Thursday, July 28, 2016

Phoenix III - Beachcruiser and Daysailer

I've told the story of how I came to design Phoenix III several times previously, but for those who haven't heard it before, the basic details are:-

  • after 45 years of dinghy sailing, I settled on 15ft x 4ft 6ins (to the inside of the planking) as being the best compromise between light-weight and compact size on the one hand, and carrying capacity, speed and capability on the other. All of this viewed in the context of a single-hander, or a two person crew;
  • good rowing geometry and performance;
  • self-rescuing;
  • trailerable;
  • a selection of simple, traditional, interchangeable rigs, all using the same mast step and mast partner.
The very first Phoenix III , beautifully built by Paul Hernes
The original builder, Paul Hernes, from Caloundra, Australia, has used his boat extensively in the more than ten years since initial launching. Paul has done what I encourage everybody to do - he has continually experimented with the various rigs, making changes to the running rigging, and learning the characteristics of his boat. I am indebted to Paul for his feed-back and photos.

Another person to whom I owe a debt of gratitude is Tom Pamperin, from Wisconsin in the United States. Tom has notched up months of cruising time in a Phoenix III built by his brother, Lance. You can read about some of Tom's cruising adventures, and view his superb photos by following these links:-

http://forum.woodenboat.com/showthread.php?186576-A-Phoenix-III-in-Georgian-Bay&p=4422412#post4422412

http://forum.woodenboat.com/showthread.php?134797-A-Phoenix-III-in-the-North-Channel

More recently, Tom and a friend competed in the 2016 "Texas 200", and Tom has kindly written a nice article on the trip. It is a great story and you can see it here: -


A Phoenix III in the Texas 200

by Tom Pamperin
www.tompamperin.com

The Texas 200 is hard to describe. It’s not a race. And it’s not really a group cruise, either. I think of it as more of a multi-day endurance event for small boats: 40 to 50-mile sailing days, strong winds, tricky navigation, intense sun, remote campsites, extreme shallow water, and no shade. There’s some big water, too. Although the route roughly parallels the Intracoastal Waterway, and is sheltered from the open water of the Gulf of Mexico by a series of low barrier islands, it can get rough out on the larger bays. Conditions can be tough enough to be intimidating—or at least exciting—at times. This year, 57 boats started and 29 finished, with just 18 boats making it to every camp along the way. My brother was kind enough to loan me his Phoenix III for the trip so that my friend Pete and I could give it a shot.

Magnolia Beach, Texas—finish line of the Texas 200. (Peter Martens photo)




The sign sets the tone perfectly—this ain’t no marina cruise. Logistics for the Texas 200 can be daunting. Most sailors arrive a day early to drop off their boats at the start (Port Isabel, Texas, a tourist town near the Mexican border), and then drive their car and trailer 5 hours north to the finish line at Magnolia Beach and catch a shuttle bus back to Port Isabel that afternoon—another 5 hours of driving.



Day One: Crossing the Laguna Madre. (Jennifer Votaw Crow photo)



Our trip started out with a long day of surfing along on a broad reach to a run at 5-6 knots for 40 miles non-stop. These are typical Texas 200 conditions, with winds at 20 knots or more in the morning and getting stronger all day, all on the starboard tack. The Phoenix III handled it beautifully, with fingertip control of the tiller and no tendency to broach.

To keep things interesting, the day ended with a 5-6 mile beat up a narrow channel dredged through the barrier island forming the eastern edge of the Laguna Madre, with the campsite located right on the edge of the Gulf of Mexico. More than a few boats quickly abandoned the attempt to beat up the channel; for us in the Phoenix III, it was a simple series of tacks through steep chop—a bit wet, but we never missed a tack and stayed perfectly in control. Pete shot a bit of video at the camp that night to give his family some idea of what the Texas 200 is all about:

On the beach at the Port Mansfield jetties. (Peter Martens video)



 Day Two: More of the Laguna Madre. (Peter Martens video)


More of the same for day two—big wind, broad reach to a run. Continue for 8 hours. Pete shot the brief video on his IPhone while we were surfing along. He’s done some Hobie sailing back in Wisconsin, but I don’t think he had ever seen this kind of sustained surfing before.

Day Three: Northward to Bird Island. (Matt Schiemer photo)


 The photo above shows the campsite for the evening of day three near Bird Island, just outside of Corpus Christi. Another 40 miles on a broad reach to a run to get here—with a side trip to the barrier islands. At one point we were completely surrounded by porpoises, who started launching themselves into full-on aerial leaps all around us. Pete and I were laughing out loud. Later on we “parked” the boat to wait for a sailor who had fallen behind by simply letting the sheet run free, letting the sail weathervane freely while we drifted slowly and peacefully to leeward, broadside to the wind—a nice feature of the Phoenix III’s balance lug rig. 


Day Four: Pete at the helm, entering Corpus Christi Bay.


 The low sheeting loads on the lug rig make expensive blocks and hardware unnecessary—we simply ran the sheet around a horn cleat on the leeward quarter, forward to the oarlock, and back to the helmsman’s hand. Another advantage of such a simple arrangement is that the sheet can be kept much shorter, leaving less line to tangle around the crew’s feet. We also sometimes ran the sheet through a ring on a simple rope traveler over the tiller, another cheap and easy method that’s a bit handier for gybing.

The winds finally relented a bit—down to 20 knots, maybe—so we spent the day under full sail. Today brought the big water and long fetches of Corpus Christie Bay, so we hugged the windward shore, sliding through narrow channels along and around the barrier islands, sailing in water so shallow that, board up, the keel was dragging through the mud. “Deep water” on the Texas coast means water that might get your knees wet if you stepped overboard.

Later in the day we could have cut back into the deep buoyed route of the ICW, but there was a better option for boats like ours: Corpus Christie Bayou. We simply ignored the marked channel and sailed up to a crumbling ramp at the edge of a bridge, lowered the mast to row through, and re-hoisted the sail. From here the route to camp was an exercise in extreme shoal-water sailing, trying to find a twisting channel which had shuffled itself outside of its own markers, forcing us to guess where deeper water might be found.

Again, not a problem in the Phoenix III. Since the channel wasn’t reliable, we simply cut across the flats, sailing along in water so deep that the keel (board up) was once again buried in the mud. We only had to get out and pull the boat along for about thirty yards, and we were through to deeper water and the oyster-shell beach of the Quarantine Shores campsite.


 Camp at Quarantine Shores—plenty of home-built boats, and not much else. (Peter Martens photo)


Day Five: Sailing through the night. (Bill Fisher photo)



Light winds, for Texas at least. We spent the day on a broad reach under full sail, still doing between four and five knots. In the afternoon the winds picked up, shifting eastward far enough to put us close-hauled—the first time since day one that we hadn’t been on a broad reach or a run.

The day ended at Hidden Pass, where we sailed through a cut almost narrow enough to jump from island to the next—with a running start. Maybe. I couldn’t get Pete to try it, so we’ll never know for sure. We did find an alligator skeleton on the beach, so perhaps his reluctance to risk a swim was well-founded.

At camp that night, everyone with radios and smart phones was talking about tomorrow’s weather forecast: very hot, with light winds. “It might not be the dumbest idea to just keep going through the night,” I told Pete. True, there’d be some tricky navigation getting through one of three marked cuts into the next bay—but the moon was nearly full. And we had a good breeze now. It would be a pleasure to sail while it was cool for once; we had been decked out in long sleeves and long pants for days, trying to protect ourselves from the fierce sun.

And so we hung out with the fleet at camp until sunset—right around the time that mosquitoes would have forced a retreat into tents anyway—and then set out across Espiritu Santo Bay, the last big water of the trip. Perfect sailing! A nice 15-knot breeze, cool air, and the fierce red eye of the sun hidden safely below the horizon. I was surprised no other boats came along, but I guess they wanted to see how we did before they tried it for themselves. Maybe next year it’ll become a popular strategy.
The winds picked up as we went, and then suddenly fish began popping out of the sea all around us. Quite remarkable—they would hurl themselves straight up, four or five feet into the air. One of them even jumped over the foredeck.

Then one of them jumped into the boat. And another. Using a boat cushion, I scooped them down toward Pete, who had his hands full already with the tiller and sheet. “Fish in the boat!” I shouted as another one threw itself aboard. “Fish in the boat!” He threw them overboard one by one and mocked me for my timidity. I kept wielding my cushion and pushing them his way.

The rain of fish kept on for half an hour. They were mullets, sleek silvery fish half the length of my forearm, and were no doubt being pursued by bigger, hungrier fish. Porpoises, perhaps. I sympathized with them, but still, I wasn’t letting them stay aboard.

By the time we reached the far shore of the bay on our moonlit sail, we weren’t sure of our exact location. I don’t carry a GPS (I cling to a stubborn curmudgeonly belief that such devices remove many of the rewards of sailing, and make us less skillful and less aware), so we had steered a compass course designed to take us far enough south of our goal that we would know to turn north when we hit the shore.

It worked, kind of. Bumping along northward through the shallows, using the centerboard as a depth sounder, we followed the far shore of the bay until a vague cluster of lights showed up ahead. Somewhere near there would be our cut. We passed a marker buoy from the ICW, but weren’t able to locate the channel itself in the darkness. And then suddenly we had land on both sides of the boat, a development that was difficult to reconcile with the chart, using a tiny red headlamp as the waves tossed the boat this way and that. But eventually, despite the first faint stirrings of seasickness, I was able to get a pretty good guess at where we were.

Which proved wrong in the next moment as we discovered a buoyed channel cutting directly across our path: it was the last of the three channels we had been looking for, and we had found our way successfully through the darkness.

The rest of the night was a quiet sail northward as the winds gradually dropped away, until around 4 a.m. we coasted up onto the beach under oars. Magnolia Beach. If the Texas 200 had been a race (it isn’t), we would have just won. Then again, given how much we had enjoyed our nighttime sail, we had won. Everyone else would be bobbing and baking in hot sun and no wind for hours. Pete and I pulled the boat ashore, set up our tents, and enjoyed a few hours of sleep in the cool air of the morning.


Conclusions: A very good boat. (Peter Martens photo)


 The author and his brother’s boat at the finish line: the beach at Magnolia Beach.

Judging by the results—57 entries, 29 finishers, and only 18 boats (including us) making it to every campsite— this year’s Texas 200 was a tough event for a lot of people. For Pete and me aboard the Phoenix III, it was a pleasure cruise. I’ve put a lot of miles on my brother’s boat, and the more I sail it, the more I like it. Anything I’d be brave enough to try in a small boat, I’d be happy trying in a Phoenix III.

I’ll end by explaining a few of the features of the design that I have really come to appreciate. These may not all be the things that come easily to mind when you’re new to this kind of sailing—they are instead appreciations that have evolved gradually, after many hundreds of miles of cruising under sail and oar, rolling the boat up onto beaches, anchoring off and sleeping aboard, the whole spectrum of cruising life. In short, these are the things I didn’t know enough to want from a boat until I had put in some sea miles.

1. The simple balance lug rig is easy to reef, easy to strike for rowing, docile and well-mannered in use (gybing is particularly simple and stress-free), and allows you to “park” the boat by simply letting the sheet fly so the boat drifts quietly broadside to the waves. It’s also easy to raise the sail anywhere on the starboard tack (if you rig with yard to port as I do)—no need to hold the bow precisely into the wind as on a Marconi rig (and thus no need for the complications of a mizzen). And the mast is simple to drop if you need to slip under a low bridge.

2. Capsize recovery. My brother and I tested this on a windy day (20 knots+) and found it EXTREMELY difficult to capsize this boat, even on purpose. But when we did (after leaning 400+ pounds over the leeward gunwale for 20 seconds), it was easy to right and re-board—so easy I’m confident I can do it for real if the situation ever comes up. And the centerboard design puts the top of the case well above the water level, meaning the boat can be bailed dry without taking in more water through the case.

3. Sleeping platform. The optional set-up for sleeping aboard works well for two sailors, and is luxurious (by backpacker standards) for a solo sailor. Simply carry an extra plank under each side bench and the entire width of the boat becomes a comfortable sleeping space. A simple tarp on a line from mast to rudder head makes a good boom tent to keep you dry. I’ve switched almost entirely to sleeping aboard because of how simple and comfortable it is.

4. Good rowing performance. The Phoenix III is no racing shell, but I was able to outrun a Hobie with a pedal-powered Mirage drive for an hour while rowing at a pace slightly faster than my all-day endurance pace. This boat makes rowing a pleasure rather than an ordeal.

5. Good windward ability. Gentlemen don’t sail to windward—except sometimes you have to. The Phoenix III keeps up good speed and points well, and the fine entry and wide gunwales make it a fairly dry ride.

6. Glued lapstrake plywood construction. I’d rather be sailing than sanding and fairing, and lapstrake is probably the quickest and most pleasant route to get there if you’re building a new boat. It also makes for a stiff, strong, lightweight hull.

But the best feature of the Phoenix III—a quality I have not often seen to this degree in other designs—is less quantifiable: it’s just right. The layout and proportions feel natural; it all works, in a very practical and user-friendly way. This is a boat that seems to have been designed by someone who actually goes cruising, and has thought a lot about what works and what doesn’t. The thwart divides the boat neatly into stowage (forward) and living areas (aft). The anchor bucket fits easily along the forward bulkhead alongside the mast. Large duffel bags stow neatly alongside the centerboard case, held in place under the thwart—it’s much easier to carry a couple of bags ashore than it is to dig through small hatches. The bags also increase flotation if the boat is swamped or capsized.

In fact, the ergonomics of this boat work so well that even two large (6’ 2”) adults can fit comfortably aboard for a long cruise. And sailing solo, the helmsman can slide fore and aft along the side benches, moving all the way forward to the thwart for windward work, and sliding back to the sternsheets for running, keeping his weight right where it needs to be.

And because the centerboard is designed so that it does not intrude on the helmsman’s space (after experiencing this, I’ll never accept a cruising boat without it), it is VERY easy to switch sides when tacking and gybing. This is something you’ll do hundreds of times (if not thousands) aboard a cruising dinghy, and it is a simple and enjoyable move every time on the Phoenix III.

All in all, I haven’t seen a boat I like better for sail-and-oar cruising. I doubt I ever will.









Saturday, May 14, 2016

Trailer Design for Displacement Smallcraft

If you go shopping for a boat trailer, the offerings from the stock manufacturers are almost exclusively designed to carry a planing hull. By that I mean a boat (or jetski) which has buttock lines which run parallel from the midsection aft. This type of hull is frequently referred to as a "monohedron" hull.

The Planing Hull/Displacement Hull Trailer Problem

Monohedron hulls, and the related type commonly know as a "warped-vee" sit well on a trailer which has longitudinal skids (or bunks), for lateral support and centreline rollers to support the keel. Because in most planing hulls the keel and buttock lines are parallel, or close to parallel, these stock trailers work well with the limited adjustment built into their roller and bunk mountings.

This is a Phil Bolger-designed Diablo built by Patrick Querengasser. You can see how the conventional trailer arrangement works very well with a monohedron hull such as this.
To get an idea of the difference in hull-form to which I refer, have a look at my Flint and Fleet designs in profile. Both boats are very similar with the exception that Flint is a displacement hull with curved buttock lines, and Fleet is a planing hull with something close to a monohedron hull. Fleet is not quite a true monohedron, as she has a slightly "warped-vee" hull-form, but this illustrates the matter quite well.

Fleet (top) and Flint (bottom) compared in profile
Now, a conventional commercially-manufactured trailer can be made to work very well with longitudinal bunks (or slides) as long as they are carefully positioned so that the curved, or "rockered" bottom of the boat runs along the bunk touching tangentially. This is very well illustrated in this photo of the Bolger Micro I built for Dr. Paul Truscott about thirteen years ago. In the case of Micro, the installation was made easier because the bottom of the keel runs aft in a line parallel with the waterline, just like the keel of a planing hull - so the centreline rollers towards the rear of the trailer are basically in a straight line, and the boat rolls off the trailer easily as she is launched.

Micro sitting comfortably on her trailer, with the longitudinal side bunks just touching the rockered bottom tangentially,
and the centreline keel rollers running back in a straightline from about the midsection. The side bunks are not carrying any load, but are simply giving side support to stop the boat from tipping sideways.
The situation becomes more complicated when you have a displacement hull with a rockered bottom, and no keel to straighten things out. What I do when designing these sorts of boats is to incorporate a skeg (which is usually beneficial hydro-dynamically anyway) and I usually draw the bottom of the skeg parallel with the waterline. This is a clear case of making a practical compromise, with the skeg performing two functions - a hydro-dynamic function, and a very practical trailering function.

Note how the skeg allows the centreline rollers to run aft in a straight line.
Here you can clearly see that although the keel and skeg design allows for a straight set of centreline rollers, the longitudinal bunks must still be very carefully arranged so that they just kiss the hull tangentially.
No Skeg, No Keel Batten, and Flat Bottom

But what happens if the designer of the boat does not incorporate an external keel or a skeg? A few years back I built a Jim Michalak-designed Mayfly 14 for a customer. I really like the Mayfly 14, but she does not have a skeg, does not have an external keel batten, and does have very marked rocker in the bottom.

Mayfly 14 - beautifully adapted to the water, but a real problem when it comes to trailer design.

Because Mayfly 14 has a flat bottom, and no keel batten to engage in the normal "cotton reel" centreline rollers on a production trailer, a bit of lateral thinking was required.

Here is the sort of external keel batten I normally design. This one is still very rough, but you get the idea - just a tapered piece of 3/4" stock glued and screwed on the flat.

To have a commercially-built, hot-dip galvanised trailer custom-made would have been far too expensive, so what I did was to select a suitably sized trailer frame from the manufacturer's standard line, and purchase it without any of the rollers and bunks fitted. I then padded the straight cross pieces with lengths of UHMW polyethylene (or at least that is what I think it is! At any rate, "slippery plastic") and placed an extra cross piece at the forward end supported by stock-standard adjustable forks.

The rear and mid cross-beams complete with slippery plastic cap-strips. The two longitudinal lengths of wood are guides which bear against the chines of the boat to keep the hull centred as it is winched onto the trailer. Before the boat was put on the trailer, I covered the inner edges of the guides with strips of carpet.

Here is the boat loaded on the trailer, showing the adjustable, elevated forward cross-piece.

Looking aft along the port side of the boat, showing how the wooden longitudinals guide the boat onto the trailer and prevent sideways movement during transport. This photo was taken before I had padded the longitudinals with carpet.
The Mayfly 14 trailer turned out to be exceptionally successful, and has made me consider a developed arrangement for boats other than those with wide, flat bottoms such as Mayfly 14.

The Bending Trailer Problem

The commercial trailer frames that we use for light-weight sailing, rowing, and motoring boats are built to a minimum standard in order that the manufacturers can compete effectively in the market. The box-section steel (RHS) used in the majority of these light trailers is quite springy, and the trailers are usually supported by a single axle. In most cases the light-weight trailers have a keel roller at the rear and front cross-pieces, and one on a cross-piece near the middle - which is normally in the same sort of longitudinal location as the trailer axle.

On this Periwinkle trailer you can see the three centreline keel rollers
The problem is that when the trailer hits a bump at road speed, the axle and springs push upwards violently, and the trailer frame works like a leaf-spring, driving the middle roller up into the keel of the boat. If the boat is tied-down at the bow and stern, the tendency is to break the back of the boat.

I have three approaches to solving this problem. Firstly, I try to tie down the boat using a single strapping arrangement (usually with a strongback incorporated) located fairly close to the longitudinal location of the axle and middle trailer roller. It doesn't have to be exact, but just in the general area. Secondly, I arrange things so that the bow and stern are free to move upwards a little under load.

Lastly, and far and away most importantly, I position the centreline rollers such that the middle one is below the level of the forward and aft rollers. This way, as the boat is winched onto the trailer, the bow rides up on the rear roller, moves forward onto the middle roller, and then finally rolls upwards onto the forward roller. So, the middle roller supports the boat as she comes forward on the trailer during retrieval, but as the boat is winched into the final location with the bow against the winch-post, the keel lifts clear of the middle roller. Ideally, the forward and rear rollers should be positioned under a frame or bulkhead so as to distribute loads throughout the hull.

The reason for the vertical location of the rollers which I have just described is to allow the trailer to bend upwards due to road shocks without the middle roller actually touching the hull, and tending to break the back of the hull.

A Better Trailer for Lightweight Boats of Traditional Design?

Currently I'm designing an experimental trailer to carry boats such as Phoenix III, First Mate, and Periwinkle. This trailer will incorporate transverse supports instead of the longitudinally positioned keel rollers of the standard commercially-built trailers. Remember how well this worked for the Mayfly 14 trailer problem?

There will be a total of three transverse supports, but the middle one will only support the boat during loading (refer to the previous few paragraphs), and when the boat is fully loaded on the the trailer, she will be supported vertically at only two places - both of which will coincide with frames or bulkheads in the boat.

The trailer design is not yet finalised, and I'll have a couple of different frame designs, depending on the frame material (they will not always be made of steel, nor even aluminium....). However, in order to illustrate the basic idea, I have included some rough sketches for your information and to aid visualisation.

Click on the image to expand it, and you will note that the boat (First Mate in this case just as an example) is supported at only two locations when fully loaded, and that these locations correspond with internal bulkheads. You can see that there is a crossbeam in the trailer frame between the two supports, but that the boat is sitting well above that beam. In practise, the two transverse supports, and the middle crossbeam, will be padded with carpet. The boat can rest on the middle crossbeam as she is winched forward, but will rise above the middle beam as the bow reaches the forward support. This will protect the boat from trailer bending due to road shocks - no more boats with broken backs!

With boats as light as First Mate and Phoenix III etc., there should be no problem lifting the bow up onto each support as the boat moves forward. In fact on one boat I currently load twice a week, I don't even use the winch - I just pull her onto the trailer using muscle-power. Anyway, supplementary rollers or guides could be added.


This is a very rough isometric sketch I did to show the above trailer frame with out any clutter. Axle location will be somewhere in the vicinity of the middle crossbeam, which will be padded with carpet in the same way as the two main transverse supports.
The Catch

There always has to be a catch, and this case is no different. Unless you are lucky enough to find a commercial trailer frame which will adapt to the dimensions of your boat (as I did with Mayfly 14), you will have to pay a lot of money to have one built as a custom project, or you will have to build it yourself. Rules will be different in different places, but where I come from there are regulations and standards that have to be met before a home-made trailer can be registered for use - so do your homework. As you can see from what I wrote at the beginning of the article, for most boats a commercial product can be used as long as it is correctly adjusted. The single most important element as far as I'm concerned is making sure that the middle support or roller is not going to damage your boat due to road shocks.

Thursday, March 17, 2016

Pre-coating Plywood

Recently, I was contacted by Phoenix III builder, Jonathan McNally regarding some persistent cracking he has noticed in his boat where the garboard strake (i.e. the plank closest to the keel) overlaps, and is glued to, the keelson.

Photograph of the keelson of Jonathan McNally's Phoenix III , where you can just see a feint crack in the outer edge of the epoxy fillet on the inside surface of the garboard strake.
According to Jonathan's report, he has re-epoxied this section several times, but the slight cracking keeps coming back. He and I have discussed the matter by 'Trans-Pacific' email, and have diagnosed the problem, tracing it back to (we believe) the high-quality, but unusually flexible plywood used - that is another story.

However, Jonathan's story brings up several matters which I'd like to discuss regarding the use of epoxy as an adhesive, and as a surface sealant i.e. epoxy encapsulation. For those who have missed it, here is a link to a recent blog post I put up about the hull structure of Phoenix III after Jonathan first reported his problem.

http://rosslillistonewoodenboat.blogspot.com.au/2016/02/phoenix-iii-hull-structure.html

Two of the possibilities I had considered in regard to Jonathan's cracking problem were: -

  • perhaps the planks had been pre-coated with epoxy, and when glued into position on the boat, the cured epoxy coating may not have been adequately sanded; and/or
  • the pre-thickened epoxy glue may not have been laid onto a freshly primed gluing surface.
Neither of those possibilities were to blame as it turned out, but they do bring up issues about which people need to be aware.


Epoxy is my favourite marine adhesive by far, although I do make use of a number of other glues for specific jobs. But epoxy is the most versatile adhesive I use, and the vast majority of my gluing is done using epoxy and suitable additives. Epoxy is gap-filling in a truly structural sense, and that is the key to its versatility.


 When using epoxy as an adhesive and/or as a filleting agent it is really important that all of the gluing surfaces be primed with an application of un-thickened epoxy resin/hardener. This relatively low-viscosity application will penetrate the surface of the timber and form an excellent foundation to which the thickened adhesive mixture will bond chemically. For this to occur, the priming application should be applied no more than a few hours before the adhesive, so that it will still be chemically active when the adhesive mixture is applied.

Here you can see how I have primed (or wet-out) two adjoining surfaces prior to laying down thickened epoxy which will be formed into a fillet.

In this photo, the joints on the left have had the epoxy formed into a fillet over the primed surfaces of the joint, and glass tape has been placed over the fillet, and wet-out with another application of un-thickened epoxy. The lady on the right is brushing epoxy through glass tape which has been laid into the still wet epoxy priming coat and the wet thickened epoxy fillet.

On face grain, epoxy does not penetrate a long distance - I've heard various distances mentioned, from fractions of a millimetre to as much as a millimetre in the case of some very porous timbers - but on a molecular scale it is a very substantial distance, and the epoxy adhesive will adhere tenaciously. In end-grain, epoxy penetrates a much longer distance indeed.

Now this brings me onto the subject of pre-coating plywood - or any wood for that matter - and what I see as being some stumbling blocks. Pre-coating sheets of plywood laid flat on a bench is certainly convenient, and efficient from the coating application perspective. But the problem is that when the components are cut from those pre-coated sheets, all surfaces which are going to be glued MUST be very well abraded so that the epoxy adhesive (and its priming coat) have a 'key' or 'tooth' to which a mechanical bond can be established. This represents an extra step in the building process, and detracts from gains made through the pre-coating. Also, the mechanical bond between the fresh epoxy and the previously applied pre-coat represents a 'secondary' bond - good if well executed, but not as good as a chemical bond.

I also have concerns about the cured epoxy on pre-coated sheets being subjected to tension and compression when components are bent into position. In my mind's eye, I see micro cracks forming on the tension side of the material, and crushing occurring on the compression side. Unfortunately, I do not have the engineering or chemical qualifications to claim that I know what I'm talking about!

Under some circumstances there may be a place for pre-coating - an example would be the under-surface of a cabin-top or a deck, where subsequent sanding would be very difficult. In that situation, the under-surface could be pre-coated, and then sanded to the point where it is ready to accept adhesive where it sits on deck-beams etc, and it would also be ready to accept paint.

Other than in the cases mentioned in the preceding paragraph, I much prefer to build the boat structurally, and then apply any epoxy coatings. I have fairly strong opinions about where epoxy coating is of value, but that can be the subject of another post.


Saturday, February 27, 2016

Phoenix III Hull Structure

Glued-lapstrake is a wonderful method of construction for small-craft - the appearance is elegant (as long as the lining-off of the planking is tastefully done), the interior of the boat is relatively clear of structure, making maintenance of the paintwork easy, the method makes efficient use of sheet plywood, and the amount of epoxy work is relatively low. In addition, the plank overlaps on the outside of the hull perform very effectively as a series of spray rails.

Periwinkle showing the 'spray-rail' effect of the plank laps....

...and Phoenix III doing the same
In addition to all of the benefits I've mentioned above, what I think is the the most important element of the glued-lapstrake method of construction is that each overlap in the planking produces what is, in effect, an integral stringer! This stringer effect is caused by two characteristics - firstly the thickness of the hull planking is almost doubled where the planks overlap, and secondly, on a round hull, the adjacent planks are at a different angles relative to each other. The angular difference gives additional stiffness in exactly the way that corrugations in roofing iron add stiffness.



The structural benefits of the overlapping planks mean that a lapstrake hull can (within limits) be built with reduced internal framing, and in the case of 'Phoenix III' I specified no transverse framing from the semi-bulkhead at the forward end of the centreboard case through to the bulkhead at the forward end of the stern seat (i.e. 'sternsheets') - a distance of 2280mm or 7-1/2 feet. However, there is other structure present in the form of a substantial transverse thwart structure, the keelson, and the centreboard case.

I had some minor misgivings about whether I was taking the matter of a structurally clean interior to an extreme, but until very recently I have had no reports of problems. In fact, the very first Phoenix III built is now more than nine years old, and has been used heavily, going on the water weekly for that entire time, and having travelled long distances on a trailer (trailers damage boats more than anything else).

Despite the lack of structural problems reported, in 2007 I placed this entry into the instruction manual which accompanies the plans:-

Planking

One of the design aims with Phoenix III was to have a clean and uncluttered interior. This has the benefit of making sanding and painting easier, makes cleaning easier, and produces a smooth interior hull surface for sleeping aboard.

Another design aim was to make the boat as light as possible. The lighter a trailer boat is, the more she will be used. The clean and frameless interior is in line with the quest for light weight.

There are no transverse floor timbers (frames) specified in the plans between the half-bulkhead at the forward end of the centerboard case, and the half-depth bulkhead at the forward end of the stern sheets (seat). Between these two points, the hull relies upon the strength of the planking, the glued plank laps, the keelson (or hog), the centerboard case, and the main thwart.

The resulting structure is strong, clean, and slightly springy. But, it is very important that the builder pays close attention to the standard of gluing – particularly along the plank laps. Use of epoxy fillets along the internal lap lines will prevent water sitting in the laps, and will add considerable strength to the joint. This is only really important in the lower planks.



 For those who prefer additional strength, or who need a base upon which to place raised floorboards, transverse floor timbers can easily be added during construction. Consult one of the suggested test books, or contact me for details. My preference would be for bent floor timbers (steam-bent if necessary) glued across the top of the keelson, extending out to cover the first two laps. Size is arbitrary, but I would be thinking of 9mm x  22mm/ 3/8” x 7/8” as recommended by John Brooks for his design, ‘Ellen”. 

When Woodenboat Magazine asked me to write a 'How to Build' article about 'Phoenix III', I re-drafted the plans to make them better suited for magazine publication, and while I was at it, I drew a pair of half frames to go under the main thwart, on either side of the centreboard case. That would deal with any lingering concerns about the expanse of unsupported planking once and for all, but at the expense of the clear interior.



Now, having told this overly long story, I have to tell you that my customer and friend (email friend, that is - we live on opposite sides of the globe) Jonathan McNally, has reported a persistent cracking problem in the joint between the garboard strake (i.e. the plank closest to the keel) and the keelson on his 'Phoenix III'. Jonathan's boat was built without any extra framing structure, and is a good example of the 'pure' original design. The cracking is minor, but it does indicate a potential problem - as I had feared. 

Very fine crack in the paint work on Jonathan's boat just above the keelson in this photo
Jonathan believes that the cracking was initiated by heavy foot-falls on the planking, and he intends to put in some steam-bent ribs and light floorboards to distribute human foot pressure. This is very similar to my comments listed above in the except from my building instructions.

I'm hoping that this whole business is a case of me worrying too much, as nobody else has told me of the problem. I asked Jonathan about the eopxy products used, and they were all perfect for the job. However, the plywood came from a very highly regarded European manufacturer, but there is a twist. A very good friend of mine who is a Naval Architect conducted engineering tests on a range of plywoods on the Australian market, one of which was this fancy European brand. The results of the testing were surprising. This particular 'super high quality' ply came out as:-
  • lowest bending strength;
  • lowest peak load at breakage;
  • lowest modulus of elasticity;
  • lowest strength-to-weight ratio;
  • 2nd lowest stiffness-to-weight ratio;
  • lowest structural efficiency (adjusted)
So, many lessons to be learnt. If building a 'Phoenix III', I am now changing the status of the two half frames under the main thwart from, 'Optional' to 'Recommended', even if they may not really be required.

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:-  https://www.facebook.com/groups/RLBuilders/

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.