About our Sailing RowCruiser

by Angus Rowboats 4 Comments

Part of the motivation behind our efforts to design the sailing version of the RowCruiser came from the Race to Alaska (R2AK).  As competitors in the race, we wanted something that was fast by oar and sail and could be raced non-stop for more than one week by two people.

We feel this overall concept will also make a fun recreational boat, and we will be selling kits and plans for the sailing version this fall.  The beauty of this concept is the central hull can also be used on its own for quick rowing, camping or fishing trips, or the amas and sails can be affixed for more exciting adventures.

Using the basic RowCruiser hull as a starting point, we mulled various concepts for months in our efforts to create an effective sailing system that works harmoniously with the sliding seat rowing rig.   Below, I discuss some of the various concepts incorporated into the design and some of the thoughts that went into the developments.  

 

Amas (outriggers)

Designing ideal amas  was a huge challenge.  The hydrodynamics of multihull craft are extraordinarily complex, and we struggled to find much information on the pros and cons of various existing ama designs. 

For example, what is the difference in performance between a longer ama and a shorter ama?  For us, we needed to create shorter amas so there would be sufficient clearance for the oars.  Short amas would also provide additional benefits such as lighter weight and easier storage, in particular for trailering. We ended up creating 8’ planing amas. 

Each one provides 150 lbs of buoyancy and weighs 9 lbs.  The planing aspect of the amas serves two purposes.  First, when sailing, the amas will skip lightly over the surface creating very little drag compared to the speed restrictions arising from a short displacement-shaped hull.  Additionally, just like water skis, the shape of planing amas push upwards at speed meaning that more than just buoyancy keeps them on top of the water, helping counter the force of the sails.  This is ideal when the boat is sailing fast, as much less of the ama is submerged than a non-planing ama, and the boat heels less.
 

In testing, the amas performed just as hoped.  Maximum speeds reached so far have been 9 knots with two people and gear in the boat.  I suspect speeds of up to 12 knots will be attainable when sailing with one person in ideal conditions.  The amas provide enormous stability, and the boat can easily be rowed and sailed simultaneously, since the amas keep the central hull level.

Akas (ama cross-supports)

Since we planned on using the boat in very challenging and remote waters in the R2AK it was important that the akas were up for the job.  Additionally, we wanted to make them aerodynamically shaped, an aspect often ignored by designers, but very important for good performance.  The akas are hollow shaft, created by laminating three layers of spruce (we used knot free 2 x4’s milled with a tablesaw for an economical and sound solution).  It is a relatively easy process. The three lamination layers are coated with epoxy, bent over a frame, and clamped along their length.  The akas are then shaped with a planer to create an elegant and aerodynamic shape. 
 

Our finished 10’ akas each weigh 8 lbs, and are much stiffer and stronger than a standard 2x4. Each aka is curved to a different radius since they are positioned at different levels on the boat.

One slight mistake we made in creating the prototype akas is creating too much curvature in the forward aka.  Since we are pioneering the concept of curved hollow-shaft akas, we had very little information to go on.  In calculating the spring-back from the lamination, we assumed it would be the same as standard three layer solid lamination.  In fact, since the middle layer is mostly hollow, the spring-back forces are less, and it did not straighten out as much as calculated.  As a result, the forward akas have had to be raised from the deck on blocks.  These numbers will be corrected for our upcoming plans. Overall, the amas and akas together provide an enormous amount of righting force with a modest total weight of just over 30 lbs.  The added benefit of having amas affixed to the boat is having great stability while anchored, fishing etc. 

Amas can be released in second while providing a secure connection.

Aka Connections and Safety

We came up with a novel way of affixing the akas to the amas to significantly enhance safety.  The greatest danger with multihull boats is capsizing and being unable to right the boat due to the great stability in the inverted position.  With our planned race to R2AK safety was paramount, and we wanted an easy solution for re-righting.  The solution is to be able to remove one of the amas.  With an ama removed, the boat can be righted as easily as a Laser sailboat.  The problem, however, was how to achieve a connection that could be quickly and easily disengaged, yet be robust and secure while sailing.  Bolts are far to challenging to undo in a rough stormy ocean.  Even wing nuts are next to impossible to loosen up when flailing around in the water with numb fingers and hypothermia setting in.  Our solution was to use cinch straps.  The amas and akas mate together with a Lego-like connection (which you can see here), and then are cinched firmly together using a strap.  A simple push on the release mechanism immediately disengages the two components.  With this setup an ama can be disengaged in under 30 seconds (connected with a tether to the main hull , so it doesn’t blow away), and the boat righted.

The akas are secured to main hull using bolts and washers.
 

Offset Daggerboard

The daggerboard case is situated in the aft end of the cabin and is offset to allow sufficient room for the occupant to sleep comfortably.  There is negligible performance loss with an offset daggerboard.  In light to medium wind speeds, the helm is balanced allowing for hands free steering from a broad reach and up when the sails are trimmed properly.  In heavier winds, as the forward amas are pushed down, the center of lateral resistance moves forward slightly creating slight weather helm (slight weather helm in heavy winds is a positive attribute in a sailboat).

Overall Safety

In the Pacific Northwest it is far too easy to die in the frigid waters.  A series of mishaps can lead to immersion followed by hypothermia.  The good news is with a solid knowledge of boat design and the potential dangers, it is possible to create boats that significantly minimize these dangers.  With a family at home, and no desire to visit Davy Jones, I spent a long time pondering potential dangerous scenarios, and how the crew and boat could respond to these various situations.  Below are some of the most likely situations to occur, and design implementations to enhance chances of survival.

There is always a possibility of hitting an object at high speed and holing the boat. The sailing RowCruiser is comprised of seven independent sealed compartments meaning that even a large hole will not fully compromise the boat.  Apart from being smashed to pieces in a collision with a large ship, the RowCruiser would have the capability to limp to shore in most situations incurring hull damage.

Capsize 

As mentioned above, the amas are designed to disengage in seconds so the boat can be easily re-righted.  Once one ama is removed, the boat is righted by standing on the inverted aka while holding onto the daggerboard and leaning back.  Because of the shaping of the cockpit, only a few gallons of water will need to be bailed out after righting.

Rough Weather 

As with any sailboat strengthening winds are initially dealt with by downsizing sail.  In open ocean conditions there are various tactics for dealing with heavy weather, but a popular strategy is hoving to.  This involves shifting the overall center of effort and center of lateral resistance so the boat shoulders into the wind and wind spills from the sails.  The beauty of a ketch rig (as with the RowCruiser) is the boat can quickly and easily be hove to.  The mizzen is simply sheeted tight, and the main released and suddenly everything becomes tranquil.   In this state, the wind has very little effect on the boat, and the bow points into the waves.  It is the ideal configuration to make sail changes, or to simply wait out the weather.  Or for exhausted solo sailors in gale-force winds, it’s the best way to have a break – make a cup of coffee and have your lunch before carrying on.

Propulsion Failure

By having an efficient sailing and rowing rig, there is always a backup system if one or the other fails for any reason.

Sails

The sails we used are very economical while providing good performance and robust durability.  Sail area is 78 square feet, modest for the amount of righting force provided by the amas.  This means that the boat is very forgiving, and the sails don’t need downsizing until the winds are very stiff.  Despite having a relatively small sail area, the boat moves surprisingly quickly in light winds.  And of course, sail speed can be augmented by rowing and sailing at the same time. We chose not to incorporate a larger sailing rig for many reasons.  The complexity, weight and cost of the boat would increase significantly, and rowing (it’s a rowboat at heart, after all) would become more sluggish.  As is, the masts and sails can quickly be removed and stored in the cabin (the masts break into two pieces).  It’s a pretty elegant and easy solution that offers impressive speeds.

Reefing

We’ve created a unique way of reefing that can be viewed on our Facebook page here -   It takes a little more effort than standard reefing, but is more efficient, and much more economical than roller furling systems.  It can be done carried out in rough seas by the athletically inclined, or on the beach for those a little less enamored with the idea of scrambling around on a pitching deck. For an easier  (and much more expensive) system of reefing, we would recommend the mast furling style of sail such as those offered by Hobie. 

 

Steering

Creating a steering system for small trimarans can be challenging.  The cockpit is too far forward for a standard tiller to work.  Often the solution is using a push-pull rudder stick, however, this doesn’t work so well with a mizzen mast in the way.  Instead we came up with a  solution utilizing dual tillers on both sides of the cockpit connected to the rudder using a system of spindles and blocks.  This system is relatively unique and offers easy 

Dual tillers on both sides of the cockpit allow for easy steering. The rudder foil is designed to kick up when coming into shallow water.

 

 

 

 

Rowing System

We use the standard sliding seat rowing system that has been thoroughly tested in the standard RowCruiser.  The entire sailing rig, including the amas, akas and steering system has been designed so as not to interfere with the oars.  

The oars are completely clear of any obstructions and powerful smooth strokes can quickly propel the boat in windless conditions.  Since the amas keep the boat level when the sails are in use, the oars can also be used in light winds for “motor sailing”.  When not in use, the oars are easily pulled up onto the amas and held in place with bungies, where they are out of the way and fully clear of the water.

Reinforcing

The decks of the sailing RowCruiser have been further reinforced (from the rowing-only version) to support the weight of an individual changing sails.  This has been achieved by adding additional quarter knees and cross supports.

Weight 

Our racing version of the sailing RowCruiser weighs less than 200 lbs, which includes the sails, daggerboard, rudder, rudder, all spars, rowing hardware, amas akas, etc.  This is incredibly light, considering a standard Hobie 18 catamaran weighs over 400 lbs, or a Laser Radial (not much more than a pregnant windsurfer) weighs 130 lbs (hull only).

We wouldn’t recommend building a recreational model quite so light, however.  While the lightweight version is fully capable of dealing with all rigors on the ocean, it is more vulnerable to being dropped or sustaining damage when hitting objects.  The main weight savings from our racing version come from utilizing a single layer of 4 oz fiberglass cloth on the outside, instead of overlapping layers of 6 oz.  Additionally, only glass strips were used on the inside instead of full glass swaths.  A completed recreational version would weigh about 30 to 40 lbs more coming in at about 220 lbs complete.  Amas, akas, masts, booms all packed in the main hatch. Nice and compact. 

Trailering

We recommend using a SUT 220 trailer for transporting the boat.  The amas and akas all fit through the main hatch for easy and compact trailering.

Cost

This versatile and sexy boat is surprisingly affordable to build.  For those building from kits, the total cost of the boat, including all the building materials, sails, spars and sliding seat hardware is just over $6000.  For those building from full-sized plans (bear in mind a lot more time is required for construction) the boat can be built for just under $4000.

Kits and plans for the main RowCruiser hull are currently available and kits and plans for the sailing version will be available in the fall of 2015.  For those wishing to start building now, we recommend starting with the main hull and building to the point of laying the decks.  The daggerboard case and sail mounts can be installed after the decks, however, it is easier to do prior.

We have postponed our entry in the R2AK race due to an unfortunate accident (forgetting to tie the boat to the trailer after a training run) a couple days prior to the race start.  The boat will, however, be competing in an upcoming R2AK. 

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