Thursday, May 24, 2018

Trim, Seamanship, and Small Boats

Hugh Blank purchased plans for First Mate in 2009, and after seven years of building (interrupted by a very heavy work schedule), launched the boat in 2016. Hugh is the man for whom the Bermudan and Balance Lug rigs were added to the plans.

I have received an interesting message from Hugh regarding certain observations he has made about using the boat, and he has agreed to me making his comments, and my reply, public. This is a good way for us all to benefit from the experiences of individual builders:-

I have sorted out how I use the standing lug rig for casual racing at my club, and also happy with the way the main can be used with the jib I have. Gives me plenty of options, depending on crew available.

The other day I had occasion to try the boat out in preparation for the other activity I built it for - cruising. I was planning to take a trip out to an island a couple of kilometres offshore, in some water that can get fairly boisterous. In preparation for this trip I took the boat down to the inner harbour at Porirua, one of two places I usually sail at - the other being the other arm of the same harbour. The wind was about 12 to 15 knots, with gusts up to about 25 knots - fairly much what you need to allow for around Wellington. There was a short little chop in the harbour, of about 1 to 2 feet.The main point of this exercise was to make sure I could raise and lower the (reefed) main in these conditions. Although there are a few small changes I am busy making to my set up - as a result of this little expedition - there are a couple of fundamental issues I came across for the first time in the boat: - When well forward in the boat - I was sailing on my own - I found that the boat pitched rather alarmingly while I was trying to manipulate the rigging. (And for that matter when dealing with the anchor at another stage.)- Part of the problem was probably caused by the fact that the centreboard case prevented my being able to balance the boat better by keeping central as much as possible. But I do also feel that there may be too little buoyancy in this part of the boat, to allow even my weight (about 72 kg) to be perched on one side of the centrecase, right forward by the mast. You may remember I asked you when building the boat about substituting a more conventional centreboard/centrecase arrangement. My original concern was the inconvenience (of the height) to any crew, and I have found this to be the case to some extent. I am now inclined to modify the arrangement for the original reason, plus the newly identified issue. Can you please comment - perhaps I am missing some points or barking up the wrong tree - has been known to happen! As for the buoyancy forward, I haven't seem a P3 in the flesh for a while, but looking at photos I just wonder if that version of the boat doesn't have just a bit more volume forward. I guess the advantage of slenderness in the bow is amply evident in the way the boat moves so nicely through the water. And I appreciate that every design is a compromise of the often conflicting forces of physics and desired outcomes. I would however appreciate your input concerning how to use the boat safely and effectively for the cruising activities I have in mind. I don't intend to go to mad places, but I want to be able to work with the rig in 1 metre+ seas. CheersHugh 22.05.18

This message brings up a number of issues, with the primary one being reserve buoyancy and stability when the centre-of-gravity of the boat and crew is moved too far forward. In a small boat, it is basic seamanship to keep weight out of the ends as much as possible, and keep weight as low as possible. Loss of stability is most pronounced when crew weight is moved to the bow - as Hugh has discovered! What he described is a very common phenomenon - even in boats with legendary seaworthiness. Phil Bolger's Gloucester Light Dory Type 6 is renowned for exceptional sea-kindliness, but even the designer stated that if you move too close to the bow, the boat will flick you overboard and come up laughing, without taking water.

I accept that a modified centreboard shape would allow a lower case, and perhaps one could stay on centreline while moving closer to the mast partner. But the distance from the point at which the existing centreboard case starts rising up (very close to the forward edge of the thwart) to the mast partner is only 3' 5" - well within reach of a person with arm extended while leaning the body forward. If I was intending to work on the mast partner, I would straddle the centreboard case on my feet, in a crouching position and lean forward. Better still, if conditions were bad, I would sit on the bottom of the boat on one or other side of the case. In my experience sailing First Mate I have not had a problem, but I do accept Hugh's comments.

If in doubt, head for a handy beach or sandbank when you decide to reef. It is much easier, and going ashore on a bank is fun in itself.

My idea is that as much boat work as possible should be done from the middle of the boat. Here are some photos of how I rigged the First Mate I built for my friend, Ian Hamilton.

Mast lashed into the partner. On the port side you can see the boom downhaul, and on the starboard side, the halyard. The down-haul is a double purchase and the halyard a single purchase. Both of these lines are the blue ones, and on the far starboard side you can see a Hemp-coloured line - that is the running yard parrel.

In this view you can see how the halyard and downhaul both run through the partner, through bull's-eye fairleads, and then back to belay on the side of the centreboard case, in easy reach of the helmsman. The lines could just as easily run through turning blocks on the upper side of the partner, but my method keeps the lines lower.

View from the port-side, showing the downhaul. The halyard and down-haul are the only lines which require frequent attention. Some people may say that V-jammers are not adequate for holding these lines securely - well, in that case use horn cleats instead.

I am not against the idea of a different centreboard and centreboard-case shape, but do keep in mind that the high case prevents water entry in rough conditions in a partially flooded boat - say, after a capsise. I have a number of drawings for higher aspect ratio boards with cases which are no higher than the thwart, but there are difficulties getting the required centreboard area without having the case extend aft of the thwart into the main cockpit area. If I thought that I really needed a lower case, I would use a daggerboard. Nothing is worse for the performance of a sailing dinghy than having a board which does not have enough area. Boat-speed is seriously compromised, and windward ability is degraded.

It is correct to say that First Mate (and Phoenix III) do not have a huge amount of reserve buoyancy forward. But all boat designs are made up of a long list of compromises, and my stated aims from the beginning included the ability to cut through a steep chop with minimal pounding and spray generation, plus a hull shape conducive to satisfying performance under oars. Both of these designs have proven to be unusually dry for their size and speed, as well as being pleasant to row.

Hugh has asked whether Phoenix III has more volume, relatively speaking, than First Mate in the forward sections. Both boats have the same designed displacement, and their centres-of-longitudinal displacement vary by only a tiny fraction over 1%! So as far as the numbers are concerned they are very, very close.However, Phoenix III may have a little more reserve buoyancy forward, as these sketches show (First Mate in black and Phoenix III in red).

As for working in 1 metre+ seas, First Mate has done this many times with ease.

Maybe not a metre, but a lumpy swell, none the less...

Leaping clear of a choppy wave...

Heading down below the chop-line.

On the day that the above photos were taken, the boat was being sailed by my son, David. He has the longitudinal trim just about perfect, sitting either on the bottom up against the main thwart, or on the side-deck in the same longitudinal position. Longitudinal trim is critical to efficient sailing. Note also that even though he is hard on the wind in the first two pictures, he has not over-sheeted the main, therefore giving the lugsail room to breath. The boat was sailing really nicely, and Dave said that not a drop of water came into the boat in all the time we were out there shooting photos and video.

When it comes to anchoring, it is best to have the anchor stowed low in the boat, preferably in the bin just in front of the centreboard case. If conditions are such that one cannot safely handle the anchor rode from a crouching position forward, I would start the trip with the anchor-rode made-off to the stem-eye (trailer winch attachment point) and lead aft to enter the boat over the side, to be coiled down in the anchor bin. It would be sensible to run it up over a bow-chock or similar to prevent it dragging in the water. Before deploying the anchor, clip a snap-shackle over the anchor-rode, attached to a two or three metre length of line leading into the boat near the thwart, and securely attached to a hard point. The anchor can then be lowered over the side from within the cockpit (never throw the anchor). The anchor-rode will then pull against the stem-eye, which is relatively low to the water. The separate snap-shackle and line will slide loosely on the anchor rode, until you want to retrieve the anchor. By hauling in on the short line with the snap-shackle, the anchor-rode will be brought back to your hands in the cockpit for retrieval. If caught out without a snap-shackle, a simple bowline in the end of the lanyard will do the job.

These are small boats, despite their 15 foot LOA, and need to sailed with understanding and the application of seamanship. Sailed within their natural limitations they will give reliable performance, and their light-weight will be of enormous benefit in the long-term.

Saturday, January 6, 2018

Simple Cruising

This is a re-print of a very short article I wrote for an Australian magazine about fourteen years ago. I tend to cringe when I re-read my work from the past, but there may still be something in the words....

The 15' 2-1/2" Cruising Dinghy referred to in the text. This photo should convince skeptics that a Lug-Sail can set well and take a boat to windward efficiently.

When it comes to boatbuilding, dreams don’t always come true. Those of us who are afflicted with this boat addiction know the cycle – thinking about one boat leads to thoughts about another and so on to eternity. The dreams are necessary, because without them nothing would ever get done; however they need to be kept under control.

Mike Rowe and his friend Ian were both dreamers. However as youth gave way to middle age, the dreams had become more realistic – the size and complexity of their dreamboats had reduced in inverse proportion to their experience.

As they relaxed in the cockpit of Mike’s little cat-yawl, the conversation had turned to this very subject…

“Why is it,” said Mike, “that there are so few decent cruising dinghies on the market?”

“Because people automatically assume that if you are going to sleep aboard a boat, you need a cabin,” answered Ian. “Look at the boom in production trailerable yachts during the seventies and eighties – everybody wanted the convenience of a trailer boat with the accommodations of an H28. But what they got was a very small cabin boat which was difficult to launch and retrieve, heavy to tow, too big to store in a garage and took too long to rig and unrig. No wonder the bubble burst!”

Mike stared thoughtfully at the wake before answering. He was remembering that some of his best boating experiences had taken place in a 15-½ foot cruising dinghy, sleeping on the floorboards under a makeshift boom-tent. But he was also thinking about sand, clutter, wet clothes and mosquitoes.

“You’re right, Ian, but to be fair, lots of people did lots of sailing in those trailer-sailers. To make dinghy cruising successful one has to be better organised than we have ever been.” was his response, “Let’s take a look at what is required.”

They talked well into the evening, enjoying the easy companionship which came from common interests and a friendship which dated from high school. It would take too much space to record the entire conversation, but a number of points kept cropping up: -

·        Simple projects are more likely to be finished than those which are large and complicated;
·        Small boats get used more than large ones;
·        Small boats are easy to store in a garage;
·        We live in a wonderful country for boating;
·        It is liberating as well as challenging to leave the motor at home;
·        Shoal draft boats have access to cruising grounds denied to keelboats;
·        Cabins don’t get used as much as cockpits, so we should think twice before trading cockpit space for a cabin;
·        There are very few open boats on the market which lend themselves to daysailing and overnighting. This is especially the case if spirited sailing performance is a high priority;

  The irony of this line of conversation was that it took place in the cabin of a particularly comfortable and capable keelboat, measuring only 15-½ ft LOA. She was relatively light, had been simple to build at home, carried not one inch of standing rigging, and got to windward better than most. This sparkling performance was due to brilliant design on the part of a designer who was blessed with an open mind. His deep understanding of hydrodynamics allowed him to wring good performance from his designs – even (especially) those with rectangular hull sections. He had been schooled by such greats as Lindsay Lord, L. Francis Herreshoff, and Howard Chapelle. Although known for his rectangular boats, about ninety percent of his published work was classic and conventional.

In the following week, Mike continued working on a group of three boats in his workshop. All were capable open boats ranging in size from 12ft to 18ft length-over-all; two were cruising dinghies of the very type which he had been discussing with his friend. He hoped that this situation was an indication that the wheel was turning a full circle.

These days, as always, building a small boat is a fine investment of your time. Whether it be a sailingboat, a powerboat, a beautiful rowing craft or a canoe, the result will be worth the effort. But effort and application are required – dreams are only the first bit. Dreams, like so many other things, can be addictive. Pick a simple project and start! 

Wednesday, December 6, 2017

Periwinkle - Design Essay

How Periwinkle came to be designed

This design came about as a direct consequence of the pleasant handling and satisfying speed of the sail-and-oar beach-cruiser, Phoenix III. I guess this will come as no surprise to those who know Phoenix III - a slim hull (L/B ratio of about 3.4:1 in the case of both Phoenix III and Periwinkle) with a five-strake-per-side glued-lapstrake (clinker) half-decked hull arranged for oars as the primary auxiliary, and a self-draining outboard motor splash well mounted off-centre on the transom in case motorised propusion is considered necessary.

Phoenix III was my very first lapstrake design, and marked a huge step forward in my self-education in small boat design. I had started drawing many years earlier - around 1990 - but it wasn't until 2003 that Phoenix III started to take shape on my very basic 2D CAD program (AutoSKETCH 8 by AutoDESK). Until then, my design work had been for personal learning so that I would be able to better understand the work of established designers.

Drawn at the unexpected request of Paul Hernes, Phoenix III came along at a time when domestic circumstances prevented the use of my large drawing board, so I took the leap into 2D CAD, treating it as a combination electronic drawing board and very accurate scale rule. Paul Hernes did a miraculous job of turning my sketchy drawings into a functioning boat named Willie Wagtail.

Paul Hernes sailing his Phoenix III in the early days
Paul's sailing attracted a number of like-minded people on the beautiful "Sunshine Coast" of Queensland, Australia, and before long there was a regular group of semi-retirees sailing on Tuesdays.
...a Tuesday morning
One of the regulars was John Shrapnel, and although he was well-equipped with his own boats, John took a shine to Phoenix III and Paul found it difficult to get a sail in his own Willie Wagtail!
John Shrapnel sailing Paul's Phoenix III in an enthusiastic manner. Note the excellent longitudinal weight distribution, and the nicely setting sails. The rig is free-standing, but the compression in the sprit puts the head of the mainsail in tension, which is in turn transferred to tension in the luff of the flying jib. This is one of the few un-stayed rigs which will allow a flying jib to stand effectively without back-stays or angled shrouds.

John soon decided that he needed his own boat of similar design, but he specified that she be slightly larger than Paul's, and that a condition of the design specification was that Paul Hernes must be beaten in every sailing encounter. Another preference was for a split rig using balance lugsails. I was unnerved by the design constraints, because balance lugsails are not known for being either close-winded, nor particularly fast when hard on the wind. John was philosophical, and liked the romance of the cat-ketch lug rig - so Periwinkle was born!
Design Elements

1. Easily-driven Hull  Just like Phoenix III, I wanted the new design to be an effective sail-and-oar boat, so correct rowing geometry and a slim hull were essential. At 17ft LOA and 5ft beam, Periwinkle is relatively lean and long. Although being a bigger boat than Phoenix III by about 132% volume and carrying capacity, she is pleasant to row as long as proper oars and oarlocks are used. A critical part of using oars in a boat such as this is to get the rig down completely, and keep the centreboard and most of the rudder up;

2. Choice of Rigs  As with many of my designs, I laid out the mast locations and position of the centreboard so that a number of quite different rigs may be used without having to perform carpentry on the boat. It takes a bit of effort to work through the compromises and proportions, but it is well worth the time.

Sail arrangements possible with the standard balance lug Cat-Ketch. The boat has a third mast stepping location inbetween the normal main and mizzen mast positions.

Mizzen left at home, and the main-mast moved to the third position. In this configuration the boat sails superbly well, with good hull-balance and an uncluttered rig.

Mizzen set on the main-mast in the third location, although the mizzen mast could have been used. With just 51sq.ft. of sail set, the boat recorded up to 8 knots by GPS this particular day. But speed is not the aim - safety and comfortable sailing in a hard chance is the desired outcome.

Just the mizzen set in the middle position. John is sitting comfortably inside the boat in a relaxed manner. Believe it or not, he was actually overtaking the boat in the background. This is a good lesson in physics. Once the wind gets to a certain speed, a boat will often be capable of higher speeds if the sail area is reduced! Read "High Performance Sailing" by Frank Bethwaite for the science.

Some of the possible rig options, all of which use existing mast locations, and all but two of which use the same main mast

3. Ability to cut through a chop and remain dry  Periwinkle (and Phoenix III) have very fine sections forward. I drew them this way because I grew-up on Moreton Bay, which is known for its short, steep chop. Having spent my youth getting soaked by water smashed into the air by conventional bow shapes, I was determined to keep everything sharp and fine up front. The clinker laps also help by performing the function of a series of spray-rails - it is amazing just how much water they knock down.

Topcoat on the hull and primer on the deck. This shot shows how fine she is in her forward sections.

Plank laps working well as spray-rails. Note the flat and undisturbed wake behind the stern.

I consider that for comfortable cruising, this combination of fine forward sections and clinker laps is of great importance. In a racing dinghy one doesn't worry about getting wet, but for cruising, it can mean the difference between a happy or a miserable day!

4. Emergency Buoyancy  Being able to right a capsized boat without external assistance is absolutely critical to safe and responsible dinghy cruising. Racing boats are designed to be righted by an athletic crew and sailed away instantly without bailing being required. The situation is very different in a cruising dinghy or recreational day-sailing boat. Carriage of supplies and equipment dictate dry-stowage volumes which are easily accessible, while at the same time being effective emergency buoyancy.

Many people make what I consider to be the mistake of using side buoyancy tanks and/or enclosed side seating. This sort of emergency buoyancy is fine for a racing boat because it keeps her floating high in the water after a knock-down and means there is little water aboard after righting. For cruising and day-sailing there are several problems with such an arrangement - the mast is held high above the water at deck-level, and the tip touches the water at quite an angle. This means that the boat is floating at well over 90 degrees to the surface - say 100 or 110 degrees - and there is a strong tendency for the boat to continue to roll given that only the tip of the mast is floating on the surface. Not only that, but when the boat is righted, having taken little water, she floats at her normal water line. A strong nineteen-year-old may have no difficulty getting aboard, but for someone like me (in my mid-sixties) it can be a real, life threatening problem.

In Periwinkle, the emergency buoyancy is contained within two bulkheaded compartments - one forward and the other aft. In the event of a capsize, the boat settles much lower in the water than would be the case with side tanks, and the bow and stern buoyancy compartments mean that she is longitudinally-stable. The lower floating condition means that the masts are floating for most of their length, making them - in combination with gaffs or yards- very effective outriggers. Vulnerable members of the crew can simply swim or roll into the flooded hull before righting and then the skipper simply puts weight on the centreboard to right the boat.

Here is a video from Gerry Lavoie, who built a boat from my First Mate design. Although First Mate is much smaller than Periwinkle and Gerry was playing in smooth water, the principles I've described are well demonstrated.

In the case of Periwinkle, the aft tank is unusually large, providing exceptional buoyancy and storage space in a part of the boat which is easily accessed. The main hatch is on centreline so that even if the hatch cover is left open, the opening is above the capsized waterline.

Large aft buoyancy/storage compartment. Note how the hatch is on centreline, which means it is unlikely to take water in a capsize, even with hatch-cover removed.
During capsize trials, my procedure was:-

  • release the main-sheet;
  • swim the bow head-to-wind;
  • right the boat;
  • tighten the mizzen sheet to hold the sail tightly on centreline. This ensured that the boat would reliably ride head-to-wind;
  • push down on one gunwale to bring the deck close to the water-line and simply roll into the boat;
  • sit comfortably on the aft seat (stern sheets) and bail at my leisure.
Secure and comfortable aft seating. During capsize testing, I found it convenient to sit on the seat and bail between my legs at leisure. Note the handy open storage under the seat. When lying on the floorboards, this space is very easy to access, and it can hold a lot of loose gear
Good ergonomics for camping aboard. The nice floorboards and the gentle curve of the planking make for a secure sleeping position with easy access to the stowage under the aft seating.The centreboard case makes for a sense of privacy from someone on the other side! I'm just an inch short of six feet tall, and you can see there is still length available at my feet. 
 5. Simple Mast Stepping  The easier it is to set and strike the rig, the more often you will actually get on the water. Almost all of my rigs (not just for Periwinkle) are fee-standing - i.e. no stays nor shrouds - and the result is a rig which can be erected and lowered in minutes. The heaviest component is the main mast, and when placed in the normal location, it is simply a matter of popping the heel into the mast step and pushing the mast forwards into a horse shoe-style mast partner.

The main-mast steps on the keelson and is simply pushed forward into the mast partner at deck level. In the forground you can see that if the third mast location is used, the mast has to be lifted to thwart level and dropped through the partner in the forward thwart.

Third mast location in the foreground
The setting-up of transport supports for a rig can be a real pain, but in the case of Periwinkle, the short length of the masts, and the lack of tangled stays and shrouds made it fairly easy.

6. Other rigs in use  I mentioned earlier that most of my designs make provision for alternative rigs, using existing masts and mast locations where ever possible. Here are a few photos and videos in what is an on-going journey:-

Original rig a few days after launching

Launching day

Original rig

Original rig

Gaff-Headed Cat Rig

Gaff-Headed Cat Rig

Mizzen removed - original main-mast and mainsail moved aft to third mast location as a balance lug

Mizzen removed - original main-mast and mainsail moved aft to third mast location as a balance lug

Mizzen set in the third location

Bruce Drever's beautifully-built example of Periwinkle sailing with the gaff-headed cat rig with small jib set flying. This is one of the rigs featured in the plans package

Bruce Drever's beautifully-built example of Periwinkle sailing with the gaff-headed cat rig with small jib set flying. This is one of the rigs featured in the plans package

John Shrapnel trying out a windsurfer rig just for fun

John Shrapnel sailing Periwinkle with the mizzen removed, the mainsail left in the forward (standard) location, and with the tack of the sail pulled aft to the mainmast. This makes it a Standing Lug, and John says that if he is going out for a solo sail, this is his rig of choice. John has found that when sailing alone, a 25kg (55lb) ingot of lead secured on the keelson is of great benefit.

John Shrapnel's Periwinkle sailing in very light conditions, but showing just how easily-driven is this hull.

John sailing his Periwinkle with only the mainsail set, arranged as a standing lug. The boat behind is an Oughtred Fulmar with one reef tied into the main. Note that Periwinkle is holding boat-speed, while getting up to windward of the Fulmar. The mainsail of Perwinkle is only 104 sq.ft., which is a very modest sail area.

I will be writing some more about hull forms, so you will be hearing more about Periwinkle.

Monday, June 5, 2017

Three Brothers - a 3D Virtual Assembly

As part of my attempt to learn how to use a 3D CAD program, I have been using my Three Brothers powerboat design as an exercise. Although the design is still under development, I thought that some people may be interested in seeing a stage-by-stage stitch-and-glue assembly sequence.

This assembly sequence is only one of several approaches to stitch-and-glue construction, but most have a common theme of not requiring a strongback or mould set-up. The shape of the boat is determined by the accurate design, marking-out, and cutting-out of the primary parts - if everything is done correctly, the boat assumes the correct three-dimensional shape without a strongback and set of station moulds, greatly increasing the speed of construction.

Three of the six main panels cut from plywood and laid on the floor. The accuracy of the design and cutting of such panels is the key to a successful build.

Two bottom panels stitched together along the stem (bow) and centreline of the bottom. Stitching is carried out with the two panels laying on each other, and when complete, the panels are opened up 'book fashion'. The assembly will sit on the floor as shown, but it is sensible to have some cradles for a project of this size (details will be provided in the plans).
Pre-fabricated bulkheads, frames, and transom are positioned on station marks and loosely sewn into location using cable ties.
Topside panels stitched into position. By this stage the glass-taping of joints will be taking place.

Cabin sides, including coamings, stitched into place.
Longitudinal webs glued and taped into position. Ventilation holes are suggestive only, and may be changed depending on style of emergency flotation employed
Outboard motor splash-well structure added.
Floorboards and other horizontal panels introduced.
Longitudinal deck-beams and roof structure in place.
Fore-deck and aft-deck panels attached.
Plywood cabin roof and front panel of cabin attached.
Gunwales, outer stem, and structural trim around cabin and coaming finish the basic job.
This is a very quick illustration of the basic assembly method. For more detail, I suggest reading Sam Devlin's wonderful book on the subject, "Devlin's Boatbuilding.