2015

Flint and Alby Sailing Videos

I've written a fair amount about a group of my designs which make use of a very simple boat-building method, know by a range of names including "Stitch-and-Glue", "Taped-Seam", "Tack-and-Tape", "Composite-Chine", and so on.

A taped-seam hull under construction - in this case a hull made from my First Mate design.
There are some significant advantages associated with this construction method, with notable ones being:-

  • if properly designed, hull panels can be marked directly onto the sheets of plywood used in the boat's construction;
  • the builder can produce a "flat-pack" kit ahead of time, which allows those who have limited building space to get a head-start on the job;
  • again, if the boat has been properly designed, accurately marked, and carefully cut, the hull can be built without a fixed strong-back and station mould assembly - a very significant saving in time and resources;
  • the amount of timber framing in the hull can be reduced to a minimum, saving cost, reducing weight, and avoiding rot-traps - all without sacrifice in strength;
  • the vulnerable edge-grain of the plywood is exceptionally well protected within a cocoon of thickened epoxy and glass firbes;
  • sanding, painting, and maintenance are all made easier due to the clean interior (and exterior) of the hull.
Please do not get me wrong - I am not advocating this system over other methods of construction. All construction methods have advantages and disadvantages, and every boat design and building project must be carefully considered in the light of many compromises. What I am saying is that taped-seam/stitch-and-glue/composite chine should be given the respect that it deserves.

I continue to design boats to be built glued-lapstrake (glued-clinker), glued-strip-plank, cold-moulded, and taped-seam. Frequently the design itself determines which method will be the most appropriate, and it is very important that the builder understands the design, materials, and application very clearly. Education is the word!

Here are two video clips of taped-seam (stitch-and-glue etc) boats under sail.

The first is a clip shot by Paul Hernes, a Phoenix III owner-builder, showing a boat built to my Flint design by Paul McShea. Flint was designed primarily to be a rowing boat, but her hull shape assumes that some will feel the need to sail her, and/or mount a small outboard motor. The plans include details for a sailing rig, daggerboard and rudder. However, Paul McShea had a Heron rig on hand, and it happens to be just about the right size and shape for Flint.

I've also been able to shoot a short clip showing my Alby design under sail, showing-off her tanbark-coloured balance lugsail. There are plenty of eight foot long pram dinghies in the world, but what is important about Alby is that she has an unusually large carrying capacity, and due to the design of her chine-line, she is still able to travel quite fast while leaving a relatively flat wake. Both Alby and Flint have easily-driven hulls for their size.

This particular Alby carries a short foredeck, which is a variation from the plans - something I do not recommend.

Tuesday, August 4, 2015

First Mate Capsize Test.

As I have mentioned on several occasions, First Mate is one of my favourite designs. For those who don't already know, she was designed to be a stitch-and-glue version of Phoenix III in functional terms, with an internal layout, rigs, centreboard, mast, and rudder all virtually identical to those on the glued-lapstrake boat.

First Mate  

Phoenix III  (photo - Paul Hernes)
Each of these boats share a selection of rig options, and both use the same emergency floatation arrangement, which is a combination of a large buoyancy tank under the foredeck, and a corresponding buoyancy tank under the aft deck and stern sheets (i.e. aft seat).

Many people have asked me why I don't have side seating incorporating side buoyancy tanks. Well, the answer comes in two parts. Firstly, side-seating which is fixed is a real thief when it comes to space. When cruising in small sailing craft, my favourite seating position is down on the bottom (on floorboards if you like) with my upper back supported by the side-deck carlings, or the hull topside planking if side-decks aren't part of a design. You can see this position nicely displayed by my son, David, in the photo of First Mate above.

This seating location is comfortable, and is particularly effective for human ballast positioning when the boat starts to heel. In a racing boat, where comfort is a secondary consideration, hiking-out on the side-decks is effective. But it is tiring and uncomfortable. For cruising, where the boat has to be sailed for longer periods and in difficult conditions, the comfort and protection afforded by sitting in the weather bilge is more seaman-like, and safer. Not only that, but as the boat heels, human ballast in the weather bilge becomes more effective, while human ballast on the side deck becomes less effective.

That is me sailing my 1956 International Finn in very light conditions. Even though the weather is pleasant in this shot, the hiking position becomes tiring after a relatively short time. Good for the stomach muscles!
Getting back to the original discussion, fixed side-tanks rob you of the best space in the boat, but they do prevent much water coming aboard in a capsize. The problem is that the side-tanks mean that a capsized boat floats so much higher, that the mast points downwards towards the surface of the water significantly, and it is easy for the mast to submerge completely. The boat will then turn-turtle. This is a really serious problem! Unless they are provided with very significant foam floatation, alloy and carbon-fiber masts try very hard to turn themselves into keels at the first opportunity!

I do make provision for removable side seating for those who want it, and my design allows the seat to be removed completely, or moved into the centre of the boat to form a servicable sleeping platform raised above the bilge water.

Phoenix III removable side seating (First Mate has the same arrangement). Photo - Paul Hernes

Side-seating and stern-sheets in casual use (photo - Tom Pamperin)

Seats moved together on the centreline........ be used as a bunk-flat (photos - Paul Hernes and Tom Pamperin, respectively)
This seating/bunk-flat arrangement only works because of being incorporated with the generous stern-sheets and the main thwart.

So, I keep being asked to design-in side-tanks/seating in cruising dinghies, and in cruising dinghies I refuse to oblige (I do put side tanks in several powerboats though, because they don't have the option of using buoyant wooden spars as makeshift outrigger floats). Apart from the space issue, I want a capsized sailing dinghy to float a little deep while on her side, as it means that the mast, sails, and (if they are present) yard/sprit/gaff float fairly flat on the surface of the water. Getting at the rig is simple while swimming, and it is easier to reach up to the centreboard when it comes time to pull the boat upright. Once upright, it is quite practical to sit inside the partially flooded hull to set things right, and do some bailing - after all you probably won't have been in a race.

Gerry Lavoie built a First Mate and he has used her a lot, it seems. One of the pleasing things I note from Gerry's emails is that he has found that she is very effective when being used under oars - something I aimed at with the design of both Phoenix III and First Mate.

Gerry recently sent me three images showing the results of a capsize test he carried out, and I'm happy to see that the built-in buoyancy worked as I had hoped:-

Note how the buoyant wooden mast is nearly flat on the water. Combined with the yard and boom, the mast makes an excellent outrigger. Gerry has easy access to the interior of the boat while he sorts things out.

Here Gerry has climbed up onto the topside planking, and the boat is carrying his weight without a problem.

Next, he appears to have placed a foot down on the centreboard where it protrudes from underneath the bottom of the hull, and the boat has rolled upright. Another approach when the water is warm (and you aren't being chased by sharks!) is to simply swim around to the bottom of the boat and pull down on the protruding centreboard.
If there is much wind blowing, always try to swim the bow of the capsized boat around into the wind before righting - otherwise you may lose control and find yourself in another capsize situation.

Here is a little video from Gerry's collection...

Saturday, July 18, 2015

Website Being filled with More Content - At Last!

Have been working too hard in the workshop, and blog entries have suffered. However, paid building jobs are almost finished, and the website is being populated with several design page entries, and an increasing number of items on the "Shop" page.

After mid-September, I will be working predominantly on designs, website content, small video production, and more regular blog entries. I've got a stack of material from workshop jobs over the last year or so - have just been lacking time to edit photos, write copy, and publish material.

Much more to come very soon.

Monday, April 27, 2015

Folding Mast - Hollow, Sixteen-Sided (will end up round)

In Woodenboat Magazine #237 of March/April 2014, there is an article written by David McCulloch about building an "In-Mast Hinge" which he has designed and developed. I urge you to purchase a digital issue of this copy if you don't already have it, as Mr. McCulloch has written a good article, and there is an excellent coloured illustration.

David McCollough"s photograph of his "In-Mast Hinge" from the Woodenboat Magazine article. Note the detail in the upper-right corner.
This article inspired a customer of mine to inquire about including such a hinge in a replacement mast for a large, open daysailer he had recently purchased. After some discussion, and an inspection of the boat, I agreed to attempt the project. It was necessary for me to make modified drawings for the plates to fit the mast I was commissioned to build due to its different diameter from that shown in the article.

The location of pivot holes, and the radii of cuts made to all three plates alter depending on the geometry, which is itself dependent on the diameter of the mast. However, this is not at all difficult to work out, and just requires attention to detail.  For those who may be interested, here are some early progress photos: -

One half of the mast being laid up in a female station mould mounted on part of my 12 metre (40 ft)-long bench. The mast is made up of 16 staves, so this half-shell comes from 8 tapered pieces.

All eight staves glued up in the female mould. The first stave was fixed along a marked centreline in the bottom of the female stations, using 18 gauge polymer brads fired from a pneumatic branding gun through the stave and into the plywood edge of the station mould. Subsequent staves were laid up on either side of the "master" and glued using epoxy. The overwhelming reason for using epoxy is that it only requires contact pressure to form a good bond. Careful attention must be paid to priming the gluing surfaces with un-thickened epoxy before applying the thickened mixture. This method allowed me to fire polymer brads into the SIDES of each successive stave to hold it to the one before, because the epoxy did not require clamping pressure. The polymer brads stay inside the shell of the mast, and will of course never corrode. The bradder and polymer nails were purchased from Duckworks. After being glued-up, the inside of the half-shell was given three or four full coats of epoxy to ensure that the inside of the finished mast would always be protected from moisture.

Here is the station mould after the removal of the first mast half-shell. I used adhesive tape applied to the inside  of the cut-out section of each mould to prevent epoxy squeeze-out gluing the mast components into the mould. Alignment of moulds is very important, and you can see the blue chalk-line "snapped" onto the bench surface (now covered with epoxy drips!)

Two half-shells of the mast after being removed from the station mould visible in the top/right of the photo. The outer surfaces are still rough-looking due to epoxy marks. When first removed from the mould, the half-shells had lots of thickened epoxy squeeze out, which I largely removed using a heat-gun and scraper. Any gaps were filled with additional epoxy.

Here you can see the two shells clamped together with cable-ties and hose-clamps. The extra length of the staves has been roughly cut off using a handsaw and you may just be able to see that there is no glue on the opposing faces of the two shells. Note the heavy layer of sealing epoxy on the inside of the hollow mast.

This is a similar photo, but taken from the mast head. The trimming of the extra length  was done quite roughly, and the un-glued faces of the staves still need to be sanded to remove dags of cured epoxy, so the gaps in the un-glued faces are a bit open. This will change prior to final assembly. Note that the taper of the mast resulted in a reduced outside diameter, but the thickness of the staves has reduced as well. The idea is to keep the percentage wall thickness of the mast constant at about 20% of the diameter. This is something which can't normally be done with a "Bird's Mouth" mast. (see photo below)  
An off-cut from the tip of  "Bird's Mouth" mast I made. a while ago. Note how the wall thickness, which started off at the base being 17% of the diameter, has ended up being so large it almost makes the mast solid.  Compare with the previous photograph.

Three stainless steel plates to make up the hinged section of the mast (refer to the inset in the David McCulloch photo at the beginning of this post to see how this works). These plates are quite heavy, with the outer pair being 6mm thick, and the inner one being 8mm. I had these laser-cut, which saved a lot of time, and was not expensive.
This sketch shows the stainless steel plates extended and folded. The black lines depict the 8mm plate which is buried for half of its length into a solid mast stub which runs from a mast step near the keel to a short distance above the deckline of the boat. The red lines show the two 6mm stainless steel plates, which are fully buried in the base of the mast you can see in this article.
Here is a close-up of the insert from the heading photo in David McCulloch's article in Woodenboat Magazine #237. 

There needs to be a solid section at the base to hold the stainless plates. On the free-standing hollow masts which I normally make, I always insert a solid section from the base of the mast, to a reasonable distance above the mast partners. In both my normal free-standing mast inserts, and with this one, I terminate the solid insert with what is often referred to as a "Swallow Tail", the purpose of which is to ease the transition in stiffness from where the mast is solid (i.e. the hollow shell combined with the solid inset) to where it is a hollow shell. Here is a view of the early stages of the solid insert for this mast.

As you can see, there is the "Swallow Tail" section, and at the base, a cut-out slot to accept the stainless steel plates and an 8mm hardwood inset to hold them apart and allow the 8mm tongue of stainless from the mast stub to fit between. At this point I have planed a square blank into an octagonal section - it is on its way to becoming round!
At this point the blank has been planed from octagonal, to 16-sided, and them planed further to 32-sided, and then hand sanded to a round cross-section.. All of this sounds complicated and difficult, but if you start with an accurately cut square blank, and then mark carefully for the 8, to 16, to 32-sided planing work, you'll find that the work goes quickly, and is actually a satisfying and relaxing job. As with most boatbuilding work, it just a progression of simple steps. I can tell you I'm finding it more difficult to describe than it is to achieve on the bench. Other than the initial sawing of the square blank, I did all of this with a low-angle block-plane you can see in the photo before this one. It did not take long.

The hole you can see drilled through the filler block at the apex of the "Swallow Tail" is just something I do to prevent a crack propagating from the apex. This may be an over-kill, as the block will be contained within the mast shell anyway, but it only took a moment to drill - so better to be safe than sorry... 

Here is where the stainless steel plate assembly will eventually reside. Matching slots will have to be cut in the mast shells.

Checking the fit of the insert. The actual fitting will be done with the two half-shells of the mast opened up, and the plug will be laid into a bed of epoxy in one half, before the pair of shells are finally glued together to form a round, tapered mast. The tip of the mast will receive a similar (but smaller) plug to distribute loads from the shrouds and fore-stay, and to carry the attachments for the halyard blocks
I'll write more about this interesting folding mast experiment as the job progresses.

Saturday, April 18, 2015

View from my office

I've had a few exhausting days of work lately, and a lot of it hasn't been fun - just hard, messy, dusty and physically demanding labour.

But tonight after a shower, a drink, and something to eat I glanced at this sight from the verandah outside my office. Gentle rain falling in the darkness - sort of makes it all worthwhile...

She is 15 years old, and has encountered many hurdles in her life. She has been back to my workshop plenty of times, but she still looks great to my eyes - especially in the quiet of an evening after hard work.

Some of Phil Bolger's designs are an acquired taste, but none of his work should ever be underestimated - particularly those designs up to around the mid to late eighties. Trust me when I tell you that Micro is a masterpiece of design. It is such a pity that so many people fail to understand the subtleties. As Phil Bolger said about the designs of L. Francis Herreshoff, and William Atkin said about his own work -  do not ever alter anything - build exactly to the plans - that way you keep the treasure.